docs: arm64: Move arm64 documentation under Documentation/arch/

Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy.  Move
Documentation/arm64 into arch/ (along with the Chinese equvalent
translations) and fix up documentation references.

Cc: Will Deacon <will@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Hu Haowen <src.res@email.cn>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Yantengsi <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

22 files changed, 5274 insertions, 1 deletions

diff --git a/Documentation/arch/arm64/acpi_object_usage.rst b/Documentation/arch/arm64/acpi_object_usage.rst
new file mode 100644
index 00000000000000..484ef9676653e2
--- /dev/null
+++ b/Documentation/arch/arm64/acpi_object_usage.rst
@@ -0,0 +1,738 @@
+===========
+ACPI Tables
+===========
+
+The expectations of individual ACPI tables are discussed in the list that
+follows.
+
+If a section number is used, it refers to a section number in the ACPI
+specification where the object is defined.  If "Signature Reserved" is used,
+the table signature (the first four bytes of the table) is the only portion
+of the table recognized by the specification, and the actual table is defined
+outside of the UEFI Forum (see Section 5.2.6 of the specification).
+
+For ACPI on arm64, tables also fall into the following categories:
+
+       -  Required: DSDT, FADT, GTDT, MADT, MCFG, RSDP, SPCR, XSDT
+
+       -  Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT
+
+       -  Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, IBFT,
+          IORT, MCHI, MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, SPMI, SRAT,
+          STAO, TCPA, TPM2, UEFI, XENV
+
+       -  Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IVRS, LPIT, MSDM, OEMx,
+          PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT
+
+====== ========================================================================
+Table  Usage for ARMv8 Linux
+====== ========================================================================
+BERT   Section 18.3 (signature == "BERT")
+
+       **Boot Error Record Table**
+
+       Must be supplied if RAS support is provided by the platform.  It
+       is recommended this table be supplied.
+
+BOOT   Signature Reserved (signature == "BOOT")
+
+       **simple BOOT flag table**
+
+       Microsoft only table, will not be supported.
+
+BGRT   Section 5.2.22 (signature == "BGRT")
+
+       **Boot Graphics Resource Table**
+
+       Optional, not currently supported, with no real use-case for an
+       ARM server.
+
+CPEP   Section 5.2.18 (signature == "CPEP")
+
+       **Corrected Platform Error Polling table**
+
+       Optional, not currently supported, and not recommended until such
+       time as ARM-compatible hardware is available, and the specification
+       suitably modified.
+
+CSRT   Signature Reserved (signature == "CSRT")
+
+       **Core System Resources Table**
+
+       Optional, not currently supported.
+
+DBG2   Signature Reserved (signature == "DBG2")
+
+       **DeBuG port table 2**
+
+       License has changed and should be usable.  Optional if used instead
+       of earlycon=<device> on the command line.
+
+DBGP   Signature Reserved (signature == "DBGP")
+
+       **DeBuG Port table**
+
+       Microsoft only table, will not be supported.
+
+DSDT   Section 5.2.11.1 (signature == "DSDT")
+
+       **Differentiated System Description Table**
+
+       A DSDT is required; see also SSDT.
+
+       ACPI tables contain only one DSDT but can contain one or more SSDTs,
+       which are optional.  Each SSDT can only add to the ACPI namespace,
+       but cannot modify or replace anything in the DSDT.
+
+DMAR   Signature Reserved (signature == "DMAR")
+
+       **DMA Remapping table**
+
+       x86 only table, will not be supported.
+
+DRTM   Signature Reserved (signature == "DRTM")
+
+       **Dynamic Root of Trust for Measurement table**
+
+       Optional, not currently supported.
+
+ECDT   Section 5.2.16 (signature == "ECDT")
+
+       **Embedded Controller Description Table**
+
+       Optional, not currently supported, but could be used on ARM if and
+       only if one uses the GPE_BIT field to represent an IRQ number, since
+       there are no GPE blocks defined in hardware reduced mode.  This would
+       need to be modified in the ACPI specification.
+
+EINJ   Section 18.6 (signature == "EINJ")
+
+       **Error Injection table**
+
+       This table is very useful for testing platform response to error
+       conditions; it allows one to inject an error into the system as
+       if it had actually occurred.  However, this table should not be
+       shipped with a production system; it should be dynamically loaded
+       and executed with the ACPICA tools only during testing.
+
+ERST   Section 18.5 (signature == "ERST")
+
+       **Error Record Serialization Table**
+
+       On a platform supports RAS, this table must be supplied if it is not
+       UEFI-based; if it is UEFI-based, this table may be supplied. When this
+       table is not present, UEFI run time service will be utilized to save
+       and retrieve hardware error information to and from a persistent store.
+
+ETDT   Signature Reserved (signature == "ETDT")
+
+       **Event Timer Description Table**
+
+       Obsolete table, will not be supported.
+
+FACS   Section 5.2.10 (signature == "FACS")
+
+       **Firmware ACPI Control Structure**
+
+       It is unlikely that this table will be terribly useful.  If it is
+       provided, the Global Lock will NOT be used since it is not part of
+       the hardware reduced profile, and only 64-bit address fields will
+       be considered valid.
+
+FADT   Section 5.2.9 (signature == "FACP")
+
+       **Fixed ACPI Description Table**
+       Required for arm64.
+
+
+       The HW_REDUCED_ACPI flag must be set.  All of the fields that are
+       to be ignored when HW_REDUCED_ACPI is set are expected to be set to
+       zero.
+
+       If an FACS table is provided, the X_FIRMWARE_CTRL field is to be
+       used, not FIRMWARE_CTRL.
+
+       If PSCI is used (as is recommended), make sure that ARM_BOOT_ARCH is
+       filled in properly - that the PSCI_COMPLIANT flag is set and that
+       PSCI_USE_HVC is set or unset as needed (see table 5-37).
+
+       For the DSDT that is also required, the X_DSDT field is to be used,
+       not the DSDT field.
+
+FPDT   Section 5.2.23 (signature == "FPDT")
+
+       **Firmware Performance Data Table**
+
+       Optional, useful for boot performance profiling.
+
+GTDT   Section 5.2.24 (signature == "GTDT")
+
+       **Generic Timer Description Table**
+
+       Required for arm64.
+
+HEST   Section 18.3.2 (signature == "HEST")
+
+       **Hardware Error Source Table**
+
+       ARM-specific error sources have been defined; please use those or the
+       PCI types such as type 6 (AER Root Port), 7 (AER Endpoint), or 8 (AER
+       Bridge), or use type 9 (Generic Hardware Error Source).  Firmware first
+       error handling is possible if and only if Trusted Firmware is being
+       used on arm64.
+
+       Must be supplied if RAS support is provided by the platform.  It
+       is recommended this table be supplied.
+
+HPET   Signature Reserved (signature == "HPET")
+
+       **High Precision Event timer Table**
+
+       x86 only table, will not be supported.
+
+IBFT   Signature Reserved (signature == "IBFT")
+
+       **iSCSI Boot Firmware Table**
+
+       Microsoft defined table, support TBD.
+
+IORT   Signature Reserved (signature == "IORT")
+
+       **Input Output Remapping Table**
+
+       arm64 only table, required in order to describe IO topology, SMMUs,
+       and GIC ITSs, and how those various components are connected together,
+       such as identifying which components are behind which SMMUs/ITSs.
+       This table will only be required on certain SBSA platforms (e.g.,
+       when using GICv3-ITS and an SMMU); on SBSA Level 0 platforms, it
+       remains optional.
+
+IVRS   Signature Reserved (signature == "IVRS")
+
+       **I/O Virtualization Reporting Structure**
+
+       x86_64 (AMD) only table, will not be supported.
+
+LPIT   Signature Reserved (signature == "LPIT")
+
+       **Low Power Idle Table**
+
+       x86 only table as of ACPI 5.1; starting with ACPI 6.0, processor
+       descriptions and power states on ARM platforms should use the DSDT
+       and define processor container devices (_HID ACPI0010, Section 8.4,
+       and more specifically 8.4.3 and 8.4.4).
+
+MADT   Section 5.2.12 (signature == "APIC")
+
+       **Multiple APIC Description Table**
+
+       Required for arm64.  Only the GIC interrupt controller structures
+       should be used (types 0xA - 0xF).
+
+MCFG   Signature Reserved (signature == "MCFG")
+
+       **Memory-mapped ConFiGuration space**
+
+       If the platform supports PCI/PCIe, an MCFG table is required.
+
+MCHI   Signature Reserved (signature == "MCHI")
+
+       **Management Controller Host Interface table**
+
+       Optional, not currently supported.
+
+MPST   Section 5.2.21 (signature == "MPST")
+
+       **Memory Power State Table**
+
+       Optional, not currently supported.
+
+MSCT   Section 5.2.19 (signature == "MSCT")
+
+       **Maximum System Characteristic Table**
+
+       Optional, not currently supported.
+
+MSDM   Signature Reserved (signature == "MSDM")
+
+       **Microsoft Data Management table**
+
+       Microsoft only table, will not be supported.
+
+NFIT   Section 5.2.25 (signature == "NFIT")
+
+       **NVDIMM Firmware Interface Table**
+
+       Optional, not currently supported.
+
+OEMx   Signature of "OEMx" only
+
+       **OEM Specific Tables**
+
+       All tables starting with a signature of "OEM" are reserved for OEM
+       use.  Since these are not meant to be of general use but are limited
+       to very specific end users, they are not recommended for use and are
+       not supported by the kernel for arm64.
+
+PCCT   Section 14.1 (signature == "PCCT)
+
+       **Platform Communications Channel Table**
+
+       Recommend for use on arm64; use of PCC is recommended when using CPPC
+       to control performance and power for platform processors.
+
+PMTT   Section 5.2.21.12 (signature == "PMTT")
+
+       **Platform Memory Topology Table**
+
+       Optional, not currently supported.
+
+PSDT   Section 5.2.11.3 (signature == "PSDT")
+
+       **Persistent System Description Table**
+
+       Obsolete table, will not be supported.
+
+RASF   Section 5.2.20 (signature == "RASF")
+
+       **RAS Feature table**
+
+       Optional, not currently supported.
+
+RSDP   Section 5.2.5 (signature == "RSD PTR")
+
+       **Root System Description PoinTeR**
+
+       Required for arm64.
+
+RSDT   Section 5.2.7 (signature == "RSDT")
+
+       **Root System Description Table**
+
+       Since this table can only provide 32-bit addresses, it is deprecated
+       on arm64, and will not be used.  If provided, it will be ignored.
+
+SBST   Section 5.2.14 (signature == "SBST")
+
+       **Smart Battery Subsystem Table**
+
+       Optional, not currently supported.
+
+SLIC   Signature Reserved (signature == "SLIC")
+
+       **Software LIcensing table**
+
+       Microsoft only table, will not be supported.
+
+SLIT   Section 5.2.17 (signature == "SLIT")
+
+       **System Locality distance Information Table**
+
+       Optional in general, but required for NUMA systems.
+
+SPCR   Signature Reserved (signature == "SPCR")
+
+       **Serial Port Console Redirection table**
+
+       Required for arm64.
+
+SPMI   Signature Reserved (signature == "SPMI")
+
+       **Server Platform Management Interface table**
+
+       Optional, not currently supported.
+
+SRAT   Section 5.2.16 (signature == "SRAT")
+
+       **System Resource Affinity Table**
+
+       Optional, but if used, only the GICC Affinity structures are read.
+       To support arm64 NUMA, this table is required.
+
+SSDT   Section 5.2.11.2 (signature == "SSDT")
+
+       **Secondary System Description Table**
+
+       These tables are a continuation of the DSDT; these are recommended
+       for use with devices that can be added to a running system, but can
+       also serve the purpose of dividing up device descriptions into more
+       manageable pieces.
+
+       An SSDT can only ADD to the ACPI namespace.  It cannot modify or
+       replace existing device descriptions already in the namespace.
+
+       These tables are optional, however.  ACPI tables should contain only
+       one DSDT but can contain many SSDTs.
+
+STAO   Signature Reserved (signature == "STAO")
+
+       **_STA Override table**
+
+       Optional, but only necessary in virtualized environments in order to
+       hide devices from guest OSs.
+
+TCPA   Signature Reserved (signature == "TCPA")
+
+       **Trusted Computing Platform Alliance table**
+
+       Optional, not currently supported, and may need changes to fully
+       interoperate with arm64.
+
+TPM2   Signature Reserved (signature == "TPM2")
+
+       **Trusted Platform Module 2 table**
+
+       Optional, not currently supported, and may need changes to fully
+       interoperate with arm64.
+
+UEFI   Signature Reserved (signature == "UEFI")
+
+       **UEFI ACPI data table**
+
+       Optional, not currently supported.  No known use case for arm64,
+       at present.
+
+WAET   Signature Reserved (signature == "WAET")
+
+       **Windows ACPI Emulated devices Table**
+
+       Microsoft only table, will not be supported.
+
+WDAT   Signature Reserved (signature == "WDAT")
+
+       **Watch Dog Action Table**
+
+       Microsoft only table, will not be supported.
+
+WDRT   Signature Reserved (signature == "WDRT")
+
+       **Watch Dog Resource Table**
+
+       Microsoft only table, will not be supported.
+
+WPBT   Signature Reserved (signature == "WPBT")
+
+       **Windows Platform Binary Table**
+
+       Microsoft only table, will not be supported.
+
+XENV   Signature Reserved (signature == "XENV")
+
+       **Xen project table**
+
+       Optional, used only by Xen at present.
+
+XSDT   Section 5.2.8 (signature == "XSDT")
+
+       **eXtended System Description Table**
+
+       Required for arm64.
+====== ========================================================================
+
+ACPI Objects
+------------
+The expectations on individual ACPI objects that are likely to be used are
+shown in the list that follows; any object not explicitly mentioned below
+should be used as needed for a particular platform or particular subsystem,
+such as power management or PCI.
+
+===== ================ ========================================================
+Name   Section         Usage for ARMv8 Linux
+===== ================ ========================================================
+_CCA   6.2.17          This method must be defined for all bus masters
+                       on arm64 - there are no assumptions made about
+                       whether such devices are cache coherent or not.
+                       The _CCA value is inherited by all descendants of
+                       these devices so it does not need to be repeated.
+                       Without _CCA on arm64, the kernel does not know what
+                       to do about setting up DMA for the device.
+
+                       NB: this method provides default cache coherency
+                       attributes; the presence of an SMMU can be used to
+                       modify that, however.  For example, a master could
+                       default to non-coherent, but be made coherent with
+                       the appropriate SMMU configuration (see Table 17 of
+                       the IORT specification, ARM Document DEN 0049B).
+
+_CID   6.1.2           Use as needed, see also _HID.
+
+_CLS   6.1.3           Use as needed, see also _HID.
+
+_CPC   8.4.7.1         Use as needed, power management specific.  CPPC is
+                       recommended on arm64.
+
+_CRS   6.2.2           Required on arm64.
+
+_CSD   8.4.2.2         Use as needed, used only in conjunction with _CST.
+
+_CST   8.4.2.1         Low power idle states (8.4.4) are recommended instead
+                       of C-states.
+
+_DDN   6.1.4           This field can be used for a device name.  However,
+                       it is meant for DOS device names (e.g., COM1), so be
+                       careful of its use across OSes.
+
+_DSD   6.2.5           To be used with caution.  If this object is used, try
+                       to use it within the constraints already defined by the
+                       Device Properties UUID.  Only in rare circumstances
+                       should it be necessary to create a new _DSD UUID.
+
+                       In either case, submit the _DSD definition along with
+                       any driver patches for discussion, especially when
+                       device properties are used.  A driver will not be
+                       considered complete without a corresponding _DSD
+                       description.  Once approved by kernel maintainers,
+                       the UUID or device properties must then be registered
+                       with the UEFI Forum; this may cause some iteration as
+                       more than one OS will be registering entries.
+
+_DSM   9.1.1           Do not use this method.  It is not standardized, the
+                       return values are not well documented, and it is
+                       currently a frequent source of error.
+
+\_GL   5.7.1           This object is not to be used in hardware reduced
+                       mode, and therefore should not be used on arm64.
+
+_GLK   6.5.7           This object requires a global lock be defined; there
+                       is no global lock on arm64 since it runs in hardware
+                       reduced mode.  Hence, do not use this object on arm64.
+
+\_GPE  5.3.1           This namespace is for x86 use only.  Do not use it
+                       on arm64.
+
+_HID   6.1.5           This is the primary object to use in device probing,
+		       though _CID and _CLS may also be used.
+
+_INI   6.5.1           Not required, but can be useful in setting up devices
+                       when UEFI leaves them in a state that may not be what
+                       the driver expects before it starts probing.
+
+_LPI   8.4.4.3         Recommended for use with processor definitions (_HID
+		       ACPI0010) on arm64.  See also _RDI.
+
+_MLS   6.1.7           Highly recommended for use in internationalization.
+
+_OFF   7.2.2           It is recommended to define this method for any device
+                       that can be turned on or off.
+
+_ON    7.2.3           It is recommended to define this method for any device
+                       that can be turned on or off.
+
+\_OS   5.7.3           This method will return "Linux" by default (this is
+                       the value of the macro ACPI_OS_NAME on Linux).  The
+                       command line parameter acpi_os=<string> can be used
+                       to set it to some other value.
+
+_OSC   6.2.11          This method can be a global method in ACPI (i.e.,
+                       \_SB._OSC), or it may be associated with a specific
+                       device (e.g., \_SB.DEV0._OSC), or both.  When used
+                       as a global method, only capabilities published in
+                       the ACPI specification are allowed.  When used as
+                       a device-specific method, the process described for
+                       using _DSD MUST be used to create an _OSC definition;
+                       out-of-process use of _OSC is not allowed.  That is,
+                       submit the device-specific _OSC usage description as
+                       part of the kernel driver submission, get it approved
+                       by the kernel community, then register it with the
+                       UEFI Forum.
+
+\_OSI  5.7.2           Deprecated on ARM64.  As far as ACPI firmware is
+		       concerned, _OSI is not to be used to determine what
+		       sort of system is being used or what functionality
+		       is provided.  The _OSC method is to be used instead.
+
+_PDC   8.4.1           Deprecated, do not use on arm64.
+
+\_PIC  5.8.1           The method should not be used.  On arm64, the only
+                       interrupt model available is GIC.
+
+\_PR   5.3.1           This namespace is for x86 use only on legacy systems.
+                       Do not use it on arm64.
+
+_PRT   6.2.13          Required as part of the definition of all PCI root
+                       devices.
+
+_PRx   7.3.8-11        Use as needed; power management specific.  If _PR0 is
+                       defined, _PR3 must also be defined.
+
+_PSx   7.3.2-5         Use as needed; power management specific.  If _PS0 is
+                       defined, _PS3 must also be defined.  If clocks or
+                       regulators need adjusting to be consistent with power
+                       usage, change them in these methods.
+
+_RDI   8.4.4.4         Recommended for use with processor definitions (_HID
+		       ACPI0010) on arm64.  This should only be used in
+		       conjunction with _LPI.
+
+\_REV  5.7.4           Always returns the latest version of ACPI supported.
+
+\_SB   5.3.1           Required on arm64; all devices must be defined in this
+                       namespace.
+
+_SLI   6.2.15          Use is recommended when SLIT table is in use.
+
+_STA   6.3.7,          It is recommended to define this method for any device
+       7.2.4           that can be turned on or off.  See also the STAO table
+                       that provides overrides to hide devices in virtualized
+                       environments.
+
+_SRS   6.2.16          Use as needed; see also _PRS.
+
+_STR   6.1.10          Recommended for conveying device names to end users;
+                       this is preferred over using _DDN.
+
+_SUB   6.1.9           Use as needed; _HID or _CID are preferred.
+
+_SUN   6.1.11          Use as needed, but recommended.
+
+_SWS   7.4.3           Use as needed; power management specific; this may
+                       require specification changes for use on arm64.
+
+_UID   6.1.12          Recommended for distinguishing devices of the same
+                       class; define it if at all possible.
+===== ================ ========================================================
+
+
+
+
+ACPI Event Model
+----------------
+Do not use GPE block devices; these are not supported in the hardware reduced
+profile used by arm64.  Since there are no GPE blocks defined for use on ARM
+platforms, ACPI events must be signaled differently.
+
+There are two options: GPIO-signaled interrupts (Section 5.6.5), and
+interrupt-signaled events (Section 5.6.9).  Interrupt-signaled events are a
+new feature in the ACPI 6.1 specification.  Either - or both - can be used
+on a given platform, and which to use may be dependent of limitations in any
+given SoC.  If possible, interrupt-signaled events are recommended.
+
+
+ACPI Processor Control
+----------------------
+Section 8 of the ACPI specification changed significantly in version 6.0.
+Processors should now be defined as Device objects with _HID ACPI0007; do
+not use the deprecated Processor statement in ASL.  All multiprocessor systems
+should also define a hierarchy of processors, done with Processor Container
+Devices (see Section 8.4.3.1, _HID ACPI0010); do not use processor aggregator
+devices (Section 8.5) to describe processor topology.  Section 8.4 of the
+specification describes the semantics of these object definitions and how
+they interrelate.
+
+Most importantly, the processor hierarchy defined also defines the low power
+idle states that are available to the platform, along with the rules for
+determining which processors can be turned on or off and the circumstances
+that control that.  Without this information, the processors will run in
+whatever power state they were left in by UEFI.
+
+Note too, that the processor Device objects defined and the entries in the
+MADT for GICs are expected to be in synchronization.  The _UID of the Device
+object must correspond to processor IDs used in the MADT.
+
+It is recommended that CPPC (8.4.5) be used as the primary model for processor
+performance control on arm64.  C-states and P-states may become available at
+some point in the future, but most current design work appears to favor CPPC.
+
+Further, it is essential that the ARMv8 SoC provide a fully functional
+implementation of PSCI; this will be the only mechanism supported by ACPI
+to control CPU power state.  Booting of secondary CPUs using the ACPI
+parking protocol is possible, but discouraged, since only PSCI is supported
+for ARM servers.
+
+
+ACPI System Address Map Interfaces
+----------------------------------
+In Section 15 of the ACPI specification, several methods are mentioned as
+possible mechanisms for conveying memory resource information to the kernel.
+For arm64, we will only support UEFI for booting with ACPI, hence the UEFI
+GetMemoryMap() boot service is the only mechanism that will be used.
+
+
+ACPI Platform Error Interfaces (APEI)
+-------------------------------------
+The APEI tables supported are described above.
+
+APEI requires the equivalent of an SCI and an NMI on ARMv8.  The SCI is used
+to notify the OSPM of errors that have occurred but can be corrected and the
+system can continue correct operation, even if possibly degraded.  The NMI is
+used to indicate fatal errors that cannot be corrected, and require immediate
+attention.
+
+Since there is no direct equivalent of the x86 SCI or NMI, arm64 handles
+these slightly differently.  The SCI is handled as a high priority interrupt;
+given that these are corrected (or correctable) errors being reported, this
+is sufficient.  The NMI is emulated as the highest priority interrupt
+possible.  This implies some caution must be used since there could be
+interrupts at higher privilege levels or even interrupts at the same priority
+as the emulated NMI.  In Linux, this should not be the case but one should
+be aware it could happen.
+
+
+ACPI Objects Not Supported on ARM64
+-----------------------------------
+While this may change in the future, there are several classes of objects
+that can be defined, but are not currently of general interest to ARM servers.
+Some of these objects have x86 equivalents, and may actually make sense in ARM
+servers.  However, there is either no hardware available at present, or there
+may not even be a non-ARM implementation yet.  Hence, they are not currently
+supported.
+
+The following classes of objects are not supported:
+
+       -  Section 9.2: ambient light sensor devices
+
+       -  Section 9.3: battery devices
+
+       -  Section 9.4: lids (e.g., laptop lids)
+
+       -  Section 9.8.2: IDE controllers
+
+       -  Section 9.9: floppy controllers
+
+       -  Section 9.10: GPE block devices
+
+       -  Section 9.15: PC/AT RTC/CMOS devices
+
+       -  Section 9.16: user presence detection devices
+
+       -  Section 9.17: I/O APIC devices; all GICs must be enumerable via MADT
+
+       -  Section 9.18: time and alarm devices (see 9.15)
+
+       -  Section 10: power source and power meter devices
+
+       -  Section 11: thermal management
+
+       -  Section 12: embedded controllers interface
+
+       -  Section 13: SMBus interfaces
+
+
+This also means that there is no support for the following objects:
+
+====   =========================== ====   ==========
+Name   Section                     Name   Section
+====   =========================== ====   ==========
+_ALC   9.3.4                       _FDM   9.10.3
+_ALI   9.3.2                       _FIX   6.2.7
+_ALP   9.3.6                       _GAI   10.4.5
+_ALR   9.3.5                       _GHL   10.4.7
+_ALT   9.3.3                       _GTM   9.9.2.1.1
+_BCT   10.2.2.10                   _LID   9.5.1
+_BDN   6.5.3                       _PAI   10.4.4
+_BIF   10.2.2.1                    _PCL   10.3.2
+_BIX   10.2.2.1                    _PIF   10.3.3
+_BLT   9.2.3                       _PMC   10.4.1
+_BMA   10.2.2.4                    _PMD   10.4.8
+_BMC   10.2.2.12                   _PMM   10.4.3
+_BMD   10.2.2.11                   _PRL   10.3.4
+_BMS   10.2.2.5                    _PSR   10.3.1
+_BST   10.2.2.6                    _PTP   10.4.2
+_BTH   10.2.2.7                    _SBS   10.1.3
+_BTM   10.2.2.9                    _SHL   10.4.6
+_BTP   10.2.2.8                    _STM   9.9.2.1.1
+_DCK   6.5.2                       _UPD   9.16.1
+_EC    12.12                       _UPP   9.16.2
+_FDE   9.10.1                      _WPC   10.5.2
+_FDI   9.10.2                      _WPP   10.5.3
+====   =========================== ====   ==========
diff --git a/Documentation/arch/arm64/amu.rst b/Documentation/arch/arm64/amu.rst
new file mode 100644
index 00000000000000..01f2de2b0450c7
--- /dev/null
+++ b/Documentation/arch/arm64/amu.rst
@@ -0,0 +1,119 @@
+.. _amu_index:
+
+=======================================================
+Activity Monitors Unit (AMU) extension in AArch64 Linux
+=======================================================
+
+Author: Ionela Voinescu <ionela.voinescu@arm.com>
+
+Date: 2019-09-10
+
+This document briefly describes the provision of Activity Monitors Unit
+support in AArch64 Linux.
+
+
+Architecture overview
+---------------------
+
+The activity monitors extension is an optional extension introduced by the
+ARMv8.4 CPU architecture.
+
+The activity monitors unit, implemented in each CPU, provides performance
+counters intended for system management use. The AMU extension provides a
+system register interface to the counter registers and also supports an
+optional external memory-mapped interface.
+
+Version 1 of the Activity Monitors architecture implements a counter group
+of four fixed and architecturally defined 64-bit event counters.
+
+  - CPU cycle counter: increments at the frequency of the CPU.
+  - Constant counter: increments at the fixed frequency of the system
+    clock.
+  - Instructions retired: increments with every architecturally executed
+    instruction.
+  - Memory stall cycles: counts instruction dispatch stall cycles caused by
+    misses in the last level cache within the clock domain.
+
+When in WFI or WFE these counters do not increment.
+
+The Activity Monitors architecture provides space for up to 16 architected
+event counters. Future versions of the architecture may use this space to
+implement additional architected event counters.
+
+Additionally, version 1 implements a counter group of up to 16 auxiliary
+64-bit event counters.
+
+On cold reset all counters reset to 0.
+
+
+Basic support
+-------------
+
+The kernel can safely run a mix of CPUs with and without support for the
+activity monitors extension. Therefore, when CONFIG_ARM64_AMU_EXTN is
+selected we unconditionally enable the capability to allow any late CPU
+(secondary or hotplugged) to detect and use the feature.
+
+When the feature is detected on a CPU, we flag the availability of the
+feature but this does not guarantee the correct functionality of the
+counters, only the presence of the extension.
+
+Firmware (code running at higher exception levels, e.g. arm-tf) support is
+needed to:
+
+ - Enable access for lower exception levels (EL2 and EL1) to the AMU
+   registers.
+ - Enable the counters. If not enabled these will read as 0.
+ - Save/restore the counters before/after the CPU is being put/brought up
+   from the 'off' power state.
+
+When using kernels that have this feature enabled but boot with broken
+firmware the user may experience panics or lockups when accessing the
+counter registers. Even if these symptoms are not observed, the values
+returned by the register reads might not correctly reflect reality. Most
+commonly, the counters will read as 0, indicating that they are not
+enabled.
+
+If proper support is not provided in firmware it's best to disable
+CONFIG_ARM64_AMU_EXTN. To be noted that for security reasons, this does not
+bypass the setting of AMUSERENR_EL0 to trap accesses from EL0 (userspace) to
+EL1 (kernel). Therefore, firmware should still ensure accesses to AMU registers
+are not trapped in EL2/EL3.
+
+The fixed counters of AMUv1 are accessible though the following system
+register definitions:
+
+ - SYS_AMEVCNTR0_CORE_EL0
+ - SYS_AMEVCNTR0_CONST_EL0
+ - SYS_AMEVCNTR0_INST_RET_EL0
+ - SYS_AMEVCNTR0_MEM_STALL_EL0
+
+Auxiliary platform specific counters can be accessed using
+SYS_AMEVCNTR1_EL0(n), where n is a value between 0 and 15.
+
+Details can be found in: arch/arm64/include/asm/sysreg.h.
+
+
+Userspace access
+----------------
+
+Currently, access from userspace to the AMU registers is disabled due to:
+
+ - Security reasons: they might expose information about code executed in
+   secure mode.
+ - Purpose: AMU counters are intended for system management use.
+
+Also, the presence of the feature is not visible to userspace.
+
+
+Virtualization
+--------------
+
+Currently, access from userspace (EL0) and kernelspace (EL1) on the KVM
+guest side is disabled due to:
+
+ - Security reasons: they might expose information about code executed
+   by other guests or the host.
+
+Any attempt to access the AMU registers will result in an UNDEFINED
+exception being injected into the guest.
diff --git a/Documentation/arch/arm64/arm-acpi.rst b/Documentation/arch/arm64/arm-acpi.rst
new file mode 100644
index 00000000000000..1636352756bb6d
--- /dev/null
+++ b/Documentation/arch/arm64/arm-acpi.rst
@@ -0,0 +1,528 @@
+=====================
+ACPI on ARMv8 Servers
+=====================
+
+ACPI can be used for ARMv8 general purpose servers designed to follow
+the ARM SBSA (Server Base System Architecture) [0] and SBBR (Server
+Base Boot Requirements) [1] specifications.  Please note that the SBBR
+can be retrieved simply by visiting [1], but the SBSA is currently only
+available to those with an ARM login due to ARM IP licensing concerns.
+
+The ARMv8 kernel implements the reduced hardware model of ACPI version
+5.1 or later.  Links to the specification and all external documents
+it refers to are managed by the UEFI Forum.  The specification is
+available at http://www.uefi.org/specifications and documents referenced
+by the specification can be found via http://www.uefi.org/acpi.
+
+If an ARMv8 system does not meet the requirements of the SBSA and SBBR,
+or cannot be described using the mechanisms defined in the required ACPI
+specifications, then ACPI may not be a good fit for the hardware.
+
+While the documents mentioned above set out the requirements for building
+industry-standard ARMv8 servers, they also apply to more than one operating
+system.  The purpose of this document is to describe the interaction between
+ACPI and Linux only, on an ARMv8 system -- that is, what Linux expects of
+ACPI and what ACPI can expect of Linux.
+
+
+Why ACPI on ARM?
+----------------
+Before examining the details of the interface between ACPI and Linux, it is
+useful to understand why ACPI is being used.  Several technologies already
+exist in Linux for describing non-enumerable hardware, after all.  In this
+section we summarize a blog post [2] from Grant Likely that outlines the
+reasoning behind ACPI on ARMv8 servers.  Actually, we snitch a good portion
+of the summary text almost directly, to be honest.
+
+The short form of the rationale for ACPI on ARM is:
+
+-  ACPI’s byte code (AML) allows the platform to encode hardware behavior,
+   while DT explicitly does not support this.  For hardware vendors, being
+   able to encode behavior is a key tool used in supporting operating
+   system releases on new hardware.
+
+-  ACPI’s OSPM defines a power management model that constrains what the
+   platform is allowed to do into a specific model, while still providing
+   flexibility in hardware design.
+
+-  In the enterprise server environment, ACPI has established bindings (such
+   as for RAS) which are currently used in production systems.  DT does not.
+   Such bindings could be defined in DT at some point, but doing so means ARM
+   and x86 would end up using completely different code paths in both firmware
+   and the kernel.
+
+-  Choosing a single interface to describe the abstraction between a platform
+   and an OS is important.  Hardware vendors would not be required to implement
+   both DT and ACPI if they want to support multiple operating systems.  And,
+   agreeing on a single interface instead of being fragmented into per OS
+   interfaces makes for better interoperability overall.
+
+-  The new ACPI governance process works well and Linux is now at the same
+   table as hardware vendors and other OS vendors.  In fact, there is no
+   longer any reason to feel that ACPI only belongs to Windows or that
+   Linux is in any way secondary to Microsoft in this arena.  The move of
+   ACPI governance into the UEFI forum has significantly opened up the
+   specification development process, and currently, a large portion of the
+   changes being made to ACPI are being driven by Linux.
+
+Key to the use of ACPI is the support model.  For servers in general, the
+responsibility for hardware behaviour cannot solely be the domain of the
+kernel, but rather must be split between the platform and the kernel, in
+order to allow for orderly change over time.  ACPI frees the OS from needing
+to understand all the minute details of the hardware so that the OS doesn’t
+need to be ported to each and every device individually.  It allows the
+hardware vendors to take responsibility for power management behaviour without
+depending on an OS release cycle which is not under their control.
+
+ACPI is also important because hardware and OS vendors have already worked
+out the mechanisms for supporting a general purpose computing ecosystem.  The
+infrastructure is in place, the bindings are in place, and the processes are
+in place.  DT does exactly what Linux needs it to when working with vertically
+integrated devices, but there are no good processes for supporting what the
+server vendors need.  Linux could potentially get there with DT, but doing so
+really just duplicates something that already works.  ACPI already does what
+the hardware vendors need, Microsoft won’t collaborate on DT, and hardware
+vendors would still end up providing two completely separate firmware
+interfaces -- one for Linux and one for Windows.
+
+
+Kernel Compatibility
+--------------------
+One of the primary motivations for ACPI is standardization, and using that
+to provide backward compatibility for Linux kernels.  In the server market,
+software and hardware are often used for long periods.  ACPI allows the
+kernel and firmware to agree on a consistent abstraction that can be
+maintained over time, even as hardware or software change.  As long as the
+abstraction is supported, systems can be updated without necessarily having
+to replace the kernel.
+
+When a Linux driver or subsystem is first implemented using ACPI, it by
+definition ends up requiring a specific version of the ACPI specification
+-- it's baseline.  ACPI firmware must continue to work, even though it may
+not be optimal, with the earliest kernel version that first provides support
+for that baseline version of ACPI.  There may be a need for additional drivers,
+but adding new functionality (e.g., CPU power management) should not break
+older kernel versions.  Further, ACPI firmware must also work with the most
+recent version of the kernel.
+
+
+Relationship with Device Tree
+-----------------------------
+ACPI support in drivers and subsystems for ARMv8 should never be mutually
+exclusive with DT support at compile time.
+
+At boot time the kernel will only use one description method depending on
+parameters passed from the boot loader (including kernel bootargs).
+
+Regardless of whether DT or ACPI is used, the kernel must always be capable
+of booting with either scheme (in kernels with both schemes enabled at compile
+time).
+
+
+Booting using ACPI tables
+-------------------------
+The only defined method for passing ACPI tables to the kernel on ARMv8
+is via the UEFI system configuration table.  Just so it is explicit, this
+means that ACPI is only supported on platforms that boot via UEFI.
+
+When an ARMv8 system boots, it can either have DT information, ACPI tables,
+or in some very unusual cases, both.  If no command line parameters are used,
+the kernel will try to use DT for device enumeration; if there is no DT
+present, the kernel will try to use ACPI tables, but only if they are present.
+In neither is available, the kernel will not boot.  If acpi=force is used
+on the command line, the kernel will attempt to use ACPI tables first, but
+fall back to DT if there are no ACPI tables present.  The basic idea is that
+the kernel will not fail to boot unless it absolutely has no other choice.
+
+Processing of ACPI tables may be disabled by passing acpi=off on the kernel
+command line; this is the default behavior.
+
+In order for the kernel to load and use ACPI tables, the UEFI implementation
+MUST set the ACPI_20_TABLE_GUID to point to the RSDP table (the table with
+the ACPI signature "RSD PTR ").  If this pointer is incorrect and acpi=force
+is used, the kernel will disable ACPI and try to use DT to boot instead; the
+kernel has, in effect, determined that ACPI tables are not present at that
+point.
+
+If the pointer to the RSDP table is correct, the table will be mapped into
+the kernel by the ACPI core, using the address provided by UEFI.
+
+The ACPI core will then locate and map in all other ACPI tables provided by
+using the addresses in the RSDP table to find the XSDT (eXtended System
+Description Table).  The XSDT in turn provides the addresses to all other
+ACPI tables provided by the system firmware; the ACPI core will then traverse
+this table and map in the tables listed.
+
+The ACPI core will ignore any provided RSDT (Root System Description Table).
+RSDTs have been deprecated and are ignored on arm64 since they only allow
+for 32-bit addresses.
+
+Further, the ACPI core will only use the 64-bit address fields in the FADT
+(Fixed ACPI Description Table).  Any 32-bit address fields in the FADT will
+be ignored on arm64.
+
+Hardware reduced mode (see Section 4.1 of the ACPI 6.1 specification) will
+be enforced by the ACPI core on arm64.  Doing so allows the ACPI core to
+run less complex code since it no longer has to provide support for legacy
+hardware from other architectures.  Any fields that are not to be used for
+hardware reduced mode must be set to zero.
+
+For the ACPI core to operate properly, and in turn provide the information
+the kernel needs to configure devices, it expects to find the following
+tables (all section numbers refer to the ACPI 6.1 specification):
+
+    -  RSDP (Root System Description Pointer), section 5.2.5
+
+    -  XSDT (eXtended System Description Table), section 5.2.8
+
+    -  FADT (Fixed ACPI Description Table), section 5.2.9
+
+    -  DSDT (Differentiated System Description Table), section
+       5.2.11.1
+
+    -  MADT (Multiple APIC Description Table), section 5.2.12
+
+    -  GTDT (Generic Timer Description Table), section 5.2.24
+
+    -  If PCI is supported, the MCFG (Memory mapped ConFiGuration
+       Table), section 5.2.6, specifically Table 5-31.
+
+    -  If booting without a console=<device> kernel parameter is
+       supported, the SPCR (Serial Port Console Redirection table),
+       section 5.2.6, specifically Table 5-31.
+
+    -  If necessary to describe the I/O topology, SMMUs and GIC ITSs,
+       the IORT (Input Output Remapping Table, section 5.2.6, specifically
+       Table 5-31).
+
+    -  If NUMA is supported, the SRAT (System Resource Affinity Table)
+       and SLIT (System Locality distance Information Table), sections
+       5.2.16 and 5.2.17, respectively.
+
+If the above tables are not all present, the kernel may or may not be
+able to boot properly since it may not be able to configure all of the
+devices available.  This list of tables is not meant to be all inclusive;
+in some environments other tables may be needed (e.g., any of the APEI
+tables from section 18) to support specific functionality.
+
+
+ACPI Detection
+--------------
+Drivers should determine their probe() type by checking for a null
+value for ACPI_HANDLE, or checking .of_node, or other information in
+the device structure.  This is detailed further in the "Driver
+Recommendations" section.
+
+In non-driver code, if the presence of ACPI needs to be detected at
+run time, then check the value of acpi_disabled. If CONFIG_ACPI is not
+set, acpi_disabled will always be 1.
+
+
+Device Enumeration
+------------------
+Device descriptions in ACPI should use standard recognized ACPI interfaces.
+These may contain less information than is typically provided via a Device
+Tree description for the same device.  This is also one of the reasons that
+ACPI can be useful -- the driver takes into account that it may have less
+detailed information about the device and uses sensible defaults instead.
+If done properly in the driver, the hardware can change and improve over
+time without the driver having to change at all.
+
+Clocks provide an excellent example.  In DT, clocks need to be specified
+and the drivers need to take them into account.  In ACPI, the assumption
+is that UEFI will leave the device in a reasonable default state, including
+any clock settings.  If for some reason the driver needs to change a clock
+value, this can be done in an ACPI method; all the driver needs to do is
+invoke the method and not concern itself with what the method needs to do
+to change the clock.  Changing the hardware can then take place over time
+by changing what the ACPI method does, and not the driver.
+
+In DT, the parameters needed by the driver to set up clocks as in the example
+above are known as "bindings"; in ACPI, these are known as "Device Properties"
+and provided to a driver via the _DSD object.
+
+ACPI tables are described with a formal language called ASL, the ACPI
+Source Language (section 19 of the specification).  This means that there
+are always multiple ways to describe the same thing -- including device
+properties.  For example, device properties could use an ASL construct
+that looks like this: Name(KEY0, "value0").  An ACPI device driver would
+then retrieve the value of the property by evaluating the KEY0 object.
+However, using Name() this way has multiple problems: (1) ACPI limits
+names ("KEY0") to four characters unlike DT; (2) there is no industry
+wide registry that maintains a list of names, minimizing re-use; (3)
+there is also no registry for the definition of property values ("value0"),
+again making re-use difficult; and (4) how does one maintain backward
+compatibility as new hardware comes out?  The _DSD method was created
+to solve precisely these sorts of problems; Linux drivers should ALWAYS
+use the _DSD method for device properties and nothing else.
+
+The _DSM object (ACPI Section 9.14.1) could also be used for conveying
+device properties to a driver.  Linux drivers should only expect it to
+be used if _DSD cannot represent the data required, and there is no way
+to create a new UUID for the _DSD object.  Note that there is even less
+regulation of the use of _DSM than there is of _DSD.  Drivers that depend
+on the contents of _DSM objects will be more difficult to maintain over
+time because of this; as of this writing, the use of _DSM is the cause
+of quite a few firmware problems and is not recommended.
+
+Drivers should look for device properties in the _DSD object ONLY; the _DSD
+object is described in the ACPI specification section 6.2.5, but this only
+describes how to define the structure of an object returned via _DSD, and
+how specific data structures are defined by specific UUIDs.  Linux should
+only use the _DSD Device Properties UUID [5]:
+
+   - UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301
+
+   - https://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf
+
+The UEFI Forum provides a mechanism for registering device properties [4]
+so that they may be used across all operating systems supporting ACPI.
+Device properties that have not been registered with the UEFI Forum should
+not be used.
+
+Before creating new device properties, check to be sure that they have not
+been defined before and either registered in the Linux kernel documentation
+as DT bindings, or the UEFI Forum as device properties.  While we do not want
+to simply move all DT bindings into ACPI device properties, we can learn from
+what has been previously defined.
+
+If it is necessary to define a new device property, or if it makes sense to
+synthesize the definition of a binding so it can be used in any firmware,
+both DT bindings and ACPI device properties for device drivers have review
+processes.  Use them both.  When the driver itself is submitted for review
+to the Linux mailing lists, the device property definitions needed must be
+submitted at the same time.  A driver that supports ACPI and uses device
+properties will not be considered complete without their definitions.  Once
+the device property has been accepted by the Linux community, it must be
+registered with the UEFI Forum [4], which will review it again for consistency
+within the registry.  This may require iteration.  The UEFI Forum, though,
+will always be the canonical site for device property definitions.
+
+It may make sense to provide notice to the UEFI Forum that there is the
+intent to register a previously unused device property name as a means of
+reserving the name for later use.  Other operating system vendors will
+also be submitting registration requests and this may help smooth the
+process.
+
+Once registration and review have been completed, the kernel provides an
+interface for looking up device properties in a manner independent of
+whether DT or ACPI is being used.  This API should be used [6]; it can
+eliminate some duplication of code paths in driver probing functions and
+discourage divergence between DT bindings and ACPI device properties.
+
+
+Programmable Power Control Resources
+------------------------------------
+Programmable power control resources include such resources as voltage/current
+providers (regulators) and clock sources.
+
+With ACPI, the kernel clock and regulator framework is not expected to be used
+at all.
+
+The kernel assumes that power control of these resources is represented with
+Power Resource Objects (ACPI section 7.1).  The ACPI core will then handle
+correctly enabling and disabling resources as they are needed.  In order to
+get that to work, ACPI assumes each device has defined D-states and that these
+can be controlled through the optional ACPI methods _PS0, _PS1, _PS2, and _PS3;
+in ACPI, _PS0 is the method to invoke to turn a device full on, and _PS3 is for
+turning a device full off.
+
+There are two options for using those Power Resources.  They can:
+
+   -  be managed in a _PSx method which gets called on entry to power
+      state Dx.
+
+   -  be declared separately as power resources with their own _ON and _OFF
+      methods.  They are then tied back to D-states for a particular device
+      via _PRx which specifies which power resources a device needs to be on
+      while in Dx.  Kernel then tracks number of devices using a power resource
+      and calls _ON/_OFF as needed.
+
+The kernel ACPI code will also assume that the _PSx methods follow the normal
+ACPI rules for such methods:
+
+   -  If either _PS0 or _PS3 is implemented, then the other method must also
+      be implemented.
+
+   -  If a device requires usage or setup of a power resource when on, the ASL
+      should organize that it is allocated/enabled using the _PS0 method.
+
+   -  Resources allocated or enabled in the _PS0 method should be disabled
+      or de-allocated in the _PS3 method.
+
+   -  Firmware will leave the resources in a reasonable state before handing
+      over control to the kernel.
+
+Such code in _PSx methods will of course be very platform specific.  But,
+this allows the driver to abstract out the interface for operating the device
+and avoid having to read special non-standard values from ACPI tables. Further,
+abstracting the use of these resources allows the hardware to change over time
+without requiring updates to the driver.
+
+
+Clocks
+------
+ACPI makes the assumption that clocks are initialized by the firmware --
+UEFI, in this case -- to some working value before control is handed over
+to the kernel.  This has implications for devices such as UARTs, or SoC-driven
+LCD displays, for example.
+
+When the kernel boots, the clocks are assumed to be set to reasonable
+working values.  If for some reason the frequency needs to change -- e.g.,
+throttling for power management -- the device driver should expect that
+process to be abstracted out into some ACPI method that can be invoked
+(please see the ACPI specification for further recommendations on standard
+methods to be expected).  The only exceptions to this are CPU clocks where
+CPPC provides a much richer interface than ACPI methods.  If the clocks
+are not set, there is no direct way for Linux to control them.
+
+If an SoC vendor wants to provide fine-grained control of the system clocks,
+they could do so by providing ACPI methods that could be invoked by Linux
+drivers.  However, this is NOT recommended and Linux drivers should NOT use
+such methods, even if they are provided.  Such methods are not currently
+standardized in the ACPI specification, and using them could tie a kernel
+to a very specific SoC, or tie an SoC to a very specific version of the
+kernel, both of which we are trying to avoid.
+
+
+Driver Recommendations
+----------------------
+DO NOT remove any DT handling when adding ACPI support for a driver.  The
+same device may be used on many different systems.
+
+DO try to structure the driver so that it is data-driven.  That is, set up
+a struct containing internal per-device state based on defaults and whatever
+else must be discovered by the driver probe function.  Then, have the rest
+of the driver operate off of the contents of that struct.  Doing so should
+allow most divergence between ACPI and DT functionality to be kept local to
+the probe function instead of being scattered throughout the driver.  For
+example::
+
+  static int device_probe_dt(struct platform_device *pdev)
+  {
+         /* DT specific functionality */
+         ...
+  }
+
+  static int device_probe_acpi(struct platform_device *pdev)
+  {
+         /* ACPI specific functionality */
+         ...
+  }
+
+  static int device_probe(struct platform_device *pdev)
+  {
+         ...
+         struct device_node node = pdev->dev.of_node;
+         ...
+
+         if (node)
+                 ret = device_probe_dt(pdev);
+         else if (ACPI_HANDLE(&pdev->dev))
+                 ret = device_probe_acpi(pdev);
+         else
+                 /* other initialization */
+                 ...
+         /* Continue with any generic probe operations */
+         ...
+  }
+
+DO keep the MODULE_DEVICE_TABLE entries together in the driver to make it
+clear the different names the driver is probed for, both from DT and from
+ACPI::
+
+  static struct of_device_id virtio_mmio_match[] = {
+          { .compatible = "virtio,mmio", },
+          { }
+  };
+  MODULE_DEVICE_TABLE(of, virtio_mmio_match);
+
+  static const struct acpi_device_id virtio_mmio_acpi_match[] = {
+          { "LNRO0005", },
+          { }
+  };
+  MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match);
+
+
+ASWG
+----
+The ACPI specification changes regularly.  During the year 2014, for instance,
+version 5.1 was released and version 6.0 substantially completed, with most of
+the changes being driven by ARM-specific requirements.  Proposed changes are
+presented and discussed in the ASWG (ACPI Specification Working Group) which
+is a part of the UEFI Forum.  The current version of the ACPI specification
+is 6.1 release in January 2016.
+
+Participation in this group is open to all UEFI members.  Please see
+http://www.uefi.org/workinggroup for details on group membership.
+
+It is the intent of the ARMv8 ACPI kernel code to follow the ACPI specification
+as closely as possible, and to only implement functionality that complies with
+the released standards from UEFI ASWG.  As a practical matter, there will be
+vendors that provide bad ACPI tables or violate the standards in some way.
+If this is because of errors, quirks and fix-ups may be necessary, but will
+be avoided if possible.  If there are features missing from ACPI that preclude
+it from being used on a platform, ECRs (Engineering Change Requests) should be
+submitted to ASWG and go through the normal approval process; for those that
+are not UEFI members, many other members of the Linux community are and would
+likely be willing to assist in submitting ECRs.
+
+
+Linux Code
+----------
+Individual items specific to Linux on ARM, contained in the Linux
+source code, are in the list that follows:
+
+ACPI_OS_NAME
+                       This macro defines the string to be returned when
+                       an ACPI method invokes the _OS method.  On ARM64
+                       systems, this macro will be "Linux" by default.
+                       The command line parameter acpi_os=<string>
+                       can be used to set it to some other value.  The
+                       default value for other architectures is "Microsoft
+                       Windows NT", for example.
+
+ACPI Objects
+------------
+Detailed expectations for ACPI tables and object are listed in the file
+Documentation/arch/arm64/acpi_object_usage.rst.
+
+
+References
+----------
+[0] http://silver.arm.com
+    document ARM-DEN-0029, or newer:
+    "Server Base System Architecture", version 2.3, dated 27 Mar 2014
+
+[1] http://infocenter.arm.com/help/topic/com.arm.doc.den0044a/Server_Base_Boot_Requirements.pdf
+    Document ARM-DEN-0044A, or newer: "Server Base Boot Requirements, System
+    Software on ARM Platforms", dated 16 Aug 2014
+
+[2] http://www.secretlab.ca/archives/151,
+    10 Jan 2015, Copyright (c) 2015,
+    Linaro Ltd., written by Grant Likely.
+
+[3] AMD ACPI for Seattle platform documentation
+    http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Seattle_ACPI_Guide.pdf
+
+
+[4] http://www.uefi.org/acpi
+    please see the link for the "ACPI _DSD Device
+    Property Registry Instructions"
+
+[5] http://www.uefi.org/acpi
+    please see the link for the "_DSD (Device
+    Specific Data) Implementation Guide"
+
+[6] Kernel code for the unified device
+    property interface can be found in
+    include/linux/property.h and drivers/base/property.c.
+
+
+Authors
+-------
+- Al Stone <al.stone@linaro.org>
+- Graeme Gregory <graeme.gregory@linaro.org>
+- Hanjun Guo <hanjun.guo@linaro.org>
+
+- Grant Likely <grant.likely@linaro.org>, for the "Why ACPI on ARM?" section
diff --git a/Documentation/arch/arm64/asymmetric-32bit.rst b/Documentation/arch/arm64/asymmetric-32bit.rst
new file mode 100644
index 00000000000000..64a0b505da7d80
--- /dev/null
+++ b/Documentation/arch/arm64/asymmetric-32bit.rst
@@ -0,0 +1,155 @@
+======================
+Asymmetric 32-bit SoCs
+======================
+
+Author: Will Deacon <will@kernel.org>
+
+This document describes the impact of asymmetric 32-bit SoCs on the
+execution of 32-bit (``AArch32``) applications.
+
+Date: 2021-05-17
+
+Introduction
+============
+
+Some Armv9 SoCs suffer from a big.LITTLE misfeature where only a subset
+of the CPUs are capable of executing 32-bit user applications. On such
+a system, Linux by default treats the asymmetry as a "mismatch" and
+disables support for both the ``PER_LINUX32`` personality and
+``execve(2)`` of 32-bit ELF binaries, with the latter returning
+``-ENOEXEC``. If the mismatch is detected during late onlining of a
+64-bit-only CPU, then the onlining operation fails and the new CPU is
+unavailable for scheduling.
+
+Surprisingly, these SoCs have been produced with the intention of
+running legacy 32-bit binaries. Unsurprisingly, that doesn't work very
+well with the default behaviour of Linux.
+
+It seems inevitable that future SoCs will drop 32-bit support
+altogether, so if you're stuck in the unenviable position of needing to
+run 32-bit code on one of these transitionary platforms then you would
+be wise to consider alternatives such as recompilation, emulation or
+retirement. If neither of those options are practical, then read on.
+
+Enabling kernel support
+=======================
+
+Since the kernel support is not completely transparent to userspace,
+allowing 32-bit tasks to run on an asymmetric 32-bit system requires an
+explicit "opt-in" and can be enabled by passing the
+``allow_mismatched_32bit_el0`` parameter on the kernel command-line.
+
+For the remainder of this document we will refer to an *asymmetric
+system* to mean an asymmetric 32-bit SoC running Linux with this kernel
+command-line option enabled.
+
+Userspace impact
+================
+
+32-bit tasks running on an asymmetric system behave in mostly the same
+way as on a homogeneous system, with a few key differences relating to
+CPU affinity.
+
+sysfs
+-----
+
+The subset of CPUs capable of running 32-bit tasks is described in
+``/sys/devices/system/cpu/aarch32_el0`` and is documented further in
+``Documentation/ABI/testing/sysfs-devices-system-cpu``.
+
+**Note:** CPUs are advertised by this file as they are detected and so
+late-onlining of 32-bit-capable CPUs can result in the file contents
+being modified by the kernel at runtime. Once advertised, CPUs are never
+removed from the file.
+
+``execve(2)``
+-------------
+
+On a homogeneous system, the CPU affinity of a task is preserved across
+``execve(2)``. This is not always possible on an asymmetric system,
+specifically when the new program being executed is 32-bit yet the
+affinity mask contains 64-bit-only CPUs. In this situation, the kernel
+determines the new affinity mask as follows:
+
+  1. If the 32-bit-capable subset of the affinity mask is not empty,
+     then the affinity is restricted to that subset and the old affinity
+     mask is saved. This saved mask is inherited over ``fork(2)`` and
+     preserved across ``execve(2)`` of 32-bit programs.
+
+     **Note:** This step does not apply to ``SCHED_DEADLINE`` tasks.
+     See `SCHED_DEADLINE`_.
+
+  2. Otherwise, the cpuset hierarchy of the task is walked until an
+     ancestor is found containing at least one 32-bit-capable CPU. The
+     affinity of the task is then changed to match the 32-bit-capable
+     subset of the cpuset determined by the walk.
+
+  3. On failure (i.e. out of memory), the affinity is changed to the set
+     of all 32-bit-capable CPUs of which the kernel is aware.
+
+A subsequent ``execve(2)`` of a 64-bit program by the 32-bit task will
+invalidate the affinity mask saved in (1) and attempt to restore the CPU
+affinity of the task using the saved mask if it was previously valid.
+This restoration may fail due to intervening changes to the deadline
+policy or cpuset hierarchy, in which case the ``execve(2)`` continues
+with the affinity unchanged.
+
+Calls to ``sched_setaffinity(2)`` for a 32-bit task will consider only
+the 32-bit-capable CPUs of the requested affinity mask. On success, the
+affinity for the task is updated and any saved mask from a prior
+``execve(2)`` is invalidated.
+
+``SCHED_DEADLINE``
+------------------
+
+Explicit admission of a 32-bit deadline task to the default root domain
+(e.g. by calling ``sched_setattr(2)``) is rejected on an asymmetric
+32-bit system unless admission control is disabled by writing -1 to
+``/proc/sys/kernel/sched_rt_runtime_us``.
+
+``execve(2)`` of a 32-bit program from a 64-bit deadline task will
+return ``-ENOEXEC`` if the root domain for the task contains any
+64-bit-only CPUs and admission control is enabled. Concurrent offlining
+of 32-bit-capable CPUs may still necessitate the procedure described in
+`execve(2)`_, in which case step (1) is skipped and a warning is
+emitted on the console.
+
+**Note:** It is recommended that a set of 32-bit-capable CPUs are placed
+into a separate root domain if ``SCHED_DEADLINE`` is to be used with
+32-bit tasks on an asymmetric system. Failure to do so is likely to
+result in missed deadlines.
+
+Cpusets
+-------
+
+The affinity of a 32-bit task on an asymmetric system may include CPUs
+that are not explicitly allowed by the cpuset to which it is attached.
+This can occur as a result of the following two situations:
+
+  - A 64-bit task attached to a cpuset which allows only 64-bit CPUs
+    executes a 32-bit program.
+
+  - All of the 32-bit-capable CPUs allowed by a cpuset containing a
+    32-bit task are offlined.
+
+In both of these cases, the new affinity is calculated according to step
+(2) of the process described in `execve(2)`_ and the cpuset hierarchy is
+unchanged irrespective of the cgroup version.
+
+CPU hotplug
+-----------
+
+On an asymmetric system, the first detected 32-bit-capable CPU is
+prevented from being offlined by userspace and any such attempt will
+return ``-EPERM``. Note that suspend is still permitted even if the
+primary CPU (i.e. CPU 0) is 64-bit-only.
+
+KVM
+---
+
+Although KVM will not advertise 32-bit EL0 support to any vCPUs on an
+asymmetric system, a broken guest at EL1 could still attempt to execute
+32-bit code at EL0. In this case, an exit from a vCPU thread in 32-bit
+mode will return to host userspace with an ``exit_reason`` of
+``KVM_EXIT_FAIL_ENTRY`` and will remain non-runnable until successfully
+re-initialised by a subsequent ``KVM_ARM_VCPU_INIT`` operation.
diff --git a/Documentation/arch/arm64/booting.rst b/Documentation/arch/arm64/booting.rst
new file mode 100644
index 00000000000000..ffeccdd6bdac94
--- /dev/null
+++ b/Documentation/arch/arm64/booting.rst
@@ -0,0 +1,431 @@
+=====================
+Booting AArch64 Linux
+=====================
+
+Author: Will Deacon <will.deacon@arm.com>
+
+Date  : 07 September 2012
+
+This document is based on the ARM booting document by Russell King and
+is relevant to all public releases of the AArch64 Linux kernel.
+
+The AArch64 exception model is made up of a number of exception levels
+(EL0 - EL3), with EL0, EL1 and EL2 having a secure and a non-secure
+counterpart.  EL2 is the hypervisor level, EL3 is the highest priority
+level and exists only in secure mode. Both are architecturally optional.
+
+For the purposes of this document, we will use the term `boot loader`
+simply to define all software that executes on the CPU(s) before control
+is passed to the Linux kernel.  This may include secure monitor and
+hypervisor code, or it may just be a handful of instructions for
+preparing a minimal boot environment.
+
+Essentially, the boot loader should provide (as a minimum) the
+following:
+
+1. Setup and initialise the RAM
+2. Setup the device tree
+3. Decompress the kernel image
+4. Call the kernel image
+
+
+1. Setup and initialise RAM
+---------------------------
+
+Requirement: MANDATORY
+
+The boot loader is expected to find and initialise all RAM that the
+kernel will use for volatile data storage in the system.  It performs
+this in a machine dependent manner.  (It may use internal algorithms
+to automatically locate and size all RAM, or it may use knowledge of
+the RAM in the machine, or any other method the boot loader designer
+sees fit.)
+
+
+2. Setup the device tree
+-------------------------
+
+Requirement: MANDATORY
+
+The device tree blob (dtb) must be placed on an 8-byte boundary and must
+not exceed 2 megabytes in size. Since the dtb will be mapped cacheable
+using blocks of up to 2 megabytes in size, it must not be placed within
+any 2M region which must be mapped with any specific attributes.
+
+NOTE: versions prior to v4.2 also require that the DTB be placed within
+the 512 MB region starting at text_offset bytes below the kernel Image.
+
+3. Decompress the kernel image
+------------------------------
+
+Requirement: OPTIONAL
+
+The AArch64 kernel does not currently provide a decompressor and
+therefore requires decompression (gzip etc.) to be performed by the boot
+loader if a compressed Image target (e.g. Image.gz) is used.  For
+bootloaders that do not implement this requirement, the uncompressed
+Image target is available instead.
+
+
+4. Call the kernel image
+------------------------
+
+Requirement: MANDATORY
+
+The decompressed kernel image contains a 64-byte header as follows::
+
+  u32 code0;			/* Executable code */
+  u32 code1;			/* Executable code */
+  u64 text_offset;		/* Image load offset, little endian */
+  u64 image_size;		/* Effective Image size, little endian */
+  u64 flags;			/* kernel flags, little endian */
+  u64 res2	= 0;		/* reserved */
+  u64 res3	= 0;		/* reserved */
+  u64 res4	= 0;		/* reserved */
+  u32 magic	= 0x644d5241;	/* Magic number, little endian, "ARM\x64" */
+  u32 res5;			/* reserved (used for PE COFF offset) */
+
+
+Header notes:
+
+- As of v3.17, all fields are little endian unless stated otherwise.
+
+- code0/code1 are responsible for branching to stext.
+
+- when booting through EFI, code0/code1 are initially skipped.
+  res5 is an offset to the PE header and the PE header has the EFI
+  entry point (efi_stub_entry).  When the stub has done its work, it
+  jumps to code0 to resume the normal boot process.
+
+- Prior to v3.17, the endianness of text_offset was not specified.  In
+  these cases image_size is zero and text_offset is 0x80000 in the
+  endianness of the kernel.  Where image_size is non-zero image_size is
+  little-endian and must be respected.  Where image_size is zero,
+  text_offset can be assumed to be 0x80000.
+
+- The flags field (introduced in v3.17) is a little-endian 64-bit field
+  composed as follows:
+
+  ============= ===============================================================
+  Bit 0		Kernel endianness.  1 if BE, 0 if LE.
+  Bit 1-2	Kernel Page size.
+
+			* 0 - Unspecified.
+			* 1 - 4K
+			* 2 - 16K
+			* 3 - 64K
+  Bit 3		Kernel physical placement
+
+			0
+			  2MB aligned base should be as close as possible
+			  to the base of DRAM, since memory below it is not
+			  accessible via the linear mapping
+			1
+			  2MB aligned base such that all image_size bytes
+			  counted from the start of the image are within
+			  the 48-bit addressable range of physical memory
+  Bits 4-63	Reserved.
+  ============= ===============================================================
+
+- When image_size is zero, a bootloader should attempt to keep as much
+  memory as possible free for use by the kernel immediately after the
+  end of the kernel image. The amount of space required will vary
+  depending on selected features, and is effectively unbound.
+
+The Image must be placed text_offset bytes from a 2MB aligned base
+address anywhere in usable system RAM and called there. The region
+between the 2 MB aligned base address and the start of the image has no
+special significance to the kernel, and may be used for other purposes.
+At least image_size bytes from the start of the image must be free for
+use by the kernel.
+NOTE: versions prior to v4.6 cannot make use of memory below the
+physical offset of the Image so it is recommended that the Image be
+placed as close as possible to the start of system RAM.
+
+If an initrd/initramfs is passed to the kernel at boot, it must reside
+entirely within a 1 GB aligned physical memory window of up to 32 GB in
+size that fully covers the kernel Image as well.
+
+Any memory described to the kernel (even that below the start of the
+image) which is not marked as reserved from the kernel (e.g., with a
+memreserve region in the device tree) will be considered as available to
+the kernel.
+
+Before jumping into the kernel, the following conditions must be met:
+
+- Quiesce all DMA capable devices so that memory does not get
+  corrupted by bogus network packets or disk data.  This will save
+  you many hours of debug.
+
+- Primary CPU general-purpose register settings:
+
+    - x0 = physical address of device tree blob (dtb) in system RAM.
+    - x1 = 0 (reserved for future use)
+    - x2 = 0 (reserved for future use)
+    - x3 = 0 (reserved for future use)
+
+- CPU mode
+
+  All forms of interrupts must be masked in PSTATE.DAIF (Debug, SError,
+  IRQ and FIQ).
+  The CPU must be in non-secure state, either in EL2 (RECOMMENDED in order
+  to have access to the virtualisation extensions), or in EL1.
+
+- Caches, MMUs
+
+  The MMU must be off.
+
+  The instruction cache may be on or off, and must not hold any stale
+  entries corresponding to the loaded kernel image.
+
+  The address range corresponding to the loaded kernel image must be
+  cleaned to the PoC. In the presence of a system cache or other
+  coherent masters with caches enabled, this will typically require
+  cache maintenance by VA rather than set/way operations.
+  System caches which respect the architected cache maintenance by VA
+  operations must be configured and may be enabled.
+  System caches which do not respect architected cache maintenance by VA
+  operations (not recommended) must be configured and disabled.
+
+- Architected timers
+
+  CNTFRQ must be programmed with the timer frequency and CNTVOFF must
+  be programmed with a consistent value on all CPUs.  If entering the
+  kernel at EL1, CNTHCTL_EL2 must have EL1PCTEN (bit 0) set where
+  available.
+
+- Coherency
+
+  All CPUs to be booted by the kernel must be part of the same coherency
+  domain on entry to the kernel.  This may require IMPLEMENTATION DEFINED
+  initialisation to enable the receiving of maintenance operations on
+  each CPU.
+
+- System registers
+
+  All writable architected system registers at or below the exception
+  level where the kernel image will be entered must be initialised by
+  software at a higher exception level to prevent execution in an UNKNOWN
+  state.
+
+  For all systems:
+  - If EL3 is present:
+
+    - SCR_EL3.FIQ must have the same value across all CPUs the kernel is
+      executing on.
+    - The value of SCR_EL3.FIQ must be the same as the one present at boot
+      time whenever the kernel is executing.
+
+  - If EL3 is present and the kernel is entered at EL2:
+
+    - SCR_EL3.HCE (bit 8) must be initialised to 0b1.
+
+  For systems with a GICv3 interrupt controller to be used in v3 mode:
+  - If EL3 is present:
+
+      - ICC_SRE_EL3.Enable (bit 3) must be initialised to 0b1.
+      - ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b1.
+      - ICC_CTLR_EL3.PMHE (bit 6) must be set to the same value across
+        all CPUs the kernel is executing on, and must stay constant
+        for the lifetime of the kernel.
+
+  - If the kernel is entered at EL1:
+
+      - ICC.SRE_EL2.Enable (bit 3) must be initialised to 0b1
+      - ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b1.
+
+  - The DT or ACPI tables must describe a GICv3 interrupt controller.
+
+  For systems with a GICv3 interrupt controller to be used in
+  compatibility (v2) mode:
+
+  - If EL3 is present:
+
+      ICC_SRE_EL3.SRE (bit 0) must be initialised to 0b0.
+
+  - If the kernel is entered at EL1:
+
+      ICC_SRE_EL2.SRE (bit 0) must be initialised to 0b0.
+
+  - The DT or ACPI tables must describe a GICv2 interrupt controller.
+
+  For CPUs with pointer authentication functionality:
+
+  - If EL3 is present:
+
+    - SCR_EL3.APK (bit 16) must be initialised to 0b1
+    - SCR_EL3.API (bit 17) must be initialised to 0b1
+
+  - If the kernel is entered at EL1:
+
+    - HCR_EL2.APK (bit 40) must be initialised to 0b1
+    - HCR_EL2.API (bit 41) must be initialised to 0b1
+
+  For CPUs with Activity Monitors Unit v1 (AMUv1) extension present:
+
+  - If EL3 is present:
+
+    - CPTR_EL3.TAM (bit 30) must be initialised to 0b0
+    - CPTR_EL2.TAM (bit 30) must be initialised to 0b0
+    - AMCNTENSET0_EL0 must be initialised to 0b1111
+    - AMCNTENSET1_EL0 must be initialised to a platform specific value
+      having 0b1 set for the corresponding bit for each of the auxiliary
+      counters present.
+
+  - If the kernel is entered at EL1:
+
+    - AMCNTENSET0_EL0 must be initialised to 0b1111
+    - AMCNTENSET1_EL0 must be initialised to a platform specific value
+      having 0b1 set for the corresponding bit for each of the auxiliary
+      counters present.
+
+  For CPUs with the Fine Grained Traps (FEAT_FGT) extension present:
+
+  - If EL3 is present and the kernel is entered at EL2:
+
+    - SCR_EL3.FGTEn (bit 27) must be initialised to 0b1.
+
+  For CPUs with support for HCRX_EL2 (FEAT_HCX) present:
+
+  - If EL3 is present and the kernel is entered at EL2:
+
+    - SCR_EL3.HXEn (bit 38) must be initialised to 0b1.
+
+  For CPUs with Advanced SIMD and floating point support:
+
+  - If EL3 is present:
+
+    - CPTR_EL3.TFP (bit 10) must be initialised to 0b0.
+
+  - If EL2 is present and the kernel is entered at EL1:
+
+    - CPTR_EL2.TFP (bit 10) must be initialised to 0b0.
+
+  For CPUs with the Scalable Vector Extension (FEAT_SVE) present:
+
+  - if EL3 is present:
+
+    - CPTR_EL3.EZ (bit 8) must be initialised to 0b1.
+
+    - ZCR_EL3.LEN must be initialised to the same value for all CPUs the
+      kernel is executed on.
+
+  - If the kernel is entered at EL1 and EL2 is present:
+
+    - CPTR_EL2.TZ (bit 8) must be initialised to 0b0.
+
+    - CPTR_EL2.ZEN (bits 17:16) must be initialised to 0b11.
+
+    - ZCR_EL2.LEN must be initialised to the same value for all CPUs the
+      kernel will execute on.
+
+  For CPUs with the Scalable Matrix Extension (FEAT_SME):
+
+  - If EL3 is present:
+
+    - CPTR_EL3.ESM (bit 12) must be initialised to 0b1.
+
+    - SCR_EL3.EnTP2 (bit 41) must be initialised to 0b1.
+
+    - SMCR_EL3.LEN must be initialised to the same value for all CPUs the
+      kernel will execute on.
+
+ - If the kernel is entered at EL1 and EL2 is present:
+
+    - CPTR_EL2.TSM (bit 12) must be initialised to 0b0.
+
+    - CPTR_EL2.SMEN (bits 25:24) must be initialised to 0b11.
+
+    - SCTLR_EL2.EnTP2 (bit 60) must be initialised to 0b1.
+
+    - SMCR_EL2.LEN must be initialised to the same value for all CPUs the
+      kernel will execute on.
+
+    - HWFGRTR_EL2.nTPIDR2_EL0 (bit 55) must be initialised to 0b01.
+
+    - HWFGWTR_EL2.nTPIDR2_EL0 (bit 55) must be initialised to 0b01.
+
+    - HWFGRTR_EL2.nSMPRI_EL1 (bit 54) must be initialised to 0b01.
+
+    - HWFGWTR_EL2.nSMPRI_EL1 (bit 54) must be initialised to 0b01.
+
+  For CPUs with the Scalable Matrix Extension FA64 feature (FEAT_SME_FA64):
+
+  - If EL3 is present:
+
+    - SMCR_EL3.FA64 (bit 31) must be initialised to 0b1.
+
+ - If the kernel is entered at EL1 and EL2 is present:
+
+    - SMCR_EL2.FA64 (bit 31) must be initialised to 0b1.
+
+  For CPUs with the Memory Tagging Extension feature (FEAT_MTE2):
+
+  - If EL3 is present:
+
+    - SCR_EL3.ATA (bit 26) must be initialised to 0b1.
+
+  - If the kernel is entered at EL1 and EL2 is present:
+
+    - HCR_EL2.ATA (bit 56) must be initialised to 0b1.
+
+  For CPUs with the Scalable Matrix Extension version 2 (FEAT_SME2):
+
+  - If EL3 is present:
+
+    - SMCR_EL3.EZT0 (bit 30) must be initialised to 0b1.
+
+ - If the kernel is entered at EL1 and EL2 is present:
+
+    - SMCR_EL2.EZT0 (bit 30) must be initialised to 0b1.
+
+The requirements described above for CPU mode, caches, MMUs, architected
+timers, coherency and system registers apply to all CPUs.  All CPUs must
+enter the kernel in the same exception level.  Where the values documented
+disable traps it is permissible for these traps to be enabled so long as
+those traps are handled transparently by higher exception levels as though
+the values documented were set.
+
+The boot loader is expected to enter the kernel on each CPU in the
+following manner:
+
+- The primary CPU must jump directly to the first instruction of the
+  kernel image.  The device tree blob passed by this CPU must contain
+  an 'enable-method' property for each cpu node.  The supported
+  enable-methods are described below.
+
+  It is expected that the bootloader will generate these device tree
+  properties and insert them into the blob prior to kernel entry.
+
+- CPUs with a "spin-table" enable-method must have a 'cpu-release-addr'
+  property in their cpu node.  This property identifies a
+  naturally-aligned 64-bit zero-initalised memory location.
+
+  These CPUs should spin outside of the kernel in a reserved area of
+  memory (communicated to the kernel by a /memreserve/ region in the
+  device tree) polling their cpu-release-addr location, which must be
+  contained in the reserved region.  A wfe instruction may be inserted
+  to reduce the overhead of the busy-loop and a sev will be issued by
+  the primary CPU.  When a read of the location pointed to by the
+  cpu-release-addr returns a non-zero value, the CPU must jump to this
+  value.  The value will be written as a single 64-bit little-endian
+  value, so CPUs must convert the read value to their native endianness
+  before jumping to it.
+
+- CPUs with a "psci" enable method should remain outside of
+  the kernel (i.e. outside of the regions of memory described to the
+  kernel in the memory node, or in a reserved area of memory described
+  to the kernel by a /memreserve/ region in the device tree).  The
+  kernel will issue CPU_ON calls as described in ARM document number ARM
+  DEN 0022A ("Power State Coordination Interface System Software on ARM
+  processors") to bring CPUs into the kernel.
+
+  The device tree should contain a 'psci' node, as described in
+  Documentation/devicetree/bindings/arm/psci.yaml.
+
+- Secondary CPU general-purpose register settings
+
+  - x0 = 0 (reserved for future use)
+  - x1 = 0 (reserved for future use)
+  - x2 = 0 (reserved for future use)
+  - x3 = 0 (reserved for future use)
diff --git a/Documentation/arch/arm64/cpu-feature-registers.rst b/Documentation/arch/arm64/cpu-feature-registers.rst
new file mode 100644
index 00000000000000..c7adc7897df606
--- /dev/null
+++ b/Documentation/arch/arm64/cpu-feature-registers.rst
@@ -0,0 +1,400 @@
+===========================
+ARM64 CPU Feature Registers
+===========================
+
+Author: Suzuki K Poulose <suzuki.poulose@arm.com>
+
+
+This file describes the ABI for exporting the AArch64 CPU ID/feature
+registers to userspace. The availability of this ABI is advertised
+via the HWCAP_CPUID in HWCAPs.
+
+1. Motivation
+-------------
+
+The ARM architecture defines a set of feature registers, which describe
+the capabilities of the CPU/system. Access to these system registers is
+restricted from EL0 and there is no reliable way for an application to
+extract this information to make better decisions at runtime. There is
+limited information available to the application via HWCAPs, however
+there are some issues with their usage.
+
+ a) Any change to the HWCAPs requires an update to userspace (e.g libc)
+    to detect the new changes, which can take a long time to appear in
+    distributions. Exposing the registers allows applications to get the
+    information without requiring updates to the toolchains.
+
+ b) Access to HWCAPs is sometimes limited (e.g prior to libc, or
+    when ld is initialised at startup time).
+
+ c) HWCAPs cannot represent non-boolean information effectively. The
+    architecture defines a canonical format for representing features
+    in the ID registers; this is well defined and is capable of
+    representing all valid architecture variations.
+
+
+2. Requirements
+---------------
+
+ a) Safety:
+
+    Applications should be able to use the information provided by the
+    infrastructure to run safely across the system. This has greater
+    implications on a system with heterogeneous CPUs.
+    The infrastructure exports a value that is safe across all the
+    available CPU on the system.
+
+    e.g, If at least one CPU doesn't implement CRC32 instructions, while
+    others do, we should report that the CRC32 is not implemented.
+    Otherwise an application could crash when scheduled on the CPU
+    which doesn't support CRC32.
+
+ b) Security:
+
+    Applications should only be able to receive information that is
+    relevant to the normal operation in userspace. Hence, some of the
+    fields are masked out(i.e, made invisible) and their values are set to
+    indicate the feature is 'not supported'. See Section 4 for the list
+    of visible features. Also, the kernel may manipulate the fields
+    based on what it supports. e.g, If FP is not supported by the
+    kernel, the values could indicate that the FP is not available
+    (even when the CPU provides it).
+
+ c) Implementation Defined Features
+
+    The infrastructure doesn't expose any register which is
+    IMPLEMENTATION DEFINED as per ARMv8-A Architecture.
+
+ d) CPU Identification:
+
+    MIDR_EL1 is exposed to help identify the processor. On a
+    heterogeneous system, this could be racy (just like getcpu()). The
+    process could be migrated to another CPU by the time it uses the
+    register value, unless the CPU affinity is set. Hence, there is no
+    guarantee that the value reflects the processor that it is
+    currently executing on. The REVIDR is not exposed due to this
+    constraint, as REVIDR makes sense only in conjunction with the
+    MIDR. Alternately, MIDR_EL1 and REVIDR_EL1 are exposed via sysfs
+    at::
+
+	/sys/devices/system/cpu/cpu$ID/regs/identification/
+	                                              \- midr
+	                                              \- revidr
+
+3. Implementation
+--------------------
+
+The infrastructure is built on the emulation of the 'MRS' instruction.
+Accessing a restricted system register from an application generates an
+exception and ends up in SIGILL being delivered to the process.
+The infrastructure hooks into the exception handler and emulates the
+operation if the source belongs to the supported system register space.
+
+The infrastructure emulates only the following system register space::
+
+	Op0=3, Op1=0, CRn=0, CRm=0,2,3,4,5,6,7
+
+(See Table C5-6 'System instruction encodings for non-Debug System
+register accesses' in ARMv8 ARM DDI 0487A.h, for the list of
+registers).
+
+The following rules are applied to the value returned by the
+infrastructure:
+
+ a) The value of an 'IMPLEMENTATION DEFINED' field is set to 0.
+ b) The value of a reserved field is populated with the reserved
+    value as defined by the architecture.
+ c) The value of a 'visible' field holds the system wide safe value
+    for the particular feature (except for MIDR_EL1, see section 4).
+ d) All other fields (i.e, invisible fields) are set to indicate
+    the feature is missing (as defined by the architecture).
+
+4. List of registers with visible features
+-------------------------------------------
+
+  1) ID_AA64ISAR0_EL1 - Instruction Set Attribute Register 0
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | RNDR                         | [63-60] |    y    |
+     +------------------------------+---------+---------+
+     | TS                           | [55-52] |    y    |
+     +------------------------------+---------+---------+
+     | FHM                          | [51-48] |    y    |
+     +------------------------------+---------+---------+
+     | DP                           | [47-44] |    y    |
+     +------------------------------+---------+---------+
+     | SM4                          | [43-40] |    y    |
+     +------------------------------+---------+---------+
+     | SM3                          | [39-36] |    y    |
+     +------------------------------+---------+---------+
+     | SHA3                         | [35-32] |    y    |
+     +------------------------------+---------+---------+
+     | RDM                          | [31-28] |    y    |
+     +------------------------------+---------+---------+
+     | ATOMICS                      | [23-20] |    y    |
+     +------------------------------+---------+---------+
+     | CRC32                        | [19-16] |    y    |
+     +------------------------------+---------+---------+
+     | SHA2                         | [15-12] |    y    |
+     +------------------------------+---------+---------+
+     | SHA1                         | [11-8]  |    y    |
+     +------------------------------+---------+---------+
+     | AES                          | [7-4]   |    y    |
+     +------------------------------+---------+---------+
+
+
+  2) ID_AA64PFR0_EL1 - Processor Feature Register 0
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | DIT                          | [51-48] |    y    |
+     +------------------------------+---------+---------+
+     | SVE                          | [35-32] |    y    |
+     +------------------------------+---------+---------+
+     | GIC                          | [27-24] |    n    |
+     +------------------------------+---------+---------+
+     | AdvSIMD                      | [23-20] |    y    |
+     +------------------------------+---------+---------+
+     | FP                           | [19-16] |    y    |
+     +------------------------------+---------+---------+
+     | EL3                          | [15-12] |    n    |
+     +------------------------------+---------+---------+
+     | EL2                          | [11-8]  |    n    |
+     +------------------------------+---------+---------+
+     | EL1                          | [7-4]   |    n    |
+     +------------------------------+---------+---------+
+     | EL0                          | [3-0]   |    n    |
+     +------------------------------+---------+---------+
+
+
+  3) ID_AA64PFR1_EL1 - Processor Feature Register 1
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | MTE                          | [11-8]  |    y    |
+     +------------------------------+---------+---------+
+     | SSBS                         | [7-4]   |    y    |
+     +------------------------------+---------+---------+
+     | BT                           | [3-0]   |    y    |
+     +------------------------------+---------+---------+
+
+
+  4) MIDR_EL1 - Main ID Register
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | Implementer                  | [31-24] |    y    |
+     +------------------------------+---------+---------+
+     | Variant                      | [23-20] |    y    |
+     +------------------------------+---------+---------+
+     | Architecture                 | [19-16] |    y    |
+     +------------------------------+---------+---------+
+     | PartNum                      | [15-4]  |    y    |
+     +------------------------------+---------+---------+
+     | Revision                     | [3-0]   |    y    |
+     +------------------------------+---------+---------+
+
+   NOTE: The 'visible' fields of MIDR_EL1 will contain the value
+   as available on the CPU where it is fetched and is not a system
+   wide safe value.
+
+  5) ID_AA64ISAR1_EL1 - Instruction set attribute register 1
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | I8MM                         | [55-52] |    y    |
+     +------------------------------+---------+---------+
+     | DGH                          | [51-48] |    y    |
+     +------------------------------+---------+---------+
+     | BF16                         | [47-44] |    y    |
+     +------------------------------+---------+---------+
+     | SB                           | [39-36] |    y    |
+     +------------------------------+---------+---------+
+     | FRINTTS                      | [35-32] |    y    |
+     +------------------------------+---------+---------+
+     | GPI                          | [31-28] |    y    |
+     +------------------------------+---------+---------+
+     | GPA                          | [27-24] |    y    |
+     +------------------------------+---------+---------+
+     | LRCPC                        | [23-20] |    y    |
+     +------------------------------+---------+---------+
+     | FCMA                         | [19-16] |    y    |
+     +------------------------------+---------+---------+
+     | JSCVT                        | [15-12] |    y    |
+     +------------------------------+---------+---------+
+     | API                          | [11-8]  |    y    |
+     +------------------------------+---------+---------+
+     | APA                          | [7-4]   |    y    |
+     +------------------------------+---------+---------+
+     | DPB                          | [3-0]   |    y    |
+     +------------------------------+---------+---------+
+
+  6) ID_AA64MMFR0_EL1 - Memory model feature register 0
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | ECV                          | [63-60] |    y    |
+     +------------------------------+---------+---------+
+
+  7) ID_AA64MMFR2_EL1 - Memory model feature register 2
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | AT                           | [35-32] |    y    |
+     +------------------------------+---------+---------+
+
+  8) ID_AA64ZFR0_EL1 - SVE feature ID register 0
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | F64MM                        | [59-56] |    y    |
+     +------------------------------+---------+---------+
+     | F32MM                        | [55-52] |    y    |
+     +------------------------------+---------+---------+
+     | I8MM                         | [47-44] |    y    |
+     +------------------------------+---------+---------+
+     | SM4                          | [43-40] |    y    |
+     +------------------------------+---------+---------+
+     | SHA3                         | [35-32] |    y    |
+     +------------------------------+---------+---------+
+     | BF16                         | [23-20] |    y    |
+     +------------------------------+---------+---------+
+     | BitPerm                      | [19-16] |    y    |
+     +------------------------------+---------+---------+
+     | AES                          | [7-4]   |    y    |
+     +------------------------------+---------+---------+
+     | SVEVer                       | [3-0]   |    y    |
+     +------------------------------+---------+---------+
+
+  8) ID_AA64MMFR1_EL1 - Memory model feature register 1
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | AFP                          | [47-44] |    y    |
+     +------------------------------+---------+---------+
+
+  9) ID_AA64ISAR2_EL1 - Instruction set attribute register 2
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | RPRES                        | [7-4]   |    y    |
+     +------------------------------+---------+---------+
+     | WFXT                         | [3-0]   |    y    |
+     +------------------------------+---------+---------+
+
+  10) MVFR0_EL1 - AArch32 Media and VFP Feature Register 0
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | FPDP                         | [11-8]  |    y    |
+     +------------------------------+---------+---------+
+
+  11) MVFR1_EL1 - AArch32 Media and VFP Feature Register 1
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | SIMDFMAC                     | [31-28] |    y    |
+     +------------------------------+---------+---------+
+     | SIMDSP                       | [19-16] |    y    |
+     +------------------------------+---------+---------+
+     | SIMDInt                      | [15-12] |    y    |
+     +------------------------------+---------+---------+
+     | SIMDLS                       | [11-8]  |    y    |
+     +------------------------------+---------+---------+
+
+  12) ID_ISAR5_EL1 - AArch32 Instruction Set Attribute Register 5
+
+     +------------------------------+---------+---------+
+     | Name                         |  bits   | visible |
+     +------------------------------+---------+---------+
+     | CRC32                        | [19-16] |    y    |
+     +------------------------------+---------+---------+
+     | SHA2                         | [15-12] |    y    |
+     +------------------------------+---------+---------+
+     | SHA1                         | [11-8]  |    y    |
+     +------------------------------+---------+---------+
+     | AES                          | [7-4]   |    y    |
+     +------------------------------+---------+---------+
+
+
+Appendix I: Example
+-------------------
+
+::
+
+  /*
+   * Sample program to demonstrate the MRS emulation ABI.
+   *
+   * Copyright (C) 2015-2016, ARM Ltd
+   *
+   * Author: Suzuki K Poulose <suzuki.poulose@arm.com>
+   *
+   * This program is free software; you can redistribute it and/or modify
+   * it under the terms of the GNU General Public License version 2 as
+   * published by the Free Software Foundation.
+   *
+   * This program is distributed in the hope that it will be useful,
+   * but WITHOUT ANY WARRANTY; without even the implied warranty of
+   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   * GNU General Public License for more details.
+   * This program is free software; you can redistribute it and/or modify
+   * it under the terms of the GNU General Public License version 2 as
+   * published by the Free Software Foundation.
+   *
+   * This program is distributed in the hope that it will be useful,
+   * but WITHOUT ANY WARRANTY; without even the implied warranty of
+   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   * GNU General Public License for more details.
+   */
+
+  #include <asm/hwcap.h>
+  #include <stdio.h>
+  #include <sys/auxv.h>
+
+  #define get_cpu_ftr(id) ({					\
+		unsigned long __val;				\
+		asm("mrs %0, "#id : "=r" (__val));		\
+		printf("%-20s: 0x%016lx\n", #id, __val);	\
+	})
+
+  int main(void)
+  {
+
+	if (!(getauxval(AT_HWCAP) & HWCAP_CPUID)) {
+		fputs("CPUID registers unavailable\n", stderr);
+		return 1;
+	}
+
+	get_cpu_ftr(ID_AA64ISAR0_EL1);
+	get_cpu_ftr(ID_AA64ISAR1_EL1);
+	get_cpu_ftr(ID_AA64MMFR0_EL1);
+	get_cpu_ftr(ID_AA64MMFR1_EL1);
+	get_cpu_ftr(ID_AA64PFR0_EL1);
+	get_cpu_ftr(ID_AA64PFR1_EL1);
+	get_cpu_ftr(ID_AA64DFR0_EL1);
+	get_cpu_ftr(ID_AA64DFR1_EL1);
+
+	get_cpu_ftr(MIDR_EL1);
+	get_cpu_ftr(MPIDR_EL1);
+	get_cpu_ftr(REVIDR_EL1);
+
+  #if 0
+	/* Unexposed register access causes SIGILL */
+	get_cpu_ftr(ID_MMFR0_EL1);
+  #endif
+
+	return 0;
+  }
diff --git a/Documentation/arch/arm64/elf_hwcaps.rst b/Documentation/arch/arm64/elf_hwcaps.rst
new file mode 100644
index 00000000000000..58a86d5322284c
--- /dev/null
+++ b/Documentation/arch/arm64/elf_hwcaps.rst
@@ -0,0 +1,309 @@
+.. _elf_hwcaps_index:
+
+================
+ARM64 ELF hwcaps
+================
+
+This document describes the usage and semantics of the arm64 ELF hwcaps.
+
+
+1. Introduction
+---------------
+
+Some hardware or software features are only available on some CPU
+implementations, and/or with certain kernel configurations, but have no
+architected discovery mechanism available to userspace code at EL0. The
+kernel exposes the presence of these features to userspace through a set
+of flags called hwcaps, exposed in the auxiliary vector.
+
+Userspace software can test for features by acquiring the AT_HWCAP or
+AT_HWCAP2 entry of the auxiliary vector, and testing whether the relevant
+flags are set, e.g.::
+
+	bool floating_point_is_present(void)
+	{
+		unsigned long hwcaps = getauxval(AT_HWCAP);
+		if (hwcaps & HWCAP_FP)
+			return true;
+
+		return false;
+	}
+
+Where software relies on a feature described by a hwcap, it should check
+the relevant hwcap flag to verify that the feature is present before
+attempting to make use of the feature.
+
+Features cannot be probed reliably through other means. When a feature
+is not available, attempting to use it may result in unpredictable
+behaviour, and is not guaranteed to result in any reliable indication
+that the feature is unavailable, such as a SIGILL.
+
+
+2. Interpretation of hwcaps
+---------------------------
+
+The majority of hwcaps are intended to indicate the presence of features
+which are described by architected ID registers inaccessible to
+userspace code at EL0. These hwcaps are defined in terms of ID register
+fields, and should be interpreted with reference to the definition of
+these fields in the ARM Architecture Reference Manual (ARM ARM).
+
+Such hwcaps are described below in the form::
+
+    Functionality implied by idreg.field == val.
+
+Such hwcaps indicate the availability of functionality that the ARM ARM
+defines as being present when idreg.field has value val, but do not
+indicate that idreg.field is precisely equal to val, nor do they
+indicate the absence of functionality implied by other values of
+idreg.field.
+
+Other hwcaps may indicate the presence of features which cannot be
+described by ID registers alone. These may be described without
+reference to ID registers, and may refer to other documentation.
+
+
+3. The hwcaps exposed in AT_HWCAP
+---------------------------------
+
+HWCAP_FP
+    Functionality implied by ID_AA64PFR0_EL1.FP == 0b0000.
+
+HWCAP_ASIMD
+    Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0000.
+
+HWCAP_EVTSTRM
+    The generic timer is configured to generate events at a frequency of
+    approximately 10KHz.
+
+HWCAP_AES
+    Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0001.
+
+HWCAP_PMULL
+    Functionality implied by ID_AA64ISAR0_EL1.AES == 0b0010.
+
+HWCAP_SHA1
+    Functionality implied by ID_AA64ISAR0_EL1.SHA1 == 0b0001.
+
+HWCAP_SHA2
+    Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0001.
+
+HWCAP_CRC32
+    Functionality implied by ID_AA64ISAR0_EL1.CRC32 == 0b0001.
+
+HWCAP_ATOMICS
+    Functionality implied by ID_AA64ISAR0_EL1.Atomic == 0b0010.
+
+HWCAP_FPHP
+    Functionality implied by ID_AA64PFR0_EL1.FP == 0b0001.
+
+HWCAP_ASIMDHP
+    Functionality implied by ID_AA64PFR0_EL1.AdvSIMD == 0b0001.
+
+HWCAP_CPUID
+    EL0 access to certain ID registers is available, to the extent
+    described by Documentation/arch/arm64/cpu-feature-registers.rst.
+
+    These ID registers may imply the availability of features.
+
+HWCAP_ASIMDRDM
+    Functionality implied by ID_AA64ISAR0_EL1.RDM == 0b0001.
+
+HWCAP_JSCVT
+    Functionality implied by ID_AA64ISAR1_EL1.JSCVT == 0b0001.
+
+HWCAP_FCMA
+    Functionality implied by ID_AA64ISAR1_EL1.FCMA == 0b0001.
+
+HWCAP_LRCPC
+    Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0001.
+
+HWCAP_DCPOP
+    Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0001.
+
+HWCAP_SHA3
+    Functionality implied by ID_AA64ISAR0_EL1.SHA3 == 0b0001.
+
+HWCAP_SM3
+    Functionality implied by ID_AA64ISAR0_EL1.SM3 == 0b0001.
+
+HWCAP_SM4
+    Functionality implied by ID_AA64ISAR0_EL1.SM4 == 0b0001.
+
+HWCAP_ASIMDDP
+    Functionality implied by ID_AA64ISAR0_EL1.DP == 0b0001.
+
+HWCAP_SHA512
+    Functionality implied by ID_AA64ISAR0_EL1.SHA2 == 0b0010.
+
+HWCAP_SVE
+    Functionality implied by ID_AA64PFR0_EL1.SVE == 0b0001.
+
+HWCAP_ASIMDFHM
+   Functionality implied by ID_AA64ISAR0_EL1.FHM == 0b0001.
+
+HWCAP_DIT
+    Functionality implied by ID_AA64PFR0_EL1.DIT == 0b0001.
+
+HWCAP_USCAT
+    Functionality implied by ID_AA64MMFR2_EL1.AT == 0b0001.
+
+HWCAP_ILRCPC
+    Functionality implied by ID_AA64ISAR1_EL1.LRCPC == 0b0010.
+
+HWCAP_FLAGM
+    Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0001.
+
+HWCAP_SSBS
+    Functionality implied by ID_AA64PFR1_EL1.SSBS == 0b0010.
+
+HWCAP_SB
+    Functionality implied by ID_AA64ISAR1_EL1.SB == 0b0001.
+
+HWCAP_PACA
+    Functionality implied by ID_AA64ISAR1_EL1.APA == 0b0001 or
+    ID_AA64ISAR1_EL1.API == 0b0001, as described by
+    Documentation/arch/arm64/pointer-authentication.rst.
+
+HWCAP_PACG
+    Functionality implied by ID_AA64ISAR1_EL1.GPA == 0b0001 or
+    ID_AA64ISAR1_EL1.GPI == 0b0001, as described by
+    Documentation/arch/arm64/pointer-authentication.rst.
+
+HWCAP2_DCPODP
+    Functionality implied by ID_AA64ISAR1_EL1.DPB == 0b0010.
+
+HWCAP2_SVE2
+    Functionality implied by ID_AA64ZFR0_EL1.SVEVer == 0b0001.
+
+HWCAP2_SVEAES
+    Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0001.
+
+HWCAP2_SVEPMULL
+    Functionality implied by ID_AA64ZFR0_EL1.AES == 0b0010.
+
+HWCAP2_SVEBITPERM
+    Functionality implied by ID_AA64ZFR0_EL1.BitPerm == 0b0001.
+
+HWCAP2_SVESHA3
+    Functionality implied by ID_AA64ZFR0_EL1.SHA3 == 0b0001.
+
+HWCAP2_SVESM4
+    Functionality implied by ID_AA64ZFR0_EL1.SM4 == 0b0001.
+
+HWCAP2_FLAGM2
+    Functionality implied by ID_AA64ISAR0_EL1.TS == 0b0010.
+
+HWCAP2_FRINT
+    Functionality implied by ID_AA64ISAR1_EL1.FRINTTS == 0b0001.
+
+HWCAP2_SVEI8MM
+    Functionality implied by ID_AA64ZFR0_EL1.I8MM == 0b0001.
+
+HWCAP2_SVEF32MM
+    Functionality implied by ID_AA64ZFR0_EL1.F32MM == 0b0001.
+
+HWCAP2_SVEF64MM
+    Functionality implied by ID_AA64ZFR0_EL1.F64MM == 0b0001.
+
+HWCAP2_SVEBF16
+    Functionality implied by ID_AA64ZFR0_EL1.BF16 == 0b0001.
+
+HWCAP2_I8MM
+    Functionality implied by ID_AA64ISAR1_EL1.I8MM == 0b0001.
+
+HWCAP2_BF16
+    Functionality implied by ID_AA64ISAR1_EL1.BF16 == 0b0001.
+
+HWCAP2_DGH
+    Functionality implied by ID_AA64ISAR1_EL1.DGH == 0b0001.
+
+HWCAP2_RNG
+    Functionality implied by ID_AA64ISAR0_EL1.RNDR == 0b0001.
+
+HWCAP2_BTI
+    Functionality implied by ID_AA64PFR0_EL1.BT == 0b0001.
+
+HWCAP2_MTE
+    Functionality implied by ID_AA64PFR1_EL1.MTE == 0b0010, as described
+    by Documentation/arch/arm64/memory-tagging-extension.rst.
+
+HWCAP2_ECV
+    Functionality implied by ID_AA64MMFR0_EL1.ECV == 0b0001.
+
+HWCAP2_AFP
+    Functionality implied by ID_AA64MFR1_EL1.AFP == 0b0001.
+
+HWCAP2_RPRES
+    Functionality implied by ID_AA64ISAR2_EL1.RPRES == 0b0001.
+
+HWCAP2_MTE3
+    Functionality implied by ID_AA64PFR1_EL1.MTE == 0b0011, as described
+    by Documentation/arch/arm64/memory-tagging-extension.rst.
+
+HWCAP2_SME
+    Functionality implied by ID_AA64PFR1_EL1.SME == 0b0001, as described
+    by Documentation/arch/arm64/sme.rst.
+
+HWCAP2_SME_I16I64
+    Functionality implied by ID_AA64SMFR0_EL1.I16I64 == 0b1111.
+
+HWCAP2_SME_F64F64
+    Functionality implied by ID_AA64SMFR0_EL1.F64F64 == 0b1.
+
+HWCAP2_SME_I8I32
+    Functionality implied by ID_AA64SMFR0_EL1.I8I32 == 0b1111.
+
+HWCAP2_SME_F16F32
+    Functionality implied by ID_AA64SMFR0_EL1.F16F32 == 0b1.
+
+HWCAP2_SME_B16F32
+    Functionality implied by ID_AA64SMFR0_EL1.B16F32 == 0b1.
+
+HWCAP2_SME_F32F32
+    Functionality implied by ID_AA64SMFR0_EL1.F32F32 == 0b1.
+
+HWCAP2_SME_FA64
+    Functionality implied by ID_AA64SMFR0_EL1.FA64 == 0b1.
+
+HWCAP2_WFXT
+    Functionality implied by ID_AA64ISAR2_EL1.WFXT == 0b0010.
+
+HWCAP2_EBF16
+    Functionality implied by ID_AA64ISAR1_EL1.BF16 == 0b0010.
+
+HWCAP2_SVE_EBF16
+    Functionality implied by ID_AA64ZFR0_EL1.BF16 == 0b0010.
+
+HWCAP2_CSSC
+    Functionality implied by ID_AA64ISAR2_EL1.CSSC == 0b0001.
+
+HWCAP2_RPRFM
+    Functionality implied by ID_AA64ISAR2_EL1.RPRFM == 0b0001.
+
+HWCAP2_SVE2P1
+    Functionality implied by ID_AA64ZFR0_EL1.SVEver == 0b0010.
+
+HWCAP2_SME2
+    Functionality implied by ID_AA64SMFR0_EL1.SMEver == 0b0001.
+
+HWCAP2_SME2P1
+    Functionality implied by ID_AA64SMFR0_EL1.SMEver == 0b0010.
+
+HWCAP2_SMEI16I32
+    Functionality implied by ID_AA64SMFR0_EL1.I16I32 == 0b0101
+
+HWCAP2_SMEBI32I32
+    Functionality implied by ID_AA64SMFR0_EL1.BI32I32 == 0b1
+
+HWCAP2_SMEB16B16
+    Functionality implied by ID_AA64SMFR0_EL1.B16B16 == 0b1
+
+HWCAP2_SMEF16F16
+    Functionality implied by ID_AA64SMFR0_EL1.F16F16 == 0b1
+
+4. Unused AT_HWCAP bits
+-----------------------
+
+For interoperation with userspace, the kernel guarantees that bits 62
+and 63 of AT_HWCAP will always be returned as 0.
diff --git a/Documentation/arch/arm64/features.rst b/Documentation/arch/arm64/features.rst
new file mode 100644
index 00000000000000..dfa4cb3cd3efa5
--- /dev/null
+++ b/Documentation/arch/arm64/features.rst
@@ -0,0 +1,3 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. kernel-feat:: $srctree/Documentation/features arm64
diff --git a/Documentation/arch/arm64/hugetlbpage.rst b/Documentation/arch/arm64/hugetlbpage.rst
new file mode 100644
index 00000000000000..a110124c11e388
--- /dev/null
+++ b/Documentation/arch/arm64/hugetlbpage.rst
@@ -0,0 +1,43 @@
+.. _hugetlbpage_index:
+
+====================
+HugeTLBpage on ARM64
+====================
+
+Hugepage relies on making efficient use of TLBs to improve performance of
+address translations. The benefit depends on both -
+
+  - the size of hugepages
+  - size of entries supported by the TLBs
+
+The ARM64 port supports two flavours of hugepages.
+
+1) Block mappings at the pud/pmd level
+--------------------------------------
+
+These are regular hugepages where a pmd or a pud page table entry points to a
+block of memory. Regardless of the supported size of entries in TLB, block
+mappings reduce the depth of page table walk needed to translate hugepage
+addresses.
+
+2) Using the Contiguous bit
+---------------------------
+
+The architecture provides a contiguous bit in the translation table entries
+(D4.5.3, ARM DDI 0487C.a) that hints to the MMU to indicate that it is one of a
+contiguous set of entries that can be cached in a single TLB entry.
+
+The contiguous bit is used in Linux to increase the mapping size at the pmd and
+pte (last) level. The number of supported contiguous entries varies by page size
+and level of the page table.
+
+
+The following hugepage sizes are supported -
+
+  ====== ========   ====    ========    ===
+  -      CONT PTE    PMD    CONT PMD    PUD
+  ====== ========   ====    ========    ===
+  4K:         64K     2M         32M     1G
+  16K:         2M    32M          1G
+  64K:         2M   512M         16G
+  ====== ========   ====    ========    ===
diff --git a/Documentation/arch/arm64/index.rst b/Documentation/arch/arm64/index.rst
new file mode 100644
index 00000000000000..ae21f811883022
--- /dev/null
+++ b/Documentation/arch/arm64/index.rst
@@ -0,0 +1,36 @@
+.. _arm64_index:
+
+==================
+ARM64 Architecture
+==================
+
+.. toctree::
+    :maxdepth: 1
+
+    acpi_object_usage
+    amu
+    arm-acpi
+    asymmetric-32bit
+    booting
+    cpu-feature-registers
+    elf_hwcaps
+    hugetlbpage
+    legacy_instructions
+    memory
+    memory-tagging-extension
+    perf
+    pointer-authentication
+    silicon-errata
+    sme
+    sve
+    tagged-address-abi
+    tagged-pointers
+
+    features
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`
diff --git a/Documentation/arch/arm64/kasan-offsets.sh b/Documentation/arch/arm64/kasan-offsets.sh
new file mode 100644
index 00000000000000..2dc5f9e18039b3
--- /dev/null
+++ b/Documentation/arch/arm64/kasan-offsets.sh
@@ -0,0 +1,26 @@
+#!/bin/sh
+
+# Print out the KASAN_SHADOW_OFFSETS required to place the KASAN SHADOW
+# start address at the top of the linear region
+
+print_kasan_offset () {
+	printf "%02d\t" $1
+	printf "0x%08x00000000\n" $(( (0xffffffff & (-1 << ($1 - 1 - 32))) \
+			- (1 << (64 - 32 - $2)) ))
+}
+
+echo KASAN_SHADOW_SCALE_SHIFT = 3
+printf "VABITS\tKASAN_SHADOW_OFFSET\n"
+print_kasan_offset 48 3
+print_kasan_offset 47 3
+print_kasan_offset 42 3
+print_kasan_offset 39 3
+print_kasan_offset 36 3
+echo
+echo KASAN_SHADOW_SCALE_SHIFT = 4
+printf "VABITS\tKASAN_SHADOW_OFFSET\n"
+print_kasan_offset 48 4
+print_kasan_offset 47 4
+print_kasan_offset 42 4
+print_kasan_offset 39 4
+print_kasan_offset 36 4
diff --git a/Documentation/arch/arm64/legacy_instructions.rst b/Documentation/arch/arm64/legacy_instructions.rst
new file mode 100644
index 00000000000000..54401b22cb8f93
--- /dev/null
+++ b/Documentation/arch/arm64/legacy_instructions.rst
@@ -0,0 +1,68 @@
+===================
+Legacy instructions
+===================
+
+The arm64 port of the Linux kernel provides infrastructure to support
+emulation of instructions which have been deprecated, or obsoleted in
+the architecture. The infrastructure code uses undefined instruction
+hooks to support emulation. Where available it also allows turning on
+the instruction execution in hardware.
+
+The emulation mode can be controlled by writing to sysctl nodes
+(/proc/sys/abi). The following explains the different execution
+behaviours and the corresponding values of the sysctl nodes -
+
+* Undef
+    Value: 0
+
+  Generates undefined instruction abort. Default for instructions that
+  have been obsoleted in the architecture, e.g., SWP
+
+* Emulate
+    Value: 1
+
+  Uses software emulation. To aid migration of software, in this mode
+  usage of emulated instruction is traced as well as rate limited
+  warnings are issued. This is the default for deprecated
+  instructions, .e.g., CP15 barriers
+
+* Hardware Execution
+    Value: 2
+
+  Although marked as deprecated, some implementations may support the
+  enabling/disabling of hardware support for the execution of these
+  instructions. Using hardware execution generally provides better
+  performance, but at the loss of ability to gather runtime statistics
+  about the use of the deprecated instructions.
+
+The default mode depends on the status of the instruction in the
+architecture. Deprecated instructions should default to emulation
+while obsolete instructions must be undefined by default.
+
+Note: Instruction emulation may not be possible in all cases. See
+individual instruction notes for further information.
+
+Supported legacy instructions
+-----------------------------
+* SWP{B}
+
+:Node: /proc/sys/abi/swp
+:Status: Obsolete
+:Default: Undef (0)
+
+* CP15 Barriers
+
+:Node: /proc/sys/abi/cp15_barrier
+:Status: Deprecated
+:Default: Emulate (1)
+
+* SETEND
+
+:Node: /proc/sys/abi/setend
+:Status: Deprecated
+:Default: Emulate (1)*
+
+  Note: All the cpus on the system must have mixed endian support at EL0
+  for this feature to be enabled. If a new CPU - which doesn't support mixed
+  endian - is hotplugged in after this feature has been enabled, there could
+  be unexpected results in the application.
diff --git a/Documentation/arch/arm64/memory-tagging-extension.rst b/Documentation/arch/arm64/memory-tagging-extension.rst
new file mode 100644
index 00000000000000..679725030731d0
--- /dev/null
+++ b/Documentation/arch/arm64/memory-tagging-extension.rst
@@ -0,0 +1,375 @@
+===============================================
+Memory Tagging Extension (MTE) in AArch64 Linux
+===============================================
+
+Authors: Vincenzo Frascino <vincenzo.frascino@arm.com>
+         Catalin Marinas <catalin.marinas@arm.com>
+
+Date: 2020-02-25
+
+This document describes the provision of the Memory Tagging Extension
+functionality in AArch64 Linux.
+
+Introduction
+============
+
+ARMv8.5 based processors introduce the Memory Tagging Extension (MTE)
+feature. MTE is built on top of the ARMv8.0 virtual address tagging TBI
+(Top Byte Ignore) feature and allows software to access a 4-bit
+allocation tag for each 16-byte granule in the physical address space.
+Such memory range must be mapped with the Normal-Tagged memory
+attribute. A logical tag is derived from bits 59-56 of the virtual
+address used for the memory access. A CPU with MTE enabled will compare
+the logical tag against the allocation tag and potentially raise an
+exception on mismatch, subject to system registers configuration.
+
+Userspace Support
+=================
+
+When ``CONFIG_ARM64_MTE`` is selected and Memory Tagging Extension is
+supported by the hardware, the kernel advertises the feature to
+userspace via ``HWCAP2_MTE``.
+
+PROT_MTE
+--------
+
+To access the allocation tags, a user process must enable the Tagged
+memory attribute on an address range using a new ``prot`` flag for
+``mmap()`` and ``mprotect()``:
+
+``PROT_MTE`` - Pages allow access to the MTE allocation tags.
+
+The allocation tag is set to 0 when such pages are first mapped in the
+user address space and preserved on copy-on-write. ``MAP_SHARED`` is
+supported and the allocation tags can be shared between processes.
+
+**Note**: ``PROT_MTE`` is only supported on ``MAP_ANONYMOUS`` and
+RAM-based file mappings (``tmpfs``, ``memfd``). Passing it to other
+types of mapping will result in ``-EINVAL`` returned by these system
+calls.
+
+**Note**: The ``PROT_MTE`` flag (and corresponding memory type) cannot
+be cleared by ``mprotect()``.
+
+**Note**: ``madvise()`` memory ranges with ``MADV_DONTNEED`` and
+``MADV_FREE`` may have the allocation tags cleared (set to 0) at any
+point after the system call.
+
+Tag Check Faults
+----------------
+
+When ``PROT_MTE`` is enabled on an address range and a mismatch between
+the logical and allocation tags occurs on access, there are three
+configurable behaviours:
+
+- *Ignore* - This is the default mode. The CPU (and kernel) ignores the
+  tag check fault.
+
+- *Synchronous* - The kernel raises a ``SIGSEGV`` synchronously, with
+  ``.si_code = SEGV_MTESERR`` and ``.si_addr = <fault-address>``. The
+  memory access is not performed. If ``SIGSEGV`` is ignored or blocked
+  by the offending thread, the containing process is terminated with a
+  ``coredump``.
+
+- *Asynchronous* - The kernel raises a ``SIGSEGV``, in the offending
+  thread, asynchronously following one or multiple tag check faults,
+  with ``.si_code = SEGV_MTEAERR`` and ``.si_addr = 0`` (the faulting
+  address is unknown).
+
+- *Asymmetric* - Reads are handled as for synchronous mode while writes
+  are handled as for asynchronous mode.
+
+The user can select the above modes, per thread, using the
+``prctl(PR_SET_TAGGED_ADDR_CTRL, flags, 0, 0, 0)`` system call where ``flags``
+contains any number of the following values in the ``PR_MTE_TCF_MASK``
+bit-field:
+
+- ``PR_MTE_TCF_NONE``  - *Ignore* tag check faults
+                         (ignored if combined with other options)
+- ``PR_MTE_TCF_SYNC``  - *Synchronous* tag check fault mode
+- ``PR_MTE_TCF_ASYNC`` - *Asynchronous* tag check fault mode
+
+If no modes are specified, tag check faults are ignored. If a single
+mode is specified, the program will run in that mode. If multiple
+modes are specified, the mode is selected as described in the "Per-CPU
+preferred tag checking modes" section below.
+
+The current tag check fault configuration can be read using the
+``prctl(PR_GET_TAGGED_ADDR_CTRL, 0, 0, 0, 0)`` system call. If
+multiple modes were requested then all will be reported.
+
+Tag checking can also be disabled for a user thread by setting the
+``PSTATE.TCO`` bit with ``MSR TCO, #1``.
+
+**Note**: Signal handlers are always invoked with ``PSTATE.TCO = 0``,
+irrespective of the interrupted context. ``PSTATE.TCO`` is restored on
+``sigreturn()``.
+
+**Note**: There are no *match-all* logical tags available for user
+applications.
+
+**Note**: Kernel accesses to the user address space (e.g. ``read()``
+system call) are not checked if the user thread tag checking mode is
+``PR_MTE_TCF_NONE`` or ``PR_MTE_TCF_ASYNC``. If the tag checking mode is
+``PR_MTE_TCF_SYNC``, the kernel makes a best effort to check its user
+address accesses, however it cannot always guarantee it. Kernel accesses
+to user addresses are always performed with an effective ``PSTATE.TCO``
+value of zero, regardless of the user configuration.
+
+Excluding Tags in the ``IRG``, ``ADDG`` and ``SUBG`` instructions
+-----------------------------------------------------------------
+
+The architecture allows excluding certain tags to be randomly generated
+via the ``GCR_EL1.Exclude`` register bit-field. By default, Linux
+excludes all tags other than 0. A user thread can enable specific tags
+in the randomly generated set using the ``prctl(PR_SET_TAGGED_ADDR_CTRL,
+flags, 0, 0, 0)`` system call where ``flags`` contains the tags bitmap
+in the ``PR_MTE_TAG_MASK`` bit-field.
+
+**Note**: The hardware uses an exclude mask but the ``prctl()``
+interface provides an include mask. An include mask of ``0`` (exclusion
+mask ``0xffff``) results in the CPU always generating tag ``0``.
+
+Per-CPU preferred tag checking mode
+-----------------------------------
+
+On some CPUs the performance of MTE in stricter tag checking modes
+is similar to that of less strict tag checking modes. This makes it
+worthwhile to enable stricter checks on those CPUs when a less strict
+checking mode is requested, in order to gain the error detection
+benefits of the stricter checks without the performance downsides. To
+support this scenario, a privileged user may configure a stricter
+tag checking mode as the CPU's preferred tag checking mode.
+
+The preferred tag checking mode for each CPU is controlled by
+``/sys/devices/system/cpu/cpu<N>/mte_tcf_preferred``, to which a
+privileged user may write the value ``async``, ``sync`` or ``asymm``.  The
+default preferred mode for each CPU is ``async``.
+
+To allow a program to potentially run in the CPU's preferred tag
+checking mode, the user program may set multiple tag check fault mode
+bits in the ``flags`` argument to the ``prctl(PR_SET_TAGGED_ADDR_CTRL,
+flags, 0, 0, 0)`` system call. If both synchronous and asynchronous
+modes are requested then asymmetric mode may also be selected by the
+kernel. If the CPU's preferred tag checking mode is in the task's set
+of provided tag checking modes, that mode will be selected. Otherwise,
+one of the modes in the task's mode will be selected by the kernel
+from the task's mode set using the preference order:
+
+	1. Asynchronous
+	2. Asymmetric
+	3. Synchronous
+
+Note that there is no way for userspace to request multiple modes and
+also disable asymmetric mode.
+
+Initial process state
+---------------------
+
+On ``execve()``, the new process has the following configuration:
+
+- ``PR_TAGGED_ADDR_ENABLE`` set to 0 (disabled)
+- No tag checking modes are selected (tag check faults ignored)
+- ``PR_MTE_TAG_MASK`` set to 0 (all tags excluded)
+- ``PSTATE.TCO`` set to 0
+- ``PROT_MTE`` not set on any of the initial memory maps
+
+On ``fork()``, the new process inherits the parent's configuration and
+memory map attributes with the exception of the ``madvise()`` ranges
+with ``MADV_WIPEONFORK`` which will have the data and tags cleared (set
+to 0).
+
+The ``ptrace()`` interface
+--------------------------
+
+``PTRACE_PEEKMTETAGS`` and ``PTRACE_POKEMTETAGS`` allow a tracer to read
+the tags from or set the tags to a tracee's address space. The
+``ptrace()`` system call is invoked as ``ptrace(request, pid, addr,
+data)`` where:
+
+- ``request`` - one of ``PTRACE_PEEKMTETAGS`` or ``PTRACE_POKEMTETAGS``.
+- ``pid`` - the tracee's PID.
+- ``addr`` - address in the tracee's address space.
+- ``data`` - pointer to a ``struct iovec`` where ``iov_base`` points to
+  a buffer of ``iov_len`` length in the tracer's address space.
+
+The tags in the tracer's ``iov_base`` buffer are represented as one
+4-bit tag per byte and correspond to a 16-byte MTE tag granule in the
+tracee's address space.
+
+**Note**: If ``addr`` is not aligned to a 16-byte granule, the kernel
+will use the corresponding aligned address.
+
+``ptrace()`` return value:
+
+- 0 - tags were copied, the tracer's ``iov_len`` was updated to the
+  number of tags transferred. This may be smaller than the requested
+  ``iov_len`` if the requested address range in the tracee's or the
+  tracer's space cannot be accessed or does not have valid tags.
+- ``-EPERM`` - the specified process cannot be traced.
+- ``-EIO`` - the tracee's address range cannot be accessed (e.g. invalid
+  address) and no tags copied. ``iov_len`` not updated.
+- ``-EFAULT`` - fault on accessing the tracer's memory (``struct iovec``
+  or ``iov_base`` buffer) and no tags copied. ``iov_len`` not updated.
+- ``-EOPNOTSUPP`` - the tracee's address does not have valid tags (never
+  mapped with the ``PROT_MTE`` flag). ``iov_len`` not updated.
+
+**Note**: There are no transient errors for the requests above, so user
+programs should not retry in case of a non-zero system call return.
+
+``PTRACE_GETREGSET`` and ``PTRACE_SETREGSET`` with ``addr ==
+``NT_ARM_TAGGED_ADDR_CTRL`` allow ``ptrace()`` access to the tagged
+address ABI control and MTE configuration of a process as per the
+``prctl()`` options described in
+Documentation/arch/arm64/tagged-address-abi.rst and above. The corresponding
+``regset`` is 1 element of 8 bytes (``sizeof(long))``).
+
+Core dump support
+-----------------
+
+The allocation tags for user memory mapped with ``PROT_MTE`` are dumped
+in the core file as additional ``PT_AARCH64_MEMTAG_MTE`` segments. The
+program header for such segment is defined as:
+
+:``p_type``: ``PT_AARCH64_MEMTAG_MTE``
+:``p_flags``: 0
+:``p_offset``: segment file offset
+:``p_vaddr``: segment virtual address, same as the corresponding
+  ``PT_LOAD`` segment
+:``p_paddr``: 0
+:``p_filesz``: segment size in file, calculated as ``p_mem_sz / 32``
+  (two 4-bit tags cover 32 bytes of memory)
+:``p_memsz``: segment size in memory, same as the corresponding
+  ``PT_LOAD`` segment
+:``p_align``: 0
+
+The tags are stored in the core file at ``p_offset`` as two 4-bit tags
+in a byte. With the tag granule of 16 bytes, a 4K page requires 128
+bytes in the core file.
+
+Example of correct usage
+========================
+
+*MTE Example code*
+
+.. code-block:: c
+
+    /*
+     * To be compiled with -march=armv8.5-a+memtag
+     */
+    #include <errno.h>
+    #include <stdint.h>
+    #include <stdio.h>
+    #include <stdlib.h>
+    #include <unistd.h>
+    #include <sys/auxv.h>
+    #include <sys/mman.h>
+    #include <sys/prctl.h>
+
+    /*
+     * From arch/arm64/include/uapi/asm/hwcap.h
+     */
+    #define HWCAP2_MTE              (1 << 18)
+
+    /*
+     * From arch/arm64/include/uapi/asm/mman.h
+     */
+    #define PROT_MTE                 0x20
+
+    /*
+     * From include/uapi/linux/prctl.h
+     */
+    #define PR_SET_TAGGED_ADDR_CTRL 55
+    #define PR_GET_TAGGED_ADDR_CTRL 56
+    # define PR_TAGGED_ADDR_ENABLE  (1UL << 0)
+    # define PR_MTE_TCF_SHIFT       1
+    # define PR_MTE_TCF_NONE        (0UL << PR_MTE_TCF_SHIFT)
+    # define PR_MTE_TCF_SYNC        (1UL << PR_MTE_TCF_SHIFT)
+    # define PR_MTE_TCF_ASYNC       (2UL << PR_MTE_TCF_SHIFT)
+    # define PR_MTE_TCF_MASK        (3UL << PR_MTE_TCF_SHIFT)
+    # define PR_MTE_TAG_SHIFT       3
+    # define PR_MTE_TAG_MASK        (0xffffUL << PR_MTE_TAG_SHIFT)
+
+    /*
+     * Insert a random logical tag into the given pointer.
+     */
+    #define insert_random_tag(ptr) ({                       \
+            uint64_t __val;                                 \
+            asm("irg %0, %1" : "=r" (__val) : "r" (ptr));   \
+            __val;                                          \
+    })
+
+    /*
+     * Set the allocation tag on the destination address.
+     */
+    #define set_tag(tagged_addr) do {                                      \
+            asm volatile("stg %0, [%0]" : : "r" (tagged_addr) : "memory"); \
+    } while (0)
+
+    int main()
+    {
+            unsigned char *a;
+            unsigned long page_sz = sysconf(_SC_PAGESIZE);
+            unsigned long hwcap2 = getauxval(AT_HWCAP2);
+
+            /* check if MTE is present */
+            if (!(hwcap2 & HWCAP2_MTE))
+                    return EXIT_FAILURE;
+
+            /*
+             * Enable the tagged address ABI, synchronous or asynchronous MTE
+             * tag check faults (based on per-CPU preference) and allow all
+             * non-zero tags in the randomly generated set.
+             */
+            if (prctl(PR_SET_TAGGED_ADDR_CTRL,
+                      PR_TAGGED_ADDR_ENABLE | PR_MTE_TCF_SYNC | PR_MTE_TCF_ASYNC |
+                      (0xfffe << PR_MTE_TAG_SHIFT),
+                      0, 0, 0)) {
+                    perror("prctl() failed");
+                    return EXIT_FAILURE;
+            }
+
+            a = mmap(0, page_sz, PROT_READ | PROT_WRITE,
+                     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+            if (a == MAP_FAILED) {
+                    perror("mmap() failed");
+                    return EXIT_FAILURE;
+            }
+
+            /*
+             * Enable MTE on the above anonymous mmap. The flag could be passed
+             * directly to mmap() and skip this step.
+             */
+            if (mprotect(a, page_sz, PROT_READ | PROT_WRITE | PROT_MTE)) {
+                    perror("mprotect() failed");
+                    return EXIT_FAILURE;
+            }
+
+            /* access with the default tag (0) */
+            a[0] = 1;
+            a[1] = 2;
+
+            printf("a[0] = %hhu a[1] = %hhu\n", a[0], a[1]);
+
+            /* set the logical and allocation tags */
+            a = (unsigned char *)insert_random_tag(a);
+            set_tag(a);
+
+            printf("%p\n", a);
+
+            /* non-zero tag access */
+            a[0] = 3;
+            printf("a[0] = %hhu a[1] = %hhu\n", a[0], a[1]);
+
+            /*
+             * If MTE is enabled correctly the next instruction will generate an
+             * exception.
+             */
+            printf("Expecting SIGSEGV...\n");
+            a[16] = 0xdd;
+
+            /* this should not be printed in the PR_MTE_TCF_SYNC mode */
+            printf("...haven't got one\n");
+
+            return EXIT_FAILURE;
+    }
diff --git a/Documentation/arch/arm64/memory.rst b/Documentation/arch/arm64/memory.rst
new file mode 100644
index 00000000000000..2a641ba7be3b71
--- /dev/null
+++ b/Documentation/arch/arm64/memory.rst
@@ -0,0 +1,167 @@
+==============================
+Memory Layout on AArch64 Linux
+==============================
+
+Author: Catalin Marinas <catalin.marinas@arm.com>
+
+This document describes the virtual memory layout used by the AArch64
+Linux kernel. The architecture allows up to 4 levels of translation
+tables with a 4KB page size and up to 3 levels with a 64KB page size.
+
+AArch64 Linux uses either 3 levels or 4 levels of translation tables
+with the 4KB page configuration, allowing 39-bit (512GB) or 48-bit
+(256TB) virtual addresses, respectively, for both user and kernel. With
+64KB pages, only 2 levels of translation tables, allowing 42-bit (4TB)
+virtual address, are used but the memory layout is the same.
+
+ARMv8.2 adds optional support for Large Virtual Address space. This is
+only available when running with a 64KB page size and expands the
+number of descriptors in the first level of translation.
+
+User addresses have bits 63:48 set to 0 while the kernel addresses have
+the same bits set to 1. TTBRx selection is given by bit 63 of the
+virtual address. The swapper_pg_dir contains only kernel (global)
+mappings while the user pgd contains only user (non-global) mappings.
+The swapper_pg_dir address is written to TTBR1 and never written to
+TTBR0.
+
+
+AArch64 Linux memory layout with 4KB pages + 4 levels (48-bit)::
+
+  Start			End			Size		Use
+  -----------------------------------------------------------------------
+  0000000000000000	0000ffffffffffff	 256TB		user
+  ffff000000000000	ffff7fffffffffff	 128TB		kernel logical memory map
+ [ffff600000000000	ffff7fffffffffff]	  32TB		[kasan shadow region]
+  ffff800000000000	ffff800007ffffff	 128MB		modules
+  ffff800008000000	fffffbffefffffff	 124TB		vmalloc
+  fffffbfff0000000	fffffbfffdffffff	 224MB		fixed mappings (top down)
+  fffffbfffe000000	fffffbfffe7fffff	   8MB		[guard region]
+  fffffbfffe800000	fffffbffff7fffff	  16MB		PCI I/O space
+  fffffbffff800000	fffffbffffffffff	   8MB		[guard region]
+  fffffc0000000000	fffffdffffffffff	   2TB		vmemmap
+  fffffe0000000000	ffffffffffffffff	   2TB		[guard region]
+
+
+AArch64 Linux memory layout with 64KB pages + 3 levels (52-bit with HW support)::
+
+  Start			End			Size		Use
+  -----------------------------------------------------------------------
+  0000000000000000	000fffffffffffff	   4PB		user
+  fff0000000000000	ffff7fffffffffff	  ~4PB		kernel logical memory map
+ [fffd800000000000	ffff7fffffffffff]	 512TB		[kasan shadow region]
+  ffff800000000000	ffff800007ffffff	 128MB		modules
+  ffff800008000000	fffffbffefffffff	 124TB		vmalloc
+  fffffbfff0000000	fffffbfffdffffff	 224MB		fixed mappings (top down)
+  fffffbfffe000000	fffffbfffe7fffff	   8MB		[guard region]
+  fffffbfffe800000	fffffbffff7fffff	  16MB		PCI I/O space
+  fffffbffff800000	fffffbffffffffff	   8MB		[guard region]
+  fffffc0000000000	ffffffdfffffffff	  ~4TB		vmemmap
+  ffffffe000000000	ffffffffffffffff	 128GB		[guard region]
+
+
+Translation table lookup with 4KB pages::
+
+  +--------+--------+--------+--------+--------+--------+--------+--------+
+  |63    56|55    48|47    40|39    32|31    24|23    16|15     8|7      0|
+  +--------+--------+--------+--------+--------+--------+--------+--------+
+   |                 |         |         |         |         |
+   |                 |         |         |         |         v
+   |                 |         |         |         |   [11:0]  in-page offset
+   |                 |         |         |         +-> [20:12] L3 index
+   |                 |         |         +-----------> [29:21] L2 index
+   |                 |         +---------------------> [38:30] L1 index
+   |                 +-------------------------------> [47:39] L0 index
+   +-------------------------------------------------> [63] TTBR0/1
+
+
+Translation table lookup with 64KB pages::
+
+  +--------+--------+--------+--------+--------+--------+--------+--------+
+  |63    56|55    48|47    40|39    32|31    24|23    16|15     8|7      0|
+  +--------+--------+--------+--------+--------+--------+--------+--------+
+   |                 |    |               |              |
+   |                 |    |               |              v
+   |                 |    |               |            [15:0]  in-page offset
+   |                 |    |               +----------> [28:16] L3 index
+   |                 |    +--------------------------> [41:29] L2 index
+   |                 +-------------------------------> [47:42] L1 index (48-bit)
+   |                                                   [51:42] L1 index (52-bit)
+   +-------------------------------------------------> [63] TTBR0/1
+
+
+When using KVM without the Virtualization Host Extensions, the
+hypervisor maps kernel pages in EL2 at a fixed (and potentially
+random) offset from the linear mapping. See the kern_hyp_va macro and
+kvm_update_va_mask function for more details. MMIO devices such as
+GICv2 gets mapped next to the HYP idmap page, as do vectors when
+ARM64_SPECTRE_V3A is enabled for particular CPUs.
+
+When using KVM with the Virtualization Host Extensions, no additional
+mappings are created, since the host kernel runs directly in EL2.
+
+52-bit VA support in the kernel
+-------------------------------
+If the ARMv8.2-LVA optional feature is present, and we are running
+with a 64KB page size; then it is possible to use 52-bits of address
+space for both userspace and kernel addresses. However, any kernel
+binary that supports 52-bit must also be able to fall back to 48-bit
+at early boot time if the hardware feature is not present.
+
+This fallback mechanism necessitates the kernel .text to be in the
+higher addresses such that they are invariant to 48/52-bit VAs. Due
+to the kasan shadow being a fraction of the entire kernel VA space,
+the end of the kasan shadow must also be in the higher half of the
+kernel VA space for both 48/52-bit. (Switching from 48-bit to 52-bit,
+the end of the kasan shadow is invariant and dependent on ~0UL,
+whilst the start address will "grow" towards the lower addresses).
+
+In order to optimise phys_to_virt and virt_to_phys, the PAGE_OFFSET
+is kept constant at 0xFFF0000000000000 (corresponding to 52-bit),
+this obviates the need for an extra variable read. The physvirt
+offset and vmemmap offsets are computed at early boot to enable
+this logic.
+
+As a single binary will need to support both 48-bit and 52-bit VA
+spaces, the VMEMMAP must be sized large enough for 52-bit VAs and
+also must be sized large enough to accommodate a fixed PAGE_OFFSET.
+
+Most code in the kernel should not need to consider the VA_BITS, for
+code that does need to know the VA size the variables are
+defined as follows:
+
+VA_BITS		constant	the *maximum* VA space size
+
+VA_BITS_MIN	constant	the *minimum* VA space size
+
+vabits_actual	variable	the *actual* VA space size
+
+
+Maximum and minimum sizes can be useful to ensure that buffers are
+sized large enough or that addresses are positioned close enough for
+the "worst" case.
+
+52-bit userspace VAs
+--------------------
+To maintain compatibility with software that relies on the ARMv8.0
+VA space maximum size of 48-bits, the kernel will, by default,
+return virtual addresses to userspace from a 48-bit range.
+
+Software can "opt-in" to receiving VAs from a 52-bit space by
+specifying an mmap hint parameter that is larger than 48-bit.
+
+For example:
+
+.. code-block:: c
+
+   maybe_high_address = mmap(~0UL, size, prot, flags,...);
+
+It is also possible to build a debug kernel that returns addresses
+from a 52-bit space by enabling the following kernel config options:
+
+.. code-block:: sh
+
+   CONFIG_EXPERT=y && CONFIG_ARM64_FORCE_52BIT=y
+
+Note that this option is only intended for debugging applications
+and should not be used in production.
diff --git a/Documentation/arch/arm64/perf.rst b/Documentation/arch/arm64/perf.rst
new file mode 100644
index 00000000000000..1f87b57c233240
--- /dev/null
+++ b/Documentation/arch/arm64/perf.rst
@@ -0,0 +1,166 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+.. _perf_index:
+
+====
+Perf
+====
+
+Perf Event Attributes
+=====================
+
+:Author: Andrew Murray <andrew.murray@arm.com>
+:Date: 2019-03-06
+
+exclude_user
+------------
+
+This attribute excludes userspace.
+
+Userspace always runs at EL0 and thus this attribute will exclude EL0.
+
+
+exclude_kernel
+--------------
+
+This attribute excludes the kernel.
+
+The kernel runs at EL2 with VHE and EL1 without. Guest kernels always run
+at EL1.
+
+For the host this attribute will exclude EL1 and additionally EL2 on a VHE
+system.
+
+For the guest this attribute will exclude EL1. Please note that EL2 is
+never counted within a guest.
+
+
+exclude_hv
+----------
+
+This attribute excludes the hypervisor.
+
+For a VHE host this attribute is ignored as we consider the host kernel to
+be the hypervisor.
+
+For a non-VHE host this attribute will exclude EL2 as we consider the
+hypervisor to be any code that runs at EL2 which is predominantly used for
+guest/host transitions.
+
+For the guest this attribute has no effect. Please note that EL2 is
+never counted within a guest.
+
+
+exclude_host / exclude_guest
+----------------------------
+
+These attributes exclude the KVM host and guest, respectively.
+
+The KVM host may run at EL0 (userspace), EL1 (non-VHE kernel) and EL2 (VHE
+kernel or non-VHE hypervisor).
+
+The KVM guest may run at EL0 (userspace) and EL1 (kernel).
+
+Due to the overlapping exception levels between host and guests we cannot
+exclusively rely on the PMU's hardware exception filtering - therefore we
+must enable/disable counting on the entry and exit to the guest. This is
+performed differently on VHE and non-VHE systems.
+
+For non-VHE systems we exclude EL2 for exclude_host - upon entering and
+exiting the guest we disable/enable the event as appropriate based on the
+exclude_host and exclude_guest attributes.
+
+For VHE systems we exclude EL1 for exclude_guest and exclude both EL0,EL2
+for exclude_host. Upon entering and exiting the guest we modify the event
+to include/exclude EL0 as appropriate based on the exclude_host and
+exclude_guest attributes.
+
+The statements above also apply when these attributes are used within a
+non-VHE guest however please note that EL2 is never counted within a guest.
+
+
+Accuracy
+--------
+
+On non-VHE hosts we enable/disable counters on the entry/exit of host/guest
+transition at EL2 - however there is a period of time between
+enabling/disabling the counters and entering/exiting the guest. We are
+able to eliminate counters counting host events on the boundaries of guest
+entry/exit when counting guest events by filtering out EL2 for
+exclude_host. However when using !exclude_hv there is a small blackout
+window at the guest entry/exit where host events are not captured.
+
+On VHE systems there are no blackout windows.
+
+Perf Userspace PMU Hardware Counter Access
+==========================================
+
+Overview
+--------
+The perf userspace tool relies on the PMU to monitor events. It offers an
+abstraction layer over the hardware counters since the underlying
+implementation is cpu-dependent.
+Arm64 allows userspace tools to have access to the registers storing the
+hardware counters' values directly.
+
+This targets specifically self-monitoring tasks in order to reduce the overhead
+by directly accessing the registers without having to go through the kernel.
+
+How-to
+------
+The focus is set on the armv8 PMUv3 which makes sure that the access to the pmu
+registers is enabled and that the userspace has access to the relevant
+information in order to use them.
+
+In order to have access to the hardware counters, the global sysctl
+kernel/perf_user_access must first be enabled:
+
+.. code-block:: sh
+
+  echo 1 > /proc/sys/kernel/perf_user_access
+
+It is necessary to open the event using the perf tool interface with config1:1
+attr bit set: the sys_perf_event_open syscall returns a fd which can
+subsequently be used with the mmap syscall in order to retrieve a page of memory
+containing information about the event. The PMU driver uses this page to expose
+to the user the hardware counter's index and other necessary data. Using this
+index enables the user to access the PMU registers using the `mrs` instruction.
+Access to the PMU registers is only valid while the sequence lock is unchanged.
+In particular, the PMSELR_EL0 register is zeroed each time the sequence lock is
+changed.
+
+The userspace access is supported in libperf using the perf_evsel__mmap()
+and perf_evsel__read() functions. See `tools/lib/perf/tests/test-evsel.c`_ for
+an example.
+
+About heterogeneous systems
+---------------------------
+On heterogeneous systems such as big.LITTLE, userspace PMU counter access can
+only be enabled when the tasks are pinned to a homogeneous subset of cores and
+the corresponding PMU instance is opened by specifying the 'type' attribute.
+The use of generic event types is not supported in this case.
+
+Have a look at `tools/perf/arch/arm64/tests/user-events.c`_ for an example. It
+can be run using the perf tool to check that the access to the registers works
+correctly from userspace:
+
+.. code-block:: sh
+
+  perf test -v user
+
+About chained events and counter sizes
+--------------------------------------
+The user can request either a 32-bit (config1:0 == 0) or 64-bit (config1:0 == 1)
+counter along with userspace access. The sys_perf_event_open syscall will fail
+if a 64-bit counter is requested and the hardware doesn't support 64-bit
+counters. Chained events are not supported in conjunction with userspace counter
+access. If a 32-bit counter is requested on hardware with 64-bit counters, then
+userspace must treat the upper 32-bits read from the counter as UNKNOWN. The
+'pmc_width' field in the user page will indicate the valid width of the counter
+and should be used to mask the upper bits as needed.
+
+.. Links
+.. _tools/perf/arch/arm64/tests/user-events.c:
+   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/arch/arm64/tests/user-events.c
+.. _tools/lib/perf/tests/test-evsel.c:
+   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/lib/perf/tests/test-evsel.c
diff --git a/Documentation/arch/arm64/pointer-authentication.rst b/Documentation/arch/arm64/pointer-authentication.rst
new file mode 100644
index 00000000000000..e5dad2e40aa893
--- /dev/null
+++ b/Documentation/arch/arm64/pointer-authentication.rst
@@ -0,0 +1,142 @@
+=======================================
+Pointer authentication in AArch64 Linux
+=======================================
+
+Author: Mark Rutland <mark.rutland@arm.com>
+
+Date: 2017-07-19
+
+This document briefly describes the provision of pointer authentication
+functionality in AArch64 Linux.
+
+
+Architecture overview
+---------------------
+
+The ARMv8.3 Pointer Authentication extension adds primitives that can be
+used to mitigate certain classes of attack where an attacker can corrupt
+the contents of some memory (e.g. the stack).
+
+The extension uses a Pointer Authentication Code (PAC) to determine
+whether pointers have been modified unexpectedly. A PAC is derived from
+a pointer, another value (such as the stack pointer), and a secret key
+held in system registers.
+
+The extension adds instructions to insert a valid PAC into a pointer,
+and to verify/remove the PAC from a pointer. The PAC occupies a number
+of high-order bits of the pointer, which varies dependent on the
+configured virtual address size and whether pointer tagging is in use.
+
+A subset of these instructions have been allocated from the HINT
+encoding space. In the absence of the extension (or when disabled),
+these instructions behave as NOPs. Applications and libraries using
+these instructions operate correctly regardless of the presence of the
+extension.
+
+The extension provides five separate keys to generate PACs - two for
+instruction addresses (APIAKey, APIBKey), two for data addresses
+(APDAKey, APDBKey), and one for generic authentication (APGAKey).
+
+
+Basic support
+-------------
+
+When CONFIG_ARM64_PTR_AUTH is selected, and relevant HW support is
+present, the kernel will assign random key values to each process at
+exec*() time. The keys are shared by all threads within the process, and
+are preserved across fork().
+
+Presence of address authentication functionality is advertised via
+HWCAP_PACA, and generic authentication functionality via HWCAP_PACG.
+
+The number of bits that the PAC occupies in a pointer is 55 minus the
+virtual address size configured by the kernel. For example, with a
+virtual address size of 48, the PAC is 7 bits wide.
+
+When ARM64_PTR_AUTH_KERNEL is selected, the kernel will be compiled
+with HINT space pointer authentication instructions protecting
+function returns. Kernels built with this option will work on hardware
+with or without pointer authentication support.
+
+In addition to exec(), keys can also be reinitialized to random values
+using the PR_PAC_RESET_KEYS prctl. A bitmask of PR_PAC_APIAKEY,
+PR_PAC_APIBKEY, PR_PAC_APDAKEY, PR_PAC_APDBKEY and PR_PAC_APGAKEY
+specifies which keys are to be reinitialized; specifying 0 means "all
+keys".
+
+
+Debugging
+---------
+
+When CONFIG_ARM64_PTR_AUTH is selected, and HW support for address
+authentication is present, the kernel will expose the position of TTBR0
+PAC bits in the NT_ARM_PAC_MASK regset (struct user_pac_mask), which
+userspace can acquire via PTRACE_GETREGSET.
+
+The regset is exposed only when HWCAP_PACA is set. Separate masks are
+exposed for data pointers and instruction pointers, as the set of PAC
+bits can vary between the two. Note that the masks apply to TTBR0
+addresses, and are not valid to apply to TTBR1 addresses (e.g. kernel
+pointers).
+
+Additionally, when CONFIG_CHECKPOINT_RESTORE is also set, the kernel
+will expose the NT_ARM_PACA_KEYS and NT_ARM_PACG_KEYS regsets (struct
+user_pac_address_keys and struct user_pac_generic_keys). These can be
+used to get and set the keys for a thread.
+
+
+Virtualization
+--------------
+
+Pointer authentication is enabled in KVM guest when each virtual cpu is
+initialised by passing flags KVM_ARM_VCPU_PTRAUTH_[ADDRESS/GENERIC] and
+requesting these two separate cpu features to be enabled. The current KVM
+guest implementation works by enabling both features together, so both
+these userspace flags are checked before enabling pointer authentication.
+The separate userspace flag will allow to have no userspace ABI changes
+if support is added in the future to allow these two features to be
+enabled independently of one another.
+
+As Arm Architecture specifies that Pointer Authentication feature is
+implemented along with the VHE feature so KVM arm64 ptrauth code relies
+on VHE mode to be present.
+
+Additionally, when these vcpu feature flags are not set then KVM will
+filter out the Pointer Authentication system key registers from
+KVM_GET/SET_REG_* ioctls and mask those features from cpufeature ID
+register. Any attempt to use the Pointer Authentication instructions will
+result in an UNDEFINED exception being injected into the guest.
+
+
+Enabling and disabling keys
+---------------------------
+
+The prctl PR_PAC_SET_ENABLED_KEYS allows the user program to control which
+PAC keys are enabled in a particular task. It takes two arguments, the
+first being a bitmask of PR_PAC_APIAKEY, PR_PAC_APIBKEY, PR_PAC_APDAKEY
+and PR_PAC_APDBKEY specifying which keys shall be affected by this prctl,
+and the second being a bitmask of the same bits specifying whether the key
+should be enabled or disabled. For example::
+
+  prctl(PR_PAC_SET_ENABLED_KEYS,
+        PR_PAC_APIAKEY | PR_PAC_APIBKEY | PR_PAC_APDAKEY | PR_PAC_APDBKEY,
+        PR_PAC_APIBKEY, 0, 0);
+
+disables all keys except the IB key.
+
+The main reason why this is useful is to enable a userspace ABI that uses PAC
+instructions to sign and authenticate function pointers and other pointers
+exposed outside of the function, while still allowing binaries conforming to
+the ABI to interoperate with legacy binaries that do not sign or authenticate
+pointers.
+
+The idea is that a dynamic loader or early startup code would issue this
+prctl very early after establishing that a process may load legacy binaries,
+but before executing any PAC instructions.
+
+For compatibility with previous kernel versions, processes start up with IA,
+IB, DA and DB enabled, and are reset to this state on exec(). Processes created
+via fork() and clone() inherit the key enabled state from the calling process.
+
+It is recommended to avoid disabling the IA key, as this has higher performance
+overhead than disabling any of the other keys.
diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst
new file mode 100644
index 00000000000000..9e311bc43e05ea
--- /dev/null
+++ b/Documentation/arch/arm64/silicon-errata.rst
@@ -0,0 +1,216 @@
+=======================================
+Silicon Errata and Software Workarounds
+=======================================
+
+Author: Will Deacon <will.deacon@arm.com>
+
+Date  : 27 November 2015
+
+It is an unfortunate fact of life that hardware is often produced with
+so-called "errata", which can cause it to deviate from the architecture
+under specific circumstances.  For hardware produced by ARM, these
+errata are broadly classified into the following categories:
+
+  ==========  ========================================================
+  Category A  A critical error without a viable workaround.
+  Category B  A significant or critical error with an acceptable
+              workaround.
+  Category C  A minor error that is not expected to occur under normal
+              operation.
+  ==========  ========================================================
+
+For more information, consult one of the "Software Developers Errata
+Notice" documents available on infocenter.arm.com (registration
+required).
+
+As far as Linux is concerned, Category B errata may require some special
+treatment in the operating system. For example, avoiding a particular
+sequence of code, or configuring the processor in a particular way. A
+less common situation may require similar actions in order to declassify
+a Category A erratum into a Category C erratum. These are collectively
+known as "software workarounds" and are only required in the minority of
+cases (e.g. those cases that both require a non-secure workaround *and*
+can be triggered by Linux).
+
+For software workarounds that may adversely impact systems unaffected by
+the erratum in question, a Kconfig entry is added under "Kernel
+Features" -> "ARM errata workarounds via the alternatives framework".
+These are enabled by default and patched in at runtime when an affected
+CPU is detected. For less-intrusive workarounds, a Kconfig option is not
+available and the code is structured (preferably with a comment) in such
+a way that the erratum will not be hit.
+
+This approach can make it slightly onerous to determine exactly which
+errata are worked around in an arbitrary kernel source tree, so this
+file acts as a registry of software workarounds in the Linux Kernel and
+will be updated when new workarounds are committed and backported to
+stable kernels.
+
++----------------+-----------------+-----------------+-----------------------------+
+| Implementor    | Component       | Erratum ID      | Kconfig                     |
++================+=================+=================+=============================+
+| Allwinner      | A64/R18         | UNKNOWN1        | SUN50I_ERRATUM_UNKNOWN1     |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2457168        | ARM64_ERRATUM_2457168       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2064142        | ARM64_ERRATUM_2064142       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2038923        | ARM64_ERRATUM_2038923       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #1902691        | ARM64_ERRATUM_1902691       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A53      | #826319         | ARM64_ERRATUM_826319        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A53      | #827319         | ARM64_ERRATUM_827319        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A53      | #824069         | ARM64_ERRATUM_824069        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A53      | #819472         | ARM64_ERRATUM_819472        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A53      | #845719         | ARM64_ERRATUM_845719        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A53      | #843419         | ARM64_ERRATUM_843419        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A55      | #1024718        | ARM64_ERRATUM_1024718       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A55      | #1530923        | ARM64_ERRATUM_1530923       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A55      | #2441007        | ARM64_ERRATUM_2441007       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A57      | #832075         | ARM64_ERRATUM_832075        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A57      | #852523         | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A57      | #834220         | ARM64_ERRATUM_834220        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A57      | #1319537        | ARM64_ERRATUM_1319367       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A57      | #1742098        | ARM64_ERRATUM_1742098       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A72      | #853709         | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A72      | #1319367        | ARM64_ERRATUM_1319367       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A72      | #1655431        | ARM64_ERRATUM_1742098       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A73      | #858921         | ARM64_ERRATUM_858921        |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A76      | #1188873,1418040| ARM64_ERRATUM_1418040       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A76      | #1165522        | ARM64_ERRATUM_1165522       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A76      | #1286807        | ARM64_ERRATUM_1286807       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A76      | #1463225        | ARM64_ERRATUM_1463225       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A77      | #1508412        | ARM64_ERRATUM_1508412       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2051678        | ARM64_ERRATUM_2051678       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2077057        | ARM64_ERRATUM_2077057       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2441009        | ARM64_ERRATUM_2441009       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A510     | #2658417        | ARM64_ERRATUM_2658417       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A710     | #2119858        | ARM64_ERRATUM_2119858       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A710     | #2054223        | ARM64_ERRATUM_2054223       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A710     | #2224489        | ARM64_ERRATUM_2224489       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-A715     | #2645198        | ARM64_ERRATUM_2645198       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-X2       | #2119858        | ARM64_ERRATUM_2119858       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Cortex-X2       | #2224489        | ARM64_ERRATUM_2224489       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Neoverse-N1     | #1188873,1418040| ARM64_ERRATUM_1418040       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Neoverse-N1     | #1349291        | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Neoverse-N1     | #1542419        | ARM64_ERRATUM_1542419       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Neoverse-N2     | #2139208        | ARM64_ERRATUM_2139208       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Neoverse-N2     | #2067961        | ARM64_ERRATUM_2067961       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | Neoverse-N2     | #2253138        | ARM64_ERRATUM_2253138       |
++----------------+-----------------+-----------------+-----------------------------+
+| ARM            | MMU-500         | #841119,826419  | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Broadcom       | Brahma-B53      | N/A             | ARM64_ERRATUM_845719        |
++----------------+-----------------+-----------------+-----------------------------+
+| Broadcom       | Brahma-B53      | N/A             | ARM64_ERRATUM_843419        |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX ITS    | #22375,24313    | CAVIUM_ERRATUM_22375        |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX ITS    | #23144          | CAVIUM_ERRATUM_23144        |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX GICv3  | #23154,38545    | CAVIUM_ERRATUM_23154        |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX GICv3  | #38539          | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX Core   | #27456          | CAVIUM_ERRATUM_27456        |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX Core   | #30115          | CAVIUM_ERRATUM_30115        |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX SMMUv2 | #27704          | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX2 SMMUv3| #74             | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX2 SMMUv3| #126            | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| Cavium         | ThunderX2 Core  | #219            | CAVIUM_TX2_ERRATUM_219      |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Marvell        | ARM-MMU-500     | #582743         | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| NVIDIA         | Carmel Core     | N/A             | NVIDIA_CARMEL_CNP_ERRATUM   |
++----------------+-----------------+-----------------+-----------------------------+
+| NVIDIA         | T241 GICv3/4.x  | T241-FABRIC-4   | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Freescale/NXP  | LS2080A/LS1043A | A-008585        | FSL_ERRATUM_A008585         |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Hisilicon      | Hip0{5,6,7}     | #161010101      | HISILICON_ERRATUM_161010101 |
++----------------+-----------------+-----------------+-----------------------------+
+| Hisilicon      | Hip0{6,7}       | #161010701      | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| Hisilicon      | Hip0{6,7}       | #161010803      | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
+| Hisilicon      | Hip07           | #161600802      | HISILICON_ERRATUM_161600802 |
++----------------+-----------------+-----------------+-----------------------------+
+| Hisilicon      | Hip08 SMMU PMCG | #162001800      | N/A                         |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Kryo/Falkor v1  | E1003           | QCOM_FALKOR_ERRATUM_1003    |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Kryo/Falkor v1  | E1009           | QCOM_FALKOR_ERRATUM_1009    |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | QDF2400 ITS     | E0065           | QCOM_QDF2400_ERRATUM_0065   |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Falkor v{1,2}   | E1041           | QCOM_FALKOR_ERRATUM_1041    |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Kryo4xx Gold    | N/A             | ARM64_ERRATUM_1463225       |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Kryo4xx Gold    | N/A             | ARM64_ERRATUM_1418040       |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Kryo4xx Silver  | N/A             | ARM64_ERRATUM_1530923       |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Kryo4xx Silver  | N/A             | ARM64_ERRATUM_1024718       |
++----------------+-----------------+-----------------+-----------------------------+
+| Qualcomm Tech. | Kryo4xx Gold    | N/A             | ARM64_ERRATUM_1286807       |
++----------------+-----------------+-----------------+-----------------------------+
++----------------+-----------------+-----------------+-----------------------------+
+| Rockchip       | RK3588          | #3588001        | ROCKCHIP_ERRATUM_3588001    |
++----------------+-----------------+-----------------+-----------------------------+
+
++----------------+-----------------+-----------------+-----------------------------+
+| Fujitsu        | A64FX           | E#010001        | FUJITSU_ERRATUM_010001      |
++----------------+-----------------+-----------------+-----------------------------+
diff --git a/Documentation/arch/arm64/sme.rst b/Documentation/arch/arm64/sme.rst
new file mode 100644
index 00000000000000..ba529a1dc6065e
--- /dev/null
+++ b/Documentation/arch/arm64/sme.rst
@@ -0,0 +1,468 @@
+===================================================
+Scalable Matrix Extension support for AArch64 Linux
+===================================================
+
+This document outlines briefly the interface provided to userspace by Linux in
+order to support use of the ARM Scalable Matrix Extension (SME).
+
+This is an outline of the most important features and issues only and not
+intended to be exhaustive.  It should be read in conjunction with the SVE
+documentation in sve.rst which provides details on the Streaming SVE mode
+included in SME.
+
+This document does not aim to describe the SME architecture or programmer's
+model.  To aid understanding, a minimal description of relevant programmer's
+model features for SME is included in Appendix A.
+
+
+1.  General
+-----------
+
+* PSTATE.SM, PSTATE.ZA, the streaming mode vector length, the ZA and (when
+  present) ZTn register state and TPIDR2_EL0 are tracked per thread.
+
+* The presence of SME is reported to userspace via HWCAP2_SME in the aux vector
+  AT_HWCAP2 entry.  Presence of this flag implies the presence of the SME
+  instructions and registers, and the Linux-specific system interfaces
+  described in this document.  SME is reported in /proc/cpuinfo as "sme".
+
+* The presence of SME2 is reported to userspace via HWCAP2_SME2 in the
+  aux vector AT_HWCAP2 entry.  Presence of this flag implies the presence of
+  the SME2 instructions and ZT0, and the Linux-specific system interfaces
+  described in this document.  SME2 is reported in /proc/cpuinfo as "sme2".
+
+* Support for the execution of SME instructions in userspace can also be
+  detected by reading the CPU ID register ID_AA64PFR1_EL1 using an MRS
+  instruction, and checking that the value of the SME field is nonzero. [3]
+
+  It does not guarantee the presence of the system interfaces described in the
+  following sections: software that needs to verify that those interfaces are
+  present must check for HWCAP2_SME instead.
+
+* There are a number of optional SME features, presence of these is reported
+  through AT_HWCAP2 through:
+
+	HWCAP2_SME_I16I64
+	HWCAP2_SME_F64F64
+	HWCAP2_SME_I8I32
+	HWCAP2_SME_F16F32
+	HWCAP2_SME_B16F32
+	HWCAP2_SME_F32F32
+	HWCAP2_SME_FA64
+        HWCAP2_SME2
+
+  This list may be extended over time as the SME architecture evolves.
+
+  These extensions are also reported via the CPU ID register ID_AA64SMFR0_EL1,
+  which userspace can read using an MRS instruction.  See elf_hwcaps.txt and
+  cpu-feature-registers.txt for details.
+
+* Debuggers should restrict themselves to interacting with the target via the
+  NT_ARM_SVE, NT_ARM_SSVE, NT_ARM_ZA and NT_ARM_ZT regsets.  The recommended
+  way of detecting support for these regsets is to connect to a target process
+  first and then attempt a
+
+	ptrace(PTRACE_GETREGSET, pid, NT_ARM_<regset>, &iov).
+
+* Whenever ZA register values are exchanged in memory between userspace and
+  the kernel, the register value is encoded in memory as a series of horizontal
+  vectors from 0 to VL/8-1 stored in the same endianness invariant format as is
+  used for SVE vectors.
+
+* On thread creation TPIDR2_EL0 is preserved unless CLONE_SETTLS is specified,
+  in which case it is set to 0.
+
+2.  Vector lengths
+------------------
+
+SME defines a second vector length similar to the SVE vector length which is
+controls the size of the streaming mode SVE vectors and the ZA matrix array.
+The ZA matrix is square with each side having as many bytes as a streaming
+mode SVE vector.
+
+
+3.  Sharing of streaming and non-streaming mode SVE state
+---------------------------------------------------------
+
+It is implementation defined which if any parts of the SVE state are shared
+between streaming and non-streaming modes.  When switching between modes
+via software interfaces such as ptrace if no register content is provided as
+part of switching no state will be assumed to be shared and everything will
+be zeroed.
+
+
+4.  System call behaviour
+-------------------------
+
+* On syscall PSTATE.ZA is preserved, if PSTATE.ZA==1 then the contents of the
+  ZA matrix and ZTn (if present) are preserved.
+
+* On syscall PSTATE.SM will be cleared and the SVE registers will be handled
+  as per the standard SVE ABI.
+
+* None of the SVE registers, ZA or ZTn are used to pass arguments to
+  or receive results from any syscall.
+
+* On process creation (eg, clone()) the newly created process will have
+  PSTATE.SM cleared.
+
+* All other SME state of a thread, including the currently configured vector
+  length, the state of the PR_SME_VL_INHERIT flag, and the deferred vector
+  length (if any), is preserved across all syscalls, subject to the specific
+  exceptions for execve() described in section 6.
+
+
+5.  Signal handling
+-------------------
+
+* Signal handlers are invoked with streaming mode and ZA disabled.
+
+* A new signal frame record TPIDR2_MAGIC is added formatted as a struct
+  tpidr2_context to allow access to TPIDR2_EL0 from signal handlers.
+
+* A new signal frame record za_context encodes the ZA register contents on
+  signal delivery. [1]
+
+* The signal frame record for ZA always contains basic metadata, in particular
+  the thread's vector length (in za_context.vl).
+
+* The ZA matrix may or may not be included in the record, depending on
+  the value of PSTATE.ZA.  The registers are present if and only if:
+  za_context.head.size >= ZA_SIG_CONTEXT_SIZE(sve_vq_from_vl(za_context.vl))
+  in which case PSTATE.ZA == 1.
+
+* If matrix data is present, the remainder of the record has a vl-dependent
+  size and layout.  Macros ZA_SIG_* are defined [1] to facilitate access to
+  them.
+
+* The matrix is stored as a series of horizontal vectors in the same format as
+  is used for SVE vectors.
+
+* If the ZA context is too big to fit in sigcontext.__reserved[], then extra
+  space is allocated on the stack, an extra_context record is written in
+  __reserved[] referencing this space.  za_context is then written in the
+  extra space.  Refer to [1] for further details about this mechanism.
+
+* If ZTn is supported and PSTATE.ZA==1 then a signal frame record for ZTn will
+  be generated.
+
+* The signal record for ZTn has magic ZT_MAGIC (0x5a544e01) and consists of a
+  standard signal frame header followed by a struct zt_context specifying
+  the number of ZTn registers supported by the system, then zt_context.nregs
+  blocks of 64 bytes of data per register.
+
+
+5.  Signal return
+-----------------
+
+When returning from a signal handler:
+
+* If there is no za_context record in the signal frame, or if the record is
+  present but contains no register data as described in the previous section,
+  then ZA is disabled.
+
+* If za_context is present in the signal frame and contains matrix data then
+  PSTATE.ZA is set to 1 and ZA is populated with the specified data.
+
+* The vector length cannot be changed via signal return.  If za_context.vl in
+  the signal frame does not match the current vector length, the signal return
+  attempt is treated as illegal, resulting in a forced SIGSEGV.
+
+* If ZTn is not supported or PSTATE.ZA==0 then it is illegal to have a
+  signal frame record for ZTn, resulting in a forced SIGSEGV.
+
+
+6.  prctl extensions
+--------------------
+
+Some new prctl() calls are added to allow programs to manage the SME vector
+length:
+
+prctl(PR_SME_SET_VL, unsigned long arg)
+
+    Sets the vector length of the calling thread and related flags, where
+    arg == vl | flags.  Other threads of the calling process are unaffected.
+
+    vl is the desired vector length, where sve_vl_valid(vl) must be true.
+
+    flags:
+
+	PR_SME_VL_INHERIT
+
+	    Inherit the current vector length across execve().  Otherwise, the
+	    vector length is reset to the system default at execve().  (See
+	    Section 9.)
+
+	PR_SME_SET_VL_ONEXEC
+
+	    Defer the requested vector length change until the next execve()
+	    performed by this thread.
+
+	    The effect is equivalent to implicit execution of the following
+	    call immediately after the next execve() (if any) by the thread:
+
+		prctl(PR_SME_SET_VL, arg & ~PR_SME_SET_VL_ONEXEC)
+
+	    This allows launching of a new program with a different vector
+	    length, while avoiding runtime side effects in the caller.
+
+	    Without PR_SME_SET_VL_ONEXEC, the requested change takes effect
+	    immediately.
+
+
+    Return value: a nonnegative on success, or a negative value on error:
+	EINVAL: SME not supported, invalid vector length requested, or
+	    invalid flags.
+
+
+    On success:
+
+    * Either the calling thread's vector length or the deferred vector length
+      to be applied at the next execve() by the thread (dependent on whether
+      PR_SME_SET_VL_ONEXEC is present in arg), is set to the largest value
+      supported by the system that is less than or equal to vl.  If vl ==
+      SVE_VL_MAX, the value set will be the largest value supported by the
+      system.
+
+    * Any previously outstanding deferred vector length change in the calling
+      thread is cancelled.
+
+    * The returned value describes the resulting configuration, encoded as for
+      PR_SME_GET_VL.  The vector length reported in this value is the new
+      current vector length for this thread if PR_SME_SET_VL_ONEXEC was not
+      present in arg; otherwise, the reported vector length is the deferred
+      vector length that will be applied at the next execve() by the calling
+      thread.
+
+    * Changing the vector length causes all of ZA, ZTn, P0..P15, FFR and all
+      bits of Z0..Z31 except for Z0 bits [127:0] .. Z31 bits [127:0] to become
+      unspecified, including both streaming and non-streaming SVE state.
+      Calling PR_SME_SET_VL with vl equal to the thread's current vector
+      length, or calling PR_SME_SET_VL with the PR_SVE_SET_VL_ONEXEC flag,
+      does not constitute a change to the vector length for this purpose.
+
+    * Changing the vector length causes PSTATE.ZA and PSTATE.SM to be cleared.
+      Calling PR_SME_SET_VL with vl equal to the thread's current vector
+      length, or calling PR_SME_SET_VL with the PR_SVE_SET_VL_ONEXEC flag,
+      does not constitute a change to the vector length for this purpose.
+
+
+prctl(PR_SME_GET_VL)
+
+    Gets the vector length of the calling thread.
+
+    The following flag may be OR-ed into the result:
+
+	PR_SME_VL_INHERIT
+
+	    Vector length will be inherited across execve().
+
+    There is no way to determine whether there is an outstanding deferred
+    vector length change (which would only normally be the case between a
+    fork() or vfork() and the corresponding execve() in typical use).
+
+    To extract the vector length from the result, bitwise and it with
+    PR_SME_VL_LEN_MASK.
+
+    Return value: a nonnegative value on success, or a negative value on error:
+	EINVAL: SME not supported.
+
+
+7.  ptrace extensions
+---------------------
+
+* A new regset NT_ARM_SSVE is defined for access to streaming mode SVE
+  state via PTRACE_GETREGSET and  PTRACE_SETREGSET, this is documented in
+  sve.rst.
+
+* A new regset NT_ARM_ZA is defined for ZA state for access to ZA state via
+  PTRACE_GETREGSET and PTRACE_SETREGSET.
+
+  Refer to [2] for definitions.
+
+The regset data starts with struct user_za_header, containing:
+
+    size
+
+	Size of the complete regset, in bytes.
+	This depends on vl and possibly on other things in the future.
+
+	If a call to PTRACE_GETREGSET requests less data than the value of
+	size, the caller can allocate a larger buffer and retry in order to
+	read the complete regset.
+
+    max_size
+
+	Maximum size in bytes that the regset can grow to for the target
+	thread.  The regset won't grow bigger than this even if the target
+	thread changes its vector length etc.
+
+    vl
+
+	Target thread's current streaming vector length, in bytes.
+
+    max_vl
+
+	Maximum possible streaming vector length for the target thread.
+
+    flags
+
+	Zero or more of the following flags, which have the same
+	meaning and behaviour as the corresponding PR_SET_VL_* flags:
+
+	    SME_PT_VL_INHERIT
+
+	    SME_PT_VL_ONEXEC (SETREGSET only).
+
+* The effects of changing the vector length and/or flags are equivalent to
+  those documented for PR_SME_SET_VL.
+
+  The caller must make a further GETREGSET call if it needs to know what VL is
+  actually set by SETREGSET, unless is it known in advance that the requested
+  VL is supported.
+
+* The size and layout of the payload depends on the header fields.  The
+  SME_PT_ZA_*() macros are provided to facilitate access to the data.
+
+* In either case, for SETREGSET it is permissible to omit the payload, in which
+  case the vector length and flags are changed and PSTATE.ZA is set to 0
+  (along with any consequences of those changes).  If a payload is provided
+  then PSTATE.ZA will be set to 1.
+
+* For SETREGSET, if the requested VL is not supported, the effect will be the
+  same as if the payload were omitted, except that an EIO error is reported.
+  No attempt is made to translate the payload data to the correct layout
+  for the vector length actually set.  It is up to the caller to translate the
+  payload layout for the actual VL and retry.
+
+* The effect of writing a partial, incomplete payload is unspecified.
+
+* A new regset NT_ARM_ZT is defined for access to ZTn state via
+  PTRACE_GETREGSET and PTRACE_SETREGSET.
+
+* The NT_ARM_ZT regset consists of a single 512 bit register.
+
+* When PSTATE.ZA==0 reads of NT_ARM_ZT will report all bits of ZTn as 0.
+
+* Writes to NT_ARM_ZT will set PSTATE.ZA to 1.
+
+
+8.  ELF coredump extensions
+---------------------------
+
+* NT_ARM_SSVE notes will be added to each coredump for
+  each thread of the dumped process.  The contents will be equivalent to the
+  data that would have been read if a PTRACE_GETREGSET of the corresponding
+  type were executed for each thread when the coredump was generated.
+
+* A NT_ARM_ZA note will be added to each coredump for each thread of the
+  dumped process.  The contents will be equivalent to the data that would have
+  been read if a PTRACE_GETREGSET of NT_ARM_ZA were executed for each thread
+  when the coredump was generated.
+
+* A NT_ARM_ZT note will be added to each coredump for each thread of the
+  dumped process.  The contents will be equivalent to the data that would have
+  been read if a PTRACE_GETREGSET of NT_ARM_ZT were executed for each thread
+  when the coredump was generated.
+
+* The NT_ARM_TLS note will be extended to two registers, the second register
+  will contain TPIDR2_EL0 on systems that support SME and will be read as
+  zero with writes ignored otherwise.
+
+9.  System runtime configuration
+--------------------------------
+
+* To mitigate the ABI impact of expansion of the signal frame, a policy
+  mechanism is provided for administrators, distro maintainers and developers
+  to set the default vector length for userspace processes:
+
+/proc/sys/abi/sme_default_vector_length
+
+    Writing the text representation of an integer to this file sets the system
+    default vector length to the specified value, unless the value is greater
+    than the maximum vector length supported by the system in which case the
+    default vector length is set to that maximum.
+
+    The result can be determined by reopening the file and reading its
+    contents.
+
+    At boot, the default vector length is initially set to 32 or the maximum
+    supported vector length, whichever is smaller and supported.  This
+    determines the initial vector length of the init process (PID 1).
+
+    Reading this file returns the current system default vector length.
+
+* At every execve() call, the new vector length of the new process is set to
+  the system default vector length, unless
+
+    * PR_SME_VL_INHERIT (or equivalently SME_PT_VL_INHERIT) is set for the
+      calling thread, or
+
+    * a deferred vector length change is pending, established via the
+      PR_SME_SET_VL_ONEXEC flag (or SME_PT_VL_ONEXEC).
+
+* Modifying the system default vector length does not affect the vector length
+  of any existing process or thread that does not make an execve() call.
+
+
+Appendix A.  SME programmer's model (informative)
+=================================================
+
+This section provides a minimal description of the additions made by SME to the
+ARMv8-A programmer's model that are relevant to this document.
+
+Note: This section is for information only and not intended to be complete or
+to replace any architectural specification.
+
+A.1.  Registers
+---------------
+
+In A64 state, SME adds the following:
+
+* A new mode, streaming mode, in which a subset of the normal FPSIMD and SVE
+  features are available.  When supported EL0 software may enter and leave
+  streaming mode at any time.
+
+  For best system performance it is strongly encouraged for software to enable
+  streaming mode only when it is actively being used.
+
+* A new vector length controlling the size of ZA and the Z registers when in
+  streaming mode, separately to the vector length used for SVE when not in
+  streaming mode.  There is no requirement that either the currently selected
+  vector length or the set of vector lengths supported for the two modes in
+  a given system have any relationship.  The streaming mode vector length
+  is referred to as SVL.
+
+* A new ZA matrix register.  This is a square matrix of SVLxSVL bits.  Most
+  operations on ZA require that streaming mode be enabled but ZA can be
+  enabled without streaming mode in order to load, save and retain data.
+
+  For best system performance it is strongly encouraged for software to enable
+  ZA only when it is actively being used.
+
+* A new ZT0 register is introduced when SME2 is present. This is a 512 bit
+  register which is accessible when PSTATE.ZA is set, as ZA itself is.
+
+* Two new 1 bit fields in PSTATE which may be controlled via the SMSTART and
+  SMSTOP instructions or by access to the SVCR system register:
+
+  * PSTATE.ZA, if this is 1 then the ZA matrix is accessible and has valid
+    data while if it is 0 then ZA can not be accessed.  When PSTATE.ZA is
+    changed from 0 to 1 all bits in ZA are cleared.
+
+  * PSTATE.SM, if this is 1 then the PE is in streaming mode.  When the value
+    of PSTATE.SM is changed then it is implementation defined if the subset
+    of the floating point register bits valid in both modes may be retained.
+    Any other bits will be cleared.
+
+
+References
+==========
+
+[1] arch/arm64/include/uapi/asm/sigcontext.h
+    AArch64 Linux signal ABI definitions
+
+[2] arch/arm64/include/uapi/asm/ptrace.h
+    AArch64 Linux ptrace ABI definitions
+
+[3] Documentation/arch/arm64/cpu-feature-registers.rst
diff --git a/Documentation/arch/arm64/sve.rst b/Documentation/arch/arm64/sve.rst
new file mode 100644
index 00000000000000..0d9a426e9f858d
--- /dev/null
+++ b/Documentation/arch/arm64/sve.rst
@@ -0,0 +1,616 @@
+===================================================
+Scalable Vector Extension support for AArch64 Linux
+===================================================
+
+Author: Dave Martin <Dave.Martin@arm.com>
+
+Date:   4 August 2017
+
+This document outlines briefly the interface provided to userspace by Linux in
+order to support use of the ARM Scalable Vector Extension (SVE), including
+interactions with Streaming SVE mode added by the Scalable Matrix Extension
+(SME).
+
+This is an outline of the most important features and issues only and not
+intended to be exhaustive.
+
+This document does not aim to describe the SVE architecture or programmer's
+model.  To aid understanding, a minimal description of relevant programmer's
+model features for SVE is included in Appendix A.
+
+
+1.  General
+-----------
+
+* SVE registers Z0..Z31, P0..P15 and FFR and the current vector length VL, are
+  tracked per-thread.
+
+* In streaming mode FFR is not accessible unless HWCAP2_SME_FA64 is present
+  in the system, when it is not supported and these interfaces are used to
+  access streaming mode FFR is read and written as zero.
+
+* The presence of SVE is reported to userspace via HWCAP_SVE in the aux vector
+  AT_HWCAP entry.  Presence of this flag implies the presence of the SVE
+  instructions and registers, and the Linux-specific system interfaces
+  described in this document.  SVE is reported in /proc/cpuinfo as "sve".
+
+* Support for the execution of SVE instructions in userspace can also be
+  detected by reading the CPU ID register ID_AA64PFR0_EL1 using an MRS
+  instruction, and checking that the value of the SVE field is nonzero. [3]
+
+  It does not guarantee the presence of the system interfaces described in the
+  following sections: software that needs to verify that those interfaces are
+  present must check for HWCAP_SVE instead.
+
+* On hardware that supports the SVE2 extensions, HWCAP2_SVE2 will also
+  be reported in the AT_HWCAP2 aux vector entry.  In addition to this,
+  optional extensions to SVE2 may be reported by the presence of:
+
+	HWCAP2_SVE2
+	HWCAP2_SVEAES
+	HWCAP2_SVEPMULL
+	HWCAP2_SVEBITPERM
+	HWCAP2_SVESHA3
+	HWCAP2_SVESM4
+	HWCAP2_SVE2P1
+
+  This list may be extended over time as the SVE architecture evolves.
+
+  These extensions are also reported via the CPU ID register ID_AA64ZFR0_EL1,
+  which userspace can read using an MRS instruction.  See elf_hwcaps.txt and
+  cpu-feature-registers.txt for details.
+
+* On hardware that supports the SME extensions, HWCAP2_SME will also be
+  reported in the AT_HWCAP2 aux vector entry.  Among other things SME adds
+  streaming mode which provides a subset of the SVE feature set using a
+  separate SME vector length and the same Z/V registers.  See sme.rst
+  for more details.
+
+* Debuggers should restrict themselves to interacting with the target via the
+  NT_ARM_SVE regset.  The recommended way of detecting support for this regset
+  is to connect to a target process first and then attempt a
+  ptrace(PTRACE_GETREGSET, pid, NT_ARM_SVE, &iov).  Note that when SME is
+  present and streaming SVE mode is in use the FPSIMD subset of registers
+  will be read via NT_ARM_SVE and NT_ARM_SVE writes will exit streaming mode
+  in the target.
+
+* Whenever SVE scalable register values (Zn, Pn, FFR) are exchanged in memory
+  between userspace and the kernel, the register value is encoded in memory in
+  an endianness-invariant layout, with bits [(8 * i + 7) : (8 * i)] encoded at
+  byte offset i from the start of the memory representation.  This affects for
+  example the signal frame (struct sve_context) and ptrace interface
+  (struct user_sve_header) and associated data.
+
+  Beware that on big-endian systems this results in a different byte order than
+  for the FPSIMD V-registers, which are stored as single host-endian 128-bit
+  values, with bits [(127 - 8 * i) : (120 - 8 * i)] of the register encoded at
+  byte offset i.  (struct fpsimd_context, struct user_fpsimd_state).
+
+
+2.  Vector length terminology
+-----------------------------
+
+The size of an SVE vector (Z) register is referred to as the "vector length".
+
+To avoid confusion about the units used to express vector length, the kernel
+adopts the following conventions:
+
+* Vector length (VL) = size of a Z-register in bytes
+
+* Vector quadwords (VQ) = size of a Z-register in units of 128 bits
+
+(So, VL = 16 * VQ.)
+
+The VQ convention is used where the underlying granularity is important, such
+as in data structure definitions.  In most other situations, the VL convention
+is used.  This is consistent with the meaning of the "VL" pseudo-register in
+the SVE instruction set architecture.
+
+
+3.  System call behaviour
+-------------------------
+
+* On syscall, V0..V31 are preserved (as without SVE).  Thus, bits [127:0] of
+  Z0..Z31 are preserved.  All other bits of Z0..Z31, and all of P0..P15 and FFR
+  become zero on return from a syscall.
+
+* The SVE registers are not used to pass arguments to or receive results from
+  any syscall.
+
+* In practice the affected registers/bits will be preserved or will be replaced
+  with zeros on return from a syscall, but userspace should not make
+  assumptions about this.  The kernel behaviour may vary on a case-by-case
+  basis.
+
+* All other SVE state of a thread, including the currently configured vector
+  length, the state of the PR_SVE_VL_INHERIT flag, and the deferred vector
+  length (if any), is preserved across all syscalls, subject to the specific
+  exceptions for execve() described in section 6.
+
+  In particular, on return from a fork() or clone(), the parent and new child
+  process or thread share identical SVE configuration, matching that of the
+  parent before the call.
+
+
+4.  Signal handling
+-------------------
+
+* A new signal frame record sve_context encodes the SVE registers on signal
+  delivery. [1]
+
+* This record is supplementary to fpsimd_context.  The FPSR and FPCR registers
+  are only present in fpsimd_context.  For convenience, the content of V0..V31
+  is duplicated between sve_context and fpsimd_context.
+
+* The record contains a flag field which includes a flag SVE_SIG_FLAG_SM which
+  if set indicates that the thread is in streaming mode and the vector length
+  and register data (if present) describe the streaming SVE data and vector
+  length.
+
+* The signal frame record for SVE always contains basic metadata, in particular
+  the thread's vector length (in sve_context.vl).
+
+* The SVE registers may or may not be included in the record, depending on
+  whether the registers are live for the thread.  The registers are present if
+  and only if:
+  sve_context.head.size >= SVE_SIG_CONTEXT_SIZE(sve_vq_from_vl(sve_context.vl)).
+
+* If the registers are present, the remainder of the record has a vl-dependent
+  size and layout.  Macros SVE_SIG_* are defined [1] to facilitate access to
+  the members.
+
+* Each scalable register (Zn, Pn, FFR) is stored in an endianness-invariant
+  layout, with bits [(8 * i + 7) : (8 * i)] stored at byte offset i from the
+  start of the register's representation in memory.
+
+* If the SVE context is too big to fit in sigcontext.__reserved[], then extra
+  space is allocated on the stack, an extra_context record is written in
+  __reserved[] referencing this space.  sve_context is then written in the
+  extra space.  Refer to [1] for further details about this mechanism.
+
+
+5.  Signal return
+-----------------
+
+When returning from a signal handler:
+
+* If there is no sve_context record in the signal frame, or if the record is
+  present but contains no register data as described in the previous section,
+  then the SVE registers/bits become non-live and take unspecified values.
+
+* If sve_context is present in the signal frame and contains full register
+  data, the SVE registers become live and are populated with the specified
+  data.  However, for backward compatibility reasons, bits [127:0] of Z0..Z31
+  are always restored from the corresponding members of fpsimd_context.vregs[]
+  and not from sve_context.  The remaining bits are restored from sve_context.
+
+* Inclusion of fpsimd_context in the signal frame remains mandatory,
+  irrespective of whether sve_context is present or not.
+
+* The vector length cannot be changed via signal return.  If sve_context.vl in
+  the signal frame does not match the current vector length, the signal return
+  attempt is treated as illegal, resulting in a forced SIGSEGV.
+
+* It is permitted to enter or leave streaming mode by setting or clearing
+  the SVE_SIG_FLAG_SM flag but applications should take care to ensure that
+  when doing so sve_context.vl and any register data are appropriate for the
+  vector length in the new mode.
+
+
+6.  prctl extensions
+--------------------
+
+Some new prctl() calls are added to allow programs to manage the SVE vector
+length:
+
+prctl(PR_SVE_SET_VL, unsigned long arg)
+
+    Sets the vector length of the calling thread and related flags, where
+    arg == vl | flags.  Other threads of the calling process are unaffected.
+
+    vl is the desired vector length, where sve_vl_valid(vl) must be true.
+
+    flags:
+
+	PR_SVE_VL_INHERIT
+
+	    Inherit the current vector length across execve().  Otherwise, the
+	    vector length is reset to the system default at execve().  (See
+	    Section 9.)
+
+	PR_SVE_SET_VL_ONEXEC
+
+	    Defer the requested vector length change until the next execve()
+	    performed by this thread.
+
+	    The effect is equivalent to implicit execution of the following
+	    call immediately after the next execve() (if any) by the thread:
+
+		prctl(PR_SVE_SET_VL, arg & ~PR_SVE_SET_VL_ONEXEC)
+
+	    This allows launching of a new program with a different vector
+	    length, while avoiding runtime side effects in the caller.
+
+
+	    Without PR_SVE_SET_VL_ONEXEC, the requested change takes effect
+	    immediately.
+
+
+    Return value: a nonnegative on success, or a negative value on error:
+	EINVAL: SVE not supported, invalid vector length requested, or
+	    invalid flags.
+
+
+    On success:
+
+    * Either the calling thread's vector length or the deferred vector length
+      to be applied at the next execve() by the thread (dependent on whether
+      PR_SVE_SET_VL_ONEXEC is present in arg), is set to the largest value
+      supported by the system that is less than or equal to vl.  If vl ==
+      SVE_VL_MAX, the value set will be the largest value supported by the
+      system.
+
+    * Any previously outstanding deferred vector length change in the calling
+      thread is cancelled.
+
+    * The returned value describes the resulting configuration, encoded as for
+      PR_SVE_GET_VL.  The vector length reported in this value is the new
+      current vector length for this thread if PR_SVE_SET_VL_ONEXEC was not
+      present in arg; otherwise, the reported vector length is the deferred
+      vector length that will be applied at the next execve() by the calling
+      thread.
+
+    * Changing the vector length causes all of P0..P15, FFR and all bits of
+      Z0..Z31 except for Z0 bits [127:0] .. Z31 bits [127:0] to become
+      unspecified.  Calling PR_SVE_SET_VL with vl equal to the thread's current
+      vector length, or calling PR_SVE_SET_VL with the PR_SVE_SET_VL_ONEXEC
+      flag, does not constitute a change to the vector length for this purpose.
+
+
+prctl(PR_SVE_GET_VL)
+
+    Gets the vector length of the calling thread.
+
+    The following flag may be OR-ed into the result:
+
+	PR_SVE_VL_INHERIT
+
+	    Vector length will be inherited across execve().
+
+    There is no way to determine whether there is an outstanding deferred
+    vector length change (which would only normally be the case between a
+    fork() or vfork() and the corresponding execve() in typical use).
+
+    To extract the vector length from the result, bitwise and it with
+    PR_SVE_VL_LEN_MASK.
+
+    Return value: a nonnegative value on success, or a negative value on error:
+	EINVAL: SVE not supported.
+
+
+7.  ptrace extensions
+---------------------
+
+* New regsets NT_ARM_SVE and NT_ARM_SSVE are defined for use with
+  PTRACE_GETREGSET and PTRACE_SETREGSET. NT_ARM_SSVE describes the
+  streaming mode SVE registers and NT_ARM_SVE describes the
+  non-streaming mode SVE registers.
+
+  In this description a register set is referred to as being "live" when
+  the target is in the appropriate streaming or non-streaming mode and is
+  using data beyond the subset shared with the FPSIMD Vn registers.
+
+  Refer to [2] for definitions.
+
+The regset data starts with struct user_sve_header, containing:
+
+    size
+
+	Size of the complete regset, in bytes.
+	This depends on vl and possibly on other things in the future.
+
+	If a call to PTRACE_GETREGSET requests less data than the value of
+	size, the caller can allocate a larger buffer and retry in order to
+	read the complete regset.
+
+    max_size
+
+	Maximum size in bytes that the regset can grow to for the target
+	thread.  The regset won't grow bigger than this even if the target
+	thread changes its vector length etc.
+
+    vl
+
+	Target thread's current vector length, in bytes.
+
+    max_vl
+
+	Maximum possible vector length for the target thread.
+
+    flags
+
+	at most one of
+
+	    SVE_PT_REGS_FPSIMD
+
+		SVE registers are not live (GETREGSET) or are to be made
+		non-live (SETREGSET).
+
+		The payload is of type struct user_fpsimd_state, with the same
+		meaning as for NT_PRFPREG, starting at offset
+		SVE_PT_FPSIMD_OFFSET from the start of user_sve_header.
+
+		Extra data might be appended in the future: the size of the
+		payload should be obtained using SVE_PT_FPSIMD_SIZE(vq, flags).
+
+		vq should be obtained using sve_vq_from_vl(vl).
+
+		or
+
+	    SVE_PT_REGS_SVE
+
+		SVE registers are live (GETREGSET) or are to be made live
+		(SETREGSET).
+
+		The payload contains the SVE register data, starting at offset
+		SVE_PT_SVE_OFFSET from the start of user_sve_header, and with
+		size SVE_PT_SVE_SIZE(vq, flags);
+
+	... OR-ed with zero or more of the following flags, which have the same
+	meaning and behaviour as the corresponding PR_SET_VL_* flags:
+
+	    SVE_PT_VL_INHERIT
+
+	    SVE_PT_VL_ONEXEC (SETREGSET only).
+
+	If neither FPSIMD nor SVE flags are provided then no register
+	payload is available, this is only possible when SME is implemented.
+
+
+* The effects of changing the vector length and/or flags are equivalent to
+  those documented for PR_SVE_SET_VL.
+
+  The caller must make a further GETREGSET call if it needs to know what VL is
+  actually set by SETREGSET, unless is it known in advance that the requested
+  VL is supported.
+
+* In the SVE_PT_REGS_SVE case, the size and layout of the payload depends on
+  the header fields.  The SVE_PT_SVE_*() macros are provided to facilitate
+  access to the members.
+
+* In either case, for SETREGSET it is permissible to omit the payload, in which
+  case only the vector length and flags are changed (along with any
+  consequences of those changes).
+
+* In systems supporting SME when in streaming mode a GETREGSET for
+  NT_REG_SVE will return only the user_sve_header with no register data,
+  similarly a GETREGSET for NT_REG_SSVE will not return any register data
+  when not in streaming mode.
+
+* A GETREGSET for NT_ARM_SSVE will never return SVE_PT_REGS_FPSIMD.
+
+* For SETREGSET, if an SVE_PT_REGS_SVE payload is present and the
+  requested VL is not supported, the effect will be the same as if the
+  payload were omitted, except that an EIO error is reported.  No
+  attempt is made to translate the payload data to the correct layout
+  for the vector length actually set.  The thread's FPSIMD state is
+  preserved, but the remaining bits of the SVE registers become
+  unspecified.  It is up to the caller to translate the payload layout
+  for the actual VL and retry.
+
+* Where SME is implemented it is not possible to GETREGSET the register
+  state for normal SVE when in streaming mode, nor the streaming mode
+  register state when in normal mode, regardless of the implementation defined
+  behaviour of the hardware for sharing data between the two modes.
+
+* Any SETREGSET of NT_ARM_SVE will exit streaming mode if the target was in
+  streaming mode and any SETREGSET of NT_ARM_SSVE will enter streaming mode
+  if the target was not in streaming mode.
+
+* The effect of writing a partial, incomplete payload is unspecified.
+
+
+8.  ELF coredump extensions
+---------------------------
+
+* NT_ARM_SVE and NT_ARM_SSVE notes will be added to each coredump for
+  each thread of the dumped process.  The contents will be equivalent to the
+  data that would have been read if a PTRACE_GETREGSET of the corresponding
+  type were executed for each thread when the coredump was generated.
+
+9.  System runtime configuration
+--------------------------------
+
+* To mitigate the ABI impact of expansion of the signal frame, a policy
+  mechanism is provided for administrators, distro maintainers and developers
+  to set the default vector length for userspace processes:
+
+/proc/sys/abi/sve_default_vector_length
+
+    Writing the text representation of an integer to this file sets the system
+    default vector length to the specified value, unless the value is greater
+    than the maximum vector length supported by the system in which case the
+    default vector length is set to that maximum.
+
+    The result can be determined by reopening the file and reading its
+    contents.
+
+    At boot, the default vector length is initially set to 64 or the maximum
+    supported vector length, whichever is smaller.  This determines the initial
+    vector length of the init process (PID 1).
+
+    Reading this file returns the current system default vector length.
+
+* At every execve() call, the new vector length of the new process is set to
+  the system default vector length, unless
+
+    * PR_SVE_VL_INHERIT (or equivalently SVE_PT_VL_INHERIT) is set for the
+      calling thread, or
+
+    * a deferred vector length change is pending, established via the
+      PR_SVE_SET_VL_ONEXEC flag (or SVE_PT_VL_ONEXEC).
+
+* Modifying the system default vector length does not affect the vector length
+  of any existing process or thread that does not make an execve() call.
+
+10.  Perf extensions
+--------------------------------
+
+* The arm64 specific DWARF standard [5] added the VG (Vector Granule) register
+  at index 46. This register is used for DWARF unwinding when variable length
+  SVE registers are pushed onto the stack.
+
+* Its value is equivalent to the current SVE vector length (VL) in bits divided
+  by 64.
+
+* The value is included in Perf samples in the regs[46] field if
+  PERF_SAMPLE_REGS_USER is set and the sample_regs_user mask has bit 46 set.
+
+* The value is the current value at the time the sample was taken, and it can
+  change over time.
+
+* If the system doesn't support SVE when perf_event_open is called with these
+  settings, the event will fail to open.
+
+Appendix A.  SVE programmer's model (informative)
+=================================================
+
+This section provides a minimal description of the additions made by SVE to the
+ARMv8-A programmer's model that are relevant to this document.
+
+Note: This section is for information only and not intended to be complete or
+to replace any architectural specification.
+
+A.1.  Registers
+---------------
+
+In A64 state, SVE adds the following:
+
+* 32 8VL-bit vector registers Z0..Z31
+  For each Zn, Zn bits [127:0] alias the ARMv8-A vector register Vn.
+
+  A register write using a Vn register name zeros all bits of the corresponding
+  Zn except for bits [127:0].
+
+* 16 VL-bit predicate registers P0..P15
+
+* 1 VL-bit special-purpose predicate register FFR (the "first-fault register")
+
+* a VL "pseudo-register" that determines the size of each vector register
+
+  The SVE instruction set architecture provides no way to write VL directly.
+  Instead, it can be modified only by EL1 and above, by writing appropriate
+  system registers.
+
+* The value of VL can be configured at runtime by EL1 and above:
+  16 <= VL <= VLmax, where VL must be a multiple of 16.
+
+* The maximum vector length is determined by the hardware:
+  16 <= VLmax <= 256.
+
+  (The SVE architecture specifies 256, but permits future architecture
+  revisions to raise this limit.)
+
+* FPSR and FPCR are retained from ARMv8-A, and interact with SVE floating-point
+  operations in a similar way to the way in which they interact with ARMv8
+  floating-point operations::
+
+         8VL-1                       128               0  bit index
+        +----          ////            -----------------+
+     Z0 |                               :       V0      |
+      :                                          :
+     Z7 |                               :       V7      |
+     Z8 |                               :     * V8      |
+      :                                       :  :
+    Z15 |                               :     *V15      |
+    Z16 |                               :      V16      |
+      :                                          :
+    Z31 |                               :      V31      |
+        +----          ////            -----------------+
+                                                 31    0
+         VL-1                  0                +-------+
+        +----       ////      --+          FPSR |       |
+     P0 |                       |               +-------+
+      : |                       |         *FPCR |       |
+    P15 |                       |               +-------+
+        +----       ////      --+
+    FFR |                       |               +-----+
+        +----       ////      --+            VL |     |
+                                                +-----+
+
+(*) callee-save:
+    This only applies to bits [63:0] of Z-/V-registers.
+    FPCR contains callee-save and caller-save bits.  See [4] for details.
+
+
+A.2.  Procedure call standard
+-----------------------------
+
+The ARMv8-A base procedure call standard is extended as follows with respect to
+the additional SVE register state:
+
+* All SVE register bits that are not shared with FP/SIMD are caller-save.
+
+* Z8 bits [63:0] .. Z15 bits [63:0] are callee-save.
+
+  This follows from the way these bits are mapped to V8..V15, which are caller-
+  save in the base procedure call standard.
+
+
+Appendix B.  ARMv8-A FP/SIMD programmer's model
+===============================================
+
+Note: This section is for information only and not intended to be complete or
+to replace any architectural specification.
+
+Refer to [4] for more information.
+
+ARMv8-A defines the following floating-point / SIMD register state:
+
+* 32 128-bit vector registers V0..V31
+* 2 32-bit status/control registers FPSR, FPCR
+
+::
+
+         127           0  bit index
+        +---------------+
+     V0 |               |
+      : :               :
+     V7 |               |
+   * V8 |               |
+   :  : :               :
+   *V15 |               |
+    V16 |               |
+      : :               :
+    V31 |               |
+        +---------------+
+
+                 31    0
+                +-------+
+           FPSR |       |
+                +-------+
+          *FPCR |       |
+                +-------+
+
+(*) callee-save:
+    This only applies to bits [63:0] of V-registers.
+    FPCR contains a mixture of callee-save and caller-save bits.
+
+
+References
+==========
+
+[1] arch/arm64/include/uapi/asm/sigcontext.h
+    AArch64 Linux signal ABI definitions
+
+[2] arch/arm64/include/uapi/asm/ptrace.h
+    AArch64 Linux ptrace ABI definitions
+
+[3] Documentation/arch/arm64/cpu-feature-registers.rst
+
+[4] ARM IHI0055C
+    http://infocenter.arm.com/help/topic/com.arm.doc.ihi0055c/IHI0055C_beta_aapcs64.pdf
+    http://infocenter.arm.com/help/topic/com.arm.doc.subset.swdev.abi/index.html
+    Procedure Call Standard for the ARM 64-bit Architecture (AArch64)
+
+[5] https://github.com/ARM-software/abi-aa/blob/main/aadwarf64/aadwarf64.rst
diff --git a/Documentation/arch/arm64/tagged-address-abi.rst b/Documentation/arch/arm64/tagged-address-abi.rst
new file mode 100644
index 00000000000000..fe24a3f158c576
--- /dev/null
+++ b/Documentation/arch/arm64/tagged-address-abi.rst
@@ -0,0 +1,179 @@
+==========================
+AArch64 TAGGED ADDRESS ABI
+==========================
+
+Authors: Vincenzo Frascino <vincenzo.frascino@arm.com>
+         Catalin Marinas <catalin.marinas@arm.com>
+
+Date: 21 August 2019
+
+This document describes the usage and semantics of the Tagged Address
+ABI on AArch64 Linux.
+
+1. Introduction
+---------------
+
+On AArch64 the ``TCR_EL1.TBI0`` bit is set by default, allowing
+userspace (EL0) to perform memory accesses through 64-bit pointers with
+a non-zero top byte. This document describes the relaxation of the
+syscall ABI that allows userspace to pass certain tagged pointers to
+kernel syscalls.
+
+2. AArch64 Tagged Address ABI
+-----------------------------
+
+From the kernel syscall interface perspective and for the purposes of
+this document, a "valid tagged pointer" is a pointer with a potentially
+non-zero top-byte that references an address in the user process address
+space obtained in one of the following ways:
+
+- ``mmap()`` syscall where either:
+
+  - flags have the ``MAP_ANONYMOUS`` bit set or
+  - the file descriptor refers to a regular file (including those
+    returned by ``memfd_create()``) or ``/dev/zero``
+
+- ``brk()`` syscall (i.e. the heap area between the initial location of
+  the program break at process creation and its current location).
+
+- any memory mapped by the kernel in the address space of the process
+  during creation and with the same restrictions as for ``mmap()`` above
+  (e.g. data, bss, stack).
+
+The AArch64 Tagged Address ABI has two stages of relaxation depending on
+how the user addresses are used by the kernel:
+
+1. User addresses not accessed by the kernel but used for address space
+   management (e.g. ``mprotect()``, ``madvise()``). The use of valid
+   tagged pointers in this context is allowed with these exceptions:
+
+   - ``brk()``, ``mmap()`` and the ``new_address`` argument to
+     ``mremap()`` as these have the potential to alias with existing
+     user addresses.
+
+     NOTE: This behaviour changed in v5.6 and so some earlier kernels may
+     incorrectly accept valid tagged pointers for the ``brk()``,
+     ``mmap()`` and ``mremap()`` system calls.
+
+   - The ``range.start``, ``start`` and ``dst`` arguments to the
+     ``UFFDIO_*`` ``ioctl()``s used on a file descriptor obtained from
+     ``userfaultfd()``, as fault addresses subsequently obtained by reading
+     the file descriptor will be untagged, which may otherwise confuse
+     tag-unaware programs.
+
+     NOTE: This behaviour changed in v5.14 and so some earlier kernels may
+     incorrectly accept valid tagged pointers for this system call.
+
+2. User addresses accessed by the kernel (e.g. ``write()``). This ABI
+   relaxation is disabled by default and the application thread needs to
+   explicitly enable it via ``prctl()`` as follows:
+
+   - ``PR_SET_TAGGED_ADDR_CTRL``: enable or disable the AArch64 Tagged
+     Address ABI for the calling thread.
+
+     The ``(unsigned int) arg2`` argument is a bit mask describing the
+     control mode used:
+
+     - ``PR_TAGGED_ADDR_ENABLE``: enable AArch64 Tagged Address ABI.
+       Default status is disabled.
+
+     Arguments ``arg3``, ``arg4``, and ``arg5`` must be 0.
+
+   - ``PR_GET_TAGGED_ADDR_CTRL``: get the status of the AArch64 Tagged
+     Address ABI for the calling thread.
+
+     Arguments ``arg2``, ``arg3``, ``arg4``, and ``arg5`` must be 0.
+
+   The ABI properties described above are thread-scoped, inherited on
+   clone() and fork() and cleared on exec().
+
+   Calling ``prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0)``
+   returns ``-EINVAL`` if the AArch64 Tagged Address ABI is globally
+   disabled by ``sysctl abi.tagged_addr_disabled=1``. The default
+   ``sysctl abi.tagged_addr_disabled`` configuration is 0.
+
+When the AArch64 Tagged Address ABI is enabled for a thread, the
+following behaviours are guaranteed:
+
+- All syscalls except the cases mentioned in section 3 can accept any
+  valid tagged pointer.
+
+- The syscall behaviour is undefined for invalid tagged pointers: it may
+  result in an error code being returned, a (fatal) signal being raised,
+  or other modes of failure.
+
+- The syscall behaviour for a valid tagged pointer is the same as for
+  the corresponding untagged pointer.
+
+
+A definition of the meaning of tagged pointers on AArch64 can be found
+in Documentation/arch/arm64/tagged-pointers.rst.
+
+3. AArch64 Tagged Address ABI Exceptions
+-----------------------------------------
+
+The following system call parameters must be untagged regardless of the
+ABI relaxation:
+
+- ``prctl()`` other than pointers to user data either passed directly or
+  indirectly as arguments to be accessed by the kernel.
+
+- ``ioctl()`` other than pointers to user data either passed directly or
+  indirectly as arguments to be accessed by the kernel.
+
+- ``shmat()`` and ``shmdt()``.
+
+- ``brk()`` (since kernel v5.6).
+
+- ``mmap()`` (since kernel v5.6).
+
+- ``mremap()``, the ``new_address`` argument (since kernel v5.6).
+
+Any attempt to use non-zero tagged pointers may result in an error code
+being returned, a (fatal) signal being raised, or other modes of
+failure.
+
+4. Example of correct usage
+---------------------------
+.. code-block:: c
+
+   #include <stdlib.h>
+   #include <string.h>
+   #include <unistd.h>
+   #include <sys/mman.h>
+   #include <sys/prctl.h>
+   
+   #define PR_SET_TAGGED_ADDR_CTRL	55
+   #define PR_TAGGED_ADDR_ENABLE	(1UL << 0)
+   
+   #define TAG_SHIFT		56
+   
+   int main(void)
+   {
+   	int tbi_enabled = 0;
+   	unsigned long tag = 0;
+   	char *ptr;
+   
+   	/* check/enable the tagged address ABI */
+   	if (!prctl(PR_SET_TAGGED_ADDR_CTRL, PR_TAGGED_ADDR_ENABLE, 0, 0, 0))
+   		tbi_enabled = 1;
+   
+   	/* memory allocation */
+   	ptr = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE,
+   		   MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+   	if (ptr == MAP_FAILED)
+   		return 1;
+   
+   	/* set a non-zero tag if the ABI is available */
+   	if (tbi_enabled)
+   		tag = rand() & 0xff;
+   	ptr = (char *)((unsigned long)ptr | (tag << TAG_SHIFT));
+   
+   	/* memory access to a tagged address */
+   	strcpy(ptr, "tagged pointer\n");
+   
+   	/* syscall with a tagged pointer */
+   	write(1, ptr, strlen(ptr));
+   
+   	return 0;
+   }
diff --git a/Documentation/arch/arm64/tagged-pointers.rst b/Documentation/arch/arm64/tagged-pointers.rst
new file mode 100644
index 00000000000000..81b6c2a770dd6d
--- /dev/null
+++ b/Documentation/arch/arm64/tagged-pointers.rst
@@ -0,0 +1,88 @@
+=========================================
+Tagged virtual addresses in AArch64 Linux
+=========================================
+
+Author: Will Deacon <will.deacon@arm.com>
+
+Date  : 12 June 2013
+
+This document briefly describes the provision of tagged virtual
+addresses in the AArch64 translation system and their potential uses
+in AArch64 Linux.
+
+The kernel configures the translation tables so that translations made
+via TTBR0 (i.e. userspace mappings) have the top byte (bits 63:56) of
+the virtual address ignored by the translation hardware. This frees up
+this byte for application use.
+
+
+Passing tagged addresses to the kernel
+--------------------------------------
+
+All interpretation of userspace memory addresses by the kernel assumes
+an address tag of 0x00, unless the application enables the AArch64
+Tagged Address ABI explicitly
+(Documentation/arch/arm64/tagged-address-abi.rst).
+
+This includes, but is not limited to, addresses found in:
+
+ - pointer arguments to system calls, including pointers in structures
+   passed to system calls,
+
+ - the stack pointer (sp), e.g. when interpreting it to deliver a
+   signal,
+
+ - the frame pointer (x29) and frame records, e.g. when interpreting
+   them to generate a backtrace or call graph.
+
+Using non-zero address tags in any of these locations when the
+userspace application did not enable the AArch64 Tagged Address ABI may
+result in an error code being returned, a (fatal) signal being raised,
+or other modes of failure.
+
+For these reasons, when the AArch64 Tagged Address ABI is disabled,
+passing non-zero address tags to the kernel via system calls is
+forbidden, and using a non-zero address tag for sp is strongly
+discouraged.
+
+Programs maintaining a frame pointer and frame records that use non-zero
+address tags may suffer impaired or inaccurate debug and profiling
+visibility.
+
+
+Preserving tags
+---------------
+
+When delivering signals, non-zero tags are not preserved in
+siginfo.si_addr unless the flag SA_EXPOSE_TAGBITS was set in
+sigaction.sa_flags when the signal handler was installed. This means
+that signal handlers in applications making use of tags cannot rely
+on the tag information for user virtual addresses being maintained
+in these fields unless the flag was set.
+
+Due to architecture limitations, bits 63:60 of the fault address
+are not preserved in response to synchronous tag check faults
+(SEGV_MTESERR) even if SA_EXPOSE_TAGBITS was set. Applications should
+treat the values of these bits as undefined in order to accommodate
+future architecture revisions which may preserve the bits.
+
+For signals raised in response to watchpoint debug exceptions, the
+tag information will be preserved regardless of the SA_EXPOSE_TAGBITS
+flag setting.
+
+Non-zero tags are never preserved in sigcontext.fault_address
+regardless of the SA_EXPOSE_TAGBITS flag setting.
+
+The architecture prevents the use of a tagged PC, so the upper byte will
+be set to a sign-extension of bit 55 on exception return.
+
+This behaviour is maintained when the AArch64 Tagged Address ABI is
+enabled.
+
+
+Other considerations
+--------------------
+
+Special care should be taken when using tagged pointers, since it is
+likely that C compilers will not hazard two virtual addresses differing
+only in the upper byte.
diff --git a/Documentation/arch/index.rst b/Documentation/arch/index.rst
index 21e3d0b61004da..8458b88e9b79eb 100644
--- a/Documentation/arch/index.rst
+++ b/Documentation/arch/index.rst
@@ -11,7 +11,7 @@ implementation.
 
    arc/index
    arm/index
-   ../arm64/index
+   arm64/index
    ia64/index
    ../loongarch/index
    m68k/index