Architecture Page Table Helpers

Generic MM expects architectures (with MMU) to provide helpers to create, access and modify page table entries at various level for different memory functions. These page table helpers need to conform to a common semantics across platforms. Following tables describe the expected semantics which can also be tested during boot via CONFIG_DEBUG_VM_PGTABLE option. All future changes in here or the debug test need to be in sync.

PTE Page Table Helpers

pte_same

Tests whether both PTE entries are the same

pte_present

Tests a valid mapped PTE

pte_young

Tests a young PTE

pte_dirty

Tests a dirty PTE

pte_write

Tests a writable PTE

pte_special

Tests a special PTE

pte_protnone

Tests a PROT_NONE PTE

pte_devmap

Tests a ZONE_DEVICE mapped PTE

pte_soft_dirty

Tests a soft dirty PTE

pte_swp_soft_dirty

Tests a soft dirty swapped PTE

pte_mkyoung

Creates a young PTE

pte_mkold

Creates an old PTE

pte_mkdirty

Creates a dirty PTE

pte_mkclean

Creates a clean PTE

pte_mkwrite

Creates a writable PTE of the type specified by the VMA.

pte_mkwrite_novma

Creates a writable PTE, of the conventional type of writable.

pte_wrprotect

Creates a write protected PTE

pte_mkspecial

Creates a special PTE

pte_mkdevmap

Creates a ZONE_DEVICE mapped PTE

pte_mksoft_dirty

Creates a soft dirty PTE

pte_clear_soft_dirty

Clears a soft dirty PTE

pte_swp_mksoft_dirty

Creates a soft dirty swapped PTE

pte_swp_clear_soft_dirty

Clears a soft dirty swapped PTE

pte_mknotpresent

Invalidates a mapped PTE

ptep_clear

Clears a PTE

ptep_get_and_clear

Clears and returns PTE

ptep_get_and_clear_full

Clears and returns PTE (batched PTE unmap)

ptep_test_and_clear_young

Clears young from a PTE

ptep_set_wrprotect

Converts into a write protected PTE

ptep_set_access_flags

Converts into a more permissive PTE

PMD Page Table Helpers

pmd_same

Tests whether both PMD entries are the same

pmd_bad

Tests a non-table mapped PMD

pmd_leaf

Tests a leaf mapped PMD

pmd_huge

Tests a HugeTLB mapped PMD

pmd_trans_huge

Tests a Transparent Huge Page (THP) at PMD

pmd_present

Tests whether pmd_page() points to valid memory

pmd_young

Tests a young PMD

pmd_dirty

Tests a dirty PMD

pmd_write

Tests a writable PMD

pmd_special

Tests a special PMD

pmd_protnone

Tests a PROT_NONE PMD

pmd_devmap

Tests a ZONE_DEVICE mapped PMD

pmd_soft_dirty

Tests a soft dirty PMD

pmd_swp_soft_dirty

Tests a soft dirty swapped PMD

pmd_mkyoung

Creates a young PMD

pmd_mkold

Creates an old PMD

pmd_mkdirty

Creates a dirty PMD

pmd_mkclean

Creates a clean PMD

pmd_mkwrite

Creates a writable PMD of the type specified by the VMA.

pmd_mkwrite_novma

Creates a writable PMD, of the conventional type of writable.

pmd_wrprotect

Creates a write protected PMD

pmd_mkspecial

Creates a special PMD

pmd_mkdevmap

Creates a ZONE_DEVICE mapped PMD

pmd_mksoft_dirty

Creates a soft dirty PMD

pmd_clear_soft_dirty

Clears a soft dirty PMD

pmd_swp_mksoft_dirty

Creates a soft dirty swapped PMD

pmd_swp_clear_soft_dirty

Clears a soft dirty swapped PMD

pmd_mkinvalid

Invalidates a present PMD; do not call for non-present PMD [1]

pmd_set_huge

Creates a PMD huge mapping

pmd_clear_huge

Clears a PMD huge mapping

pmdp_get_and_clear

Clears a PMD

pmdp_get_and_clear_full

Clears a PMD

pmdp_test_and_clear_young

Clears young from a PMD

pmdp_set_wrprotect

Converts into a write protected PMD

pmdp_set_access_flags

Converts into a more permissive PMD

PUD Page Table Helpers

pud_same

Tests whether both PUD entries are the same

pud_bad

Tests a non-table mapped PUD

pud_leaf

Tests a leaf mapped PUD

pud_huge

Tests a HugeTLB mapped PUD

pud_trans_huge

Tests a Transparent Huge Page (THP) at PUD

pud_present

Tests a valid mapped PUD

pud_young

Tests a young PUD

pud_dirty

Tests a dirty PUD

pud_write

Tests a writable PUD

pud_devmap

Tests a ZONE_DEVICE mapped PUD

pud_mkyoung

Creates a young PUD

pud_mkold

Creates an old PUD

pud_mkdirty

Creates a dirty PUD

pud_mkclean

Creates a clean PUD

pud_mkwrite

Creates a writable PUD

pud_wrprotect

Creates a write protected PUD

pud_mkdevmap

Creates a ZONE_DEVICE mapped PUD

pud_mkinvalid

Invalidates a present PUD; do not call for non-present PUD [1]

pud_set_huge

Creates a PUD huge mapping

pud_clear_huge

Clears a PUD huge mapping

pudp_get_and_clear

Clears a PUD

pudp_get_and_clear_full

Clears a PUD

pudp_test_and_clear_young

Clears young from a PUD

pudp_set_wrprotect

Converts into a write protected PUD

pudp_set_access_flags

Converts into a more permissive PUD

HugeTLB Page Table Helpers

pte_huge

Tests a HugeTLB

arch_make_huge_pte

Creates a HugeTLB

huge_pte_dirty

Tests a dirty HugeTLB

huge_pte_write

Tests a writable HugeTLB

huge_pte_mkdirty

Creates a dirty HugeTLB

huge_pte_mkwrite

Creates a writable HugeTLB

huge_pte_wrprotect

Creates a write protected HugeTLB

huge_ptep_get_and_clear

Clears a HugeTLB

huge_ptep_set_wrprotect

Converts into a write protected HugeTLB

huge_ptep_set_access_flags | Converts into a more permissive HugeTLB

SWAP Page Table Helpers

__pte_to_swp_entry

Creates a swapped entry (arch) from a mapped PTE

__swp_to_pte_entry

Creates a mapped PTE from a swapped entry (arch)

__pmd_to_swp_entry

Creates a swapped entry (arch) from a mapped PMD

__swp_to_pmd_entry

Creates a mapped PMD from a swapped entry (arch)

is_migration_entry | Tests a migration (read or write) swapped entry

is_writable_migration_entry

Tests a write migration swapped entry

make_readable_migration_entry

Creates a read migration swapped entry

make_writable_migration_entry

Creates a write migration swapped entry

[1] https://lore.kernel.org/linux-mm/20181017020930.GN30832@redhat.com/