Revert "convert SLB miss handlers to C" and subsequent commits

This reverts commits:
  5e46e29e6a97 ("powerpc/64s/hash: convert SLB miss handlers to C")
  8fed04d0f6ae ("powerpc/64s/hash: remove user SLB data from the paca")
  655deecf67b2 ("powerpc/64s/hash: SLB allocation status bitmaps")
  2e1626744e8d ("powerpc/64s/hash: provide arch_setup_exec hooks for hash slice setup")
  89ca4e126a3f ("powerpc/64s/hash: Add a SLB preload cache")

This series had a few bugs, and the fixes are not all trivial. So
revert most of it for now.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 335 insertions, 0 deletions

diff --git a/arch/powerpc/mm/slb_low.S b/arch/powerpc/mm/slb_low.S
new file mode 100644
index 00000000000000..4d2e921d696e81
--- /dev/null
+++ b/arch/powerpc/mm/slb_low.S
@@ -0,0 +1,335 @@
+/*
+ * Low-level SLB routines
+ *
+ * Copyright (C) 2004 David Gibson <dwg@au.ibm.com>, IBM
+ *
+ * Based on earlier C version:
+ * Dave Engebretsen and Mike Corrigan {engebret|mikejc}@us.ibm.com
+ *    Copyright (c) 2001 Dave Engebretsen
+ * Copyright (C) 2002 Anton Blanchard <anton@au.ibm.com>, IBM
+ *
+ *  This program is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public License
+ *  as published by the Free Software Foundation; either version
+ *  2 of the License, or (at your option) any later version.
+ */
+
+#include <asm/processor.h>
+#include <asm/ppc_asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/cputable.h>
+#include <asm/page.h>
+#include <asm/mmu.h>
+#include <asm/pgtable.h>
+#include <asm/firmware.h>
+#include <asm/feature-fixups.h>
+
+/*
+ * This macro generates asm code to compute the VSID scramble
+ * function.  Used in slb_allocate() and do_stab_bolted.  The function
+ * computed is: (protovsid*VSID_MULTIPLIER) % VSID_MODULUS
+ *
+ *	rt = register containing the proto-VSID and into which the
+ *		VSID will be stored
+ *	rx = scratch register (clobbered)
+ *	rf = flags
+ *
+ *	- rt and rx must be different registers
+ *	- The answer will end up in the low VSID_BITS bits of rt.  The higher
+ *	  bits may contain other garbage, so you may need to mask the
+ *	  result.
+ */
+#define ASM_VSID_SCRAMBLE(rt, rx, rf, size)				\
+	lis	rx,VSID_MULTIPLIER_##size@h;				\
+	ori	rx,rx,VSID_MULTIPLIER_##size@l;				\
+	mulld	rt,rt,rx;		/* rt = rt * MULTIPLIER */	\
+/*									\
+ * powermac get slb fault before feature fixup, so make 65 bit part     \
+ * the default part of feature fixup					\
+ */									\
+BEGIN_MMU_FTR_SECTION							\
+	srdi	rx,rt,VSID_BITS_65_##size;				\
+	clrldi	rt,rt,(64-VSID_BITS_65_##size);				\
+	add	rt,rt,rx;						\
+	addi	rx,rt,1;						\
+	srdi	rx,rx,VSID_BITS_65_##size;				\
+	add	rt,rt,rx;						\
+	rldimi	rf,rt,SLB_VSID_SHIFT_##size,(64 - (SLB_VSID_SHIFT_##size + VSID_BITS_65_##size)); \
+MMU_FTR_SECTION_ELSE							\
+	srdi	rx,rt,VSID_BITS_##size;					\
+	clrldi	rt,rt,(64-VSID_BITS_##size);				\
+	add	rt,rt,rx;		/* add high and low bits */	\
+	addi	rx,rt,1;						\
+	srdi	rx,rx,VSID_BITS_##size;	/* extract 2^VSID_BITS bit */	\
+	add	rt,rt,rx;						\
+	rldimi	rf,rt,SLB_VSID_SHIFT_##size,(64 - (SLB_VSID_SHIFT_##size + VSID_BITS_##size)); \
+ALT_MMU_FTR_SECTION_END_IFCLR(MMU_FTR_68_BIT_VA)
+
+
+/* void slb_allocate(unsigned long ea);
+ *
+ * Create an SLB entry for the given EA (user or kernel).
+ * 	r3 = faulting address, r13 = PACA
+ *	r9, r10, r11 are clobbered by this function
+ *	r3 is preserved.
+ * No other registers are examined or changed.
+ */
+_GLOBAL(slb_allocate)
+	/*
+	 * Check if the address falls within the range of the first context, or
+	 * if we may need to handle multi context. For the first context we
+	 * allocate the slb entry via the fast path below. For large address we
+	 * branch out to C-code and see if additional contexts have been
+	 * allocated.
+	 * The test here is:
+	 *   (ea & ~REGION_MASK) >= (1ull << MAX_EA_BITS_PER_CONTEXT)
+	 */
+	rldicr. r9,r3,4,(63 - MAX_EA_BITS_PER_CONTEXT - 4)
+	bne-	8f
+
+	srdi	r9,r3,60		/* get region */
+	srdi	r10,r3,SID_SHIFT	/* get esid */
+	cmpldi	cr7,r9,0xc		/* cmp PAGE_OFFSET for later use */
+
+	/* r3 = address, r10 = esid, cr7 = <> PAGE_OFFSET */
+	blt	cr7,0f			/* user or kernel? */
+
+	/* Check if hitting the linear mapping or some other kernel space
+	*/
+	bne	cr7,1f
+
+	/* Linear mapping encoding bits, the "li" instruction below will
+	 * be patched by the kernel at boot
+	 */
+.globl slb_miss_kernel_load_linear
+slb_miss_kernel_load_linear:
+	li	r11,0
+	/*
+	 * context = (ea >> 60) - (0xc - 1)
+	 * r9 = region id.
+	 */
+	subi	r9,r9,KERNEL_REGION_CONTEXT_OFFSET
+
+BEGIN_FTR_SECTION
+	b	.Lslb_finish_load
+END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
+	b	.Lslb_finish_load_1T
+
+1:
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+	cmpldi	cr0,r9,0xf
+	bne	1f
+/* Check virtual memmap region. To be patched at kernel boot */
+.globl slb_miss_kernel_load_vmemmap
+slb_miss_kernel_load_vmemmap:
+	li	r11,0
+	b	6f
+1:
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+
+	/*
+	 * r10 contains the ESID, which is the original faulting EA shifted
+	 * right by 28 bits. We need to compare that with (H_VMALLOC_END >> 28)
+	 * which is 0xd00038000. That can't be used as an immediate, even if we
+	 * ignored the 0xd, so we have to load it into a register, and we only
+	 * have one register free. So we must load all of (H_VMALLOC_END >> 28)
+	 * into a register and compare ESID against that.
+	 */
+	lis	r11,(H_VMALLOC_END >> 32)@h	// r11 = 0xffffffffd0000000
+	ori	r11,r11,(H_VMALLOC_END >> 32)@l	// r11 = 0xffffffffd0003800
+	// Rotate left 4, then mask with 0xffffffff0
+	rldic	r11,r11,4,28			// r11 = 0xd00038000
+	cmpld	r10,r11				// if r10 >= r11
+	bge	5f				//   goto io_mapping
+
+	/*
+	 * vmalloc mapping gets the encoding from the PACA as the mapping
+	 * can be demoted from 64K -> 4K dynamically on some machines.
+	 */
+	lhz	r11,PACAVMALLOCSLLP(r13)
+	b	6f
+5:
+	/* IO mapping */
+.globl slb_miss_kernel_load_io
+slb_miss_kernel_load_io:
+	li	r11,0
+6:
+	/*
+	 * context = (ea >> 60) - (0xc - 1)
+	 * r9 = region id.
+	 */
+	subi	r9,r9,KERNEL_REGION_CONTEXT_OFFSET
+
+BEGIN_FTR_SECTION
+	b	.Lslb_finish_load
+END_MMU_FTR_SECTION_IFCLR(MMU_FTR_1T_SEGMENT)
+	b	.Lslb_finish_load_1T
+
+0:	/*
+	 * For userspace addresses, make sure this is region 0.
+	 */
+	cmpdi	r9, 0
+	bne-	8f
+        /*
+         * user space make sure we are within the allowed limit
+	 */
+	ld	r11,PACA_SLB_ADDR_LIMIT(r13)
+	cmpld	r3,r11
+	bge-	8f
+
+	/* when using slices, we extract the psize off the slice bitmaps
+	 * and then we need to get the sllp encoding off the mmu_psize_defs
+	 * array.
+	 *
+	 * XXX This is a bit inefficient especially for the normal case,
+	 * so we should try to implement a fast path for the standard page
+	 * size using the old sllp value so we avoid the array. We cannot
+	 * really do dynamic patching unfortunately as processes might flip
+	 * between 4k and 64k standard page size
+	 */
+#ifdef CONFIG_PPC_MM_SLICES
+	/* r10 have esid */
+	cmpldi	r10,16
+	/* below SLICE_LOW_TOP */
+	blt	5f
+	/*
+	 * Handle hpsizes,
+	 * r9 is get_paca()->context.high_slices_psize[index], r11 is mask_index
+	 */
+	srdi    r11,r10,(SLICE_HIGH_SHIFT - SLICE_LOW_SHIFT + 1) /* index */
+	addi	r9,r11,PACAHIGHSLICEPSIZE
+	lbzx	r9,r13,r9		/* r9 is hpsizes[r11] */
+	/* r11 = (r10 >> (SLICE_HIGH_SHIFT - SLICE_LOW_SHIFT)) & 0x1 */
+	rldicl	r11,r10,(64 - (SLICE_HIGH_SHIFT - SLICE_LOW_SHIFT)),63
+	b	6f
+
+5:
+	/*
+	 * Handle lpsizes
+	 * r9 is get_paca()->context.low_slices_psize[index], r11 is mask_index
+	 */
+	srdi    r11,r10,1 /* index */
+	addi	r9,r11,PACALOWSLICESPSIZE
+	lbzx	r9,r13,r9		/* r9 is lpsizes[r11] */
+	rldicl	r11,r10,0,63		/* r11 = r10 & 0x1 */
+6:
+	sldi	r11,r11,2  /* index * 4 */
+	/* Extract the psize and multiply to get an array offset */
+	srd	r9,r9,r11
+	andi.	r9,r9,0xf
+	mulli	r9,r9,MMUPSIZEDEFSIZE
+
+	/* Now get to the array and obtain the sllp
+	 */
+	ld	r11,PACATOC(r13)
+	ld	r11,mmu_psize_defs@got(r11)
+	add	r11,r11,r9
+	ld	r11,MMUPSIZESLLP(r11)
+	ori	r11,r11,SLB_VSID_USER
+#else
+	/* paca context sllp already contains the SLB_VSID_USER bits */
+	lhz	r11,PACACONTEXTSLLP(r13)
+#endif /* CONFIG_PPC_MM_SLICES */
+
+	ld	r9,PACACONTEXTID(r13)
+BEGIN_FTR_SECTION
+	cmpldi	r10,0x1000
+	bge	.Lslb_finish_load_1T
+END_MMU_FTR_SECTION_IFSET(MMU_FTR_1T_SEGMENT)
+	b	.Lslb_finish_load
+
+8:	/* invalid EA - return an error indication */
+	crset	4*cr0+eq		/* indicate failure */
+	blr
+
+/*
+ * Finish loading of an SLB entry and return
+ *
+ * r3 = EA, r9 = context, r10 = ESID, r11 = flags, clobbers r9, cr7 = <> PAGE_OFFSET
+ */
+.Lslb_finish_load:
+	rldimi  r10,r9,ESID_BITS,0
+	ASM_VSID_SCRAMBLE(r10,r9,r11,256M)
+	/* r3 = EA, r11 = VSID data */
+	/*
+	 * Find a slot, round robin. Previously we tried to find a
+	 * free slot first but that took too long. Unfortunately we
+	 * dont have any LRU information to help us choose a slot.
+	 */
+
+	mr	r9,r3
+
+	/* slb_finish_load_1T continues here. r9=EA with non-ESID bits clear */
+7:	ld	r10,PACASTABRR(r13)
+	addi	r10,r10,1
+	/* This gets soft patched on boot. */
+.globl slb_compare_rr_to_size
+slb_compare_rr_to_size:
+	cmpldi	r10,0
+
+	blt+	4f
+	li	r10,SLB_NUM_BOLTED
+
+4:
+	std	r10,PACASTABRR(r13)
+
+3:
+	rldimi	r9,r10,0,36		/* r9  = EA[0:35] | entry */
+	oris	r10,r9,SLB_ESID_V@h	/* r10 = r9 | SLB_ESID_V */
+
+	/* r9 = ESID data, r11 = VSID data */
+
+	/*
+	 * No need for an isync before or after this slbmte. The exception
+	 * we enter with and the rfid we exit with are context synchronizing.
+	 */
+	slbmte	r11,r10
+
+	/* we're done for kernel addresses */
+	crclr	4*cr0+eq		/* set result to "success" */
+	bgelr	cr7
+
+	/* Update the slb cache */
+	lhz	r9,PACASLBCACHEPTR(r13)	/* offset = paca->slb_cache_ptr */
+	cmpldi	r9,SLB_CACHE_ENTRIES
+	bge	1f
+
+	/* still room in the slb cache */
+	sldi	r11,r9,2		/* r11 = offset * sizeof(u32) */
+	srdi    r10,r10,28		/* get the 36 bits of the ESID */
+	add	r11,r11,r13		/* r11 = (u32 *)paca + offset */
+	stw	r10,PACASLBCACHE(r11)	/* paca->slb_cache[offset] = esid */
+	addi	r9,r9,1			/* offset++ */
+	b	2f
+1:					/* offset >= SLB_CACHE_ENTRIES */
+	li	r9,SLB_CACHE_ENTRIES+1
+2:
+	sth	r9,PACASLBCACHEPTR(r13)	/* paca->slb_cache_ptr = offset */
+	crclr	4*cr0+eq		/* set result to "success" */
+	blr
+
+/*
+ * Finish loading of a 1T SLB entry (for the kernel linear mapping) and return.
+ *
+ * r3 = EA, r9 = context, r10 = ESID(256MB), r11 = flags, clobbers r9
+ */
+.Lslb_finish_load_1T:
+	srdi	r10,r10,(SID_SHIFT_1T - SID_SHIFT)	/* get 1T ESID */
+	rldimi  r10,r9,ESID_BITS_1T,0
+	ASM_VSID_SCRAMBLE(r10,r9,r11,1T)
+
+	li	r10,MMU_SEGSIZE_1T
+	rldimi	r11,r10,SLB_VSID_SSIZE_SHIFT,0	/* insert segment size */
+
+	/* r3 = EA, r11 = VSID data */
+	clrrdi	r9,r3,SID_SHIFT_1T	/* clear out non-ESID bits */
+	b	7b
+
+
+_ASM_NOKPROBE_SYMBOL(slb_allocate)
+_ASM_NOKPROBE_SYMBOL(slb_miss_kernel_load_linear)
+_ASM_NOKPROBE_SYMBOL(slb_miss_kernel_load_io)
+_ASM_NOKPROBE_SYMBOL(slb_compare_rr_to_size)
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+_ASM_NOKPROBE_SYMBOL(slb_miss_kernel_load_vmemmap)
+#endif