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36943aba91
When swapping pages out to disk it is necessary to save any tags that have been set, and restore when swapping back in. Make use of the new page flag (PG_ARCH_2, locally named PG_mte_tagged) to identify pages with tags. When swapping out these pages the tags are stored in memory and later restored when the pages are brought back in. Because shmem can swap pages back in without restoring the userspace PTE it is also necessary to add a hook for shmem. Signed-off-by: Steven Price <steven.price@arm.com> [catalin.marinas@arm.com: move function prototypes to mte.h] [catalin.marinas@arm.com: drop '_tags' from arch_swap_restore_tags()] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Will Deacon <will@kernel.org>
151 lines
3.1 KiB
ArmAsm
151 lines
3.1 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (C) 2020 ARM Ltd.
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*/
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#include <linux/linkage.h>
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#include <asm/alternative.h>
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#include <asm/assembler.h>
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#include <asm/mte.h>
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#include <asm/page.h>
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#include <asm/sysreg.h>
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.arch armv8.5-a+memtag
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/*
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* multitag_transfer_size - set \reg to the block size that is accessed by the
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* LDGM/STGM instructions.
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*/
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.macro multitag_transfer_size, reg, tmp
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mrs_s \reg, SYS_GMID_EL1
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ubfx \reg, \reg, #SYS_GMID_EL1_BS_SHIFT, #SYS_GMID_EL1_BS_SIZE
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mov \tmp, #4
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lsl \reg, \tmp, \reg
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.endm
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/*
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* Clear the tags in a page
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* x0 - address of the page to be cleared
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*/
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SYM_FUNC_START(mte_clear_page_tags)
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multitag_transfer_size x1, x2
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1: stgm xzr, [x0]
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add x0, x0, x1
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tst x0, #(PAGE_SIZE - 1)
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b.ne 1b
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ret
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SYM_FUNC_END(mte_clear_page_tags)
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/*
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* Copy the tags from the source page to the destination one
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* x0 - address of the destination page
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* x1 - address of the source page
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*/
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SYM_FUNC_START(mte_copy_page_tags)
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mov x2, x0
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mov x3, x1
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multitag_transfer_size x5, x6
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1: ldgm x4, [x3]
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stgm x4, [x2]
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add x2, x2, x5
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add x3, x3, x5
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tst x2, #(PAGE_SIZE - 1)
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b.ne 1b
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ret
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SYM_FUNC_END(mte_copy_page_tags)
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/*
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* Read tags from a user buffer (one tag per byte) and set the corresponding
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* tags at the given kernel address. Used by PTRACE_POKEMTETAGS.
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* x0 - kernel address (to)
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* x1 - user buffer (from)
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* x2 - number of tags/bytes (n)
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* Returns:
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* x0 - number of tags read/set
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*/
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SYM_FUNC_START(mte_copy_tags_from_user)
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mov x3, x1
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cbz x2, 2f
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1:
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uao_user_alternative 2f, ldrb, ldtrb, w4, x1, 0
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lsl x4, x4, #MTE_TAG_SHIFT
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stg x4, [x0], #MTE_GRANULE_SIZE
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add x1, x1, #1
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subs x2, x2, #1
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b.ne 1b
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// exception handling and function return
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2: sub x0, x1, x3 // update the number of tags set
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ret
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SYM_FUNC_END(mte_copy_tags_from_user)
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/*
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* Get the tags from a kernel address range and write the tag values to the
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* given user buffer (one tag per byte). Used by PTRACE_PEEKMTETAGS.
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* x0 - user buffer (to)
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* x1 - kernel address (from)
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* x2 - number of tags/bytes (n)
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* Returns:
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* x0 - number of tags read/set
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*/
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SYM_FUNC_START(mte_copy_tags_to_user)
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mov x3, x0
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cbz x2, 2f
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1:
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ldg x4, [x1]
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ubfx x4, x4, #MTE_TAG_SHIFT, #MTE_TAG_SIZE
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uao_user_alternative 2f, strb, sttrb, w4, x0, 0
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add x0, x0, #1
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add x1, x1, #MTE_GRANULE_SIZE
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subs x2, x2, #1
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b.ne 1b
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// exception handling and function return
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2: sub x0, x0, x3 // update the number of tags copied
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ret
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SYM_FUNC_END(mte_copy_tags_to_user)
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/*
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* Save the tags in a page
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* x0 - page address
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* x1 - tag storage
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*/
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SYM_FUNC_START(mte_save_page_tags)
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multitag_transfer_size x7, x5
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1:
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mov x2, #0
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2:
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ldgm x5, [x0]
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orr x2, x2, x5
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add x0, x0, x7
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tst x0, #0xFF // 16 tag values fit in a register,
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b.ne 2b // which is 16*16=256 bytes
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str x2, [x1], #8
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tst x0, #(PAGE_SIZE - 1)
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b.ne 1b
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ret
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SYM_FUNC_END(mte_save_page_tags)
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/*
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* Restore the tags in a page
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* x0 - page address
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* x1 - tag storage
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*/
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SYM_FUNC_START(mte_restore_page_tags)
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multitag_transfer_size x7, x5
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1:
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ldr x2, [x1], #8
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2:
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stgm x2, [x0]
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add x0, x0, x7
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tst x0, #0xFF
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b.ne 2b
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tst x0, #(PAGE_SIZE - 1)
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b.ne 1b
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ret
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SYM_FUNC_END(mte_restore_page_tags)
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