| /* SPDX-License-Identifier: GPL-2.0-only */ |
| /* |
| * Copyright (C) 2020 ARM Ltd. |
| */ |
| #include <linux/linkage.h> |
| |
| #include <asm/alternative.h> |
| #include <asm/assembler.h> |
| #include <asm/mte.h> |
| #include <asm/page.h> |
| #include <asm/sysreg.h> |
| |
| .arch armv8.5-a+memtag |
| |
| /* |
| * multitag_transfer_size - set \reg to the block size that is accessed by the |
| * LDGM/STGM instructions. |
| */ |
| .macro multitag_transfer_size, reg, tmp |
| mrs_s \reg, SYS_GMID_EL1 |
| ubfx \reg, \reg, #SYS_GMID_EL1_BS_SHIFT, #SYS_GMID_EL1_BS_SIZE |
| mov \tmp, #4 |
| lsl \reg, \tmp, \reg |
| .endm |
| |
| /* |
| * Clear the tags in a page |
| * x0 - address of the page to be cleared |
| */ |
| SYM_FUNC_START(mte_clear_page_tags) |
| multitag_transfer_size x1, x2 |
| 1: stgm xzr, [x0] |
| add x0, x0, x1 |
| tst x0, #(PAGE_SIZE - 1) |
| b.ne 1b |
| ret |
| SYM_FUNC_END(mte_clear_page_tags) |
| |
| /* |
| * Copy the tags from the source page to the destination one |
| * x0 - address of the destination page |
| * x1 - address of the source page |
| */ |
| SYM_FUNC_START(mte_copy_page_tags) |
| mov x2, x0 |
| mov x3, x1 |
| multitag_transfer_size x5, x6 |
| 1: ldgm x4, [x3] |
| stgm x4, [x2] |
| add x2, x2, x5 |
| add x3, x3, x5 |
| tst x2, #(PAGE_SIZE - 1) |
| b.ne 1b |
| ret |
| SYM_FUNC_END(mte_copy_page_tags) |
| |
| /* |
| * Read tags from a user buffer (one tag per byte) and set the corresponding |
| * tags at the given kernel address. Used by PTRACE_POKEMTETAGS. |
| * x0 - kernel address (to) |
| * x1 - user buffer (from) |
| * x2 - number of tags/bytes (n) |
| * Returns: |
| * x0 - number of tags read/set |
| */ |
| SYM_FUNC_START(mte_copy_tags_from_user) |
| mov x3, x1 |
| cbz x2, 2f |
| 1: |
| uao_user_alternative 2f, ldrb, ldtrb, w4, x1, 0 |
| lsl x4, x4, #MTE_TAG_SHIFT |
| stg x4, [x0], #MTE_GRANULE_SIZE |
| add x1, x1, #1 |
| subs x2, x2, #1 |
| b.ne 1b |
| |
| // exception handling and function return |
| 2: sub x0, x1, x3 // update the number of tags set |
| ret |
| SYM_FUNC_END(mte_copy_tags_from_user) |
| |
| /* |
| * Get the tags from a kernel address range and write the tag values to the |
| * given user buffer (one tag per byte). Used by PTRACE_PEEKMTETAGS. |
| * x0 - user buffer (to) |
| * x1 - kernel address (from) |
| * x2 - number of tags/bytes (n) |
| * Returns: |
| * x0 - number of tags read/set |
| */ |
| SYM_FUNC_START(mte_copy_tags_to_user) |
| mov x3, x0 |
| cbz x2, 2f |
| 1: |
| ldg x4, [x1] |
| ubfx x4, x4, #MTE_TAG_SHIFT, #MTE_TAG_SIZE |
| uao_user_alternative 2f, strb, sttrb, w4, x0, 0 |
| add x0, x0, #1 |
| add x1, x1, #MTE_GRANULE_SIZE |
| subs x2, x2, #1 |
| b.ne 1b |
| |
| // exception handling and function return |
| 2: sub x0, x0, x3 // update the number of tags copied |
| ret |
| SYM_FUNC_END(mte_copy_tags_to_user) |
| |
| /* |
| * Save the tags in a page |
| * x0 - page address |
| * x1 - tag storage |
| */ |
| SYM_FUNC_START(mte_save_page_tags) |
| multitag_transfer_size x7, x5 |
| 1: |
| mov x2, #0 |
| 2: |
| ldgm x5, [x0] |
| orr x2, x2, x5 |
| add x0, x0, x7 |
| tst x0, #0xFF // 16 tag values fit in a register, |
| b.ne 2b // which is 16*16=256 bytes |
| |
| str x2, [x1], #8 |
| |
| tst x0, #(PAGE_SIZE - 1) |
| b.ne 1b |
| |
| ret |
| SYM_FUNC_END(mte_save_page_tags) |
| |
| /* |
| * Restore the tags in a page |
| * x0 - page address |
| * x1 - tag storage |
| */ |
| SYM_FUNC_START(mte_restore_page_tags) |
| multitag_transfer_size x7, x5 |
| 1: |
| ldr x2, [x1], #8 |
| 2: |
| stgm x2, [x0] |
| add x0, x0, x7 |
| tst x0, #0xFF |
| b.ne 2b |
| |
| tst x0, #(PAGE_SIZE - 1) |
| b.ne 1b |
| |
| ret |
| SYM_FUNC_END(mte_restore_page_tags) |
