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39d114ddc6
This patch adds arch specific code for kernel address sanitizer (see Documentation/kasan.txt). 1/8 of kernel addresses reserved for shadow memory. There was no big enough hole for this, so virtual addresses for shadow were stolen from vmalloc area. At early boot stage the whole shadow region populated with just one physical page (kasan_zero_page). Later, this page reused as readonly zero shadow for some memory that KASan currently don't track (vmalloc). After mapping the physical memory, pages for shadow memory are allocated and mapped. Functions like memset/memmove/memcpy do a lot of memory accesses. If bad pointer passed to one of these function it is important to catch this. Compiler's instrumentation cannot do this since these functions are written in assembly. KASan replaces memory functions with manually instrumented variants. Original functions declared as weak symbols so strong definitions in mm/kasan/kasan.c could replace them. Original functions have aliases with '__' prefix in name, so we could call non-instrumented variant if needed. Some files built without kasan instrumentation (e.g. mm/slub.c). Original mem* function replaced (via #define) with prefixed variants to disable memory access checks for such files. Signed-off-by: Andrey Ryabinin <ryabinin.a.a@gmail.com> Tested-by: Linus Walleij <linus.walleij@linaro.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
220 lines
4.9 KiB
ArmAsm
220 lines
4.9 KiB
ArmAsm
/*
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* Copyright (C) 2013 ARM Ltd.
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* Copyright (C) 2013 Linaro.
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*
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* This code is based on glibc cortex strings work originally authored by Linaro
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* and re-licensed under GPLv2 for the Linux kernel. The original code can
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* be found @
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*
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* http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
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* files/head:/src/aarch64/
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include <asm/cache.h>
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/*
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* Fill in the buffer with character c (alignment handled by the hardware)
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*
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* Parameters:
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* x0 - buf
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* x1 - c
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* x2 - n
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* Returns:
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* x0 - buf
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*/
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dstin .req x0
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val .req w1
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count .req x2
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tmp1 .req x3
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tmp1w .req w3
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tmp2 .req x4
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tmp2w .req w4
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zva_len_x .req x5
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zva_len .req w5
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zva_bits_x .req x6
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A_l .req x7
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A_lw .req w7
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dst .req x8
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tmp3w .req w9
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tmp3 .req x9
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.weak memset
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ENTRY(__memset)
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ENTRY(memset)
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mov dst, dstin /* Preserve return value. */
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and A_lw, val, #255
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orr A_lw, A_lw, A_lw, lsl #8
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orr A_lw, A_lw, A_lw, lsl #16
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orr A_l, A_l, A_l, lsl #32
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cmp count, #15
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b.hi .Lover16_proc
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/*All store maybe are non-aligned..*/
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tbz count, #3, 1f
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str A_l, [dst], #8
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1:
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tbz count, #2, 2f
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str A_lw, [dst], #4
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2:
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tbz count, #1, 3f
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strh A_lw, [dst], #2
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3:
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tbz count, #0, 4f
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strb A_lw, [dst]
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4:
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ret
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.Lover16_proc:
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/*Whether the start address is aligned with 16.*/
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neg tmp2, dst
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ands tmp2, tmp2, #15
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b.eq .Laligned
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/*
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* The count is not less than 16, we can use stp to store the start 16 bytes,
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* then adjust the dst aligned with 16.This process will make the current
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* memory address at alignment boundary.
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*/
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stp A_l, A_l, [dst] /*non-aligned store..*/
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/*make the dst aligned..*/
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sub count, count, tmp2
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add dst, dst, tmp2
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.Laligned:
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cbz A_l, .Lzero_mem
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.Ltail_maybe_long:
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cmp count, #64
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b.ge .Lnot_short
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.Ltail63:
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ands tmp1, count, #0x30
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b.eq 3f
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cmp tmp1w, #0x20
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b.eq 1f
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b.lt 2f
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stp A_l, A_l, [dst], #16
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1:
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stp A_l, A_l, [dst], #16
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2:
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stp A_l, A_l, [dst], #16
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/*
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* The last store length is less than 16,use stp to write last 16 bytes.
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* It will lead some bytes written twice and the access is non-aligned.
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*/
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3:
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ands count, count, #15
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cbz count, 4f
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add dst, dst, count
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stp A_l, A_l, [dst, #-16] /* Repeat some/all of last store. */
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4:
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ret
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/*
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* Critical loop. Start at a new cache line boundary. Assuming
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* 64 bytes per line, this ensures the entire loop is in one line.
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*/
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.p2align L1_CACHE_SHIFT
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.Lnot_short:
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sub dst, dst, #16/* Pre-bias. */
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sub count, count, #64
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1:
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stp A_l, A_l, [dst, #16]
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stp A_l, A_l, [dst, #32]
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stp A_l, A_l, [dst, #48]
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stp A_l, A_l, [dst, #64]!
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subs count, count, #64
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b.ge 1b
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tst count, #0x3f
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add dst, dst, #16
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b.ne .Ltail63
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.Lexitfunc:
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ret
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/*
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* For zeroing memory, check to see if we can use the ZVA feature to
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* zero entire 'cache' lines.
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*/
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.Lzero_mem:
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cmp count, #63
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b.le .Ltail63
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/*
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* For zeroing small amounts of memory, it's not worth setting up
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* the line-clear code.
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*/
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cmp count, #128
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b.lt .Lnot_short /*count is at least 128 bytes*/
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mrs tmp1, dczid_el0
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tbnz tmp1, #4, .Lnot_short
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mov tmp3w, #4
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and zva_len, tmp1w, #15 /* Safety: other bits reserved. */
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lsl zva_len, tmp3w, zva_len
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ands tmp3w, zva_len, #63
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/*
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* ensure the zva_len is not less than 64.
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* It is not meaningful to use ZVA if the block size is less than 64.
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*/
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b.ne .Lnot_short
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.Lzero_by_line:
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/*
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* Compute how far we need to go to become suitably aligned. We're
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* already at quad-word alignment.
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*/
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cmp count, zva_len_x
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b.lt .Lnot_short /* Not enough to reach alignment. */
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sub zva_bits_x, zva_len_x, #1
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neg tmp2, dst
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ands tmp2, tmp2, zva_bits_x
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b.eq 2f /* Already aligned. */
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/* Not aligned, check that there's enough to copy after alignment.*/
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sub tmp1, count, tmp2
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/*
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* grantee the remain length to be ZVA is bigger than 64,
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* avoid to make the 2f's process over mem range.*/
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cmp tmp1, #64
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ccmp tmp1, zva_len_x, #8, ge /* NZCV=0b1000 */
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b.lt .Lnot_short
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/*
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* We know that there's at least 64 bytes to zero and that it's safe
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* to overrun by 64 bytes.
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*/
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mov count, tmp1
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1:
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stp A_l, A_l, [dst]
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stp A_l, A_l, [dst, #16]
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stp A_l, A_l, [dst, #32]
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subs tmp2, tmp2, #64
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stp A_l, A_l, [dst, #48]
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add dst, dst, #64
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b.ge 1b
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/* We've overrun a bit, so adjust dst downwards.*/
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add dst, dst, tmp2
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2:
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sub count, count, zva_len_x
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3:
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dc zva, dst
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add dst, dst, zva_len_x
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subs count, count, zva_len_x
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b.ge 3b
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ands count, count, zva_bits_x
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b.ne .Ltail_maybe_long
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ret
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ENDPIPROC(memset)
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ENDPROC(__memset)
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