Merge branch 'for-next/strings' into for-next/core
* for-next/strings:
Revert "arm64: Mitigate MTE issues with str{n}cmp()"
arm64: lib: Import latest version of Arm Optimized Routines' strncmp
arm64: lib: Import latest version of Arm Optimized Routines' strcmp
This commit is contained in:
Will Deacon
Коммит
515e5da7b6
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@ -535,11 +535,6 @@ alternative_endif
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#define EXPORT_SYMBOL_NOKASAN(name) EXPORT_SYMBOL(name)
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#endif
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#ifdef CONFIG_KASAN_HW_TAGS
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#define EXPORT_SYMBOL_NOHWKASAN(name)
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#else
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#define EXPORT_SYMBOL_NOHWKASAN(name) EXPORT_SYMBOL_NOKASAN(name)
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#endif
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/*
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* Emit a 64-bit absolute little endian symbol reference in a way that
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* ensures that it will be resolved at build time, even when building a
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@ -12,13 +12,11 @@ extern char *strrchr(const char *, int c);
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#define __HAVE_ARCH_STRCHR
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extern char *strchr(const char *, int c);
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#ifndef CONFIG_KASAN_HW_TAGS
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#define __HAVE_ARCH_STRCMP
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extern int strcmp(const char *, const char *);
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#define __HAVE_ARCH_STRNCMP
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extern int strncmp(const char *, const char *, __kernel_size_t);
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#endif
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#define __HAVE_ARCH_STRLEN
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extern __kernel_size_t strlen(const char *);
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@ -1,9 +1,9 @@
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/* SPDX-License-Identifier: GPL-2.0-only */
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/*
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* Copyright (c) 2012-2021, Arm Limited.
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* Copyright (c) 2012-2022, Arm Limited.
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*
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* Adapted from the original at:
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* https://github.com/ARM-software/optimized-routines/blob/afd6244a1f8d9229/string/aarch64/strcmp.S
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* https://github.com/ARM-software/optimized-routines/blob/189dfefe37d54c5b/string/aarch64/strcmp.S
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*/
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#include <linux/linkage.h>
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@ -11,161 +11,175 @@
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/* Assumptions:
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*
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* ARMv8-a, AArch64
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* ARMv8-a, AArch64.
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* MTE compatible.
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*/
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#define L(label) .L ## label
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#define REP8_01 0x0101010101010101
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#define REP8_7f 0x7f7f7f7f7f7f7f7f
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#define REP8_80 0x8080808080808080
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/* Parameters and result. */
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#define src1 x0
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#define src2 x1
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#define result x0
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/* Internal variables. */
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#define data1 x2
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#define data1w w2
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#define data2 x3
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#define data2w w3
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#define has_nul x4
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#define diff x5
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#define off1 x5
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#define syndrome x6
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#define tmp1 x7
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#define tmp2 x8
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#define tmp3 x9
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#define zeroones x10
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#define pos x11
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#define tmp x6
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#define data3 x7
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#define zeroones x8
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#define shift x9
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#define off2 x10
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/* Start of performance-critical section -- one 64B cache line. */
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.align 6
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SYM_FUNC_START(__pi_strcmp)
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eor tmp1, src1, src2
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mov zeroones, #REP8_01
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tst tmp1, #7
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b.ne L(misaligned8)
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ands tmp1, src1, #7
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b.ne L(mutual_align)
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/* NUL detection works on the principle that (X - 1) & (~X) & 0x80
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/* On big-endian early bytes are at MSB and on little-endian LSB.
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LS_FW means shifting towards early bytes. */
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#ifdef __AARCH64EB__
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# define LS_FW lsl
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#else
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# define LS_FW lsr
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#endif
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/* NUL detection works on the principle that (X - 1) & (~X) & 0x80
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(=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and
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can be done in parallel across the entire word. */
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L(loop_aligned):
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ldr data1, [src1], #8
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ldr data2, [src2], #8
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L(start_realigned):
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sub tmp1, data1, zeroones
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orr tmp2, data1, #REP8_7f
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eor diff, data1, data2 /* Non-zero if differences found. */
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bic has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
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orr syndrome, diff, has_nul
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cbz syndrome, L(loop_aligned)
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/* End of performance-critical section -- one 64B cache line. */
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can be done in parallel across the entire word.
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Since carry propagation makes 0x1 bytes before a NUL byte appear
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NUL too in big-endian, byte-reverse the data before the NUL check. */
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SYM_FUNC_START(__pi_strcmp)
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sub off2, src2, src1
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mov zeroones, REP8_01
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and tmp, src1, 7
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tst off2, 7
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b.ne L(misaligned8)
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cbnz tmp, L(mutual_align)
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.p2align 4
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L(loop_aligned):
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ldr data2, [src1, off2]
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ldr data1, [src1], 8
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L(start_realigned):
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#ifdef __AARCH64EB__
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rev tmp, data1
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sub has_nul, tmp, zeroones
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orr tmp, tmp, REP8_7f
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#else
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sub has_nul, data1, zeroones
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orr tmp, data1, REP8_7f
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#endif
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bics has_nul, has_nul, tmp /* Non-zero if NUL terminator. */
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ccmp data1, data2, 0, eq
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b.eq L(loop_aligned)
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#ifdef __AARCH64EB__
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rev has_nul, has_nul
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#endif
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eor diff, data1, data2
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orr syndrome, diff, has_nul
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L(end):
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#ifndef __AARCH64EB__
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rev syndrome, syndrome
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rev data1, data1
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/* The MS-non-zero bit of the syndrome marks either the first bit
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that is different, or the top bit of the first zero byte.
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Shifting left now will bring the critical information into the
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top bits. */
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clz pos, syndrome
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rev data2, data2
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lsl data1, data1, pos
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lsl data2, data2, pos
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/* But we need to zero-extend (char is unsigned) the value and then
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perform a signed 32-bit subtraction. */
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lsr data1, data1, #56
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sub result, data1, data2, lsr #56
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ret
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#else
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/* For big-endian we cannot use the trick with the syndrome value
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as carry-propagation can corrupt the upper bits if the trailing
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bytes in the string contain 0x01. */
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/* However, if there is no NUL byte in the dword, we can generate
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the result directly. We can't just subtract the bytes as the
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MSB might be significant. */
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cbnz has_nul, 1f
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cmp data1, data2
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cset result, ne
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cneg result, result, lo
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ret
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1:
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/* Re-compute the NUL-byte detection, using a byte-reversed value. */
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rev tmp3, data1
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sub tmp1, tmp3, zeroones
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orr tmp2, tmp3, #REP8_7f
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bic has_nul, tmp1, tmp2
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rev has_nul, has_nul
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orr syndrome, diff, has_nul
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clz pos, syndrome
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/* The MS-non-zero bit of the syndrome marks either the first bit
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that is different, or the top bit of the first zero byte.
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#endif
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clz shift, syndrome
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/* The most-significant-non-zero bit of the syndrome marks either the
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first bit that is different, or the top bit of the first zero byte.
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Shifting left now will bring the critical information into the
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top bits. */
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lsl data1, data1, pos
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lsl data2, data2, pos
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lsl data1, data1, shift
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lsl data2, data2, shift
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/* But we need to zero-extend (char is unsigned) the value and then
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perform a signed 32-bit subtraction. */
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lsr data1, data1, #56
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sub result, data1, data2, lsr #56
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lsr data1, data1, 56
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sub result, data1, data2, lsr 56
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ret
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#endif
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.p2align 4
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L(mutual_align):
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/* Sources are mutually aligned, but are not currently at an
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alignment boundary. Round down the addresses and then mask off
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the bytes that preceed the start point. */
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bic src1, src1, #7
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bic src2, src2, #7
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lsl tmp1, tmp1, #3 /* Bytes beyond alignment -> bits. */
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ldr data1, [src1], #8
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neg tmp1, tmp1 /* Bits to alignment -64. */
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ldr data2, [src2], #8
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mov tmp2, #~0
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#ifdef __AARCH64EB__
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/* Big-endian. Early bytes are at MSB. */
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lsl tmp2, tmp2, tmp1 /* Shift (tmp1 & 63). */
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#else
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/* Little-endian. Early bytes are at LSB. */
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lsr tmp2, tmp2, tmp1 /* Shift (tmp1 & 63). */
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#endif
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orr data1, data1, tmp2
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orr data2, data2, tmp2
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the bytes that precede the start point. */
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bic src1, src1, 7
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ldr data2, [src1, off2]
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ldr data1, [src1], 8
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neg shift, src2, lsl 3 /* Bits to alignment -64. */
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mov tmp, -1
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LS_FW tmp, tmp, shift
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orr data1, data1, tmp
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orr data2, data2, tmp
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b L(start_realigned)
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L(misaligned8):
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/* Align SRC1 to 8 bytes and then compare 8 bytes at a time, always
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checking to make sure that we don't access beyond page boundary in
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SRC2. */
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tst src1, #7
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b.eq L(loop_misaligned)
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checking to make sure that we don't access beyond the end of SRC2. */
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cbz tmp, L(src1_aligned)
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L(do_misaligned):
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ldrb data1w, [src1], #1
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ldrb data2w, [src2], #1
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cmp data1w, #1
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ccmp data1w, data2w, #0, cs /* NZCV = 0b0000. */
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ldrb data1w, [src1], 1
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ldrb data2w, [src2], 1
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cmp data1w, 0
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ccmp data1w, data2w, 0, ne /* NZCV = 0b0000. */
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b.ne L(done)
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tst src1, #7
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tst src1, 7
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b.ne L(do_misaligned)
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L(loop_misaligned):
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/* Test if we are within the last dword of the end of a 4K page. If
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yes then jump back to the misaligned loop to copy a byte at a time. */
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and tmp1, src2, #0xff8
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eor tmp1, tmp1, #0xff8
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cbz tmp1, L(do_misaligned)
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ldr data1, [src1], #8
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ldr data2, [src2], #8
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L(src1_aligned):
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neg shift, src2, lsl 3
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bic src2, src2, 7
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ldr data3, [src2], 8
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#ifdef __AARCH64EB__
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rev data3, data3
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#endif
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lsr tmp, zeroones, shift
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orr data3, data3, tmp
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sub has_nul, data3, zeroones
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orr tmp, data3, REP8_7f
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bics has_nul, has_nul, tmp
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b.ne L(tail)
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sub tmp1, data1, zeroones
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orr tmp2, data1, #REP8_7f
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eor diff, data1, data2 /* Non-zero if differences found. */
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bic has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
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sub off1, src2, src1
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.p2align 4
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L(loop_unaligned):
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ldr data3, [src1, off1]
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ldr data2, [src1, off2]
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#ifdef __AARCH64EB__
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rev data3, data3
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#endif
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sub has_nul, data3, zeroones
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orr tmp, data3, REP8_7f
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ldr data1, [src1], 8
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bics has_nul, has_nul, tmp
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ccmp data1, data2, 0, eq
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b.eq L(loop_unaligned)
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lsl tmp, has_nul, shift
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#ifdef __AARCH64EB__
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rev tmp, tmp
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#endif
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eor diff, data1, data2
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orr syndrome, diff, tmp
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cbnz syndrome, L(end)
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L(tail):
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ldr data1, [src1]
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neg shift, shift
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lsr data2, data3, shift
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lsr has_nul, has_nul, shift
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#ifdef __AARCH64EB__
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rev data2, data2
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rev has_nul, has_nul
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#endif
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eor diff, data1, data2
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orr syndrome, diff, has_nul
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cbz syndrome, L(loop_misaligned)
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b L(end)
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L(done):
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@ -173,4 +187,4 @@ L(done):
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ret
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SYM_FUNC_END(__pi_strcmp)
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SYM_FUNC_ALIAS_WEAK(strcmp, __pi_strcmp)
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EXPORT_SYMBOL_NOHWKASAN(strcmp)
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EXPORT_SYMBOL_NOKASAN(strcmp)
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|
|
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|
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@ -1,9 +1,9 @@
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/* SPDX-License-Identifier: GPL-2.0-only */
|
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/*
|
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* Copyright (c) 2013-2021, Arm Limited.
|
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* Copyright (c) 2013-2022, Arm Limited.
|
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*
|
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* Adapted from the original at:
|
||||
* https://github.com/ARM-software/optimized-routines/blob/e823e3abf5f89ecb/string/aarch64/strncmp.S
|
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* https://github.com/ARM-software/optimized-routines/blob/189dfefe37d54c5b/string/aarch64/strncmp.S
|
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*/
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#include <linux/linkage.h>
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|
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@ -11,14 +11,14 @@
|
|||
|
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/* Assumptions:
|
||||
*
|
||||
* ARMv8-a, AArch64
|
||||
* ARMv8-a, AArch64.
|
||||
* MTE compatible.
|
||||
*/
|
||||
|
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#define L(label) .L ## label
|
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|
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#define REP8_01 0x0101010101010101
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#define REP8_7f 0x7f7f7f7f7f7f7f7f
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#define REP8_80 0x8080808080808080
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|
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/* Parameters and result. */
|
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#define src1 x0
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|
|
@ -39,10 +39,24 @@
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#define tmp3 x10
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#define zeroones x11
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#define pos x12
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#define limit_wd x13
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#define mask x14
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#define endloop x15
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#define mask x13
|
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#define endloop x14
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#define count mask
|
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#define offset pos
|
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#define neg_offset x15
|
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|
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/* Define endian dependent shift operations.
|
||||
On big-endian early bytes are at MSB and on little-endian LSB.
|
||||
LS_FW means shifting towards early bytes.
|
||||
LS_BK means shifting towards later bytes.
|
||||
*/
|
||||
#ifdef __AARCH64EB__
|
||||
#define LS_FW lsl
|
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#define LS_BK lsr
|
||||
#else
|
||||
#define LS_FW lsr
|
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#define LS_BK lsl
|
||||
#endif
|
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|
||||
SYM_FUNC_START(__pi_strncmp)
|
||||
cbz limit, L(ret0)
|
||||
|
|
@ -52,9 +66,6 @@ SYM_FUNC_START(__pi_strncmp)
|
|||
and count, src1, #7
|
||||
b.ne L(misaligned8)
|
||||
cbnz count, L(mutual_align)
|
||||
/* Calculate the number of full and partial words -1. */
|
||||
sub limit_wd, limit, #1 /* limit != 0, so no underflow. */
|
||||
lsr limit_wd, limit_wd, #3 /* Convert to Dwords. */
|
||||
|
||||
/* NUL detection works on the principle that (X - 1) & (~X) & 0x80
|
||||
(=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and
|
||||
|
|
@ -64,30 +75,45 @@ L(loop_aligned):
|
|||
ldr data1, [src1], #8
|
||||
ldr data2, [src2], #8
|
||||
L(start_realigned):
|
||||
subs limit_wd, limit_wd, #1
|
||||
subs limit, limit, #8
|
||||
sub tmp1, data1, zeroones
|
||||
orr tmp2, data1, #REP8_7f
|
||||
eor diff, data1, data2 /* Non-zero if differences found. */
|
||||
csinv endloop, diff, xzr, pl /* Last Dword or differences. */
|
||||
csinv endloop, diff, xzr, hi /* Last Dword or differences. */
|
||||
bics has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
|
||||
ccmp endloop, #0, #0, eq
|
||||
b.eq L(loop_aligned)
|
||||
/* End of main loop */
|
||||
|
||||
/* Not reached the limit, must have found the end or a diff. */
|
||||
tbz limit_wd, #63, L(not_limit)
|
||||
|
||||
/* Limit % 8 == 0 => all bytes significant. */
|
||||
ands limit, limit, #7
|
||||
b.eq L(not_limit)
|
||||
|
||||
lsl limit, limit, #3 /* Bits -> bytes. */
|
||||
mov mask, #~0
|
||||
#ifdef __AARCH64EB__
|
||||
lsr mask, mask, limit
|
||||
L(full_check):
|
||||
#ifndef __AARCH64EB__
|
||||
orr syndrome, diff, has_nul
|
||||
add limit, limit, 8 /* Rewind limit to before last subs. */
|
||||
L(syndrome_check):
|
||||
/* Limit was reached. Check if the NUL byte or the difference
|
||||
is before the limit. */
|
||||
rev syndrome, syndrome
|
||||
rev data1, data1
|
||||
clz pos, syndrome
|
||||
rev data2, data2
|
||||
lsl data1, data1, pos
|
||||
cmp limit, pos, lsr #3
|
||||
lsl data2, data2, pos
|
||||
/* But we need to zero-extend (char is unsigned) the value and then
|
||||
perform a signed 32-bit subtraction. */
|
||||
lsr data1, data1, #56
|
||||
sub result, data1, data2, lsr #56
|
||||
csel result, result, xzr, hi
|
||||
ret
|
||||
#else
|
||||
lsl mask, mask, limit
|
||||
#endif
|
||||
/* Not reached the limit, must have found the end or a diff. */
|
||||
tbz limit, #63, L(not_limit)
|
||||
add tmp1, limit, 8
|
||||
cbz limit, L(not_limit)
|
||||
|
||||
lsl limit, tmp1, #3 /* Bits -> bytes. */
|
||||
mov mask, #~0
|
||||
lsr mask, mask, limit
|
||||
bic data1, data1, mask
|
||||
bic data2, data2, mask
|
||||
|
||||
|
|
@ -95,25 +121,6 @@ L(start_realigned):
|
|||
orr has_nul, has_nul, mask
|
||||
|
||||
L(not_limit):
|
||||
orr syndrome, diff, has_nul
|
||||
|
||||
#ifndef __AARCH64EB__
|
||||
rev syndrome, syndrome
|
||||
rev data1, data1
|
||||
/* The MS-non-zero bit of the syndrome marks either the first bit
|
||||
that is different, or the top bit of the first zero byte.
|
||||
Shifting left now will bring the critical information into the
|
||||
top bits. */
|
||||
clz pos, syndrome
|
||||
rev data2, data2
|
||||
lsl data1, data1, pos
|
||||
lsl data2, data2, pos
|
||||
/* But we need to zero-extend (char is unsigned) the value and then
|
||||
perform a signed 32-bit subtraction. */
|
||||
lsr data1, data1, #56
|
||||
sub result, data1, data2, lsr #56
|
||||
ret
|
||||
#else
|
||||
/* For big-endian we cannot use the trick with the syndrome value
|
||||
as carry-propagation can corrupt the upper bits if the trailing
|
||||
bytes in the string contain 0x01. */
|
||||
|
|
@ -134,10 +141,11 @@ L(not_limit):
|
|||
rev has_nul, has_nul
|
||||
orr syndrome, diff, has_nul
|
||||
clz pos, syndrome
|
||||
/* The MS-non-zero bit of the syndrome marks either the first bit
|
||||
that is different, or the top bit of the first zero byte.
|
||||
/* The most-significant-non-zero bit of the syndrome marks either the
|
||||
first bit that is different, or the top bit of the first zero byte.
|
||||
Shifting left now will bring the critical information into the
|
||||
top bits. */
|
||||
L(end_quick):
|
||||
lsl data1, data1, pos
|
||||
lsl data2, data2, pos
|
||||
/* But we need to zero-extend (char is unsigned) the value and then
|
||||
|
|
@ -159,22 +167,12 @@ L(mutual_align):
|
|||
neg tmp3, count, lsl #3 /* 64 - bits(bytes beyond align). */
|
||||
ldr data2, [src2], #8
|
||||
mov tmp2, #~0
|
||||
sub limit_wd, limit, #1 /* limit != 0, so no underflow. */
|
||||
#ifdef __AARCH64EB__
|
||||
/* Big-endian. Early bytes are at MSB. */
|
||||
lsl tmp2, tmp2, tmp3 /* Shift (count & 63). */
|
||||
#else
|
||||
/* Little-endian. Early bytes are at LSB. */
|
||||
lsr tmp2, tmp2, tmp3 /* Shift (count & 63). */
|
||||
#endif
|
||||
and tmp3, limit_wd, #7
|
||||
lsr limit_wd, limit_wd, #3
|
||||
/* Adjust the limit. Only low 3 bits used, so overflow irrelevant. */
|
||||
add limit, limit, count
|
||||
add tmp3, tmp3, count
|
||||
LS_FW tmp2, tmp2, tmp3 /* Shift (count & 63). */
|
||||
/* Adjust the limit and ensure it doesn't overflow. */
|
||||
adds limit, limit, count
|
||||
csinv limit, limit, xzr, lo
|
||||
orr data1, data1, tmp2
|
||||
orr data2, data2, tmp2
|
||||
add limit_wd, limit_wd, tmp3, lsr #3
|
||||
b L(start_realigned)
|
||||
|
||||
.p2align 4
|
||||
|
|
@ -197,13 +195,11 @@ L(done):
|
|||
/* Align the SRC1 to a dword by doing a bytewise compare and then do
|
||||
the dword loop. */
|
||||
L(try_misaligned_words):
|
||||
lsr limit_wd, limit, #3
|
||||
cbz count, L(do_misaligned)
|
||||
cbz count, L(src1_aligned)
|
||||
|
||||
neg count, count
|
||||
and count, count, #7
|
||||
sub limit, limit, count
|
||||
lsr limit_wd, limit, #3
|
||||
|
||||
L(page_end_loop):
|
||||
ldrb data1w, [src1], #1
|
||||
|
|
@ -214,48 +210,101 @@ L(page_end_loop):
|
|||
subs count, count, #1
|
||||
b.hi L(page_end_loop)
|
||||
|
||||
L(do_misaligned):
|
||||
/* Prepare ourselves for the next page crossing. Unlike the aligned
|
||||
loop, we fetch 1 less dword because we risk crossing bounds on
|
||||
SRC2. */
|
||||
mov count, #8
|
||||
subs limit_wd, limit_wd, #1
|
||||
b.lo L(done_loop)
|
||||
/* The following diagram explains the comparison of misaligned strings.
|
||||
The bytes are shown in natural order. For little-endian, it is
|
||||
reversed in the registers. The "x" bytes are before the string.
|
||||
The "|" separates data that is loaded at one time.
|
||||
src1 | a a a a a a a a | b b b c c c c c | . . .
|
||||
src2 | x x x x x a a a a a a a a b b b | c c c c c . . .
|
||||
|
||||
After shifting in each step, the data looks like this:
|
||||
STEP_A STEP_B STEP_C
|
||||
data1 a a a a a a a a b b b c c c c c b b b c c c c c
|
||||
data2 a a a a a a a a b b b 0 0 0 0 0 0 0 0 c c c c c
|
||||
|
||||
The bytes with "0" are eliminated from the syndrome via mask.
|
||||
|
||||
Align SRC2 down to 16 bytes. This way we can read 16 bytes at a
|
||||
time from SRC2. The comparison happens in 3 steps. After each step
|
||||
the loop can exit, or read from SRC1 or SRC2. */
|
||||
L(src1_aligned):
|
||||
/* Calculate offset from 8 byte alignment to string start in bits. No
|
||||
need to mask offset since shifts are ignoring upper bits. */
|
||||
lsl offset, src2, #3
|
||||
bic src2, src2, #0xf
|
||||
mov mask, -1
|
||||
neg neg_offset, offset
|
||||
ldr data1, [src1], #8
|
||||
ldp tmp1, tmp2, [src2], #16
|
||||
LS_BK mask, mask, neg_offset
|
||||
and neg_offset, neg_offset, #63 /* Need actual value for cmp later. */
|
||||
/* Skip the first compare if data in tmp1 is irrelevant. */
|
||||
tbnz offset, 6, L(misaligned_mid_loop)
|
||||
|
||||
L(loop_misaligned):
|
||||
and tmp2, src2, #0xff8
|
||||
eor tmp2, tmp2, #0xff8
|
||||
cbz tmp2, L(page_end_loop)
|
||||
/* STEP_A: Compare full 8 bytes when there is enough data from SRC2.*/
|
||||
LS_FW data2, tmp1, offset
|
||||
LS_BK tmp1, tmp2, neg_offset
|
||||
subs limit, limit, #8
|
||||
orr data2, data2, tmp1 /* 8 bytes from SRC2 combined from two regs.*/
|
||||
sub has_nul, data1, zeroones
|
||||
eor diff, data1, data2 /* Non-zero if differences found. */
|
||||
orr tmp3, data1, #REP8_7f
|
||||
csinv endloop, diff, xzr, hi /* If limit, set to all ones. */
|
||||
bic has_nul, has_nul, tmp3 /* Non-zero if NUL byte found in SRC1. */
|
||||
orr tmp3, endloop, has_nul
|
||||
cbnz tmp3, L(full_check)
|
||||
|
||||
ldr data1, [src1], #8
|
||||
ldr data2, [src2], #8
|
||||
sub tmp1, data1, zeroones
|
||||
orr tmp2, data1, #REP8_7f
|
||||
eor diff, data1, data2 /* Non-zero if differences found. */
|
||||
bics has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
|
||||
ccmp diff, #0, #0, eq
|
||||
b.ne L(not_limit)
|
||||
subs limit_wd, limit_wd, #1
|
||||
b.pl L(loop_misaligned)
|
||||
L(misaligned_mid_loop):
|
||||
/* STEP_B: Compare first part of data1 to second part of tmp2. */
|
||||
LS_FW data2, tmp2, offset
|
||||
#ifdef __AARCH64EB__
|
||||
/* For big-endian we do a byte reverse to avoid carry-propagation
|
||||
problem described above. This way we can reuse the has_nul in the
|
||||
next step and also use syndrome value trick at the end. */
|
||||
rev tmp3, data1
|
||||
#define data1_fixed tmp3
|
||||
#else
|
||||
#define data1_fixed data1
|
||||
#endif
|
||||
sub has_nul, data1_fixed, zeroones
|
||||
orr tmp3, data1_fixed, #REP8_7f
|
||||
eor diff, data2, data1 /* Non-zero if differences found. */
|
||||
bic has_nul, has_nul, tmp3 /* Non-zero if NUL terminator. */
|
||||
#ifdef __AARCH64EB__
|
||||
rev has_nul, has_nul
|
||||
#endif
|
||||
cmp limit, neg_offset, lsr #3
|
||||
orr syndrome, diff, has_nul
|
||||
bic syndrome, syndrome, mask /* Ignore later bytes. */
|
||||
csinv tmp3, syndrome, xzr, hi /* If limit, set to all ones. */
|
||||
cbnz tmp3, L(syndrome_check)
|
||||
|
||||
L(done_loop):
|
||||
/* We found a difference or a NULL before the limit was reached. */
|
||||
and limit, limit, #7
|
||||
cbz limit, L(not_limit)
|
||||
/* Read the last word. */
|
||||
sub src1, src1, 8
|
||||
sub src2, src2, 8
|
||||
ldr data1, [src1, limit]
|
||||
ldr data2, [src2, limit]
|
||||
sub tmp1, data1, zeroones
|
||||
orr tmp2, data1, #REP8_7f
|
||||
eor diff, data1, data2 /* Non-zero if differences found. */
|
||||
bics has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */
|
||||
ccmp diff, #0, #0, eq
|
||||
b.ne L(not_limit)
|
||||
/* STEP_C: Compare second part of data1 to first part of tmp1. */
|
||||
ldp tmp1, tmp2, [src2], #16
|
||||
cmp limit, #8
|
||||
LS_BK data2, tmp1, neg_offset
|
||||
eor diff, data2, data1 /* Non-zero if differences found. */
|
||||
orr syndrome, diff, has_nul
|
||||
and syndrome, syndrome, mask /* Ignore earlier bytes. */
|
||||
csinv tmp3, syndrome, xzr, hi /* If limit, set to all ones. */
|
||||
cbnz tmp3, L(syndrome_check)
|
||||
|
||||
ldr data1, [src1], #8
|
||||
sub limit, limit, #8
|
||||
b L(loop_misaligned)
|
||||
|
||||
#ifdef __AARCH64EB__
|
||||
L(syndrome_check):
|
||||
clz pos, syndrome
|
||||
cmp pos, limit, lsl #3
|
||||
b.lo L(end_quick)
|
||||
#endif
|
||||
|
||||
L(ret0):
|
||||
mov result, #0
|
||||
ret
|
||||
SYM_FUNC_END(__pi_strncmp)
|
||||
SYM_FUNC_ALIAS_WEAK(strncmp, __pi_strncmp)
|
||||
EXPORT_SYMBOL_NOHWKASAN(strncmp)
|
||||
EXPORT_SYMBOL_NOKASAN(strncmp)
|
||||
|
|
|
|||
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