diff options
author | Will Deacon <will@kernel.org> | 2022-03-14 19:02:52 +0000 |
---|---|---|
committer | Will Deacon <will@kernel.org> | 2022-03-14 19:02:52 +0000 |
commit | 515e5da7b6b52c5d6c7a54fe34165b86361041b5 (patch) | |
tree | a47fc7d71ec30ef8a776f3d5e2fa0f020afa7443 /arch/arm64 | |
parent | 92051a107ae795f73ee303453780fd28ff41fa7c (diff) | |
parent | e33c89256e66ba64ce5190c7f2c2741e619c6321 (diff) | |
download | linux-515e5da7b6b52c5d6c7a54fe34165b86361041b5.tar.bz2 |
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
Diffstat (limited to 'arch/arm64')
-rw-r--r-- | arch/arm64/include/asm/assembler.h | 5 | ||||
-rw-r--r-- | arch/arm64/include/asm/string.h | 2 | ||||
-rw-r--r-- | arch/arm64/lib/strcmp.S | 240 | ||||
-rw-r--r-- | arch/arm64/lib/strncmp.S | 235 |
4 files changed, 269 insertions, 213 deletions
diff --git a/arch/arm64/include/asm/assembler.h b/arch/arm64/include/asm/assembler.h index e8bd0af0141c..8df412178efb 100644 --- a/arch/arm64/include/asm/assembler.h +++ b/arch/arm64/include/asm/assembler.h @@ -535,11 +535,6 @@ alternative_endif #define EXPORT_SYMBOL_NOKASAN(name) EXPORT_SYMBOL(name) #endif -#ifdef CONFIG_KASAN_HW_TAGS -#define EXPORT_SYMBOL_NOHWKASAN(name) -#else -#define EXPORT_SYMBOL_NOHWKASAN(name) EXPORT_SYMBOL_NOKASAN(name) -#endif /* * Emit a 64-bit absolute little endian symbol reference in a way that * ensures that it will be resolved at build time, even when building a diff --git a/arch/arm64/include/asm/string.h b/arch/arm64/include/asm/string.h index 95f7686b728d..3a3264ff47b9 100644 --- a/arch/arm64/include/asm/string.h +++ b/arch/arm64/include/asm/string.h @@ -12,13 +12,11 @@ extern char *strrchr(const char *, int c); #define __HAVE_ARCH_STRCHR extern char *strchr(const char *, int c); -#ifndef CONFIG_KASAN_HW_TAGS #define __HAVE_ARCH_STRCMP extern int strcmp(const char *, const char *); #define __HAVE_ARCH_STRNCMP extern int strncmp(const char *, const char *, __kernel_size_t); -#endif #define __HAVE_ARCH_STRLEN extern __kernel_size_t strlen(const char *); diff --git a/arch/arm64/lib/strcmp.S b/arch/arm64/lib/strcmp.S index cda7de747efc..9b89b4533607 100644 --- a/arch/arm64/lib/strcmp.S +++ b/arch/arm64/lib/strcmp.S @@ -1,9 +1,9 @@ /* SPDX-License-Identifier: GPL-2.0-only */ /* - * Copyright (c) 2012-2021, Arm Limited. + * Copyright (c) 2012-2022, Arm Limited. * * Adapted from the original at: - * https://github.com/ARM-software/optimized-routines/blob/afd6244a1f8d9229/string/aarch64/strcmp.S + * https://github.com/ARM-software/optimized-routines/blob/189dfefe37d54c5b/string/aarch64/strcmp.S */ #include <linux/linkage.h> @@ -11,161 +11,175 @@ /* Assumptions: * - * ARMv8-a, AArch64 + * ARMv8-a, AArch64. + * MTE compatible. */ #define L(label) .L ## label #define REP8_01 0x0101010101010101 #define REP8_7f 0x7f7f7f7f7f7f7f7f -#define REP8_80 0x8080808080808080 -/* Parameters and result. */ #define src1 x0 #define src2 x1 #define result x0 -/* Internal variables. */ #define data1 x2 #define data1w w2 #define data2 x3 #define data2w w3 #define has_nul x4 #define diff x5 +#define off1 x5 #define syndrome x6 -#define tmp1 x7 -#define tmp2 x8 -#define tmp3 x9 -#define zeroones x10 -#define pos x11 - - /* Start of performance-critical section -- one 64B cache line. */ - .align 6 +#define tmp x6 +#define data3 x7 +#define zeroones x8 +#define shift x9 +#define off2 x10 + +/* On big-endian early bytes are at MSB and on little-endian LSB. + LS_FW means shifting towards early bytes. */ +#ifdef __AARCH64EB__ +# define LS_FW lsl +#else +# define LS_FW lsr +#endif + +/* NUL detection works on the principle that (X - 1) & (~X) & 0x80 + (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and + can be done in parallel across the entire word. + Since carry propagation makes 0x1 bytes before a NUL byte appear + NUL too in big-endian, byte-reverse the data before the NUL check. */ + + SYM_FUNC_START(__pi_strcmp) - eor tmp1, src1, src2 - mov zeroones, #REP8_01 - tst tmp1, #7 + sub off2, src2, src1 + mov zeroones, REP8_01 + and tmp, src1, 7 + tst off2, 7 b.ne L(misaligned8) - ands tmp1, src1, #7 - b.ne L(mutual_align) - /* NUL detection works on the principle that (X - 1) & (~X) & 0x80 - (=> (X - 1) & ~(X | 0x7f)) is non-zero iff a byte is zero, and - can be done in parallel across the entire word. */ + cbnz tmp, L(mutual_align) + + .p2align 4 + L(loop_aligned): - ldr data1, [src1], #8 - ldr data2, [src2], #8 + ldr data2, [src1, off2] + ldr data1, [src1], 8 L(start_realigned): - sub tmp1, data1, zeroones - orr tmp2, data1, #REP8_7f - eor diff, data1, data2 /* Non-zero if differences found. */ - bic has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */ +#ifdef __AARCH64EB__ + rev tmp, data1 + sub has_nul, tmp, zeroones + orr tmp, tmp, REP8_7f +#else + sub has_nul, data1, zeroones + orr tmp, data1, REP8_7f +#endif + bics has_nul, has_nul, tmp /* Non-zero if NUL terminator. */ + ccmp data1, data2, 0, eq + b.eq L(loop_aligned) +#ifdef __AARCH64EB__ + rev has_nul, has_nul +#endif + eor diff, data1, data2 orr syndrome, diff, has_nul - cbz syndrome, L(loop_aligned) - /* End of performance-critical section -- one 64B cache line. */ - L(end): -#ifndef __AARCH64EB__ +#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. */ - /* However, if there is no NUL byte in the dword, we can generate - the result directly. We can't just subtract the bytes as the - MSB might be significant. */ - cbnz has_nul, 1f - cmp data1, data2 - cset result, ne - cneg result, result, lo - ret -1: - /* Re-compute the NUL-byte detection, using a byte-reversed value. */ - rev tmp3, data1 - sub tmp1, tmp3, zeroones - orr tmp2, tmp3, #REP8_7f - bic has_nul, tmp1, tmp2 - 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. +#endif + clz shift, syndrome + /* 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. */ - lsl data1, data1, pos - lsl data2, data2, pos + lsl data1, data1, shift + lsl data2, data2, shift /* 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 + lsr data1, data1, 56 + sub result, data1, data2, lsr 56 ret -#endif + + .p2align 4 L(mutual_align): /* Sources are mutually aligned, but are not currently at an alignment boundary. Round down the addresses and then mask off - the bytes that preceed the start point. */ - bic src1, src1, #7 - bic src2, src2, #7 - lsl tmp1, tmp1, #3 /* Bytes beyond alignment -> bits. */ - ldr data1, [src1], #8 - neg tmp1, tmp1 /* Bits to alignment -64. */ - ldr data2, [src2], #8 - mov tmp2, #~0 -#ifdef __AARCH64EB__ - /* Big-endian. Early bytes are at MSB. */ - lsl tmp2, tmp2, tmp1 /* Shift (tmp1 & 63). */ -#else - /* Little-endian. Early bytes are at LSB. */ - lsr tmp2, tmp2, tmp1 /* Shift (tmp1 & 63). */ -#endif - orr data1, data1, tmp2 - orr data2, data2, tmp2 + the bytes that precede the start point. */ + bic src1, src1, 7 + ldr data2, [src1, off2] + ldr data1, [src1], 8 + neg shift, src2, lsl 3 /* Bits to alignment -64. */ + mov tmp, -1 + LS_FW tmp, tmp, shift + orr data1, data1, tmp + orr data2, data2, tmp b L(start_realigned) L(misaligned8): /* Align SRC1 to 8 bytes and then compare 8 bytes at a time, always - checking to make sure that we don't access beyond page boundary in - SRC2. */ - tst src1, #7 - b.eq L(loop_misaligned) + checking to make sure that we don't access beyond the end of SRC2. */ + cbz tmp, L(src1_aligned) L(do_misaligned): - ldrb data1w, [src1], #1 - ldrb data2w, [src2], #1 - cmp data1w, #1 - ccmp data1w, data2w, #0, cs /* NZCV = 0b0000. */ + ldrb data1w, [src1], 1 + ldrb data2w, [src2], 1 + cmp data1w, 0 + ccmp data1w, data2w, 0, ne /* NZCV = 0b0000. */ b.ne L(done) - tst src1, #7 + tst src1, 7 b.ne L(do_misaligned) -L(loop_misaligned): - /* Test if we are within the last dword of the end of a 4K page. If - yes then jump back to the misaligned loop to copy a byte at a time. */ - and tmp1, src2, #0xff8 - eor tmp1, tmp1, #0xff8 - cbz tmp1, L(do_misaligned) - 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. */ - bic has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */ +L(src1_aligned): + neg shift, src2, lsl 3 + bic src2, src2, 7 + ldr data3, [src2], 8 +#ifdef __AARCH64EB__ + rev data3, data3 +#endif + lsr tmp, zeroones, shift + orr data3, data3, tmp + sub has_nul, data3, zeroones + orr tmp, data3, REP8_7f + bics has_nul, has_nul, tmp + b.ne L(tail) + + sub off1, src2, src1 + + .p2align 4 + +L(loop_unaligned): + ldr data3, [src1, off1] + ldr data2, [src1, off2] +#ifdef __AARCH64EB__ + rev data3, data3 +#endif + sub has_nul, data3, zeroones + orr tmp, data3, REP8_7f + ldr data1, [src1], 8 + bics has_nul, has_nul, tmp + ccmp data1, data2, 0, eq + b.eq L(loop_unaligned) + + lsl tmp, has_nul, shift +#ifdef __AARCH64EB__ + rev tmp, tmp +#endif + eor diff, data1, data2 + orr syndrome, diff, tmp + cbnz syndrome, L(end) +L(tail): + ldr data1, [src1] + neg shift, shift + lsr data2, data3, shift + lsr has_nul, has_nul, shift +#ifdef __AARCH64EB__ + rev data2, data2 + rev has_nul, has_nul +#endif + eor diff, data1, data2 orr syndrome, diff, has_nul - cbz syndrome, L(loop_misaligned) b L(end) L(done): @@ -173,4 +187,4 @@ L(done): ret SYM_FUNC_END(__pi_strcmp) SYM_FUNC_ALIAS_WEAK(strcmp, __pi_strcmp) -EXPORT_SYMBOL_NOHWKASAN(strcmp) +EXPORT_SYMBOL_NOKASAN(strcmp) diff --git a/arch/arm64/lib/strncmp.S b/arch/arm64/lib/strncmp.S index a848abcec975..fe7bbc0b42a7 100644 --- a/arch/arm64/lib/strncmp.S +++ b/arch/arm64/lib/strncmp.S @@ -1,9 +1,9 @@ /* SPDX-License-Identifier: GPL-2.0-only */ /* - * Copyright (c) 2013-2021, Arm Limited. + * Copyright (c) 2013-2022, Arm Limited. * * Adapted from the original at: - * https://github.com/ARM-software/optimized-routines/blob/e823e3abf5f89ecb/string/aarch64/strncmp.S + * https://github.com/ARM-software/optimized-routines/blob/189dfefe37d54c5b/string/aarch64/strncmp.S */ #include <linux/linkage.h> @@ -11,14 +11,14 @@ /* Assumptions: * - * ARMv8-a, AArch64 + * ARMv8-a, AArch64. + * MTE compatible. */ #define L(label) .L ## label #define REP8_01 0x0101010101010101 #define REP8_7f 0x7f7f7f7f7f7f7f7f -#define REP8_80 0x8080808080808080 /* Parameters and result. */ #define src1 x0 @@ -39,10 +39,24 @@ #define tmp3 x10 #define zeroones x11 #define pos x12 -#define limit_wd x13 -#define mask x14 -#define endloop x15 +#define mask x13 +#define endloop x14 #define count mask +#define offset pos +#define neg_offset x15 + +/* 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 +#define LS_BK lsr +#else +#define LS_FW lsr +#define LS_BK lsl +#endif 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 @@ -64,56 +75,52 @@ 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 -#else - lsl mask, mask, limit -#endif - bic data1, data1, mask - bic data2, data2, mask - - /* Make sure that the NUL byte is marked in the syndrome. */ - orr has_nul, has_nul, mask - -L(not_limit): +L(full_check): +#ifndef __AARCH64EB__ orr syndrome, diff, has_nul - -#ifndef __AARCH64EB__ + 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 - /* 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 + 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 + /* 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 + + /* Make sure that the NUL byte is marked in the syndrome. */ + orr has_nul, has_nul, mask + +L(not_limit): /* 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) -L(loop_misaligned): - and tmp2, src2, #0xff8 - eor tmp2, tmp2, #0xff8 - cbz tmp2, L(page_end_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 - 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) + 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(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 +L(loop_misaligned): + /* 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. */ - bics has_nul, tmp1, tmp2 /* Non-zero if NUL terminator. */ - ccmp diff, #0, #0, eq - b.ne L(not_limit) + 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 +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) + + /* 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) |