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Tue, 1 Mar 2022 10:14:43 +0000 From: Joey Gouly To: CC: , , , , , Subject: [PATCH v2 1/3] arm64: lib: Import latest version of Arm Optimized Routines' strcmp Date: Tue, 1 Mar 2022 10:14:33 +0000 Message-ID: <20220301101435.19327-2-joey.gouly@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220301101435.19327-1-joey.gouly@arm.com> References: <20220301101435.19327-1-joey.gouly@arm.com> MIME-Version: 1.0 X-EOPAttributedMessage: 1 X-MS-Office365-Filtering-Correlation-Id: af56e389-d13b-47fc-55ce-08d9fb6c5246 X-MS-TrafficTypeDiagnostic: AM9PR08MB7216:EE_|VE1EUR03FT012:EE_|HE1PR0801MB1865:EE_ X-Microsoft-Antispam-PRVS: x-checkrecipientrouted: true NoDisclaimer: true X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam-Untrusted: BCL:0; X-Microsoft-Antispam-Message-Info-Original: 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 X-Forefront-Antispam-Report-Untrusted: CIP:40.67.248.234; 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Note that for simplicity Arm have chosen to contribute this code to Linux under GPLv2 rather than the original MIT OR Apache-2.0 WITH LLVM-exception license. Arm is the sole copyright holder for this code. Signed-off-by: Joey Gouly Cc: Robin Murphy Cc: Mark Rutland Cc: Catalin Marinas Cc: Will Deacon Acked-by: Mark Rutland --- arch/arm64/lib/strcmp.S | 238 +++++++++++++++++++++------------------- 1 file changed, 126 insertions(+), 112 deletions(-) diff --git a/arch/arm64/lib/strcmp.S b/arch/arm64/lib/strcmp.S index 83bcad72ec97..758de77afd2f 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 @@ -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_WEAK_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):