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arm64: Import latest version of Cortex Strings' memcmp
Import the latest version of the former Cortex Strings - now Arm Optimized Routines - memcmp function based on the upstream code of string/aarch64/memcmp.S at commit e823e3a from https://github.com/ARM-software/optimized-routines Note that for simplicity Arm have chosen to contribute this code to Linux under GPLv2 rather than the original MIT license. Signed-off-by: Sam Tebbs <sam.tebbs@arm.com> [ rm: update attribution and commit message ] Signed-off-by: Robin Murphy <robin.murphy@arm.com> Acked-by: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/r/2889de2d41054f3f508fb3addad784a3606ef383.1622128527.git.robin.murphy@arm.com Signed-off-by: Will Deacon <will@kernel.org>
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| @@ -1,247 +1,139 @@ | ||
| /* SPDX-License-Identifier: GPL-2.0-only */ | ||
| /* | ||
| * Copyright (C) 2013 ARM Ltd. | ||
| * Copyright (C) 2013 Linaro. | ||
| * Copyright (c) 2013-2020, Arm Limited. | ||
| * | ||
| * This code is based on glibc cortex strings work originally authored by Linaro | ||
| * be found @ | ||
| * | ||
| * http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/ | ||
| * files/head:/src/aarch64/ | ||
| * Adapted from the original at: | ||
| * https://github.com/ARM-software/optimized-routines/blob/master/string/aarch64/memcmp.S | ||
| */ | ||
|
|
||
| #include <linux/linkage.h> | ||
| #include <asm/assembler.h> | ||
|
|
||
| /* | ||
| * compare memory areas(when two memory areas' offset are different, | ||
| * alignment handled by the hardware) | ||
| * | ||
| * Parameters: | ||
| * x0 - const memory area 1 pointer | ||
| * x1 - const memory area 2 pointer | ||
| * x2 - the maximal compare byte length | ||
| * Returns: | ||
| * x0 - a compare result, maybe less than, equal to, or greater than ZERO | ||
| */ | ||
| /* Assumptions: | ||
| * | ||
| * ARMv8-a, AArch64, unaligned accesses. | ||
| */ | ||
|
|
||
| #define L(label) .L ## label | ||
|
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||
| /* Parameters and result. */ | ||
| src1 .req x0 | ||
| src2 .req x1 | ||
| limit .req x2 | ||
| result .req x0 | ||
| #define src1 x0 | ||
| #define src2 x1 | ||
| #define limit x2 | ||
| #define result w0 | ||
|
|
||
| /* Internal variables. */ | ||
| data1 .req x3 | ||
| data1w .req w3 | ||
| data2 .req x4 | ||
| data2w .req w4 | ||
| has_nul .req x5 | ||
| diff .req x6 | ||
| endloop .req x7 | ||
| tmp1 .req x8 | ||
| tmp2 .req x9 | ||
| tmp3 .req x10 | ||
| pos .req x11 | ||
| limit_wd .req x12 | ||
| mask .req x13 | ||
| #define data1 x3 | ||
| #define data1w w3 | ||
| #define data1h x4 | ||
| #define data2 x5 | ||
| #define data2w w5 | ||
| #define data2h x6 | ||
| #define tmp1 x7 | ||
| #define tmp2 x8 | ||
|
|
||
| SYM_FUNC_START_WEAK_PI(memcmp) | ||
| cbz limit, .Lret0 | ||
| eor tmp1, src1, src2 | ||
| tst tmp1, #7 | ||
| b.ne .Lmisaligned8 | ||
| ands tmp1, src1, #7 | ||
| b.ne .Lmutual_align | ||
| sub limit_wd, limit, #1 /* limit != 0, so no underflow. */ | ||
| lsr limit_wd, limit_wd, #3 /* Convert to Dwords. */ | ||
| /* | ||
| * The input source addresses are at alignment boundary. | ||
| * Directly compare eight bytes each time. | ||
| */ | ||
| .Lloop_aligned: | ||
| ldr data1, [src1], #8 | ||
| ldr data2, [src2], #8 | ||
| .Lstart_realigned: | ||
| subs limit_wd, limit_wd, #1 | ||
| eor diff, data1, data2 /* Non-zero if differences found. */ | ||
| csinv endloop, diff, xzr, cs /* Last Dword or differences. */ | ||
| cbz endloop, .Lloop_aligned | ||
|
|
||
| /* Not reached the limit, must have found a diff. */ | ||
| tbz limit_wd, #63, .Lnot_limit | ||
|
|
||
| /* Limit % 8 == 0 => the diff is in the last 8 bytes. */ | ||
| ands limit, limit, #7 | ||
| b.eq .Lnot_limit | ||
| /* | ||
| * The remained bytes less than 8. It is needed to extract valid data | ||
| * from last eight bytes of the intended memory range. | ||
| */ | ||
| lsl limit, limit, #3 /* bytes-> bits. */ | ||
| mov mask, #~0 | ||
| CPU_BE( lsr mask, mask, limit ) | ||
| CPU_LE( lsl mask, mask, limit ) | ||
| bic data1, data1, mask | ||
| bic data2, data2, mask | ||
|
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||
| orr diff, diff, mask | ||
| b .Lnot_limit | ||
|
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||
| .Lmutual_align: | ||
| /* | ||
| * Sources are mutually aligned, but are not currently at an | ||
| * alignment boundary. Round down the addresses and then mask off | ||
| * the bytes that precede the start point. | ||
| */ | ||
| bic src1, src1, #7 | ||
| bic src2, src2, #7 | ||
| ldr data1, [src1], #8 | ||
| ldr data2, [src2], #8 | ||
| /* | ||
| * We can not add limit with alignment offset(tmp1) here. Since the | ||
| * addition probably make the limit overflown. | ||
| */ | ||
| sub limit_wd, limit, #1/*limit != 0, so no underflow.*/ | ||
| and tmp3, limit_wd, #7 | ||
| lsr limit_wd, limit_wd, #3 | ||
| add tmp3, tmp3, tmp1 | ||
| add limit_wd, limit_wd, tmp3, lsr #3 | ||
| add limit, limit, tmp1/* Adjust the limit for the extra. */ | ||
|
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||
| lsl tmp1, tmp1, #3/* Bytes beyond alignment -> bits.*/ | ||
| neg tmp1, tmp1/* Bits to alignment -64. */ | ||
| mov tmp2, #~0 | ||
| /*mask off the non-intended bytes before the start address.*/ | ||
| CPU_BE( lsl tmp2, tmp2, tmp1 )/*Big-endian.Early bytes are at MSB*/ | ||
| /* Little-endian. Early bytes are at LSB. */ | ||
| CPU_LE( lsr tmp2, tmp2, tmp1 ) | ||
|
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||
| orr data1, data1, tmp2 | ||
| orr data2, data2, tmp2 | ||
| b .Lstart_realigned | ||
|
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||
| /*src1 and src2 have different alignment offset.*/ | ||
| .Lmisaligned8: | ||
| cmp limit, #8 | ||
| b.lo .Ltiny8proc /*limit < 8: compare byte by byte*/ | ||
|
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| and tmp1, src1, #7 | ||
| neg tmp1, tmp1 | ||
| add tmp1, tmp1, #8/*valid length in the first 8 bytes of src1*/ | ||
| and tmp2, src2, #7 | ||
| neg tmp2, tmp2 | ||
| add tmp2, tmp2, #8/*valid length in the first 8 bytes of src2*/ | ||
| subs tmp3, tmp1, tmp2 | ||
| csel pos, tmp1, tmp2, hi /*Choose the maximum.*/ | ||
|
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| sub limit, limit, pos | ||
| /*compare the proceeding bytes in the first 8 byte segment.*/ | ||
| .Ltinycmp: | ||
| ldrb data1w, [src1], #1 | ||
| ldrb data2w, [src2], #1 | ||
| subs pos, pos, #1 | ||
| ccmp data1w, data2w, #0, ne /* NZCV = 0b0000. */ | ||
| b.eq .Ltinycmp | ||
| cbnz pos, 1f /*diff occurred before the last byte.*/ | ||
| cmp data1w, data2w | ||
| b.eq .Lstart_align | ||
| 1: | ||
| sub result, data1, data2 | ||
| subs limit, limit, 8 | ||
| b.lo L(less8) | ||
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| ldr data1, [src1], 8 | ||
| ldr data2, [src2], 8 | ||
| cmp data1, data2 | ||
| b.ne L(return) | ||
|
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| subs limit, limit, 8 | ||
| b.gt L(more16) | ||
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| ldr data1, [src1, limit] | ||
| ldr data2, [src2, limit] | ||
| b L(return) | ||
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| L(more16): | ||
| ldr data1, [src1], 8 | ||
| ldr data2, [src2], 8 | ||
| cmp data1, data2 | ||
| bne L(return) | ||
|
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||
| /* Jump directly to comparing the last 16 bytes for 32 byte (or less) | ||
| strings. */ | ||
| subs limit, limit, 16 | ||
| b.ls L(last_bytes) | ||
|
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| /* We overlap loads between 0-32 bytes at either side of SRC1 when we | ||
| try to align, so limit it only to strings larger than 128 bytes. */ | ||
| cmp limit, 96 | ||
| b.ls L(loop16) | ||
|
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||
| /* Align src1 and adjust src2 with bytes not yet done. */ | ||
| and tmp1, src1, 15 | ||
| add limit, limit, tmp1 | ||
| sub src1, src1, tmp1 | ||
| sub src2, src2, tmp1 | ||
|
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| /* Loop performing 16 bytes per iteration using aligned src1. | ||
| Limit is pre-decremented by 16 and must be larger than zero. | ||
| Exit if <= 16 bytes left to do or if the data is not equal. */ | ||
| .p2align 4 | ||
| L(loop16): | ||
| ldp data1, data1h, [src1], 16 | ||
| ldp data2, data2h, [src2], 16 | ||
| subs limit, limit, 16 | ||
| ccmp data1, data2, 0, hi | ||
| ccmp data1h, data2h, 0, eq | ||
| b.eq L(loop16) | ||
|
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| cmp data1, data2 | ||
| bne L(return) | ||
| mov data1, data1h | ||
| mov data2, data2h | ||
| cmp data1, data2 | ||
| bne L(return) | ||
|
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| /* Compare last 1-16 bytes using unaligned access. */ | ||
| L(last_bytes): | ||
| add src1, src1, limit | ||
| add src2, src2, limit | ||
| ldp data1, data1h, [src1] | ||
| ldp data2, data2h, [src2] | ||
| cmp data1, data2 | ||
| bne L(return) | ||
| mov data1, data1h | ||
| mov data2, data2h | ||
| cmp data1, data2 | ||
|
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||
| /* Compare data bytes and set return value to 0, -1 or 1. */ | ||
| L(return): | ||
| #ifndef __AARCH64EB__ | ||
| rev data1, data1 | ||
| rev data2, data2 | ||
| #endif | ||
| cmp data1, data2 | ||
| L(ret_eq): | ||
| cset result, ne | ||
| cneg result, result, lo | ||
| ret | ||
|
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||
| .Lstart_align: | ||
| lsr limit_wd, limit, #3 | ||
| cbz limit_wd, .Lremain8 | ||
|
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| ands xzr, src1, #7 | ||
| b.eq .Lrecal_offset | ||
| /*process more leading bytes to make src1 aligned...*/ | ||
| add src1, src1, tmp3 /*backwards src1 to alignment boundary*/ | ||
| add src2, src2, tmp3 | ||
| sub limit, limit, tmp3 | ||
| lsr limit_wd, limit, #3 | ||
| cbz limit_wd, .Lremain8 | ||
| /*load 8 bytes from aligned SRC1..*/ | ||
| ldr data1, [src1], #8 | ||
| ldr data2, [src2], #8 | ||
|
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||
| subs limit_wd, limit_wd, #1 | ||
| eor diff, data1, data2 /*Non-zero if differences found.*/ | ||
| csinv endloop, diff, xzr, ne | ||
| cbnz endloop, .Lunequal_proc | ||
| /*How far is the current SRC2 from the alignment boundary...*/ | ||
| and tmp3, tmp3, #7 | ||
|
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||
| .Lrecal_offset:/*src1 is aligned now..*/ | ||
| neg pos, tmp3 | ||
| .Lloopcmp_proc: | ||
| /* | ||
| * Divide the eight bytes into two parts. First,backwards the src2 | ||
| * to an alignment boundary,load eight bytes and compare from | ||
| * the SRC2 alignment boundary. If all 8 bytes are equal,then start | ||
| * the second part's comparison. Otherwise finish the comparison. | ||
| * This special handle can garantee all the accesses are in the | ||
| * thread/task space in avoid to overrange access. | ||
| */ | ||
| ldr data1, [src1,pos] | ||
| ldr data2, [src2,pos] | ||
| eor diff, data1, data2 /* Non-zero if differences found. */ | ||
| cbnz diff, .Lnot_limit | ||
|
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||
| /*The second part process*/ | ||
| ldr data1, [src1], #8 | ||
| ldr data2, [src2], #8 | ||
| eor diff, data1, data2 /* Non-zero if differences found. */ | ||
| subs limit_wd, limit_wd, #1 | ||
| csinv endloop, diff, xzr, ne/*if limit_wd is 0,will finish the cmp*/ | ||
| cbz endloop, .Lloopcmp_proc | ||
| .Lunequal_proc: | ||
| cbz diff, .Lremain8 | ||
|
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| /* There is difference occurred in the latest comparison. */ | ||
| .Lnot_limit: | ||
| /* | ||
| * For little endian,reverse the low significant equal bits into MSB,then | ||
| * following CLZ can find how many equal bits exist. | ||
| */ | ||
| CPU_LE( rev diff, diff ) | ||
| CPU_LE( rev data1, data1 ) | ||
| CPU_LE( rev data2, data2 ) | ||
|
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||
| /* | ||
| * The MS-non-zero bit of DIFF marks either the first bit | ||
| * that is different, or the end of the significant data. | ||
| * Shifting left now will bring the critical information into the | ||
| * top bits. | ||
| */ | ||
| clz pos, diff | ||
| lsl data1, data1, pos | ||
| lsl data2, data2, pos | ||
| /* | ||
| * We need to zero-extend (char is unsigned) the value and then | ||
| * perform a signed subtraction. | ||
| */ | ||
| lsr data1, data1, #56 | ||
| sub result, data1, data2, lsr #56 | ||
| .p2align 4 | ||
| /* Compare up to 8 bytes. Limit is [-8..-1]. */ | ||
| L(less8): | ||
| adds limit, limit, 4 | ||
| b.lo L(less4) | ||
| ldr data1w, [src1], 4 | ||
| ldr data2w, [src2], 4 | ||
| cmp data1w, data2w | ||
| b.ne L(return) | ||
| sub limit, limit, 4 | ||
| L(less4): | ||
| adds limit, limit, 4 | ||
| beq L(ret_eq) | ||
| L(byte_loop): | ||
| ldrb data1w, [src1], 1 | ||
| ldrb data2w, [src2], 1 | ||
| subs limit, limit, 1 | ||
| ccmp data1w, data2w, 0, ne /* NZCV = 0b0000. */ | ||
| b.eq L(byte_loop) | ||
| sub result, data1w, data2w | ||
| ret | ||
|
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| .Lremain8: | ||
| /* Limit % 8 == 0 =>. all data are equal.*/ | ||
| ands limit, limit, #7 | ||
| b.eq .Lret0 | ||
|
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| .Ltiny8proc: | ||
| ldrb data1w, [src1], #1 | ||
| ldrb data2w, [src2], #1 | ||
| subs limit, limit, #1 | ||
|
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| ccmp data1w, data2w, #0, ne /* NZCV = 0b0000. */ | ||
| b.eq .Ltiny8proc | ||
| sub result, data1, data2 | ||
| ret | ||
| .Lret0: | ||
| mov result, #0 | ||
| ret | ||
| SYM_FUNC_END_PI(memcmp) | ||
| EXPORT_SYMBOL_NOKASAN(memcmp) |