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linux/arch/arm64/lib/memchr.S

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treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 234 Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license version 2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see http www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 503 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Reviewed-by: Enrico Weigelt <info@metux.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190602204653.811534538@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-03 07:44:50 +02:00
/* SPDX-License-Identifier: GPL-2.0-only */
arm64: klib: Optimised memory functions This patch introduces AArch64-specific memory functions (memcpy, memmove, memchr, memset). These functions are not optimised for any CPU implementation but can be used as a starting point once hardware is available. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-03-21 16:16:43 +00:00
/*
arm64: Better optimised memchr() Although we implement our own assembly version of memchr(), it turns out to be barely any better than what GCC can generate for the generic C version (and would go wrong if the size_t argument were ever large enough to be interpreted as negative). Unfortunately we can't import the tuned implementation from the Arm optimized-routines library, since that has some Advanced SIMD parts which are not really viable for general kernel library code. What we can do, however, is pep things up with some relatively straightforward word-at-a-time logic for larger calls. Adding some timing to optimized-routines' memchr() test for a simple benchmark, overall this version comes in around half as fast as the SIMD code, but still nearly 4x faster than our existing implementation. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/58471b42f9287e039dafa9e5e7035077152438fd.1622128527.git.robin.murphy@arm.com Signed-off-by: Will Deacon <will@kernel.org>
2021-05-27 16:34:47 +01:00
* Copyright (C) 2021 Arm Ltd.
arm64: klib: Optimised memory functions This patch introduces AArch64-specific memory functions (memcpy, memmove, memchr, memset). These functions are not optimised for any CPU implementation but can be used as a starting point once hardware is available. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-03-21 16:16:43 +00:00
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
/*
* Find a character in an area of memory.
*
* Parameters:
* x0 - buf
* x1 - c
* x2 - n
* Returns:
* x0 - address of first occurrence of 'c' or 0
*/
arm64: Better optimised memchr() Although we implement our own assembly version of memchr(), it turns out to be barely any better than what GCC can generate for the generic C version (and would go wrong if the size_t argument were ever large enough to be interpreted as negative). Unfortunately we can't import the tuned implementation from the Arm optimized-routines library, since that has some Advanced SIMD parts which are not really viable for general kernel library code. What we can do, however, is pep things up with some relatively straightforward word-at-a-time logic for larger calls. Adding some timing to optimized-routines' memchr() test for a simple benchmark, overall this version comes in around half as fast as the SIMD code, but still nearly 4x faster than our existing implementation. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/58471b42f9287e039dafa9e5e7035077152438fd.1622128527.git.robin.murphy@arm.com Signed-off-by: Will Deacon <will@kernel.org>
2021-05-27 16:34:47 +01:00
#define L(label) .L ## label
#define REP8_01 0x0101010101010101
#define REP8_7f 0x7f7f7f7f7f7f7f7f
#define srcin x0
#define chrin w1
#define cntin x2
#define result x0
#define wordcnt x3
#define rep01 x4
#define repchr x5
#define cur_word x6
#define cur_byte w6
#define tmp x7
#define tmp2 x8
.p2align 4
nop
arm64: lib: Use modern annotations for assembly functions In an effort to clarify and simplify the annotation of assembly functions in the kernel new macros have been introduced. These replace ENTRY and ENDPROC and also add a new annotation for static functions which previously had no ENTRY equivalent. Update the annotations in the library code to the new macros. Signed-off-by: Mark Brown <broonie@kernel.org> [will: Use SYM_FUNC_START_WEAK_PI] Signed-off-by: Will Deacon <will@kernel.org>
2020-01-06 19:58:17 +00:00
SYM_FUNC_START_WEAK_PI(memchr)
arm64: Better optimised memchr() Although we implement our own assembly version of memchr(), it turns out to be barely any better than what GCC can generate for the generic C version (and would go wrong if the size_t argument were ever large enough to be interpreted as negative). Unfortunately we can't import the tuned implementation from the Arm optimized-routines library, since that has some Advanced SIMD parts which are not really viable for general kernel library code. What we can do, however, is pep things up with some relatively straightforward word-at-a-time logic for larger calls. Adding some timing to optimized-routines' memchr() test for a simple benchmark, overall this version comes in around half as fast as the SIMD code, but still nearly 4x faster than our existing implementation. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/58471b42f9287e039dafa9e5e7035077152438fd.1622128527.git.robin.murphy@arm.com Signed-off-by: Will Deacon <will@kernel.org>
2021-05-27 16:34:47 +01:00
and chrin, chrin, #0xff
lsr wordcnt, cntin, #3
cbz wordcnt, L(byte_loop)
mov rep01, #REP8_01
mul repchr, x1, rep01
and cntin, cntin, #7
L(word_loop):
ldr cur_word, [srcin], #8
sub wordcnt, wordcnt, #1
eor cur_word, cur_word, repchr
sub tmp, cur_word, rep01
orr tmp2, cur_word, #REP8_7f
bics tmp, tmp, tmp2
b.ne L(found_word)
cbnz wordcnt, L(word_loop)
L(byte_loop):
cbz cntin, L(not_found)
ldrb cur_byte, [srcin], #1
sub cntin, cntin, #1
cmp cur_byte, chrin
b.ne L(byte_loop)
sub srcin, srcin, #1
ret
L(found_word):
CPU_LE( rev tmp, tmp)
clz tmp, tmp
sub tmp, tmp, #64
add result, srcin, tmp, asr #3
arm64: klib: Optimised memory functions This patch introduces AArch64-specific memory functions (memcpy, memmove, memchr, memset). These functions are not optimised for any CPU implementation but can be used as a starting point once hardware is available. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-03-21 16:16:43 +00:00
ret
arm64: Better optimised memchr() Although we implement our own assembly version of memchr(), it turns out to be barely any better than what GCC can generate for the generic C version (and would go wrong if the size_t argument were ever large enough to be interpreted as negative). Unfortunately we can't import the tuned implementation from the Arm optimized-routines library, since that has some Advanced SIMD parts which are not really viable for general kernel library code. What we can do, however, is pep things up with some relatively straightforward word-at-a-time logic for larger calls. Adding some timing to optimized-routines' memchr() test for a simple benchmark, overall this version comes in around half as fast as the SIMD code, but still nearly 4x faster than our existing implementation. Signed-off-by: Robin Murphy <robin.murphy@arm.com> Link: https://lore.kernel.org/r/58471b42f9287e039dafa9e5e7035077152438fd.1622128527.git.robin.murphy@arm.com Signed-off-by: Will Deacon <will@kernel.org>
2021-05-27 16:34:47 +01:00
L(not_found):
mov result, #0
arm64: klib: Optimised memory functions This patch introduces AArch64-specific memory functions (memcpy, memmove, memchr, memset). These functions are not optimised for any CPU implementation but can be used as a starting point once hardware is available. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2013-03-21 16:16:43 +00:00
ret
arm64: lib: Use modern annotations for assembly functions In an effort to clarify and simplify the annotation of assembly functions in the kernel new macros have been introduced. These replace ENTRY and ENDPROC and also add a new annotation for static functions which previously had no ENTRY equivalent. Update the annotations in the library code to the new macros. Signed-off-by: Mark Brown <broonie@kernel.org> [will: Use SYM_FUNC_START_WEAK_PI] Signed-off-by: Will Deacon <will@kernel.org>
2020-01-06 19:58:17 +00:00
SYM_FUNC_END_PI(memchr)
arm64: string: use asm EXPORT_SYMBOL() For a while now it's been possible to use EXPORT_SYMBOL() in assembly files, which allows us to place exports immediately after assembly functions, as we do for C functions. As a step towards removing arm64ksyms.c, let's move the string routine exports to the assembly files the functions are defined in. Routines which should only be exported for !KASAN builds are exported using the EXPORT_SYMBOL_NOKASAN() helper. There should be no functional change as a result of this patch. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Will Deacon <will.deacon@arm.com>
2018-12-07 18:08:21 +00:00
EXPORT_SYMBOL_NOKASAN(memchr)
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