From 211a65b2ee262f10eec0dfc17896aab1d2f0aea2 Mon Sep 17 00:00:00 2001 From: Matteo Croce Date: Thu, 17 Jun 2021 17:27:53 +0200 Subject: [PATCH] riscv: optimized memmove When the destination buffer is before the source one, or when the buffers doesn't overlap, it's safe to use memcpy() instead, which is optimized to use a bigger data size possible. Signed-off-by: Matteo Croce --- arch/riscv/include/asm/string.h | 6 ++-- arch/riscv/kernel/riscv_ksyms.c | 2 -- arch/riscv/lib/Makefile | 1 - arch/riscv/lib/memmove.S | 64 --------------------------------- arch/riscv/lib/string.c | 23 ++++++++++++ 5 files changed, 26 insertions(+), 70 deletions(-) delete mode 100644 arch/riscv/lib/memmove.S diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h index 6b5d6fc3eab497..25d9b9078569c4 100644 --- a/arch/riscv/include/asm/string.h +++ b/arch/riscv/include/asm/string.h @@ -17,11 +17,11 @@ extern asmlinkage void *__memset(void *, int, size_t); #define __HAVE_ARCH_MEMCPY extern void *memcpy(void *dest, const void *src, size_t count); extern void *__memcpy(void *dest, const void *src, size_t count); +#define __HAVE_ARCH_MEMMOVE +extern void *memmove(void *dest, const void *src, size_t count); +extern void *__memmove(void *dest, const void *src, size_t count); #endif -#define __HAVE_ARCH_MEMMOVE -extern asmlinkage void *memmove(void *, const void *, size_t); -extern asmlinkage void *__memmove(void *, const void *, size_t); /* For those files which don't want to check by kasan. */ #if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) #define memcpy(dst, src, len) __memcpy(dst, src, len) diff --git a/arch/riscv/kernel/riscv_ksyms.c b/arch/riscv/kernel/riscv_ksyms.c index 3f6d512a5b9789..361565c4db7e0a 100644 --- a/arch/riscv/kernel/riscv_ksyms.c +++ b/arch/riscv/kernel/riscv_ksyms.c @@ -10,6 +10,4 @@ * Assembly functions that may be used (directly or indirectly) by modules */ EXPORT_SYMBOL(memset); -EXPORT_SYMBOL(memmove); EXPORT_SYMBOL(__memset); -EXPORT_SYMBOL(__memmove); diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile index 2ffe85d4baeed8..484f5ff7b508ba 100644 --- a/arch/riscv/lib/Makefile +++ b/arch/riscv/lib/Makefile @@ -1,7 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only lib-y += delay.o lib-y += memset.o -lib-y += memmove.o lib-$(CONFIG_MMU) += uaccess.o lib-$(CONFIG_64BIT) += tishift.o lib-$(CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE) += string.o diff --git a/arch/riscv/lib/memmove.S b/arch/riscv/lib/memmove.S deleted file mode 100644 index 07d1d2152ba5ce..00000000000000 --- a/arch/riscv/lib/memmove.S +++ /dev/null @@ -1,64 +0,0 @@ -/* SPDX-License-Identifier: GPL-2.0 */ - -#include -#include - -ENTRY(__memmove) -WEAK(memmove) - move t0, a0 - move t1, a1 - - beq a0, a1, exit_memcpy - beqz a2, exit_memcpy - srli t2, a2, 0x2 - - slt t3, a0, a1 - beqz t3, do_reverse - - andi a2, a2, 0x3 - li t4, 1 - beqz t2, byte_copy - -word_copy: - lw t3, 0(a1) - addi t2, t2, -1 - addi a1, a1, 4 - sw t3, 0(a0) - addi a0, a0, 4 - bnez t2, word_copy - beqz a2, exit_memcpy - j byte_copy - -do_reverse: - add a0, a0, a2 - add a1, a1, a2 - andi a2, a2, 0x3 - li t4, -1 - beqz t2, reverse_byte_copy - -reverse_word_copy: - addi a1, a1, -4 - addi t2, t2, -1 - lw t3, 0(a1) - addi a0, a0, -4 - sw t3, 0(a0) - bnez t2, reverse_word_copy - beqz a2, exit_memcpy - -reverse_byte_copy: - addi a0, a0, -1 - addi a1, a1, -1 - -byte_copy: - lb t3, 0(a1) - addi a2, a2, -1 - sb t3, 0(a0) - add a1, a1, t4 - add a0, a0, t4 - bnez a2, byte_copy - -exit_memcpy: - move a0, t0 - move a1, t1 - ret -END(__memmove) diff --git a/arch/riscv/lib/string.c b/arch/riscv/lib/string.c index e48a79a045d84f..9c7009d43c39eb 100644 --- a/arch/riscv/lib/string.c +++ b/arch/riscv/lib/string.c @@ -89,3 +89,26 @@ EXPORT_SYMBOL(__memcpy); void *memcpy(void *dest, const void *src, size_t count) __weak __alias(__memcpy); EXPORT_SYMBOL(memcpy); + +/* + * Simply check if the buffer overlaps an call memcpy() in case, + * otherwise do a simple one byte at time backward copy. + */ +void *__memmove(void *dest, const void *src, size_t count) +{ + if (dest < src || src + count <= dest) + return memcpy(dest, src, count); + + if (dest > src) { + const char *s = src + count; + char *tmp = dest + count; + + while (count--) + *--tmp = *--s; + } + return dest; +} +EXPORT_SYMBOL(__memmove); + +void *memmove(void *dest, const void *src, size_t count) __weak __alias(__memmove); +EXPORT_SYMBOL(memmove);