From: Matteo Croce <mcroce@linux.microsoft.com>
To: linux-riscv@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Atish Patra <atish.patra@wdc.com>,
Emil Renner Berthing <kernel@esmil.dk>,
Akira Tsukamoto <akira.tsukamoto@gmail.com>,
Drew Fustini <drew@beagleboard.org>,
Bin Meng <bmeng.cn@gmail.com>,
David Laight <David.Laight@aculab.com>,
Guo Ren <guoren@kernel.org>
Subject: [PATCH v3 2/3] riscv: optimized memmove
Date: Thu, 17 Jun 2021 17:27:53 +0200 [thread overview]
Message-ID: <20210617152754.17960-3-mcroce@linux.microsoft.com> (raw)
In-Reply-To: <20210617152754.17960-1-mcroce@linux.microsoft.com>
From: Matteo Croce <mcroce@microsoft.com>
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 <mcroce@microsoft.com>
---
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 6b5d6fc3eab4..25d9b9078569 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 3f6d512a5b97..361565c4db7e 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 2ffe85d4baee..484f5ff7b508 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 07d1d2152ba5..000000000000
--- a/arch/riscv/lib/memmove.S
+++ /dev/null
@@ -1,64 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-
-#include <linux/linkage.h>
-#include <asm/asm.h>
-
-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 e48a79a045d8..9c7009d43c39 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);
--
2.31.1
next prev parent reply other threads:[~2021-06-17 15:28 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-17 15:27 [PATCH v3 0/3] riscv: optimized mem* functions Matteo Croce
2021-06-17 15:27 ` [PATCH v3 1/3] riscv: optimized memcpy Matteo Croce
2021-06-18 14:06 ` kernel test robot
2021-06-21 14:26 ` Christoph Hellwig
2021-06-22 8:19 ` David Laight
2021-06-22 22:53 ` Matteo Croce
2021-06-22 22:00 ` Matteo Croce
2021-06-22 0:14 ` Nick Kossifidis
2021-06-22 23:35 ` Matteo Croce
2021-06-23 9:48 ` Nick Kossifidis
2021-06-17 15:27 ` Matteo Croce [this message]
2021-06-21 14:28 ` [PATCH v3 2/3] riscv: optimized memmove Christoph Hellwig
2021-06-22 0:46 ` Nick Kossifidis
2021-06-30 4:40 ` kernel test robot
2021-06-17 15:27 ` [PATCH v3 3/3] riscv: optimized memset Matteo Croce
2021-06-21 14:32 ` Christoph Hellwig
2021-06-22 1:07 ` Nick Kossifidis
2021-06-22 8:38 ` David Laight
2021-06-23 1:14 ` Matteo Croce
2021-06-23 9:05 ` David Laight
2021-06-23 0:08 ` Matteo Croce
2021-06-22 1:09 ` [PATCH v3 0/3] riscv: optimized mem* functions Nick Kossifidis
2021-06-22 2:39 ` Guo Ren
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