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Subject[PATCH v3 3/7] x86: Implement memset16, memset32 & memset64
Date
From: Matthew Wilcox <mawilcox@microsoft.com>

These are single instructions on x86. There's no 64-bit instruction
for x86-32, but we don't yet have any user for memset64() on 32-bit
architectures, so don't bother to implement it.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
arch/x86/include/asm/string_32.h | 24 ++++++++++++++++++++++++
arch/x86/include/asm/string_64.h | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 60 insertions(+)

diff --git a/arch/x86/include/asm/string_32.h b/arch/x86/include/asm/string_32.h
index 3d3e8353ee5c..84da91fe13ac 100644
--- a/arch/x86/include/asm/string_32.h
+++ b/arch/x86/include/asm/string_32.h
@@ -331,6 +331,30 @@ void *__constant_c_and_count_memset(void *s, unsigned long pattern,
: __memset((s), (c), (count)))
#endif

+#define __HAVE_ARCH_MEMSET16
+static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
+{
+ int d0, d1;
+ asm volatile("rep\n\t"
+ "stosw"
+ : "=&c" (d0), "=&D" (d1)
+ : "a" (v), "1" (s), "0" (n)
+ : "memory");
+ return s;
+}
+
+#define __HAVE_ARCH_MEMSET_32
+static inline void *memset32(uint32_t *s, uint32_t v, size_t n)
+{
+ int d0, d1;
+ asm volatile("rep\n\t"
+ "stosl"
+ : "=&c" (d0), "=&D" (d1)
+ : "a" (v), "1" (s), "0" (n)
+ : "memory");
+ return s;
+}
+
/*
* find the first occurrence of byte 'c', or 1 past the area if none
*/
diff --git a/arch/x86/include/asm/string_64.h b/arch/x86/include/asm/string_64.h
index a164862d77e3..71c5e860c7da 100644
--- a/arch/x86/include/asm/string_64.h
+++ b/arch/x86/include/asm/string_64.h
@@ -56,6 +56,42 @@ extern void *__memcpy(void *to, const void *from, size_t len);
void *memset(void *s, int c, size_t n);
void *__memset(void *s, int c, size_t n);

+#define __HAVE_ARCH_MEMSET16
+static inline void *memset16(uint16_t *s, uint16_t v, size_t n)
+{
+ long d0, d1;
+ asm volatile("rep\n\t"
+ "stosw"
+ : "=&c" (d0), "=&D" (d1)
+ : "a" (v), "1" (s), "0" (n)
+ : "memory");
+ return s;
+}
+
+#define __HAVE_ARCH_MEMSET32
+static inline void *memset32(uint32_t *s, uint32_t v, size_t n)
+{
+ long d0, d1;
+ asm volatile("rep\n\t"
+ "stosl"
+ : "=&c" (d0), "=&D" (d1)
+ : "a" (v), "1" (s), "0" (n)
+ : "memory");
+ return s;
+}
+
+#define __HAVE_ARCH_MEMSET64
+static inline void *memset64(uint64_t *s, uint64_t v, size_t n)
+{
+ long d0, d1;
+ asm volatile("rep\n\t"
+ "stosq"
+ : "=&c" (d0), "=&D" (d1)
+ : "a" (v), "1" (s), "0" (n)
+ : "memory");
+ return s;
+}
+
#define __HAVE_ARCH_MEMMOVE
void *memmove(void *dest, const void *src, size_t count);
void *__memmove(void *dest, const void *src, size_t count);
--
2.11.0
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