powerpc/32: add memset16() (da74f659) · Commits · 戴 / test

Commit ("powerpc/string: Implement optimized memset variants") added memset16(), memset32() and memset64() for the 64 bits PPC. On 32 bits, memset64() is not relevant, and as shown below, the generic version of memset32() gives a good code, so only memset16() is candidate for an optimised version. 000009c0 <memset32>: 9c0: 2c 05 00 00 cmpwi r5,0 9c4: 39 23 ff fc addi r9,r3,-4 9c8: 4d 82 00 20 beqlr 9cc: 7c a9 03 a6 mtctr r5 9d0: 94 89 00 04 stwu r4,4(r9) 9d4: 42 00 ff fc bdnz 9d0 <memset32+0x10> 9d8: 4e 80 00 20 blr The last part of memset() handling the not 4-bytes multiples operates on bytes, making it unsuitable for handling word without modification. As it would increase memset() complexity, it is better to implement memset16() from scratch. In addition it has the advantage of allowing a more optimised memset16() than what we would have by using the memset() function. Signed-off-by:

Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by:

Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/string.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -10,6 +10,7 @@
		#define __HAVE_ARCH_MEMMOVE
		#define __HAVE_ARCH_MEMCMP
		#define __HAVE_ARCH_MEMCHR
		#define __HAVE_ARCH_MEMSET16

		extern char * strcpy(char ,const char );
		extern char * strncpy(char ,const char , __kernel_size_t);
		@@ -24,7 +25,6 @@ extern int memcmp(const void ,const void ,__kernel_size_t);
		extern void * memchr(const void *,int,__kernel_size_t);

		#ifdef CONFIG_PPC64
		#define __HAVE_ARCH_MEMSET16
		#define __HAVE_ARCH_MEMSET32
		#define __HAVE_ARCH_MEMSET64

		@@ -46,6 +46,8 @@ static inline void memset64(uint64_t p, uint64_t v, __kernel_size_t n)
		{
		return __memset64(p, v, n * 8);
		}
		#else
		extern void memset16(uint16_t , uint16_t, __kernel_size_t);
		#endif
		#endif /* __KERNEL__ */

arch/powerpc/lib/copy_32.S

+14 −0

Original line number	Diff line number	Diff line
		@@ -67,6 +67,20 @@ CACHELINE_BYTES = L1_CACHE_BYTES
		LG_CACHELINE_BYTES = L1_CACHE_SHIFT
		CACHELINE_MASK = (L1_CACHE_BYTES-1)

		_GLOBAL(memset16)
		rlwinm. r0 ,r5, 31, 1, 31
		addi r6, r3, -4
		beq- 2f
		rlwimi r4 ,r4 ,16 ,0 ,15
		mtctr r0
		1: stwu r4, 4(r6)
		bdnz 1b
		2: andi. r0, r5, 1
		beqlr
		sth r4, 4(r6)
		blr
		EXPORT_SYMBOL(memset16)

		/*
		* Use dcbz on the complete cache lines in the destination
		* to set them to zero. This requires that the destination

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