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authorMatthew Wilcox <mawilcox@microsoft.com>2017-09-08 16:13:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2017-09-08 18:26:48 -0700
commit3b3c4babd898715926d24ae10aa64778ace33aae (patch)
treedde0523225ee26548a2b59c337930088ed7033c7 /include
parent604df322363e5770735df85368f83cac4a955a24 (diff)
downloadlinux-3b3c4babd898715926d24ae10aa64778ace33aae.tar.bz2
lib/string.c: add multibyte memset functions
Patch series "Multibyte memset variations", v4. A relatively common idiom we're missing is a function to fill an area of memory with a pattern which is larger than a single byte. I first noticed this with a zram patch which wanted to fill a page with an 'unsigned long' value. There turn out to be quite a few places in the kernel which can benefit from using an optimised function rather than a loop; sometimes text size, sometimes speed, and sometimes both. The optimised PowerPC version (not included here) improves performance by about 30% on POWER8 on just the raw memset_l(). Most of the extra lines of code come from the three testcases I added. This patch (of 8): memset16(), memset32() and memset64() are like memset(), but allow the caller to fill the destination with a value larger than a single byte. memset_l() and memset_p() allow the caller to use unsigned long and pointer values respectively. Link: http://lkml.kernel.org/r/20170720184539.31609-2-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "James E.J. Bottomley" <jejb@linux.vnet.ibm.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: David Miller <davem@davemloft.net> Cc: Ingo Molnar <mingo@elte.hu> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Minchan Kim <minchan@kernel.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Richard Henderson <rth@twiddle.net> Cc: Russell King <rmk+kernel@armlinux.org.uk> Cc: Sam Ravnborg <sam@ravnborg.org> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/string.h30
1 files changed, 30 insertions, 0 deletions
diff --git a/include/linux/string.h b/include/linux/string.h
index a467e617eeb0..c8bdafffd2f0 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -99,6 +99,36 @@ extern __kernel_size_t strcspn(const char *,const char *);
#ifndef __HAVE_ARCH_MEMSET
extern void * memset(void *,int,__kernel_size_t);
#endif
+
+#ifndef __HAVE_ARCH_MEMSET16
+extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET32
+extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
+#endif
+
+#ifndef __HAVE_ARCH_MEMSET64
+extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
+#endif
+
+static inline void *memset_l(unsigned long *p, unsigned long v,
+ __kernel_size_t n)
+{
+ if (BITS_PER_LONG == 32)
+ return memset32((uint32_t *)p, v, n);
+ else
+ return memset64((uint64_t *)p, v, n);
+}
+
+static inline void *memset_p(void **p, void *v, __kernel_size_t n)
+{
+ if (BITS_PER_LONG == 32)
+ return memset32((uint32_t *)p, (uintptr_t)v, n);
+ else
+ return memset64((uint64_t *)p, (uintptr_t)v, n);
+}
+
#ifndef __HAVE_ARCH_MEMCPY
extern void * memcpy(void *,const void *,__kernel_size_t);
#endif