| From 3b3c4babd898715926d24ae10aa64778ace33aae Mon Sep 17 00:00:00 2001 |
| From: Matthew Wilcox <mawilcox@microsoft.com> |
| Date: Fri, 8 Sep 2017 16:13:48 -0700 |
| Subject: lib/string.c: add multibyte memset functions |
| |
| From: Matthew Wilcox <mawilcox@microsoft.com> |
| |
| commit 3b3c4babd898715926d24ae10aa64778ace33aae upstream. |
| |
| 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> |
| Signed-off-by: Nobuhiro Iwamatsu (CIP) <nobuhiro1.iwamatsu@toshiba.co.jp> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| include/linux/string.h | 30 ++++++++++++++++++++++ |
| lib/string.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++ |
| 2 files changed, 96 insertions(+) |
| |
| --- a/include/linux/string.h |
| +++ b/include/linux/string.h |
| @@ -103,6 +103,36 @@ extern __kernel_size_t strcspn(const cha |
| #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 |
| --- a/lib/string.c |
| +++ b/lib/string.c |
| @@ -754,6 +754,72 @@ void memzero_explicit(void *s, size_t co |
| } |
| EXPORT_SYMBOL(memzero_explicit); |
| |
| +#ifndef __HAVE_ARCH_MEMSET16 |
| +/** |
| + * memset16() - Fill a memory area with a uint16_t |
| + * @s: Pointer to the start of the area. |
| + * @v: The value to fill the area with |
| + * @count: The number of values to store |
| + * |
| + * Differs from memset() in that it fills with a uint16_t instead |
| + * of a byte. Remember that @count is the number of uint16_ts to |
| + * store, not the number of bytes. |
| + */ |
| +void *memset16(uint16_t *s, uint16_t v, size_t count) |
| +{ |
| + uint16_t *xs = s; |
| + |
| + while (count--) |
| + *xs++ = v; |
| + return s; |
| +} |
| +EXPORT_SYMBOL(memset16); |
| +#endif |
| + |
| +#ifndef __HAVE_ARCH_MEMSET32 |
| +/** |
| + * memset32() - Fill a memory area with a uint32_t |
| + * @s: Pointer to the start of the area. |
| + * @v: The value to fill the area with |
| + * @count: The number of values to store |
| + * |
| + * Differs from memset() in that it fills with a uint32_t instead |
| + * of a byte. Remember that @count is the number of uint32_ts to |
| + * store, not the number of bytes. |
| + */ |
| +void *memset32(uint32_t *s, uint32_t v, size_t count) |
| +{ |
| + uint32_t *xs = s; |
| + |
| + while (count--) |
| + *xs++ = v; |
| + return s; |
| +} |
| +EXPORT_SYMBOL(memset32); |
| +#endif |
| + |
| +#ifndef __HAVE_ARCH_MEMSET64 |
| +/** |
| + * memset64() - Fill a memory area with a uint64_t |
| + * @s: Pointer to the start of the area. |
| + * @v: The value to fill the area with |
| + * @count: The number of values to store |
| + * |
| + * Differs from memset() in that it fills with a uint64_t instead |
| + * of a byte. Remember that @count is the number of uint64_ts to |
| + * store, not the number of bytes. |
| + */ |
| +void *memset64(uint64_t *s, uint64_t v, size_t count) |
| +{ |
| + uint64_t *xs = s; |
| + |
| + while (count--) |
| + *xs++ = v; |
| + return s; |
| +} |
| +EXPORT_SYMBOL(memset64); |
| +#endif |
| + |
| #ifndef __HAVE_ARCH_MEMCPY |
| /** |
| * memcpy - Copy one area of memory to another |