From 01f33c336e2d298ea5d4ce5d6e5bcd12865cc30f Mon Sep 17 00:00:00 2001 From: Martin Wilck Date: Mon, 14 Aug 2017 22:12:38 +0200 Subject: string.h: add memcpy_and_pad() This helper function is useful for the nvme subsystem, and maybe others. Note: the warnings reported by the kbuild test robot for this patch are actually generated by the use of CONFIG_PROFILE_ALL_BRANCHES together with __FORTIFY_INLINE. Signed-off-by: Martin Wilck Reviewed-by: Sagi Grimberg Signed-off-by: Christoph Hellwig --- include/linux/string.h | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index a467e617eeb0..0bec4151b0eb 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -200,6 +200,7 @@ static inline const char *kbasename(const char *path) void fortify_panic(const char *name) __noreturn __cold; void __read_overflow(void) __compiletime_error("detected read beyond size of object passed as 1st parameter"); void __read_overflow2(void) __compiletime_error("detected read beyond size of object passed as 2nd parameter"); +void __read_overflow3(void) __compiletime_error("detected read beyond size of object passed as 3rd parameter"); void __write_overflow(void) __compiletime_error("detected write beyond size of object passed as 1st parameter"); #if !defined(__NO_FORTIFY) && defined(__OPTIMIZE__) && defined(CONFIG_FORTIFY_SOURCE) @@ -395,4 +396,33 @@ __FORTIFY_INLINE char *strcpy(char *p, const char *q) #endif +/** + * memcpy_and_pad - Copy one buffer to another with padding + * @dest: Where to copy to + * @dest_len: The destination buffer size + * @src: Where to copy from + * @count: The number of bytes to copy + * @pad: Character to use for padding if space is left in destination. + */ +__FORTIFY_INLINE void memcpy_and_pad(void *dest, size_t dest_len, + const void *src, size_t count, int pad) +{ + size_t dest_size = __builtin_object_size(dest, 0); + size_t src_size = __builtin_object_size(src, 0); + + if (__builtin_constant_p(dest_len) && __builtin_constant_p(count)) { + if (dest_size < dest_len && dest_size < count) + __write_overflow(); + else if (src_size < dest_len && src_size < count) + __read_overflow3(); + } + if (dest_size < dest_len) + fortify_panic(__func__); + if (dest_len > count) { + memcpy(dest, src, count); + memset(dest + count, pad, dest_len - count); + } else + memcpy(dest, src, dest_len); +} + #endif /* _LINUX_STRING_H_ */ -- cgit v1.2.3 From 3b3c4babd898715926d24ae10aa64778ace33aae Mon Sep 17 00:00:00 2001 From: Matthew Wilcox Date: Fri, 8 Sep 2017 16:13:48 -0700 Subject: 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 Cc: "H. Peter Anvin" Cc: "James E.J. Bottomley" Cc: "Martin K. Petersen" Cc: David Miller Cc: Ingo Molnar Cc: Ivan Kokshaysky Cc: Matt Turner Cc: Michael Ellerman Cc: Minchan Kim Cc: Ralf Baechle Cc: Richard Henderson Cc: Russell King Cc: Sam Ravnborg Cc: Sergey Senozhatsky Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/string.h | 30 +++++++++++++++++++++++ lib/string.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 96 insertions(+) (limited to 'include/linux/string.h') 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 diff --git a/lib/string.c b/lib/string.c index ebbb99c775bd..198148bb61fd 100644 --- a/lib/string.c +++ b/lib/string.c @@ -723,6 +723,72 @@ void memzero_explicit(void *s, size_t count) } 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 -- cgit v1.2.3 From 1359798f9d4082eb04575efdd19512fbd9c28464 Mon Sep 17 00:00:00 2001 From: Martin Wilck Date: Wed, 6 Sep 2017 14:36:57 +0200 Subject: string.h: un-fortify memcpy_and_pad The way I'd implemented the new helper memcpy_and_pad with __FORTIFY_INLINE caused compiler warnings for certain kernel configurations. This helper is only used in a single place at this time, and thus doesn't benefit much from fortification. So simplify the code by dropping fortification support for now. Fixes: 01f33c336e2d "string.h: add memcpy_and_pad()" Signed-off-by: Martin Wilck Acked-by: Arnd Bergmann Signed-off-by: Christoph Hellwig --- include/linux/string.h | 15 ++------------- 1 file changed, 2 insertions(+), 13 deletions(-) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index e1eeb0a8a969..54d21783e18d 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -434,20 +434,9 @@ __FORTIFY_INLINE char *strcpy(char *p, const char *q) * @count: The number of bytes to copy * @pad: Character to use for padding if space is left in destination. */ -__FORTIFY_INLINE void memcpy_and_pad(void *dest, size_t dest_len, - const void *src, size_t count, int pad) +static inline void memcpy_and_pad(void *dest, size_t dest_len, + const void *src, size_t count, int pad) { - size_t dest_size = __builtin_object_size(dest, 0); - size_t src_size = __builtin_object_size(src, 0); - - if (__builtin_constant_p(dest_len) && __builtin_constant_p(count)) { - if (dest_size < dest_len && dest_size < count) - __write_overflow(); - else if (src_size < dest_len && src_size < count) - __read_overflow3(); - } - if (dest_size < dest_len) - fortify_panic(__func__); if (dest_len > count) { memcpy(dest, src, count); memset(dest + count, pad, dest_len - count); -- cgit v1.2.3