Messages in this thread Patch in this message | | | Subject | [PATCH]: x86_64: Remove unnecessary cast in prefetch() | From | Serge Belyshev <> | Date | Fri, 07 Sep 2007 01:27:02 +0400 |
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It is ok to call prefetch() function with NULL argument, as specifically commented in include/linux/prefetch.h. But in standard C, it is invalid to dereference NULL pointer (see C99 standard 6.5.3.2 paragraph 4 and note #84). Newer gcc versions (4.3 and above) will use that to conclude that "x" argument is non-null and thus wreaking havok everywhere prefetch() was inlined. Fixed by removing cast and changing asm constraint.
This can be fixed better by using gcc's __builtin_prefetch().
Signed-off-by: Serge Belyshev <belyshev@depni.sinp.msu.ru>
--- include/asm-x86_64/processor.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux/include/asm-x86_64/processor.h =================================================================== --- linux.orig/include/asm-x86_64/processor.h +++ linux/include/asm-x86_64/processor.h @@ -373,7 +373,7 @@ static inline void sync_core(void) #define ARCH_HAS_PREFETCH static inline void prefetch(void *x) { - asm volatile("prefetcht0 %0" :: "m" (*(unsigned long *)x)); + asm volatile("prefetcht0 (%0)" :: "r" (x)); } #define ARCH_HAS_PREFETCHW 1 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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