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 <[email protected]>
---
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
-
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