| Date | Mon, 28 May 2012 04:12:15 +0100 | From | Ben Hutchings <> | Subject | [ 013/117] [PARISC] fix panic on prefetch(NULL) on PA7300LC |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: James Bottomley <JBottomley@Parallels.com>
commit b3cb8674811d1851bbf1486a73d62b90c119b994 upstream.
Due to an errata, the PA7300LC generates a TLB miss interruption even on the prefetch instruction. This means that prefetch(NULL), which is supposed to be a nop on linux actually generates a NULL deref fault. Fix this by testing the address of prefetch against NULL before doing the prefetch.
Signed-off-by: James Bottomley <JBottomley@Parallels.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- arch/parisc/include/asm/prefetch.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/arch/parisc/include/asm/prefetch.h b/arch/parisc/include/asm/prefetch.h index c5edc60..1ee7c82 100644 --- a/arch/parisc/include/asm/prefetch.h +++ b/arch/parisc/include/asm/prefetch.h @@ -21,7 +21,12 @@ #define ARCH_HAS_PREFETCH static inline void prefetch(const void *addr) { - __asm__("ldw 0(%0), %%r0" : : "r" (addr)); + __asm__( +#ifndef CONFIG_PA20 + /* Need to avoid prefetch of NULL on PA7300LC */ + " extrw,u,= %0,31,32,%%r0\n" +#endif + " ldw 0(%0), %%r0" : : "r" (addr)); } /* LDD is a PA2.0 addition. */
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