Commit b3cb8674 authored by James Bottomley's avatar James Bottomley

[PARISC] fix panic on prefetch(NULL) on PA7300LC

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.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarJames Bottomley <JBottomley@Parallels.com>
parent 207f583d
...@@ -21,7 +21,12 @@ ...@@ -21,7 +21,12 @@
#define ARCH_HAS_PREFETCH #define ARCH_HAS_PREFETCH
static inline void prefetch(const void *addr) 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. */ /* LDD is a PA2.0 addition. */
......
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