[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: James Bottomley <JBottomley@Parallels.com>
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. */
