From b3cb8674811d1851bbf1486a73d62b90c119b994 Mon Sep 17 00:00:00 2001 From: James Bottomley Date: Wed, 16 May 2012 11:10:27 +0100 Subject: [PATCH] [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 --- 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. */ -- 1.7.10.4