x86: fix prefetch workaround

some early Athlon XP's and Opterons generate bogus faults on prefetch
instructions. The workaround for this regressed over .24 - reinstate it.

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 2 insertions, 1 deletions

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index fdc667422df9..c0c82bc143c9 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -92,7 +92,8 @@ static int is_prefetch(struct pt_regs *regs, unsigned long addr,
         unsigned char *max_instr;
 
 #ifdef CONFIG_X86_32
-        if (!(__supported_pte_mask & _PAGE_NX))
+        /* Catch an obscure case of prefetch inside an NX page: */
+        if ((__supported_pte_mask & _PAGE_NX) && (error_code & 16))
                 return 0;
 #endif