From: Ingo Molnar <mingo@elte.hu>
Date: Thu, 27 Mar 2008 14:58:28 +0000 (+0100)
Subject: x86: fix prefetch workaround
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=bc713dcf35c427ae8377fb9a4d1b7f891054ce13;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

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>
---

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