From 80aa0fb4940bf8ee52bcb574d74459a7aea45621 Mon Sep 17 00:00:00 2001
From: James Yang <James.Yang@freescale.com>
Date: Tue, 25 Jun 2013 11:41:05 -0500
Subject: [PATCH] powerpc: Fix string instr. emulation for 32-bit processes on
ppc64
String instruction emulation would erroneously result in a segfault if
the upper bits of the EA are set and is so high that it fails access
check. Truncate the EA to 32 bits if the process is 32-bit.
Signed-off-by: James Yang <James.Yang@freescale.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---
arch/powerpc/kernel/traps.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 071f6e040eb2cd..300daf3e7ab06b 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -866,6 +866,10 @@ static int emulate_string_inst(struct pt_regs *regs, u32 instword)
u8 val;
u32 shift = 8 * (3 - (pos & 0x3));
+ /* if process is 32-bit, clear upper 32 bits of EA */
+ if ((regs->msr & MSR_64BIT) == 0)
+ EA &= 0xFFFFFFFF;
+
switch ((instword & PPC_INST_STRING_MASK)) {
case PPC_INST_LSWX:
case PPC_INST_LSWI:
--
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