From: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Date: Fri, 6 Feb 2009 02:02:00 +0000 (+0000)
Subject: powerpc: Don't emulate mr. instructions
X-Git-Tag: firefly_0821_release~15590^2~4
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=eef336189b2b5ae68bfbef0df24176a4a152d981;p=firefly-linux-kernel-4.4.55.git

powerpc: Don't emulate mr. instructions

Currently emulate_step() emulates mr. instructions without updating cr0
and this can be disastrous. Don't emulate mr.

This bug has been around for a while, but I am not sure if its a worthy
-stable candidate. I'll leave it to Ben do decide.

Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

diff --git a/arch/powerpc/lib/sstep.c b/arch/powerpc/lib/sstep.c
index 4aae0c387645..13b7d54f185b 100644
--- a/arch/powerpc/lib/sstep.c
+++ b/arch/powerpc/lib/sstep.c
@@ -172,6 +172,8 @@ int __kprobes emulate_step(struct pt_regs *regs, unsigned int instr)
 			}
 			break;
 		case 0x378:	/* orx */
+			if (instr & 1)
+				break;
 			rs = (instr >> 21) & 0x1f;
 			rb = (instr >> 11) & 0x1f;
 			if (rs == rb) {		/* mr */