linux-kernel - [PATCH 1/4] kmemcheck: add additional selfchecks

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Date:	Mon, 14 Apr 2014 13:44:07 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	vegard.nossum@...cle.com, penberg@...nel.org
Cc:	jamie.iles@...cle.com, hpa@...or.com, mingo@...hat.com,
	tglx@...utronix.de, x86@...nel.org,
	masami.hiramatsu.pt@...achi.com, linux-kernel@...r.kernel.org,
	linux-mm@...r.kernel.org, Sasha Levin <sasha.levin@...cle.com>
Subject: [PATCH 1/4] kmemcheck: add additional selfchecks

kmemcheck has it's own tiny opcode decoder, and is not using the
kernel's decoder for historic reasons.

While the decoder works for more cases, it fails on quite a few
opcodes and returns incorrect values, which leads to either a
failure to detect an issue, or a false positive.

This patch adds a few of those opcodes: setne, btsl and callq,
thus causing selfcheck to fail during boot.

Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
---
 arch/x86/mm/kmemcheck/selftest.c |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/x86/mm/kmemcheck/selftest.c b/arch/x86/mm/kmemcheck/selftest.c
index aef7140..c898d33 100644
--- a/arch/x86/mm/kmemcheck/selftest.c
+++ b/arch/x86/mm/kmemcheck/selftest.c
@@ -23,6 +23,12 @@ static const struct selftest_opcode selftest_opcodes[] = {
 	{1, "\x66\x0f\xbe\x51\xf8",	"movswq <mem8>, <reg16>"},
 	{1, "\x0f\xbe\x51\xf8",		"movswq <mem8>, <reg32>"},
 
+	/* SETNE */
+	{1, "\x0f\x95\xc0",		"setne <reg8>"},
+
+	/* BTSL */
+	{4, "\x0f\xba\x6b\x10\x00",	"btsl <imm8>, <mem32>"},
+
 #ifdef CONFIG_X86_64
 	/* MOVZX / MOVZXD */
 	{1, "\x49\x0f\xb6\x51\xf8",	"movzbq <mem8>, <reg64>"},
@@ -32,6 +38,9 @@ static const struct selftest_opcode selftest_opcodes[] = {
 	{1, "\x49\x0f\xbe\x51\xf8",	"movsbq <mem8>, <reg64>"},
 	{2, "\x49\x0f\xbf\x51\xf8",	"movsbq <mem16>, <reg64>"},
 	{4, "\x49\x63\x51\xf8",		"movslq <mem32>, <reg64>"},
+
+	/* CALLQ */
+	{8, "\xe8\x00\x00\x00",		"call <mem64>"},
 #endif
 };
 
-- 
1.7.10.4

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