linux-kernel - [tip:perf/urgent] perf/x86: Fix broken LBR fixup code

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Date:	Thu, 14 Jun 2012 01:40:14 -0700
From:	tip-bot for Stephane Eranian <eranian@...gle.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, eranian@...gle.com, hpa@...or.com,
	mingo@...nel.org, a.p.zijlstra@...llo.nl, tglx@...utronix.de,
	asharma@...com
Subject: [tip:perf/urgent] perf/x86: Fix broken LBR fixup code

Commit-ID:  25f42985825dd93f0593efe454e54c2aa13f7830
Gitweb:     http://git.kernel.org/tip/25f42985825dd93f0593efe454e54c2aa13f7830
Author:     Stephane Eranian <eranian@...gle.com>
AuthorDate: Mon, 11 Jun 2012 15:44:26 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 13 Jun 2012 15:00:28 +0200

perf/x86: Fix broken LBR fixup code

I noticed that the LBR fixups were not working anymore
on programs where they used to. I tracked this down to
a recent change to copy_from_user_nmi():

 db0dc75d640 ("perf/x86: Check user address explicitly in copy_from_user_nmi()")

This commit added a call to __range_not_ok() to the
copy_from_user_nmi() routine. The problem is that the logic
of the test must be reversed. __range_not_ok() returns 0 if the
range is VALID. We want to return early from copy_from_user_nmi()
if the range is NOT valid.

Signed-off-by: Stephane Eranian <eranian@...gle.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Acked-by: Arun Sharma <asharma@...com>
Link: http://lkml.kernel.org/r/20120611134426.GA7542@quad
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/lib/usercopy.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/x86/lib/usercopy.c b/arch/x86/lib/usercopy.c
index 677b1ed..4f74d94 100644
--- a/arch/x86/lib/usercopy.c
+++ b/arch/x86/lib/usercopy.c
@@ -22,7 +22,7 @@ copy_from_user_nmi(void *to, const void __user *from, unsigned long n)
 	void *map;
 	int ret;
 
-	if (__range_not_ok(from, n, TASK_SIZE) == 0)
+	if (__range_not_ok(from, n, TASK_SIZE))
 		return len;
 
 	do {
--
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