linux-kernel - [tip:perf/urgent] x86, perf: Fix static_key bug in load_mm

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Message-ID: <tip-a833581e372a4adae2319d8dc379493edbc444e9@git.kernel.org>
Date:	Fri, 10 Jul 2015 01:27:31 -0700
From:	tip-bot for Peter Zijlstra <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, keescook@...omium.org,
	mpatocka@...hat.com, vince@...ter.net, acme@...nel.org,
	paulus@...ba.org, hpa@...or.com, hillf.zj@...baba-inc.com,
	Valdis.Kletnieks@...edu, stable@...r.kernel.org,
	aarcange@...hat.com, brgerst@...il.com, luto@...capital.net,
	bp@...en8.de, mingo@...nel.org, dvlasenk@...hat.com,
	tglx@...utronix.de, peterz@...radead.org,
	torvalds@...ux-foundation.org
Subject: [tip:perf/urgent] x86, perf: Fix static_key bug in load_mm_cr4()

Commit-ID:  a833581e372a4adae2319d8dc379493edbc444e9
Gitweb:     http://git.kernel.org/tip/a833581e372a4adae2319d8dc379493edbc444e9
Author:     Peter Zijlstra <peterz@...radead.org>
AuthorDate: Thu, 9 Jul 2015 19:23:38 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 10 Jul 2015 10:24:38 +0200

x86, perf: Fix static_key bug in load_mm_cr4()

Mikulas reported his K6-3 not booting. This is because the
static_key API confusion struck and bit Andy, this wants to be
static_key_false().

Reported-by: Mikulas Patocka <mpatocka@...hat.com>
Tested-by: Mikulas Patocka <mpatocka@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: <stable@...r.kernel.org>
Cc: Andrea Arcangeli <aarcange@...hat.com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Valdis Kletnieks <Valdis.Kletnieks@...edu>
Cc: Vince Weaver <vince@...ter.net>
Cc: hillf.zj <hillf.zj@...baba-inc.com>
Fixes: a66734297f78 ("perf/x86: Add /sys/devices/cpu/rdpmc=2 to allow rdpmc for all tasks")
Link: http://lkml.kernel.org/r/20150709172338.GC19282@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/mmu_context.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/mmu_context.h b/arch/x86/include/asm/mmu_context.h
index 5e8daee..804a3a6 100644
--- a/arch/x86/include/asm/mmu_context.h
+++ b/arch/x86/include/asm/mmu_context.h
@@ -23,7 +23,7 @@ extern struct static_key rdpmc_always_available;
 
 static inline void load_mm_cr4(struct mm_struct *mm)
 {
-	if (static_key_true(&rdpmc_always_available) ||
+	if (static_key_false(&rdpmc_always_available) ||
 	    atomic_read(&mm->context.perf_rdpmc_allowed))
 		cr4_set_bits(X86_CR4_PCE);
 	else
--
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