[tip:perf/urgent] x86, perf: Fix static_key bug in load_mm_cr4()

[tip-bot for Peter Zijlstra]

Commit-ID:  a833581e372a4adae2319d8dc379493edbc444e9
Gitweb:     http://git.kernel.org/tip/a833581e372a4adae2319d8dc379493edbc444e9
Author:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
AuthorDate: Thu, 9 Jul 2015 19:23:38 +0200
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
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@xxxxxxxxxx>
Tested-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Valdis Kletnieks <Valdis.Kletnieks@xxxxxx>
Cc: Vince Weaver <vince@xxxxxxxxxx>
Cc: hillf.zj <hillf.zj@xxxxxxxxxxxxxxx>
Fixes: a66734297f78 ("perf/x86: Add /sys/devices/cpu/rdpmc=2 to allow rdpmc for all tasks")
Link: http://lkml.kernel.org/r/20150709172338.GC19282@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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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