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Subject[PATCH 4.1 049/123] x86, perf: Fix static_key bug in load_mm_cr4()
Date
4.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Zijlstra <peterz@infradead.org>

commit a833581e372a4adae2319d8dc379493edbc444e9 upstream.

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@redhat.com>
Tested-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Vince Weaver <vince@deater.net>
Cc: hillf.zj <hillf.zj@alibaba-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@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/include/asm/mmu_context.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- 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_av

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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