[PATCH] perf/rapl: fix crash in rapl_scale()

[PATCH] perf/rapl: fix crash in rapl_scale()

[Stephane Eranian]

This patch fixes a systematic crash in rapl_scale()
due to an invalid pointer.

The bug was introduced by commit:
commit 89cbc76768c2fa4ed95545bf961f3a14ddfeed21
Author: Christoph Lameter <cl@linux.com>
Date:   Sun Aug 17 12:30:40 2014 -0500

    x86: Replace __get_cpu_var uses


The fix is simple. Just put the parenthesis where it needs
to be, i.e., around rapl_pmu. To my surprise, the compiler
was not complaining about passing an integer instead of a
pointer.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Signed-off-by: Stephane Eranian <eranian@google.com>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
--

diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
index 6e434f8..c4bb8b8 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
@@ -142,7 +142,7 @@ static inline u64 rapl_scale(u64 v)
 	 * or use ldexp(count, -32).
 	 * Watts = Joules/Time delta
 	 */
-	return v << (32 - __this_cpu_read(rapl_pmu->hw_unit));
+	return v << (32 - __this_cpu_read(rapl_pmu)->hw_unit);
 }
 
 static u64 rapl_event_update(struct perf_event *event)

Re: [PATCH] perf/rapl: fix crash in rapl_scale()

[Peter Zijlstra]

On Thu, Jan 22, 2015 at 09:38:34PM +0100, Stephane Eranian wrote:
> 
> This patch fixes a systematic crash in rapl_scale()
> due to an invalid pointer.
> 
> The bug was introduced by commit:
> commit 89cbc76768c2fa4ed95545bf961f3a14ddfeed21
> Author: Christoph Lameter <cl@linux.com>
> Date:   Sun Aug 17 12:30:40 2014 -0500
> 
>     x86: Replace __get_cpu_var uses
> 
> 
> The fix is simple. Just put the parenthesis where it needs
> to be, i.e., around rapl_pmu. To my surprise, the compiler
> was not complaining about passing an integer instead of a
> pointer.
> 
> Reported-by: Vince Weaver <vincent.weaver@maine.edu>
> Signed-off-by: Stephane Eranian <eranian@google.com>
> Tested-by: Vince Weaver <vincent.weaver@maine.edu>

Thanks!

[tip:perf/urgent] perf/rapl: Fix crash in rapl_scale()

[tip-bot for Stephane Eranian]

Commit-ID:  98b008dff8452653909d9263efda925873e8d8bb
Gitweb:     http://git.kernel.org/tip/98b008dff8452653909d9263efda925873e8d8bb
Author:     Stephane Eranian <eranian@google.com>
AuthorDate: Thu, 22 Jan 2015 21:38:34 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 28 Jan 2015 13:04:35 +0100

perf/rapl: Fix crash in rapl_scale()

This patch fixes a systematic crash in rapl_scale()
due to an invalid pointer.

The bug was introduced by commit:

  89cbc76768c2 ("x86: Replace __get_cpu_var uses")

The fix is simple. Just put the parenthesis where it needs
to be, i.e., around rapl_pmu. To my surprise, the compiler
was not complaining about passing an integer instead of a
pointer.

Reported-by: Vince Weaver <vincent.weaver@maine.edu>
Tested-by: Vince Weaver <vincent.weaver@maine.edu>
Fixes: 89cbc76768c2 ("x86: Replace __get_cpu_var uses")
Signed-off-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: cl@linux.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20150122203834.GA10228@thinkpad
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/cpu/perf_event_intel_rapl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
index 6e434f8..c4bb8b8 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
@@ -142,7 +142,7 @@ static inline u64 rapl_scale(u64 v)
 	 * or use ldexp(count, -32).
 	 * Watts = Joules/Time delta
 	 */
-	return v << (32 - __this_cpu_read(rapl_pmu->hw_unit));
+	return v << (32 - __this_cpu_read(rapl_pmu)->hw_unit);
 }
 
 static u64 rapl_event_update(struct perf_event *event)