From 3c3116b745c08dc76ccbed7223c4edddcfd9a186 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 10 May 2016 14:16:54 +0200 Subject: [PATCH] perf/x86/msr: Fix SMI overflow We compute 'delta' and properly sign extend it and then ignore it and recompute the raw value, loosing the sign extention. Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Andy Lutomirski Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Cc: kan.liang@intel.com Cc: linux-kernel@vger.kernel.org Cc: luto@kernel.org Cc: ray.huang@amd.com Signed-off-by: Ingo Molnar --- arch/x86/events/msr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/events/msr.c b/arch/x86/events/msr.c index ec863b9a9f78..8bef19f098d4 100644 --- a/arch/x86/events/msr.c +++ b/arch/x86/events/msr.c @@ -166,7 +166,7 @@ again: if (unlikely(event->hw.event_base == MSR_SMI_COUNT)) delta = sign_extend64(delta, 31); - local64_add(now - prev, &event->count); + local64_add(delta, &event->count); } static void msr_event_start(struct perf_event *event, int flags) -- 2.20.1