From 359769ca6d1676ea0afbb5fed8bf49aab6215da4 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Thu, 1 Mar 2018 12:54:54 -0500 Subject: [PATCH] perf/x86/intel: Fix large period handling on Broadwell CPUs [ Upstream commit f605cfca8c39ffa2b98c06d2b9f30ba64f1e54e3 ] Large fixed period values could be truncated on Broadwell, for example: perf record -e cycles -c 10000000000 Here the fixed period is 0x2540BE400, but the period which finally applied is 0x540BE400 - which is wrong. The reason is that x86_pmu::limit_period() uses an u32 parameter, so the high 32 bits of 'period' get truncated. This bug was introduced in: commit 294fe0f52a44 ("perf/x86/intel: Add INST_RETIRED.ALL workarounds") It's safe to use u64 instead of u32: - Although the 'left' is s64, the value of 'left' must be positive when calling limit_period(). - bdw_limit_period() only modifies the lowest 6 bits, it doesn't touch the higher 32 bits. Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Jiri Olsa Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Stephane Eranian Cc: Thomas Gleixner Cc: Vince Weaver Fixes: 294fe0f52a44 ("perf/x86/intel: Add INST_RETIRED.ALL workarounds") Link: http://lkml.kernel.org/r/1519926894-3520-1-git-send-email-kan.liang@linux.intel.com [ Rewrote unacceptably bad changelog. ] Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/events/intel/core.c | 2 +- arch/x86/events/perf_event.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 526f22e..6965ee8 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3196,7 +3196,7 @@ glp_get_event_constraints(struct cpu_hw_events *cpuc, int idx, * Therefore the effective (average) period matches the requested period, * despite coarser hardware granularity. */ -static unsigned bdw_limit_period(struct perf_event *event, unsigned left) +static u64 bdw_limit_period(struct perf_event *event, u64 left) { if ((event->hw.config & INTEL_ARCH_EVENT_MASK) == X86_CONFIG(.event=0xc0, .umask=0x01)) { diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index 8e4ea143..dc4728e 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -556,7 +556,7 @@ struct x86_pmu { struct x86_pmu_quirk *quirks; int perfctr_second_write; bool late_ack; - unsigned (*limit_period)(struct perf_event *event, unsigned l); + u64 (*limit_period)(struct perf_event *event, u64 l); /* * sysfs attrs -- 2.7.4