4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx> [ 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 <kan.liang@xxxxxxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> Cc: Jiri Olsa <jolsa@xxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Stephane Eranian <eranian@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vince Weaver <vincent.weaver@xxxxxxxxx> Fixes: 294fe0f52a44 ("perf/x86/intel: Add INST_RETIRED.ALL workarounds") Link: http://lkml.kernel.org/r/1519926894-3520-1-git-send-email-kan.liang@xxxxxxxxxxxxxxx [ Rewrote unacceptably bad changelog. ] Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/events/intel/core.c | 2 +- arch/x86/events/perf_event.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) --- 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_ * 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)) { --- 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