From: Peter Zijlstra <peterz@infradead.org>
To: eranian@gmail.com
Cc: Vince Weaver <vincent.weaver@maine.edu>,
LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
kan.liang@intel.com
Subject: Re: perf: fuzzer triggered warning in intel_pmu_drain_pebs_nhm()
Date: Fri, 3 Jul 2015 21:04:20 +0200 [thread overview]
Message-ID: <20150703190420.GS3644@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CAMsRxfJurCVcQD5642R10SP70XuXxTes3CyKrrD5owu39f_AXg@mail.gmail.com>
On Fri, Jul 03, 2015 at 08:56:57PM +0200, Stephane Eranian wrote:
> Where do you see that we use cpuc->pebs_enabled after clearing it
> in pebs_disable() to check for overflow or active in drain_pebs()?
> I only see it used in get_next_pebs_record_by_bit()?
| static inline bool pebs_is_enabled(struct cpu_hw_events *cpuc)
| {
| return (cpuc->pebs_enabled & ((1ULL << MAX_PEBS_EVENTS) - 1));
| }
| void intel_pmu_pebs_disable(struct perf_event *event)
| {
| struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
| struct hw_perf_event *hwc = &event->hw;
| struct debug_store *ds = cpuc->ds;
|
| cpuc->pebs_enabled &= ~(1ULL << hwc->idx);
Here we clear it...
| if (event->hw.flags & PERF_X86_EVENT_PEBS_LDLAT)
| cpuc->pebs_enabled &= ~(1ULL << (hwc->idx + 32));
| else if (event->hw.flags & PERF_X86_EVENT_PEBS_ST)
| cpuc->pebs_enabled &= ~(1ULL << 63);
|
| if (ds->pebs_interrupt_threshold >
| ds->pebs_buffer_base + x86_pmu.pebs_record_size) {
| intel_pmu_drain_pebs_buffer();
Here we drain the buffer; which uses ->pebs_enabled
| if (!pebs_is_enabled(cpuc))
And here we test it
| perf_sched_cb_dec(event->ctx->pmu);
| }
|
| if (cpuc->enabled)
| wrmsrl(MSR_IA32_PEBS_ENABLE, cpuc->pebs_enabled);
|
| hwc->config |= ARCH_PERFMON_EVENTSEL_INT;
| }
That said, its far too warm and I might just not be making sense.
next prev parent reply other threads:[~2015-07-03 19:04 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-02 15:18 perf: fuzzer triggered warning in intel_pmu_drain_pebs_nhm() Vince Weaver
2015-07-02 19:43 ` Peter Zijlstra
2015-07-03 13:13 ` Peter Zijlstra
2015-07-03 18:56 ` Stephane Eranian
2015-07-03 19:04 ` Peter Zijlstra [this message]
2015-07-03 19:49 ` Vince Weaver
2015-07-15 6:42 ` Stephane Eranian
2015-07-15 12:35 ` Peter Zijlstra
2015-07-16 6:02 ` Stephane Eranian
2015-07-16 7:15 ` Peter Zijlstra
2015-07-16 7:30 ` Stephane Eranian
2015-07-16 21:12 ` Stephane Eranian
2015-07-03 19:03 ` Vince Weaver
2015-07-03 20:08 ` Liang, Kan
2015-07-06 10:55 ` Peter Zijlstra
2015-07-06 13:47 ` Liang, Kan
2015-07-06 16:22 ` Vince Weaver
2015-07-06 16:23 ` Liang, Kan
2015-07-06 16:51 ` Vince Weaver
2015-08-04 9:01 ` [tip:perf/core] perf/x86/intel/pebs: Fix event disable PEBS buffer drain tip-bot for Liang, Kan
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