linux-kernel - Re: [Patch v2 10/24] perf/x86/intel: Process arch-PEBS records or record fragments

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20250226093558.GR11590@noisy.programming.kicks-ass.net>
Date: Wed, 26 Feb 2025 10:35:58 +0100
From: Peter Zijlstra <peterz@...radead.org>
To: "Mi, Dapeng" <dapeng1.mi@...ux.intel.com>
Cc: Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Andi Kleen <ak@...ux.intel.com>,
	Eranian Stephane <eranian@...gle.com>, linux-kernel@...r.kernel.org,
	linux-perf-users@...r.kernel.org, Dapeng Mi <dapeng1.mi@...el.com>
Subject: Re: [Patch v2 10/24] perf/x86/intel: Process arch-PEBS records or
 record fragments

On Wed, Feb 26, 2025 at 01:20:37PM +0800, Mi, Dapeng wrote:

> > Also, should that workaround have been extended to also include
> > GLOBAL_STATUS_PERF_METRICS_OVF in that mask, or was that defect fixed
> > for every chip capable of metrics stuff?
> 
> hmm,  per my understanding, GLOBAL_STATUS_PERF_METRICS_OVF handling should
> only be skipped when fixed counter 3 or perf metrics are included in PEBS
> counter group. In this case, the slots and topdown metrics have been
> updated by PEBS handler. It should not be processed again.
> 
> @Kan Liang, is it correct?

Right, so the thing is, *any* PEBS event pending will clear METRICS_OVF
per:

                status &= x86_pmu.intel_ctrl | GLOBAL_STATUS_TRACE_TOPAPMI;