linux-kernel - Re: [PATCH v3 1/5] perf/core: Allow multiple AUX PMU events with the same module

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: <20240806211439.GB37996@noisy.programming.kicks-ass.net>
Date: Tue, 6 Aug 2024 23:14:39 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Leo Yan <leo.yan@....com>
Cc: Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	"Liang, Kan" <kan.liang@...ux.intel.com>,
	James Clark <james.clark@...aro.org>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/5] perf/core: Allow multiple AUX PMU events with the
 same module

On Tue, Aug 06, 2024 at 09:48:09PM +0100, Leo Yan wrote:
> This commit changes the condition from checking the same PMU instance to
> checking the same PMU driver module. This allows support for multiple
> PMU events with the same driver module.
> 
> As a result, more than one AUX event (e.g. arm_spe_0 and arm_spe_1) can
> record trace into the AUX ring buffer.
> 
> Signed-off-by: Leo Yan <leo.yan@....com>
> ---
>  kernel/events/core.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index aa3450bdc227..fdb8918e62a0 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -12344,9 +12344,10 @@ perf_event_set_output(struct perf_event *event, struct perf_event *output_event)
>  
>  	/*
>  	 * If both events generate aux data, they must be on the same PMU
> +	 * module but can be with different PMU instances.
>  	 */
>  	if (has_aux(event) && has_aux(output_event) &&
> -	    event->pmu != output_event->pmu)
> +	    event->pmu->module != output_event->pmu->module)

A very quick look at: arch/x86/events/intel/pt.c seems to suggest that
doesn't set pmu->module. Which seems to suggest the above won't work for
us.