linux-kernel - Re: [PATCH] perf: Ignore format attributes with an unknown perf_event

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: <CAL_JsqLW=Vd=isvPd7_X3Vwp=0XUYjKqLkGYW2cztkd6JnGntQ@mail.gmail.com>
Date:   Thu, 1 Sep 2022 14:28:39 -0500
From:   Rob Herring <robh@...nel.org>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        James Clark <james.clark@....com>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] perf: Ignore format attributes with an unknown
 perf_event_attr field

On Thu, Sep 1, 2022 at 2:22 PM Arnaldo Carvalho de Melo
<arnaldo.melo@...il.com> wrote:
>
>
>
> On September 1, 2022 3:47:10 PM GMT-03:00, Rob Herring <robh@...nel.org> wrote:
> >If the kernel exposes a new perf_event_attr field in a format attr, perf
> >will return an error stating the specified PMU can't be found. For
> >example, a format attr with 'config3:0-63' causes an error if config3 is
> >unknown to perf. This causes a compatibility issue between a newer
> >kernel and an older perf tool.
> >
> >The addition here makes any attr string up to the ':' ignored, but
> >still checks the 'bits' portion.
>
> So, can you please show what is the behavior of the tool, with an actual command line and it's output, before and after your patch?

Before this patch with a kernel adding 'config3' I get:

# perf record -e arm_spe// -- true
event syntax error: 'arm_spe//'
                     \___ Cannot find PMU `arm_spe'. Missing kernel support?
Run 'perf list' for a list of valid events

 Usage: perf record [<options>] [<command>]
    or: perf record [<options>] -- <command> [<options>]

    -e, --event <event>   event selector. use 'perf list' to list
available events

After this patch, I get:

# perf record -e arm_spe// -- true
[ perf record: Woken up 2 times to write data ]
[ perf record: Captured and wrote 0.091 MB perf.data ]

Rob