Ian Rogers 5b10c18d1b perf parse-events: Avoid SEGV if PMU lookup fails for legacy cache terms
libfuzzer found the following command could SEGV:

  $ perf stat -e cpu/L2,L2/ true

This is because the L2 term rewrites the perf_event_attr type to
PERF_TYPE_HW_CACHE which then fails the PMU lookup for the second
legacy cache term.

The new failure is consistent with repeated hardware terms:

  $ perf stat -e cpu/L2,L2/ true
  event syntax error: 'cpu/L2,L2/'
                              \___ Failed to find PMU for type 3

  Initial error:
  event syntax error: 'cpu/L2,L2/'
                              \___ Failed to find PMU for type 3
  Run 'perf list' for a list of valid events

   Usage: perf stat [<options>] [<command>]

      -e, --event <event>   event selector. use 'perf list' to list available events
  $ perf stat -e cpu/cycles,cycles/ true
  event syntax error: 'cpu/cycles,cycles/'
                                  \___ Failed to find PMU for type 0

  Initial error:
  event syntax error: 'cpu/cycles,cycles/'
                                  \___ Failed to find PMU for type 0
  Run 'perf list' for a list of valid events

   Usage: perf stat [<options>] [<command>]

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

Committer testing:

Before:

  $ perf stat -e cpu/L2,L2/ true
  Segmentation fault (core dumped)
  $

After:

  $ perf stat -e cpu/L2,L2/ true
  event syntax error: 'cpu/L2,L2/'
                              \___ Failed to find PMU for type 3

  Initial error:
  event syntax error: 'cpu/L2,L2/'
                              \___ Failed to find PMU for type 3
  Run 'perf list' for a list of valid events

   Usage: perf stat [<options>] [<command>]

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

Fixes: 6fd1e51915 ("perf parse-events: Support PMUs for legacy cache events")
Signed-off-by: Ian Rogers <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20230712065250.1450306-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-07-12 16:03:24 -03:00
2022-09-28 09:02:20 +02:00
2023-07-09 10:29:53 -07:00
2023-07-09 13:53:13 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Description
No description provided
Readme 7.9 GiB
Languages
C 97.7%
Assembly 1.6%
Makefile 0.3%
Perl 0.1%