Arnaldo Carvalho de Melo 77fe30fed1 perf tools: Fix segfault when trying to process tracepoints in perf.data and not linked with libtraceevent
When we have a perf.data file with tracepoints, such as:

  # perf evlist -f
  probe_perf:lzma_decompress_to_file
  # Tip: use 'perf evlist --trace-fields' to show fields for tracepoint events
  #

We end up segfaulting when using perf built with NO_LIBTRACEEVENT=1 by
trying to find an evsel with a NULL 'event_name' variable:

  (gdb) run report --stdio -f
  Starting program: /root/bin/perf report --stdio -f

  Program received signal SIGSEGV, Segmentation fault.
  0x000000000055219d in find_evsel (evlist=0xfda7b0, event_name=0x0) at util/sort.c:2830
  warning: Source file is more recent than executable.
  2830		if (event_name[0] == '%') {
  Missing separate debuginfos, use: dnf debuginfo-install bzip2-libs-1.0.8-11.fc36.x86_64 cyrus-sasl-lib-2.1.27-18.fc36.x86_64 elfutils-debuginfod-client-0.188-3.fc36.x86_64 elfutils-libelf-0.188-3.fc36.x86_64 elfutils-libs-0.188-3.fc36.x86_64 glibc-2.35-20.fc36.x86_64 keyutils-libs-1.6.1-4.fc36.x86_64 krb5-libs-1.19.2-12.fc36.x86_64 libbrotli-1.0.9-7.fc36.x86_64 libcap-2.48-4.fc36.x86_64 libcom_err-1.46.5-2.fc36.x86_64 libcurl-7.82.0-12.fc36.x86_64 libevent-2.1.12-6.fc36.x86_64 libgcc-12.2.1-4.fc36.x86_64 libidn2-2.3.4-1.fc36.x86_64 libnghttp2-1.51.0-1.fc36.x86_64 libpsl-0.21.1-5.fc36.x86_64 libselinux-3.3-4.fc36.x86_64 libssh-0.9.6-4.fc36.x86_64 libstdc++-12.2.1-4.fc36.x86_64 libunistring-1.0-1.fc36.x86_64 libunwind-1.6.2-2.fc36.x86_64 libxcrypt-4.4.33-4.fc36.x86_64 libzstd-1.5.2-2.fc36.x86_64 numactl-libs-2.0.14-5.fc36.x86_64 opencsd-1.2.0-1.fc36.x86_64 openldap-2.6.3-1.fc36.x86_64 openssl-libs-3.0.5-2.fc36.x86_64 slang-2.3.2-11.fc36.x86_64 xz-libs-5.2.5-9.fc36.x86_64 zlib-1.2.11-33.fc36.x86_64
  (gdb) bt
  #0  0x000000000055219d in find_evsel (evlist=0xfda7b0, event_name=0x0) at util/sort.c:2830
  #1  0x0000000000552416 in add_dynamic_entry (evlist=0xfda7b0, tok=0xffb6eb "trace", level=2) at util/sort.c:2976
  #2  0x0000000000552d26 in sort_dimension__add (list=0xf93e00 <perf_hpp_list>, tok=0xffb6eb "trace", evlist=0xfda7b0, level=2) at util/sort.c:3193
  #3  0x0000000000552e1c in setup_sort_list (list=0xf93e00 <perf_hpp_list>, str=0xffb6eb "trace", evlist=0xfda7b0) at util/sort.c:3227
  #4  0x00000000005532fa in __setup_sorting (evlist=0xfda7b0) at util/sort.c:3381
  #5  0x0000000000553cdc in setup_sorting (evlist=0xfda7b0) at util/sort.c:3608
  #6  0x000000000042eb9f in cmd_report (argc=0, argv=0x7fffffffe470) at builtin-report.c:1596
  #7  0x00000000004aee7e in run_builtin (p=0xf64ca0 <commands+288>, argc=3, argv=0x7fffffffe470) at perf.c:330
  #8  0x00000000004af0f2 in handle_internal_command (argc=3, argv=0x7fffffffe470) at perf.c:384
  #9  0x00000000004af241 in run_argv (argcp=0x7fffffffe29c, argv=0x7fffffffe290) at perf.c:428
  #10 0x00000000004af5fc in main (argc=3, argv=0x7fffffffe470) at perf.c:562
  (gdb)

So check if we have tracepoint events in add_dynamic_entry() and bail
out instead:

  # perf report --stdio -f
  This perf binary isn't linked with libtraceevent, can't process probe_perf:lzma_decompress_to_file
  Error:
  Unknown --sort key: `trace'
  #

Fixes: 378ef0f5d9 ("perf build: Use libtraceevent from the system")
Acked-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lore.kernel.org/lkml/Y7MDb7kRaHZB6APC@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2023-01-02 13:45:19 -03:00
2022-12-04 01:59:16 +01:00
2022-12-30 17:22:14 +09:00
2022-09-28 09:02:20 +02:00
2023-01-01 13:53:16 -08:00

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

There are several guides for kernel developers and users. These guides can
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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.
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