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    Subject[PATCH 2/8] perf header: Assign proper ff->ph in perf_event__synthesize_features()
    Date
    From: Song Liu <songliubraving@fb.com>

    bpf/btf write_* functions need ff->ph->env.

    With this missing, pipe-mode (perf record -o -) would crash like:

    Program terminated with signal SIGSEGV, Segmentation fault.

    This patch assign proper ph value to ff.

    Committer testing:

    (gdb) run record -o -
    Starting program: /root/bin/perf record -o -
    PERFILE2
    <SNIP start of perf.data headers>
    Thread 1 "perf" received signal SIGSEGV, Segmentation fault.
    __do_write_buf (size=4, buf=0x160, ff=0x7fffffff8f80) at util/header.c:126
    126 memcpy(ff->buf + ff->offset, buf, size);
    (gdb) bt
    #0 __do_write_buf (size=4, buf=0x160, ff=0x7fffffff8f80) at util/header.c:126
    #1 do_write (ff=ff@entry=0x7fffffff8f80, buf=buf@entry=0x160, size=4) at util/header.c:137
    #2 0x00000000004eddba in write_bpf_prog_info (ff=0x7fffffff8f80, evlist=<optimized out>) at util/header.c:912
    #3 0x00000000004f69d7 in perf_event__synthesize_features (tool=tool@entry=0x97cc00 <record>, session=session@entry=0x7fffe9c6d010,
    evlist=0x7fffe9cae010, process=process@entry=0x4435d0 <process_synthesized_event>) at util/header.c:3695
    #4 0x0000000000443c79 in record__synthesize (tail=tail@entry=false, rec=0x97cc00 <record>) at builtin-record.c:1214
    #5 0x0000000000444ec9 in __cmd_record (rec=0x97cc00 <record>, argv=<optimized out>, argc=0) at builtin-record.c:1435
    #6 cmd_record (argc=0, argv=<optimized out>) at builtin-record.c:2450
    #7 0x00000000004ae3e9 in run_builtin (p=p@entry=0x98e058 <commands+216>, argc=argc@entry=3, argv=0x7fffffffd670) at perf.c:304
    #8 0x000000000042eded in handle_internal_command (argv=<optimized out>, argc=<optimized out>) at perf.c:356
    #9 run_argv (argcp=<optimized out>, argv=<optimized out>) at perf.c:400
    #10 main (argc=3, argv=<optimized out>) at perf.c:522
    (gdb)

    After the patch the SEGSEGV is gone.

    Reported-by: David Carrillo Cisneros <davidca@fb.com>
    Signed-off-by: Song Liu <songliubraving@fb.com>
    Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    Cc: Jiri Olsa <jolsa@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: kernel-team@fb.com
    Cc: stable@vger.kernel.org # v5.1+
    Fixes: 606f972b1361 ("perf bpf: Save bpf_prog_info information as headers to perf.data")
    Link: http://lkml.kernel.org/r/20190620010453.4118689-1-songliubraving@fb.com
    Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
    ---
    tools/perf/util/header.c | 1 +
    1 file changed, 1 insertion(+)

    diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
    index 847ae51a524b..fb0aa661644b 100644
    --- a/tools/perf/util/header.c
    +++ b/tools/perf/util/header.c
    @@ -3602,6 +3602,7 @@ int perf_event__synthesize_features(struct perf_tool *tool,
    return -ENOMEM;

    ff.size = sz - sz_hdr;
    + ff.ph = &session->header;

    for_each_set_bit(feat, header->adds_features, HEADER_FEAT_BITS) {
    if (!feat_ops[feat].synthesize) {
    --
    2.20.1
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