• Wang Nan's avatar
    perf tools: Deal with kernel module names in '[]' correctly · 1f121b03
    Wang Nan authored
    Before patch ba92732e ('perf kmaps: Check kmaps to make code more
    robust'), 'perf report' and 'perf annotate' will segfault if trace data
    contains kernel module information like this:
    
     # perf report -D -i ./perf.data
     ...
     0 0 0x188 [0x50]: PERF_RECORD_MMAP -1/0: [0xffffffbff1018000(0xf068000) @ 0]: x [test_module]
     ...
    
     # perf report -i ./perf.data --objdump=/path/to/objdump --kallsyms=/path/to/kallsyms
    
     perf: Segmentation fault
     -------- backtrace --------
     /path/to/perf[0x503478]
     /lib64/libc.so.6(+0x3545f)[0x7fb201f3745f]
     /path/to/perf[0x499b56]
     /path/to/perf(dso__load_kallsyms+0x13c)[0x49b56c]
     /path/to/perf(dso__load+0x72e)[0x49c21e]
     /path/to/perf(map__load+0x6e)[0x4ae9ee]
     /path/to/perf(thread__find_addr_map+0x24c)[0x47deec]
     /path/to/perf(perf_event__preprocess_sample+0x88)[0x47e238]
     /path/to/perf[0x43ad02]
     /path/to/perf[0x4b55bc]
     /path/to/perf(ordered_events__flush+0xca)[0x4b57ea]
     /path/to/perf[0x4b1a01]
     /path/to/perf(perf_session__process_events+0x3be)[0x4b428e]
     /path/to/perf(cmd_report+0xf11)[0x43bfc1]
     /path/to/perf[0x474702]
     /path/to/perf(main+0x5f5)[0x42de95]
     /lib64/libc.so.6(__libc_start_main+0xf4)[0x7fb201f23bd4]
     /path/to/perf[0x42dfc4]
    
    This is because __kmod_path__parse treats '[' leading names as kernel
    name instead of names of kernel module.
    
    If perf.data contains build information and the buildid of such modules
    can be found, the dso->kernel of it will be set to DSO_TYPE_KERNEL by
    __event_process_build_id(), not kernel module.
    
    It will then be passed to dso__load() -> dso__load_kernel_sym() ->
    dso__load_kcore() if --kallsyms is provided.
    
    The refered patch adds NULL pointer checker to avoid segfault. However,
    such kernel modules are still processed incorrectly.
    
    This patch fixes __kmod_path__parse, makes it treat names like
    '[test_module]' as kernel modules.
    
    kmod-path.c is also update to reflect the above changes.
    Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
    Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
    Cc: Namhyung Kim <namhyung@kernel.org>
    Cc: Zefan Li <lizefan@huawei.com>
    Link: http://lkml.kernel.org/r/1433321541-170245-1-git-send-email-wangnan0@huawei.com
    [ Fixed the merged with 0443f36b ("perf machine: Fix the search
      for the kernel DSO on the unified list" ]
    Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
    1f121b03
machine.c 45.9 KB