perf tools: Deal with kernel module names in '[]' correctly

2015-06-03T13:02:38+00:00

Before patch ba92732e9808 ('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: Wang Nan 
Acked-by: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Zefan Li 
Link: http://lkml.kernel.org/r/1433321541-170245-1-git-send-email-wangnan0@huawei.com
[ Fixed the merged with 0443f36b0de0 ("perf machine: Fix the search
  for the kernel DSO on the unified list" ]
Signed-off-by: Arnaldo Carvalho de Melo

perf tools: Add kmod_path__parse function

2015-03-21T17:53:41+00:00

Provides united way of parsing kernel module path
into several components.

The new kmod_path__parse function and few defines:

  int __kmod_path__parse(struct kmod_path *m, const char *path,
                         bool alloc_name, bool alloc_ext);

  #define kmod_path__parse(__m, __p)      __kmod_path__parse(__m, __p, false, false)
  #define kmod_path__parse_name(__m, __p) __kmod_path__parse(__m, __p, true , false)
  #define kmod_path__parse_ext(__m, __p)  __kmod_path__parse(__m, __p, false, true)

parse kernel module @path and updates @m argument like:

  @comp - true if @path contains supported compression suffix,
          false otherwise
  @kmod - true if @path contains '.ko' suffix in right position,
          false otherwise
  @name - if (@alloc_name && @kmod) is true, it contains strdup-ed base name
          of the kernel module without suffixes, otherwise strudup-ed
          base name of @path
  @ext  - if (@alloc_ext && @comp) is true, it contains strdup-ed string
          the compression suffix

It returns 0 if there's no strdup error, -ENOMEM otherwise.

Signed-off-by: Jiri Olsa 
Acked-by: Namhyung Kim 
Cc: Adrian Hunter 
Cc: Corey Ashford 
Cc: David Ahern 
Cc: Frederic Weisbecker 
Cc: Paul Mackerras 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: http://lkml.kernel.org/n/tip-9t6eqg8j610r94l743hkntiv@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo

linux-toradex.git/tools/perf/tests/kmod-path.c, branch v4.4.85

perf tools: Deal with kernel module names in '[]' correctly

perf tools: Add kmod_path__parse function