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perf trace: Support multiple "vfs_getname" probes

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With a suitably defined "probe:vfs_getname" probe, 'perf trace' can
"beautify" its output, so syscalls like open() or openat() can print the
"filename" argument instead of just its hex address, like:

  $ perf trace -e open -- touch /dev/null
  [...]
       0.590 ( 0.014 ms): touch/18063 open(filename: /dev/null, flags: CREAT|NOCTTY|NONBLOCK|WRONLY, mode: IRUGO|IWUGO) = 3
  [...]

The output without such beautifier looks like:

     0.529 ( 0.011 ms): touch/18075 open(filename: 0xc78cf288, flags: CREAT|NOCTTY|NONBLOCK|WRONLY, mode: IRUGO|IWUGO) = 3

However, when the vfs_getname probe expands to multiple probes and it is
not the first one that is hit, the beautifier fails, as following:

     0.326 ( 0.010 ms): touch/18072 open(filename: , flags: CREAT|NOCTTY|NONBLOCK|WRONLY, mode: IRUGO|IWUGO) = 3

Fix it by hooking into all the expanded probes (inlines), now, for instance:

  [root@quaco ~]# perf probe -l
    probe:vfs_getname    (on getname_flags:73@fs/namei.c with pathname)
    probe:vfs_getname_1  (on getname_flags:73@fs/namei.c with pathname)
  [root@quaco ~]# perf trace -e open* sleep 1
       0.010 ( 0.005 ms): sleep/5588 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: RDONLY|CLOEXEC)   = 3
       0.029 ( 0.006 ms): sleep/5588 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: RDONLY|CLOEXEC)   = 3
       0.194 ( 0.008 ms): sleep/5588 openat(dfd: CWD, filename: /usr/lib/locale/locale-archive, flags: RDONLY|CLOEXEC) = 3
  [root@quaco ~]#

Works, further verified with:

  [root@quaco ~]# perf test vfs
  65: Use vfs_getname probe to get syscall args filenames   : Ok
  66: Add vfs_getname probe to get syscall args filenames   : Ok
  67: Check open filename arg using perf trace + vfs_getname: Ok
  [root@quaco ~]#

Reported-by: Michael Petlan <mpetlan@redhat.com>
Tested-by: Michael Petlan <mpetlan@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lkml.kernel.org/n/tip-mv8kolk17xla1smvmp3qabv1@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2019-01-29 15:12:34 +01:00
parent 59a1770691
commit 6ab3bc240a
1 changed files with 18 additions and 7 deletions
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25
tools/perf/builtin-trace.c
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@ -2514,19 +2514,30 @@ static size_t trace__fprintf_thread_summary(struct trace *trace, FILE *fp);
static bool perf_evlist__add_vfs_getname(struct perf_evlist *evlist)
{
struct perf_evsel *evsel = perf_evsel__newtp("probe", "vfs_getname");
bool found = false;
struct perf_evsel *evsel, *tmp;
struct parse_events_error err = { .idx = 0, };
int ret = parse_events(evlist, "probe:vfs_getname*", &err);
if (IS_ERR(evsel))
if (ret)
return false;
if (perf_evsel__field(evsel, "pathname") == NULL) {
evlist__for_each_entry_safe(evlist, evsel, tmp) {
if (!strstarts(perf_evsel__name(evsel), "probe:vfs_getname"))
continue;
if (perf_evsel__field(evsel, "pathname")) {
evsel->handler = trace__vfs_getname;
found = true;
continue;
}
list_del_init(&evsel->node);
evsel->evlist = NULL;
perf_evsel__delete(evsel);
return false;
}
evsel->handler = trace__vfs_getname;
perf_evlist__add(evlist, evsel);
return true;
return found;
}
static struct perf_evsel *perf_evsel__new_pgfault(u64 config)