perf probe: Skip if the function address is 0

Skip probes if the entry address of the target function is 0.  This can
happen when we're handling C++ debuginfo files.

E.g. without this fix, below case still fail.
  ----
  $ ./perf probe -x /usr/lib64/libstdc++.so.6 -vD is_open
  probe-definition(0): is_open
  symbol:is_open file:(null) line:0 offset:0 return:0 lazy:(null)
  0 arguments
  symbol:catch file:(null) line:0 offset:0 return:0 lazy:(null)
  symbol:throw file:(null) line:0 offset:0 return:0 lazy:(null)
  symbol:rethrow file:(null) line:0 offset:0 return:0 lazy:(null)
  Open Debuginfo file: /usr/lib/debug/usr/lib64/libstdc++.so.6.0.22.debug
  Try to find probe point from debuginfo.
  Matched function: is_open [295df]
  found inline addr: 0x8ca80
  Probe point found: is_open+0
  found inline addr: 0x8ca70
  Probe point found: is_open+0
  found inline addr: 0x8ca60
  Probe point found: is_open+0
  Matched function: is_open [6527f]
  Matched function: is_open [9fe8a]
  Probe point found: is_open+0
  Matched function: is_open [19710b]
  found inline addr: 0xecca9
  Probe point found: stdio_filebuf+57
  found inline addr: 0x0
  Probe point found: swap+0
  Matched function: is_open [19fc9d]
  Probe point found: is_open+0
  Found 7 probe_trace_events.
  p:probe_libstdc++/is_open /usr/lib64/libstdc++.so.6.0.22:0x8ca80
  p:probe_libstdc++/is_open_1 /usr/lib64/libstdc++.so.6.0.22:0x8ca70
  p:probe_libstdc++/is_open_2 /usr/lib64/libstdc++.so.6.0.22:0x8ca60
  p:probe_libstdc++/is_open_3 /usr/lib64/libstdc++.so.6.0.22:0xb0ad0
  p:probe_libstdc++/is_open_4 /usr/lib64/libstdc++.so.6.0.22:0xecca9
  Failed to synthesize probe trace event.
    Error: Failed to add events. Reason: Invalid argument (Code: -22)
  ----
This is because some instances have entry_pc == 0 (see 19710b and
19fc9d). With this fix, those are skipped.

  ----
  $ ./perf probe -x /usr/lib64/libstdc++.so.6 -D is_open
  p:probe_libstdc++/is_open /usr/lib64/libstdc++.so.6.0.22:0x8ca80
  p:probe_libstdc++/is_open_1 /usr/lib64/libstdc++.so.6.0.22:0x8ca70
  p:probe_libstdc++/is_open_2 /usr/lib64/libstdc++.so.6.0.22:0x8ca60
  p:probe_libstdc++/is_open_3 /usr/lib64/libstdc++.so.6.0.22:0xb0ad0
  p:probe_libstdc++/is_open_4 /usr/lib64/libstdc++.so.6.0.22:0xecca9
  ----

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Tested-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/147464490707.29804.14277897643725143867.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 5fe8325e81f28cd84b40c90d218366379f5f0141..df4debe564daabce2e739289b14360d49185bc6f 100644 (file)
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -955,6 +955,11 @@ static int probe_point_inline_cb(Dwarf_Die *in_die, void *data)
                                   dwarf_diename(in_die));
                        return -ENOENT;
                }
+               if (addr == 0) {
+                       pr_debug("%s has no valid entry address. skipped.\n",
+                                dwarf_diename(in_die));
+                       return -ENOENT;
+               }
                pf->addr = addr;
                pf->addr += pp->offset;
                pr_debug("found inline addr: 0x%jx\n",
@@ -998,8 +1003,13 @@ static int probe_point_search_cb(Dwarf_Die *sp_die, void *data)
        } else if (die_is_func_instance(sp_die)) {
                /* Instances always have the entry address */
                dwarf_entrypc(sp_die, &pf->addr);
+               /* But in some case the entry address is 0 */
+               if (pf->addr == 0) {
+                       pr_debug("%s has no entry PC. Skipped\n",
+                                dwarf_diename(sp_die));
+                       param->retval = 0;
                /* Real function */
-               if (pp->lazy_line)
+               } else if (pp->lazy_line)
                        param->retval = find_probe_point_lazy(sp_die, pf);
                else {
                        skip_prologue(sp_die, pf);