perf symbols: Save DSO loading errno to better report errors
Before, when some problem happened while trying to load the kernel
symtab, 'perf top' would show:
┌─Warning:───────────────────────────┐
│The vmlinux file can't be used. │
│Kernel samples will not be resolved.│
│ │
│ │
│Press any key... │
└────────────────────────────────────┘
Now, it reports:
# perf top --vmlinux /dev/null
┌─Warning:───────────────────────────────────────────┐
│The /tmp/passwd file can't be used: Invalid ELF file│
│Kernel samples will not be resolved. │
│ │
│ │
│Press any key... │
└────────────────────────────────────────────────────┘
This is possible because we now register the reason for not being able
to load the symtab in the dso->load_errno member, and provide a
dso__strerror_load() routine to format this error into a strerror like
string with a short reason for the error while loading.
That can be just forwarding the dso__strerror_load() call to
strerror_r(), or, for a separate errno range providing a custom message.
Reported-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-u5rb5uq63xqhkfb8uv2lxd5u@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 0d3667f..fc0ddd5 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -1137,3 +1137,36 @@
return dso__type_fd(fd);
}
+
+int dso__strerror_load(struct dso *dso, char *buf, size_t buflen)
+{
+ int idx, errnum = dso->load_errno;
+ /*
+ * This must have a same ordering as the enum dso_load_errno.
+ */
+ static const char *dso_load__error_str[] = {
+ "Internal tools/perf/ library error",
+ "Invalid ELF file",
+ "Can not read build id",
+ "Mismatching build id",
+ "Decompression failure",
+ };
+
+ BUG_ON(buflen == 0);
+
+ if (errnum >= 0) {
+ const char *err = strerror_r(errnum, buf, buflen);
+
+ if (err != buf)
+ scnprintf(buf, buflen, "%s", err);
+
+ return 0;
+ }
+
+ if (errnum < __DSO_LOAD_ERRNO__START || errnum >= __DSO_LOAD_ERRNO__END)
+ return -1;
+
+ idx = errnum - __DSO_LOAD_ERRNO__START;
+ scnprintf(buf, buflen, "%s", dso_load__error_str[idx]);
+ return 0;
+}