[PATCH 3/3] perf annotate: Improve handling of corrupted ~/.debug

[Andi Kleen <andi@firstfloor.org>]

From: Andi Kleen <ak@linux.intel.com>

Sometimes ~/.debug can get corrupted and contain files that still
have symbol tables, but which objdump cannot handle. Add a fallback
to read the "original" file in such a case. This might be wrong
too if it's different, but in many cases when profiling
on the same host it will work.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
 tools/perf/util/annotate.c | 27 +++++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c
index 1748f528b6e9..cff5f36786fa 100644
--- a/tools/perf/util/annotate.c
+++ b/tools/perf/util/annotate.c
@@ -1638,19 +1638,22 @@ int symbol__strerror_disassemble(struct symbol *sym __maybe_unused, struct map *
 	return 0;
 }
 
-static int dso__disassemble_filename(struct dso *dso, char *filename, size_t filename_size)
+static int dso__disassemble_filename(struct dso *dso, char *filename, size_t filename_size,
+				     bool *build_id)
 {
 	char linkname[PATH_MAX];
 	char *build_id_filename;
 	char *build_id_path = NULL;
 	char *pos;
 
+	*build_id = false;
 	if (dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
 	    !dso__is_kcore(dso))
 		return SYMBOL_ANNOTATE_ERRNO__NO_VMLINUX;
 
 	build_id_filename = dso__build_id_filename(dso, NULL, 0, false);
 	if (build_id_filename) {
+		*build_id = true;
 		__symbol__join_symfs(filename, filename_size, build_id_filename);
 		free(build_id_filename);
 	} else {
@@ -1854,11 +1857,14 @@ static int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
 	int lineno = 0;
 	int nline;
 	pid_t pid;
-	int err = dso__disassemble_filename(dso, symfs_filename, sizeof(symfs_filename));
+	bool build_id;
+	int err = dso__disassemble_filename(dso, symfs_filename, sizeof(symfs_filename),
+					    &build_id);
 
 	if (err)
 		return err;
 
+again:
 	pr_debug("%s: filename=%s, sym=%s, start=%#" PRIx64 ", end=%#" PRIx64 "\n", __func__,
 		 symfs_filename, sym->name, map->unmap_ip(map, sym->start),
 		 map->unmap_ip(map, sym->end));
@@ -1955,8 +1961,21 @@ static int symbol__disassemble(struct symbol *sym, struct annotate_args *args)
 		nline++;
 	}
 
-	if (nline == 0)
-		pr_err("No output from %s\n", command);
+	if (nline == 0) {
+		pr_err("No objdump output for %s. Corrupted file?\n", symfs_filename);
+		if (build_id) {
+			/*
+			 * It could be that the buildid file is corrupted.
+			 * Try again with the "true" file. This might be wrong
+			 * too, but it's better than nothing.
+			 * We could move the build id file here?
+			 */
+			__symbol__join_symfs(symfs_filename, sizeof(symfs_filename),
+					     dso->long_name);
+			build_id = false;
+			goto again;
+		}
+	}
 
 	/*
 	 * kallsyms does not have symbol sizes so there may a nop at the end.
-- 
2.21.0