perf probe: Find compilation directory path for lazy matching

If we use lazy matching, it failed to open a souce file if perf command
is invoked outside of compilation directory:

$ perf probe -a '__schedule;clear_*'
Failed to open kernel/sched/core.c: No such file or directory
  Error: Failed to add events. (-2)

OTOH, other commands like "probe -L" can solve the souce directory by
themselves. Let's make it possible for lazy matching too!

Signed-off-by: Naohiro Aota <naota@elisp.net>
Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1426223923-1493-1-git-send-email-naota@elisp.net
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 70 insertions, 1 deletions

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 7831e2d93949..ff7865ca3ca3 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -855,11 +855,22 @@ static int probe_point_lazy_walker(const char *fname, int lineno,
 static int find_probe_point_lazy(Dwarf_Die *sp_die, struct probe_finder *pf)
 {
 	int ret = 0;
+	char *fpath;
 
 	if (intlist__empty(pf->lcache)) {
+		const char *comp_dir;
+
+		comp_dir = cu_get_comp_dir(&pf->cu_die);
+		ret = get_real_path(pf->fname, comp_dir, &fpath);
+		if (ret < 0) {
+			pr_warning("Failed to find source file path.\n");
+			return ret;
+		}
+
 		/* Matching lazy line pattern */
-		ret = find_lazy_match_lines(pf->lcache, pf->fname,
+		ret = find_lazy_match_lines(pf->lcache, fpath,
 					    pf->pev->point.lazy_line);
+		free(fpath);
 		if (ret <= 0)
 			return ret;
 	}
@@ -1622,3 +1633,61 @@ found:
 	return (ret < 0) ? ret : lf.found;
 }
 
+/*
+ * Find a src file from a DWARF tag path. Prepend optional source path prefix
+ * and chop off leading directories that do not exist. Result is passed back as
+ * a newly allocated path on success.
+ * Return 0 if file was found and readable, -errno otherwise.
+ */
+int get_real_path(const char *raw_path, const char *comp_dir,
+			 char **new_path)
+{
+	const char *prefix = symbol_conf.source_prefix;
+
+	if (!prefix) {
+		if (raw_path[0] != '/' && comp_dir)
+			/* If not an absolute path, try to use comp_dir */
+			prefix = comp_dir;
+		else {
+			if (access(raw_path, R_OK) == 0) {
+				*new_path = strdup(raw_path);
+				return *new_path ? 0 : -ENOMEM;
+			} else
+				return -errno;
+		}
+	}
+
+	*new_path = malloc((strlen(prefix) + strlen(raw_path) + 2));
+	if (!*new_path)
+		return -ENOMEM;
+
+	for (;;) {
+		sprintf(*new_path, "%s/%s", prefix, raw_path);
+
+		if (access(*new_path, R_OK) == 0)
+			return 0;
+
+		if (!symbol_conf.source_prefix) {
+			/* In case of searching comp_dir, don't retry */
+			zfree(new_path);
+			return -errno;
+		}
+
+		switch (errno) {
+		case ENAMETOOLONG:
+		case ENOENT:
+		case EROFS:
+		case EFAULT:
+			raw_path = strchr(++raw_path, '/');
+			if (!raw_path) {
+				zfree(new_path);
+				return -ENOENT;
+			}
+			continue;
+
+		default:
+			zfree(new_path);
+			return -errno;
+		}
+	}
+}