[PATCH v3] perf probe: Find compilation directory path for lazy matching

[Naohiro Aota <naota@elisp.net>]

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>
---
 tools/perf/util/probe-event.c  | 59 -----------------------------------
 tools/perf/util/probe-finder.c | 71 +++++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/probe-finder.h |  4 +++
 3 files changed, 74 insertions(+), 60 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index f272a71..32a429b 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -648,65 +648,6 @@ static int try_to_find_probe_trace_events(struct perf_probe_event *pev,
 	return ntevs;
 }
 
-/*
- * 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.
- */
-static 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;
-		}
-	}
-}
-
 #define LINEBUF_SIZE 256
 #define NR_ADDITIONAL_LINES 2
 
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 46f009a..0fd2df4 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -849,11 +849,22 @@ 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;
 	}
@@ -1616,3 +1627,61 @@ 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;
+		}
+	}
+}
diff --git a/tools/perf/util/probe-finder.h b/tools/perf/util/probe-finder.h
index 92590b2..ebf8c8c 100644
--- a/tools/perf/util/probe-finder.h
+++ b/tools/perf/util/probe-finder.h
@@ -55,6 +55,10 @@ extern int debuginfo__find_available_vars_at(struct debuginfo *dbg,
 					     struct variable_list **vls,
 					     int max_points, bool externs);
 
+/* Find a src file from a DWARF tag path */
+int get_real_path(const char *raw_path, const char *comp_dir,
+			 char **new_path);
+
 struct probe_finder {
 	struct perf_probe_event	*pev;		/* Target probe event */
 
-- 
2.3.1