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;
+                }
+        }
+}