perf probe: Support comp_dir to find an absolute source path
Gcc generates DW_AT_comp_dir and stores relative source path if building kernel
without O= option. In that case, perf probe --line sometimes doesn't work
without --source option, because it tries to access relative source path.
This adds DW_AT_comp_dir support to perf probe for finding an absolute source
path when no --source option.
LKML-Reference: <4C36EBE7.3060802@hitachi.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index a934a36..37dcdb6 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -144,6 +144,15 @@
return src;
}
+/* Get DW_AT_comp_dir (should be NULL with older gcc) */
+static const char *cu_get_comp_dir(Dwarf_Die *cu_die)
+{
+ Dwarf_Attribute attr;
+ if (dwarf_attr(cu_die, DW_AT_comp_dir, &attr) == NULL)
+ return NULL;
+ return dwarf_formstring(&attr);
+}
+
/* Compare diename and tname */
static bool die_compare_name(Dwarf_Die *dw_die, const char *tname)
{
@@ -1374,6 +1383,7 @@
size_t cuhl;
Dwarf_Die *diep;
Dwarf *dbg;
+ const char *comp_dir;
dbg = dwarf_begin(fd, DWARF_C_READ);
if (!dbg) {
@@ -1409,6 +1419,17 @@
}
off = noff;
}
+
+ /* Store comp_dir */
+ if (lf.found) {
+ comp_dir = cu_get_comp_dir(&lf.cu_die);
+ if (comp_dir) {
+ lr->comp_dir = strdup(comp_dir);
+ if (!lr->comp_dir)
+ ret = -ENOMEM;
+ }
+ }
+
pr_debug("path: %s\n", lr->path);
dwarf_end(dbg);