linux-kernel - [PATCH v2] perf: fix the probe finder location (.dwo files)

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Date:   Mon,  3 Oct 2022 14:10:39 -0400
From:   Henry Castro <hcvcastro@...il.com>
To:     hcvcastro@...il.com
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2] perf: fix the probe finder location (.dwo files)

If the file object is compiled using -gsplit-dwarf,
the probe finder location will fail.

Signed-off-by: Henry Castro <hcvcastro@...il.com>
---

> Anyway I think it'd be safer to do
>
>    if (dwarf_cu_info() == 0 && unit_type == skeleton)
>        pf->cu_die = subdie;

Thank you, I have modifed the patch :)


 tools/perf/util/probe-finder.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 50d861a80f57..b27039f5f04b 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1161,7 +1161,8 @@ static int debuginfo__find_probe_location(struct debuginfo *dbg,
 	struct perf_probe_point *pp = &pf->pev->point;
 	Dwarf_Off off, noff;
 	size_t cuhl;
-	Dwarf_Die *diep;
+	Dwarf_Die *diep, cudie, subdie;
+	uint8_t unit_type;
 	int ret = 0;

 	off = 0;
@@ -1200,6 +1201,14 @@ static int debuginfo__find_probe_location(struct debuginfo *dbg,
 			continue;
 		}

+#if _ELFUTILS_VERSION >= 171
+		/* Check separate debug information file. */
+		if (dwarf_cu_info(pf->cu_die.cu, NULL, &unit_type,
+				  &cudie, &subdie, NULL, NULL, NULL) == 0
+		    && unit_type == DW_UT_skeleton)
+			pf->cu_die = subdie;
+#endif
+
 		/* Check if target file is included. */
 		if (pp->file)
 			pf->fname = cu_find_realpath(&pf->cu_die, pp->file);
--
2.20.1