[tip:perf/core] perf libdw: Check for mmaps also in MAP__VARIABLE tree

[tip-bot for Jiri Olsa]

Commit-ID:  0ba98149f8c8b6b2ba36be9938afb731fa719004
Gitweb:     http://git.kernel.org/tip/0ba98149f8c8b6b2ba36be9938afb731fa719004
Author:     Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Thu, 7 Jan 2016 10:14:02 +0100
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 8 Jan 2016 14:16:57 -0300

perf libdw: Check for mmaps also in MAP__VARIABLE tree

We've seen cases (softice) where DWARF unwinder went through non
executable mmaps, which we need to lookup in MAP__VARIABLE tree.

Reported-and-Tested-by: Noel Grandin <noelgrandin@xxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1452158050-28061-6-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/unwind-libdw.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/perf/util/unwind-libdw.c b/tools/perf/util/unwind-libdw.c
index db8142b..cf5e250 100644
--- a/tools/perf/util/unwind-libdw.c
+++ b/tools/perf/util/unwind-libdw.c
@@ -96,6 +96,16 @@ static int access_dso_mem(struct unwind_info *ui, Dwarf_Addr addr,
 	thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
 			      MAP__FUNCTION, addr, &al);
 	if (!al.map) {
+		/*
+		 * We've seen cases (softice) where DWARF unwinder went
+		 * through non executable mmaps, which we need to lookup
+		 * in MAP__VARIABLE tree.
+		 */
+		thread__find_addr_map(ui->thread, PERF_RECORD_MISC_USER,
+				      MAP__VARIABLE, addr, &al);
+	}
+
+	if (!al.map) {
 		pr_debug("unwind: no map for %lx\n", (unsigned long)addr);
 		return -1;
 	}