[tip: perf/urgent] perf script report: Fix SEGFAULT when using DWARF mode

[tip-bot2 for Andreas Gerstmayr]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     1a4025f06059eeaecb2ef24363350ea3431568df
Gitweb:        https://git.kernel.org/tip/1a4025f06059eeaecb2ef24363350ea3431568df
Author:        Andreas Gerstmayr <agerstmayr@xxxxxxxxxx>
AuthorDate:    Thu, 02 Apr 2020 14:54:16 +02:00
Committer:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Fri, 03 Apr 2020 09:39:53 -03:00

perf script report: Fix SEGFAULT when using DWARF mode

When running perf script report with a Python script and a callgraph in
DWARF mode, intr_regs->regs can be 0 and therefore crashing the regs_map
function.

Added a check for this condition (same check as in builtin-script.c:595).

Signed-off-by: Andreas Gerstmayr <agerstmayr@xxxxxxxxxx>
Tested-by: Kim Phillips <kim.phillips@xxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Link: http://lore.kernel.org/lkml/20200402125417.422232-1-agerstmayr@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/util/scripting-engines/trace-event-python.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/perf/util/scripting-engines/trace-event-python.c b/tools/perf/util/scripting-engines/trace-event-python.c
index 8c1b27c..2c372cf 100644
--- a/tools/perf/util/scripting-engines/trace-event-python.c
+++ b/tools/perf/util/scripting-engines/trace-event-python.c
@@ -694,6 +694,9 @@ static int regs_map(struct regs_dump *regs, uint64_t mask, char *bf, int size)
 
 	bf[0] = 0;
 
+	if (!regs || !regs->regs)
+		return 0;
+
 	for_each_set_bit(r, (unsigned long *) &mask, sizeof(mask) * 8) {
 		u64 val = regs->regs[i++];