[PATCH 06/28] perf annotate browser: Be more robust when drawing jump arrows

Arnaldo Carvalho de Melo
2018-03-05T14:38:39Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

This first happened with a gcc function, _cpp_lex_token, that has the
usual jumps:

│1159e6c: ↓ jne 115aa32 <_cpp_lex_token@@Base+0xf92>

I.e. jumps to a label inside that function (_cpp_lex_token), and those
works, but also this kind:

│1159e8b: ↓ jne c469be <cpp_named_operator2name@@Base+0xa72>

I.e. jumps to another function, outside _cpp_lex_token, which are not
being correctly handled generating as a side effect references to
ab->offset[] entries that are set to NULL, so to make this code more
robust, check that here.

A proper fix for will be put in place, looking at the function name
right after the '<' token and probably treating this like a 'call'
instruction.

For now just don't draw the arrow.

Reported-by: Ingo Molnar <mingo@kernel.org>
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Jin Yao <yao.jin@intel.com>
Cc: Kan Liang <kan.liang@intel.com>
Link: https://lkml.kernel.org/n/tip-5tzvb875ep2sel03aeefgmud@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/ui/browsers/annotate.c | 25 +++++++++++++++++++++++++
1 file changed, 25 insertions(+)

diff --git a/tools/perf/ui/browsers/annotate.c b/tools/perf/ui/browsers/annotate.c
index e2f666391ac4..6ff6839558b0 100644
--- a/tools/perf/ui/browsers/annotate.c
+++ b/tools/perf/ui/browsers/annotate.c
@@ -328,7 +328,32 @@ static void annotate_browser__draw_current_jump(struct ui_browser *browser)
if (!disasm_line__is_valid_jump(cursor, sym))
return;

+ /*
+ * This first was seen with a gcc function, _cpp_lex_token, that
+ * has the usual jumps:
+ *
+ * │1159e6c: ↓ jne 115aa32 <_cpp_lex_token@@Base+0xf92>
+ *
+ * I.e. jumps to a label inside that function (_cpp_lex_token), and
+ * those works, but also this kind:
+ *
+ * │1159e8b: ↓ jne c469be <cpp_named_operator2name@@Base+0xa72>
+ *
+ * I.e. jumps to another function, outside _cpp_lex_token, which
+ * are not being correctly handled generating as a side effect references
+ * to ab->offset[] entries that are set to NULL, so to make this code
+ * more robust, check that here.
+ *
+ * A proper fix for will be put in place, looking at the function
+ * name right after the '<' token and probably treating this like a
+ * 'call' instruction.
+ */
target = ab->offsets[cursor->ops.target.offset];
+ if (target == NULL) {
+ ui_helpline__printf("WARN: jump target inconsistency, press 'o', ab->offsets[%#x] = NULL\n",
+ cursor->ops.target.offset);
+ return;
+ }

bcursor = browser_line(&cursor->al);
btarget = browser_line(target);
--
2.14.3