linux-kernel - [PATCH 1/2] perf annotate: Fallback to objdump when capstone fails

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Message-ID: <20240425005157.1104789-1-namhyung@kernel.org>
Date: Wed, 24 Apr 2024 17:51:56 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Kan Liang <kan.liang@...ux.intel.com>
Cc: Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org
Subject: [PATCH 1/2] perf annotate: Fallback to objdump when capstone fails

I found some cases that capstone failed to disassemble.  Probably my
capstone is an old version but anyway there's a chance it can fail.  And
then it silently stopped in the middle.  In my case, it didn't
understand "RDPKRU" instruction.

Let's check if the capstone disassemble reached to the end of the
function.  And fallback to objdump if not.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/util/disasm.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/tools/perf/util/disasm.c b/tools/perf/util/disasm.c
index 92937809be85..412101f2cf2a 100644
--- a/tools/perf/util/disasm.c
+++ b/tools/perf/util/disasm.c
@@ -1542,6 +1542,20 @@ static int symbol__disassemble_capstone(char *filename, struct symbol *sym,
 		offset += insn[i].size;
 	}
 
+	/* It failed in the middle: probably due to unknown instructions */
+	if (offset != len) {
+		struct list_head *list = &notes->src->source;
+
+		/* Discard all lines and fallback to objdump */
+		while (!list_empty(list)) {
+			dl = list_first_entry(list, struct disasm_line, al.node);
+
+			list_del_init(&dl->al.node);
+			disasm_line__free(dl);
+		}
+		count = -1;
+	}
+
 out:
 	if (needs_cs_close)
 		cs_close(&handle);
-- 
2.44.0.769.g3c40516874-goog