perf annotate: Fallback disassemble 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 the end of the function
and fallback to objdump if not.
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20240425005157.1104789-1-namhyung@kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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);