linux-kernel - [PATCH 2/3] perf jvmti: Do not report error when missing debug information

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Date:   Mon, 27 Apr 2020 14:15:15 +0800
From:   Nick Gasson <nick.gasson@....com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>
Cc:     Nick Gasson <nick.gasson@....com>, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] perf jvmti: Do not report error when missing debug information

If the Java sources are compiled with -g:none to disable debug
information the perf JVMTI plugin reports a lot of errors like:

  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION
  java: GetLineNumberTable failed with JVMTI_ERROR_ABSENT_INFORMATION

Instead if GetLineNumberTable returns JVMTI_ERROR_ABSENT_INFORMATION
simply skip emitting line number information for that method. Unlike the
previous patch these errors don't affect the jitdump generation, they
just generate a lot of noise.

Similarly for native methods which also don't have line tables.

Signed-off-by: Nick Gasson <nick.gasson@....com>
---
 tools/perf/jvmti/libjvmti.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
index 50ef524b5cd4..a9a056d68416 100644
--- a/tools/perf/jvmti/libjvmti.c
+++ b/tools/perf/jvmti/libjvmti.c
@@ -41,7 +41,11 @@ do_get_line_numbers(jvmtiEnv *jvmti, void *pc, jmethodID m, jint bci,
 	jvmtiError ret;
 
 	ret = (*jvmti)->GetLineNumberTable(jvmti, m, &nr_lines, &loc_tab);
-	if (ret != JVMTI_ERROR_NONE) {
+	if (ret == JVMTI_ERROR_ABSENT_INFORMATION || ret == JVMTI_ERROR_NATIVE_METHOD) {
+		/* No debug information for this method */
+		*nr = 0;
+		return JVMTI_ERROR_NONE;
+	} else if (ret != JVMTI_ERROR_NONE) {
 		print_error(jvmti, "GetLineNumberTable", ret);
 		return ret;
 	}
@@ -93,6 +97,9 @@ get_line_numbers(jvmtiEnv *jvmti, const void *compile_info, jvmti_line_info_t **
 					/* free what was allocated for nothing */
 					(*jvmti)->Deallocate(jvmti, (unsigned char *)lne);
 					nr_total += (int)nr;
+				} else if (ret == JVMTI_ERROR_ABSENT_INFORMATION
+					   || ret == JVMTI_ERROR_NATIVE_METHOD) {
+					/* No debug information for this method */
 				} else {
 					print_error(jvmti, "GetLineNumberTable", ret);
 				}
@@ -262,7 +269,9 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
 	if (has_line_numbers && map && map_length) {
 		ret = get_line_numbers(jvmti, compile_info, &line_tab, &nr_lines);
 		if (ret != JVMTI_ERROR_NONE) {
-			warnx("jvmti: cannot get line table for method");
+			if (ret != JVMTI_ERROR_NOT_FOUND) {
+				warnx("jvmti: cannot get line table for method");
+			}
 			nr_lines = 0;
 		} else if (nr_lines > 0) {
 			line_file_names = malloc(sizeof(char*) * nr_lines);
-- 
2.26.1