linux-kernel - [PATCH 1/3] perf jvmti: Fix jitdump for methods without debug info

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Date:   Mon, 27 Apr 2020 14:15:14 +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 1/3] perf jvmti: Fix jitdump for methods without debug info

If a Java class is compiled with -g:none to omit debug information, the
JVMTI plugin won't write jitdump entries for any method in this class
and prints a lot of errors like:

    java: GetSourceFileName failed with JVMTI_ERROR_ABSENT_INFORMATION

The call to GetSourceFileName is used to derive the file name `fn`, but
this value is not actually used since commit ca58d7e64bdf ("perf jvmti:
Generate correct debug information for inlined code") which moved the
file name lookup into fill_source_filenames(). So the call to
GetSourceFileName and related code can be safely removed.

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

diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
index c441a34cb1c0..50ef524b5cd4 100644
--- a/tools/perf/jvmti/libjvmti.c
+++ b/tools/perf/jvmti/libjvmti.c
@@ -246,8 +246,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
 	char *class_sign = NULL;
 	char *func_name = NULL;
 	char *func_sign = NULL;
-	char *file_name = NULL;
-	char fn[PATH_MAX];
 	uint64_t addr = (uint64_t)(uintptr_t)code_addr;
 	jvmtiError ret;
 	int nr_lines = 0; /* in line_tab[] */
@@ -282,12 +280,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
 		}
 	}
 
-	ret = (*jvmti)->GetSourceFileName(jvmti, decl_class, &file_name);
-	if (ret != JVMTI_ERROR_NONE) {
-		print_error(jvmti, "GetSourceFileName", ret);
-		goto error;
-	}
-
 	ret = (*jvmti)->GetClassSignature(jvmti, decl_class,
 					  &class_sign, NULL);
 	if (ret != JVMTI_ERROR_NONE) {
@@ -302,8 +294,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
 		goto error;
 	}
 
-	copy_class_filename(class_sign, file_name, fn, PATH_MAX);
-
 	/*
 	 * write source line info record if we have it
 	 */
@@ -323,7 +313,6 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
 	(*jvmti)->Deallocate(jvmti, (unsigned char *)func_name);
 	(*jvmti)->Deallocate(jvmti, (unsigned char *)func_sign);
 	(*jvmti)->Deallocate(jvmti, (unsigned char *)class_sign);
-	(*jvmti)->Deallocate(jvmti, (unsigned char *)file_name);
 	free(line_tab);
 	while (line_file_names && (nr_lines > 0)) {
 	    if (line_file_names[nr_lines - 1]) {
-- 
2.26.1