perf jit: Improve error messages from JVMTI

This patch improves the usefulness of error messages generated by the
JVMTI interfac.e This can help identify the root cause of a problem by
printing the actual error code. The patch adds a new helper function
called print_error().

Signed-off-by: Stephane Eranian <eranian@google.com>
Cc: Anton Blanchard <anton@ozlabs.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nilay Vaish <nilayvaish@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1476356383-30100-2-git-send-email-eranian@google.com
[ Handle failure to convert numeric error to a string in print_error() ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 29 insertions, 10 deletions

diff --git a/tools/perf/jvmti/libjvmti.c b/tools/perf/jvmti/libjvmti.c
index ac12e4b91a92..5612641c69b4 100644
--- a/tools/perf/jvmti/libjvmti.c
+++ b/tools/perf/jvmti/libjvmti.c
@@ -12,6 +12,19 @@
 static int has_line_numbers;
 void *jvmti_agent;
 
+static void print_error(jvmtiEnv *jvmti, const char *msg, jvmtiError ret)
+{
+        char *err_msg = NULL;
+        jvmtiError err;
+        err = (*jvmti)->GetErrorName(jvmti, ret, &err_msg);
+        if (err == JVMTI_ERROR_NONE) {
+                warnx("%s failed with %s", msg, err_msg);
+                (*jvmti)->Deallocate(jvmti, (unsigned char *)err_msg);
+        } else {
+                warnx("%s failed with an unknown error %d", msg, ret);
+        }
+}
+
 static jvmtiError
 do_get_line_numbers(jvmtiEnv *jvmti, void *pc, jmethodID m, jint bci,
                     jvmti_line_info_t *tab, jint *nr)
@@ -22,8 +35,10 @@ 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_NONE) {
+                print_error(jvmti, "GetLineNumberTable", ret);
                 return ret;
+        }
 
         for (i = 0; i < nr_lines; i++) {
                 if (loc_tab[i].start_location < bci) {
@@ -71,6 +86,8 @@ 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 {
+                                        print_error(jvmti, "GetLineNumberTable", ret);
                                 }
                         }
                 }
@@ -130,7 +147,7 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
         ret = (*jvmti)->GetMethodDeclaringClass(jvmti, method,
                                                 &decl_class);
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: cannot get declaring class");
+                print_error(jvmti, "GetMethodDeclaringClass", ret);
                 return;
         }
 
@@ -144,21 +161,21 @@ compiled_method_load_cb(jvmtiEnv *jvmti,
 
         ret = (*jvmti)->GetSourceFileName(jvmti, decl_class, &file_name);
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: cannot get source filename ret=%d", ret);
+                print_error(jvmti, "GetSourceFileName", ret);
                 goto error;
         }
 
         ret = (*jvmti)->GetClassSignature(jvmti, decl_class,
                                           &class_sign, NULL);
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: getclassignature failed");
+                print_error(jvmti, "GetClassSignature", ret);
                 goto error;
         }
 
         ret = (*jvmti)->GetMethodName(jvmti, method, &func_name,
                                       &func_sign, NULL);
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: failed getmethodname");
+                print_error(jvmti, "GetMethodName", ret);
                 goto error;
         }
 
@@ -253,7 +270,7 @@ Agent_OnLoad(JavaVM *jvm, char *options, void *reserved __unused)
 
         ret = (*jvmti)->AddCapabilities(jvmti, &caps1);
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: acquire compiled_method capability failed");
+                print_error(jvmti, "AddCapabilities", ret);
                 return -1;
         }
         ret = (*jvmti)->GetJLocationFormat(jvmti, &format);
@@ -264,7 +281,9 @@ Agent_OnLoad(JavaVM *jvm, char *options, void *reserved __unused)
                 ret = (*jvmti)->AddCapabilities(jvmti, &caps1);
                 if (ret == JVMTI_ERROR_NONE)
                         has_line_numbers = 1;
-        }
+        } else if (ret != JVMTI_ERROR_NONE)
+                print_error(jvmti, "GetJLocationFormat", ret);
+
 
         memset(&cb, 0, sizeof(cb));
 
@@ -273,21 +292,21 @@ Agent_OnLoad(JavaVM *jvm, char *options, void *reserved __unused)
 
         ret = (*jvmti)->SetEventCallbacks(jvmti, &cb, sizeof(cb));
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: cannot set event callbacks");
+                print_error(jvmti, "SetEventCallbacks", ret);
                 return -1;
         }
 
         ret = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
                         JVMTI_EVENT_COMPILED_METHOD_LOAD, NULL);
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: setnotification failed for method_load");
+                print_error(jvmti, "SetEventNotificationMode(METHOD_LOAD)", ret);
                 return -1;
         }
 
         ret = (*jvmti)->SetEventNotificationMode(jvmti, JVMTI_ENABLE,
                         JVMTI_EVENT_DYNAMIC_CODE_GENERATED, NULL);
         if (ret != JVMTI_ERROR_NONE) {
-                warnx("jvmti: setnotification failed on code_generated");
+                print_error(jvmti, "SetEventNotificationMode(CODE_GENERATED)", ret);
                 return -1;
         }
         return 0;