summaryrefslogtreecommitdiffstats
path: root/qemu/trace/ftrace.c
diff options
context:
space:
mode:
Diffstat (limited to 'qemu/trace/ftrace.c')
-rw-r--r--qemu/trace/ftrace.c79
1 files changed, 79 insertions, 0 deletions
diff --git a/qemu/trace/ftrace.c b/qemu/trace/ftrace.c
new file mode 100644
index 000000000..a7ae371e6
--- /dev/null
+++ b/qemu/trace/ftrace.c
@@ -0,0 +1,79 @@
+/*
+ * Ftrace trace backend
+ *
+ * Copyright (C) 2013 Hitachi, Ltd.
+ * Created by Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ *
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <fcntl.h>
+#include <limits.h>
+#include "trace.h"
+#include "trace/control.h"
+
+int trace_marker_fd;
+
+static int find_debugfs(char *debugfs)
+{
+ char type[100];
+ FILE *fp;
+
+ fp = fopen("/proc/mounts", "r");
+ if (fp == NULL) {
+ return 0;
+ }
+
+ while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
+ debugfs, type) == 2) {
+ if (strcmp(type, "debugfs") == 0) {
+ break;
+ }
+ }
+ fclose(fp);
+
+ if (strcmp(type, "debugfs") != 0) {
+ return 0;
+ }
+ return 1;
+}
+
+bool ftrace_init(void)
+{
+ char debugfs[PATH_MAX];
+ char path[PATH_MAX];
+ int debugfs_found;
+ int trace_fd = -1;
+
+ debugfs_found = find_debugfs(debugfs);
+ if (debugfs_found) {
+ snprintf(path, PATH_MAX, "%s/tracing/tracing_on", debugfs);
+ trace_fd = open(path, O_WRONLY);
+ if (trace_fd < 0) {
+ perror("Could not open ftrace 'tracing_on' file");
+ return false;
+ } else {
+ if (write(trace_fd, "1", 1) < 0) {
+ perror("Could not write to 'tracing_on' file");
+ close(trace_fd);
+ return false;
+ }
+ close(trace_fd);
+ }
+ snprintf(path, PATH_MAX, "%s/tracing/trace_marker", debugfs);
+ trace_marker_fd = open(path, O_WRONLY);
+ if (trace_marker_fd < 0) {
+ perror("Could not open ftrace 'trace_marker' file");
+ return false;
+ }
+ } else {
+ fprintf(stderr, "debugfs is not mounted\n");
+ return false;
+ }
+
+ return true;
+}