Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
[qemu.git] / trace / ftrace.c
1 /*
2 * Ftrace trace backend
3 *
4 * Copyright (C) 2013 Hitachi, Ltd.
5 * Created by Eiichi Tsukata <eiichi.tsukata.xh@hitachi.com>
6 *
7 * This work is licensed under the terms of the GNU GPL, version 2. See
8 * the COPYING file in the top-level directory.
9 *
10 */
11
12 #include <stdio.h>
13 #include <string.h>
14 #include <fcntl.h>
15 #include <limits.h>
16 #include "trace.h"
17 #include "trace/control.h"
18
19 int trace_marker_fd;
20
21 static int find_debugfs(char *debugfs)
22 {
23 char type[100];
24 FILE *fp;
25
26 fp = fopen("/proc/mounts", "r");
27 if (fp == NULL) {
28 return 0;
29 }
30
31 while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
32 debugfs, type) == 2) {
33 if (strcmp(type, "debugfs") == 0) {
34 break;
35 }
36 }
37 fclose(fp);
38
39 if (strcmp(type, "debugfs") != 0) {
40 return 0;
41 }
42 return 1;
43 }
44
45 void trace_print_events(FILE *stream, fprintf_function stream_printf)
46 {
47 TraceEventID i;
48
49 for (i = 0; i < trace_event_count(); i++) {
50 TraceEvent *ev = trace_event_id(i);
51 stream_printf(stream, "%s [Event ID %u] : state %u\n",
52 trace_event_get_name(ev), i, trace_event_get_state_dynamic(ev));
53 }
54 }
55
56 void trace_event_set_state_dynamic_backend(TraceEvent *ev, bool state)
57 {
58 ev->dstate = state;
59 }
60
61 bool trace_backend_init(const char *events, const char *file)
62 {
63 char debugfs[PATH_MAX];
64 char path[PATH_MAX];
65 int debugfs_found;
66 int trace_fd = -1;
67
68 if (file) {
69 fprintf(stderr, "error: -trace file=...: "
70 "option not supported by the selected tracing backend\n");
71 return false;
72 }
73
74 debugfs_found = find_debugfs(debugfs);
75 if (debugfs_found) {
76 snprintf(path, PATH_MAX, "%s/tracing/tracing_on", debugfs);
77 trace_fd = open(path, O_WRONLY);
78 if (trace_fd < 0) {
79 perror("Could not open ftrace 'tracing_on' file");
80 return false;
81 } else {
82 if (write(trace_fd, "1", 1) < 0) {
83 perror("Could not write to 'tracing_on' file");
84 close(trace_fd);
85 return false;
86 }
87 close(trace_fd);
88 }
89 snprintf(path, PATH_MAX, "%s/tracing/trace_marker", debugfs);
90 trace_marker_fd = open(path, O_WRONLY);
91 if (trace_marker_fd < 0) {
92 perror("Could not open ftrace 'trace_marker' file");
93 return false;
94 }
95 } else {
96 fprintf(stderr, "debugfs is not mounted\n");
97 return false;
98 }
99
100 trace_backend_init_events(events);
101 return true;
102 }