tests/docker: Update the tricore container to debian 10
[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 "qemu/osdep.h"
13 #include "trace/control.h"
14 #include "trace/ftrace.h"
15
16 int trace_marker_fd;
17
18 static int find_mount(char *mount_point, const char *fstype)
19 {
20 char type[100];
21 FILE *fp;
22 int ret = 0;
23
24 fp = fopen("/proc/mounts", "r");
25 if (fp == NULL) {
26 return 0;
27 }
28
29 while (fscanf(fp, "%*s %" STR(PATH_MAX) "s %99s %*s %*d %*d\n",
30 mount_point, type) == 2) {
31 if (strcmp(type, fstype) == 0) {
32 ret = 1;
33 break;
34 }
35 }
36 fclose(fp);
37
38 return ret;
39 }
40
41 bool ftrace_init(void)
42 {
43 char mount_point[PATH_MAX];
44 char path[PATH_MAX];
45 int tracefs_found;
46 int trace_fd = -1;
47 const char *subdir = "";
48
49 tracefs_found = find_mount(mount_point, "tracefs");
50 if (!tracefs_found) {
51 tracefs_found = find_mount(mount_point, "debugfs");
52 subdir = "/tracing";
53 }
54
55 if (tracefs_found) {
56 if (snprintf(path, PATH_MAX, "%s%s/tracing_on", mount_point, subdir)
57 >= sizeof(path)) {
58 fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n");
59 return false;
60 }
61 trace_fd = open(path, O_WRONLY);
62 if (trace_fd < 0) {
63 if (errno == EACCES) {
64 trace_marker_fd = open("/dev/null", O_WRONLY);
65 if (trace_marker_fd != -1) {
66 return true;
67 }
68 }
69 perror("Could not open ftrace 'tracing_on' file");
70 return false;
71 } else {
72 if (write(trace_fd, "1", 1) < 0) {
73 perror("Could not write to 'tracing_on' file");
74 close(trace_fd);
75 return false;
76 }
77 close(trace_fd);
78 }
79 if (snprintf(path, PATH_MAX, "%s%s/trace_marker", mount_point, subdir)
80 >= sizeof(path)) {
81 fprintf(stderr, "Using tracefs mountpoint would exceed PATH_MAX\n");
82 return false;
83 }
84 trace_marker_fd = open(path, O_WRONLY);
85 if (trace_marker_fd < 0) {
86 perror("Could not open ftrace 'trace_marker' file");
87 return false;
88 }
89 } else {
90 fprintf(stderr, "tracefs is not mounted\n");
91 return false;
92 }
93
94 return true;
95 }