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 } 103