/* * 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; }