1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include <errno.h> 18 #include <fcntl.h> 19 #include <limits.h> 20 #include <pthread.h> 21 #include <stdbool.h> 22 #include <stdlib.h> 23 #include <string.h> 24 #include <sys/types.h> 25 #include <cutils/atomic.h> 26 #include <cutils/compiler.h> 27 #include <cutils/properties.h> 28 #include <cutils/trace.h> 29 30 #define LOG_TAG "cutils-trace" 31 #include <cutils/log.h> 32 33 volatile int32_t atrace_is_ready = 0; 34 int atrace_marker_fd = -1; 35 uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY; 36 static bool atrace_is_debuggable = false; 37 static volatile int32_t atrace_is_enabled = 1; 38 static pthread_once_t atrace_once_control = PTHREAD_ONCE_INIT; 39 static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER; 40 41 // Set whether this process is debuggable, which determines whether 42 // application-level tracing is allowed when the ro.debuggable system property 43 // is not set to '1'. 44 void atrace_set_debuggable(bool debuggable) 45 { 46 atrace_is_debuggable = debuggable; 47 atrace_update_tags(); 48 } 49 50 // Set whether tracing is enabled in this process. This is used to prevent 51 // the Zygote process from tracing. 52 void atrace_set_tracing_enabled(bool enabled) 53 { 54 android_atomic_release_store(enabled ? 1 : 0, &atrace_is_enabled); 55 atrace_update_tags(); 56 } 57 58 // Check whether the given command line matches one of the comma-separated 59 // values listed in the app_cmdlines property. 60 static bool atrace_is_cmdline_match(const char* cmdline) 61 { 62 char value[PROPERTY_VALUE_MAX]; 63 char* start = value; 64 65 property_get("debug.atrace.app_cmdlines", value, ""); 66 67 while (start != NULL) { 68 char* end = strchr(start, ','); 69 70 if (end != NULL) { 71 *end = '\0'; 72 end++; 73 } 74 75 if (strcmp(cmdline, start) == 0) { 76 return true; 77 } 78 79 start = end; 80 } 81 82 return false; 83 } 84 85 // Determine whether application-level tracing is enabled for this process. 86 static bool atrace_is_app_tracing_enabled() 87 { 88 bool sys_debuggable = false; 89 bool proc_debuggable = false; 90 char value[PROPERTY_VALUE_MAX]; 91 bool result = false; 92 93 // Check whether the system is debuggable. 94 property_get("ro.debuggable", value, "0"); 95 if (value[0] == '1') { 96 sys_debuggable = true; 97 } 98 99 if (sys_debuggable || atrace_is_debuggable) { 100 // Check whether tracing is enabled for this process. 101 FILE * file = fopen("/proc/self/cmdline", "r"); 102 if (file) { 103 char cmdline[4096]; 104 if (fgets(cmdline, sizeof(cmdline), file)) { 105 result = atrace_is_cmdline_match(cmdline); 106 } else { 107 ALOGE("Error reading cmdline: %s (%d)", strerror(errno), errno); 108 } 109 fclose(file); 110 } else { 111 ALOGE("Error opening /proc/self/cmdline: %s (%d)", strerror(errno), 112 errno); 113 } 114 } 115 116 return result; 117 } 118 119 // Read the sysprop and return the value tags should be set to 120 static uint64_t atrace_get_property() 121 { 122 char value[PROPERTY_VALUE_MAX]; 123 char *endptr; 124 uint64_t tags; 125 126 property_get("debug.atrace.tags.enableflags", value, "0"); 127 errno = 0; 128 tags = strtoull(value, &endptr, 0); 129 if (value[0] == '\0' || *endptr != '\0') { 130 ALOGE("Error parsing trace property: Not a number: %s", value); 131 return 0; 132 } else if (errno == ERANGE || tags == ULLONG_MAX) { 133 ALOGE("Error parsing trace property: Number too large: %s", value); 134 return 0; 135 } 136 137 // Only set the "app" tag if this process was selected for app-level debug 138 // tracing. 139 if (atrace_is_app_tracing_enabled()) { 140 tags |= ATRACE_TAG_APP; 141 } else { 142 tags &= ~ATRACE_TAG_APP; 143 } 144 145 return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK; 146 } 147 148 // Update tags if tracing is ready. Useful as a sysprop change callback. 149 void atrace_update_tags() 150 { 151 uint64_t tags; 152 if (CC_UNLIKELY(android_atomic_acquire_load(&atrace_is_ready))) { 153 if (android_atomic_acquire_load(&atrace_is_enabled)) { 154 tags = atrace_get_property(); 155 pthread_mutex_lock(&atrace_tags_mutex); 156 atrace_enabled_tags = tags; 157 pthread_mutex_unlock(&atrace_tags_mutex); 158 } else { 159 // Tracing is disabled for this process, so we simply don't 160 // initialize the tags. 161 pthread_mutex_lock(&atrace_tags_mutex); 162 atrace_enabled_tags = ATRACE_TAG_NOT_READY; 163 pthread_mutex_unlock(&atrace_tags_mutex); 164 } 165 } 166 } 167 168 static void atrace_init_once() 169 { 170 atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY); 171 if (atrace_marker_fd == -1) { 172 ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno); 173 atrace_enabled_tags = 0; 174 goto done; 175 } 176 177 atrace_enabled_tags = atrace_get_property(); 178 179 done: 180 android_atomic_release_store(1, &atrace_is_ready); 181 } 182 183 void atrace_setup() 184 { 185 pthread_once(&atrace_once_control, atrace_init_once); 186 } 187
