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#define LOG_TAG "cutils-trace" 18 19#include <errno.h> 20#include <fcntl.h> 21#include <limits.h> 22#include <pthread.h> 23#include <stdatomic.h> 24#include <stdbool.h> 25#include <stdlib.h> 26#include <string.h> 27#include <sys/types.h> 28 29#include <cutils/compiler.h> 30#include <cutils/properties.h> 31#include <cutils/trace.h> 32#include <log/log.h> 33#include <log/log_properties.h> 34 35/** 36 * Maximum size of a message that can be logged to the trace buffer. 37 * Note this message includes a tag, the pid, and the string given as the name. 38 * Names should be kept short to get the most use of the trace buffer. 39 */ 40#define ATRACE_MESSAGE_LENGTH 1024 41 42atomic_bool atrace_is_ready = ATOMIC_VAR_INIT(false); 43int atrace_marker_fd = -1; 44uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY; 45static bool atrace_is_debuggable = false; 46static atomic_bool atrace_is_enabled = ATOMIC_VAR_INIT(true); 47static pthread_once_t atrace_once_control = PTHREAD_ONCE_INIT; 48static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER; 49 50// Set whether this process is debuggable, which determines whether 51// application-level tracing is allowed when the ro.debuggable system property 52// is not set to '1'. 53void atrace_set_debuggable(bool debuggable) 54{ 55 atrace_is_debuggable = debuggable; 56 atrace_update_tags(); 57} 58 59// Set whether tracing is enabled in this process. This is used to prevent 60// the Zygote process from tracing. 61void atrace_set_tracing_enabled(bool enabled) 62{ 63 atomic_store_explicit(&atrace_is_enabled, enabled, memory_order_release); 64 atrace_update_tags(); 65} 66 67// Check whether the given command line matches one of the comma-separated 68// values listed in the app_cmdlines property. 69static bool atrace_is_cmdline_match(const char* cmdline) 70{ 71 int count = property_get_int32("debug.atrace.app_number", 0); 72 73 char buf[PROPERTY_KEY_MAX]; 74 char value[PROPERTY_VALUE_MAX]; 75 76 for (int i = 0; i < count; i++) { 77 snprintf(buf, sizeof(buf), "debug.atrace.app_%d", i); 78 property_get(buf, value, ""); 79 if (strcmp(value, cmdline) == 0) { 80 return true; 81 } 82 } 83 84 return false; 85} 86 87// Determine whether application-level tracing is enabled for this process. 88static bool atrace_is_app_tracing_enabled() 89{ 90 bool sys_debuggable = __android_log_is_debuggable(); 91 bool result = false; 92 93 if (sys_debuggable || atrace_is_debuggable) { 94 // Check whether tracing is enabled for this process. 95 FILE * file = fopen("/proc/self/cmdline", "re"); 96 if (file) { 97 char cmdline[4096]; 98 if (fgets(cmdline, sizeof(cmdline), file)) { 99 result = atrace_is_cmdline_match(cmdline); 100 } else { 101 ALOGE("Error reading cmdline: %s (%d)", strerror(errno), errno); 102 } 103 fclose(file); 104 } else { 105 ALOGE("Error opening /proc/self/cmdline: %s (%d)", strerror(errno), 106 errno); 107 } 108 } 109 110 return result; 111} 112 113// Read the sysprop and return the value tags should be set to 114static uint64_t atrace_get_property() 115{ 116 char value[PROPERTY_VALUE_MAX]; 117 char *endptr; 118 uint64_t tags; 119 120 property_get("debug.atrace.tags.enableflags", value, "0"); 121 errno = 0; 122 tags = strtoull(value, &endptr, 0); 123 if (value[0] == '\0' || *endptr != '\0') { 124 ALOGE("Error parsing trace property: Not a number: %s", value); 125 return 0; 126 } else if (errno == ERANGE || tags == ULLONG_MAX) { 127 ALOGE("Error parsing trace property: Number too large: %s", value); 128 return 0; 129 } 130 131 // Only set the "app" tag if this process was selected for app-level debug 132 // tracing. 133 if (atrace_is_app_tracing_enabled()) { 134 tags |= ATRACE_TAG_APP; 135 } else { 136 tags &= ~ATRACE_TAG_APP; 137 } 138 139 return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK; 140} 141 142// Update tags if tracing is ready. Useful as a sysprop change callback. 143void atrace_update_tags() 144{ 145 uint64_t tags; 146 if (CC_UNLIKELY(atomic_load_explicit(&atrace_is_ready, memory_order_acquire))) { 147 if (atomic_load_explicit(&atrace_is_enabled, memory_order_acquire)) { 148 tags = atrace_get_property(); 149 pthread_mutex_lock(&atrace_tags_mutex); 150 atrace_enabled_tags = tags; 151 pthread_mutex_unlock(&atrace_tags_mutex); 152 } else { 153 // Tracing is disabled for this process, so we simply don't 154 // initialize the tags. 155 pthread_mutex_lock(&atrace_tags_mutex); 156 atrace_enabled_tags = ATRACE_TAG_NOT_READY; 157 pthread_mutex_unlock(&atrace_tags_mutex); 158 } 159 } 160} 161 162static void atrace_init_once() 163{ 164 atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY | O_CLOEXEC); 165 if (atrace_marker_fd == -1) { 166 ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno); 167 atrace_enabled_tags = 0; 168 goto done; 169 } 170 171 atrace_enabled_tags = atrace_get_property(); 172 173done: 174 atomic_store_explicit(&atrace_is_ready, true, memory_order_release); 175} 176 177void atrace_setup() 178{ 179 pthread_once(&atrace_once_control, atrace_init_once); 180} 181 182void atrace_begin_body(const char* name) 183{ 184 char buf[ATRACE_MESSAGE_LENGTH]; 185 186 int len = snprintf(buf, sizeof(buf), "B|%d|%s", getpid(), name); 187 if (len >= (int) sizeof(buf)) { 188 ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name); 189 len = sizeof(buf) - 1; 190 } 191 write(atrace_marker_fd, buf, len); 192} 193 194void atrace_end_body() 195{ 196 char c = 'E'; 197 write(atrace_marker_fd, &c, 1); 198} 199 200#define WRITE_MSG(format_begin, format_end, pid, name, value) { \ 201 char buf[ATRACE_MESSAGE_LENGTH]; \ 202 int len = snprintf(buf, sizeof(buf), format_begin "%s" format_end, pid, \ 203 name, value); \ 204 if (len >= (int) sizeof(buf)) { \ 205 /* Given the sizeof(buf), and all of the current format buffers, \ 206 * it is impossible for name_len to be < 0 if len >= sizeof(buf). */ \ 207 int name_len = strlen(name) - (len - sizeof(buf)) - 1; \ 208 /* Truncate the name to make the message fit. */ \ 209 ALOGW("Truncated name in %s: %s\n", __FUNCTION__, name); \ 210 len = snprintf(buf, sizeof(buf), format_begin "%.*s" format_end, pid, \ 211 name_len, name, value); \ 212 } \ 213 write(atrace_marker_fd, buf, len); \ 214} 215 216void atrace_async_begin_body(const char* name, int32_t cookie) 217{ 218 WRITE_MSG("S|%d|", "|%" PRId32, getpid(), name, cookie); 219} 220 221void atrace_async_end_body(const char* name, int32_t cookie) 222{ 223 WRITE_MSG("F|%d|", "|%" PRId32, getpid(), name, cookie); 224} 225 226void atrace_int_body(const char* name, int32_t value) 227{ 228 WRITE_MSG("C|%d|", "|%" PRId32, getpid(), name, value); 229} 230 231void atrace_int64_body(const char* name, int64_t value) 232{ 233 WRITE_MSG("C|%d|", "|%" PRId64, getpid(), name, value); 234} 235