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