774f929991
This change adds support for tracing using the ATRACE_TAG_APP tag. This tag is enabled only for processes in which the /proc/<pid>/cmdline value appears in the comma-separated list of such values in the debug.atrace.app_cmdlines system property. It is also only enabled if either the ro.debuggable system property is set to 1 or the application has declared itself debuggable in its manifest, which gets reported to libcutils by the framework. Change-Id: Ic94ba55f4e70a9cf994056acbf151e523428b65d
168 lines
4.8 KiB
C
168 lines
4.8 KiB
C
/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <pthread.h>
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#include <stdbool.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/types.h>
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#include <cutils/atomic.h>
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#include <cutils/compiler.h>
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#include <cutils/properties.h>
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#include <cutils/trace.h>
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#define LOG_TAG "cutils-trace"
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#include <cutils/log.h>
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int32_t atrace_is_ready = 0;
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int atrace_marker_fd = -1;
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uint64_t atrace_enabled_tags = ATRACE_TAG_NOT_READY;
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static bool atrace_is_debuggable = false;
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static pthread_once_t atrace_once_control = PTHREAD_ONCE_INIT;
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static pthread_mutex_t atrace_tags_mutex = PTHREAD_MUTEX_INITIALIZER;
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// Set whether this process is debuggable, which determines whether
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// application-level tracing is allowed when the ro.debuggable system property
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// is not set to '1'.
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void atrace_set_debuggable(bool debuggable)
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{
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atrace_is_debuggable = debuggable;
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atrace_update_tags();
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}
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// Check whether the given command line matches one of the comma-separated
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// values listed in the app_cmdlines property.
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static bool atrace_is_cmdline_match(const char* cmdline) {
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char value[PROPERTY_VALUE_MAX];
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char* start = value;
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property_get("debug.atrace.app_cmdlines", value, "");
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while (start != NULL) {
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char* end = strchr(start, ',');
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if (end != NULL) {
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*end = '\0';
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end++;
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}
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if (strcmp(cmdline, start) == 0) {
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return true;
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}
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start = end;
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}
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return false;
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}
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// Determine whether application-level tracing is enabled for this process.
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static bool atrace_is_app_tracing_enabled()
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{
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bool sys_debuggable = false;
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bool proc_debuggable = false;
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char value[PROPERTY_VALUE_MAX];
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bool result = false;
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// Check whether the system is debuggable.
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property_get("ro.debuggable", value, "0");
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if (value[0] == '1') {
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sys_debuggable = true;
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}
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if (sys_debuggable || atrace_is_debuggable) {
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// Check whether tracing is enabled for this process.
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FILE * file = fopen("/proc/self/cmdline", "r");
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if (file) {
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char cmdline[4096];
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if (fgets(cmdline, sizeof(cmdline), file)) {
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result = atrace_is_cmdline_match(cmdline);
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} else {
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ALOGE("Error reading cmdline: %s (%d)", strerror(errno), errno);
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}
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fclose(file);
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} else {
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ALOGE("Error opening /proc/self/cmdline: %s (%d)", strerror(errno),
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errno);
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}
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}
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return result;
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}
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// Read the sysprop and return the value tags should be set to
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static uint64_t atrace_get_property()
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{
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char value[PROPERTY_VALUE_MAX];
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char *endptr;
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uint64_t tags;
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property_get("debug.atrace.tags.enableflags", value, "0");
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errno = 0;
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tags = strtoull(value, &endptr, 0);
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if (value[0] == '\0' || *endptr != '\0') {
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ALOGE("Error parsing trace property: Not a number: %s", value);
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return 0;
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} else if (errno == ERANGE || tags == ULLONG_MAX) {
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ALOGE("Error parsing trace property: Number too large: %s", value);
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return 0;
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}
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// Only set the "app" tag if this process was selected for app-level debug
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// tracing.
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if (atrace_is_app_tracing_enabled()) {
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tags |= ATRACE_TAG_APP;
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} else {
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tags &= ~ATRACE_TAG_APP;
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}
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return (tags | ATRACE_TAG_ALWAYS) & ATRACE_TAG_VALID_MASK;
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}
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// Update tags if tracing is ready. Useful as a sysprop change callback.
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void atrace_update_tags()
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{
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uint64_t tags;
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if (CC_UNLIKELY(android_atomic_acquire_load(&atrace_is_ready))) {
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tags = atrace_get_property();
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pthread_mutex_lock(&atrace_tags_mutex);
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atrace_enabled_tags = tags;
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pthread_mutex_unlock(&atrace_tags_mutex);
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}
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}
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static void atrace_init_once()
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{
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atrace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_WRONLY);
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if (atrace_marker_fd == -1) {
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ALOGE("Error opening trace file: %s (%d)", strerror(errno), errno);
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atrace_enabled_tags = 0;
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goto done;
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}
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atrace_enabled_tags = atrace_get_property();
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done:
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android_atomic_release_store(1, &atrace_is_ready);
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}
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void atrace_setup()
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{
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pthread_once(&atrace_once_control, atrace_init_once);
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}
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