ad5f772dba
tracefs will be mounted at /sys/kernel/tracing when debugfs is not mounted. Bug: 134669095 Test: atest bionic-unit-tests-static Change-Id: Ic224cf13500efc570da8b6a27ce925bbcf068fdd
105 lines
2.8 KiB
C++
105 lines
2.8 KiB
C++
/*
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* Copyright (C) 2014 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 <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "private/bionic_lock.h"
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#include "private/bionic_systrace.h"
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#include "private/CachedProperty.h"
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#include <async_safe/log.h>
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#include <cutils/trace.h> // For ATRACE_TAG_BIONIC.
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#define WRITE_OFFSET 32
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static Lock g_lock;
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static CachedProperty g_debug_atrace_tags_enableflags("debug.atrace.tags.enableflags");
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static uint64_t g_tags;
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static int g_trace_marker_fd = -1;
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static bool should_trace() {
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g_lock.lock();
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if (g_debug_atrace_tags_enableflags.DidChange()) {
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g_tags = strtoull(g_debug_atrace_tags_enableflags.Get(), nullptr, 0);
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}
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g_lock.unlock();
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return ((g_tags & ATRACE_TAG_BIONIC) != 0);
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}
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static int get_trace_marker_fd() {
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g_lock.lock();
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if (g_trace_marker_fd == -1) {
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g_trace_marker_fd = open("/sys/kernel/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
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if (g_trace_marker_fd == -1) {
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g_trace_marker_fd = open("/sys/kernel/debug/tracing/trace_marker", O_CLOEXEC | O_WRONLY);
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}
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}
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g_lock.unlock();
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return g_trace_marker_fd;
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}
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void bionic_trace_begin(const char* message) {
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if (!should_trace()) {
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return;
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}
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int trace_marker_fd = get_trace_marker_fd();
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if (trace_marker_fd == -1) {
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return;
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}
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// If bionic tracing has been enabled, then write the message to the
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// kernel trace_marker.
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int length = strlen(message);
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char buf[length + WRITE_OFFSET];
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size_t len = async_safe_format_buffer(buf, length + WRITE_OFFSET, "B|%d|%s", getpid(), message);
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// Tracing may stop just after checking property and before writing the message.
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// So the write is acceptable to fail. See b/20666100.
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TEMP_FAILURE_RETRY(write(trace_marker_fd, buf, len));
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}
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void bionic_trace_end() {
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if (!should_trace()) {
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return;
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}
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int trace_marker_fd = get_trace_marker_fd();
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if (trace_marker_fd == -1) {
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return;
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}
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TEMP_FAILURE_RETRY(write(trace_marker_fd, "E|", 2));
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}
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ScopedTrace::ScopedTrace(const char* message) : called_end_(false) {
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bionic_trace_begin(message);
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}
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ScopedTrace::~ScopedTrace() {
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End();
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}
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void ScopedTrace::End() {
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if (!called_end_) {
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bionic_trace_end();
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called_end_ = true;
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}
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}
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