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329 lines
11 KiB
329 lines
11 KiB
/*
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* Copyright (C) 2015 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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#define ATRACE_TAG ATRACE_TAG_ALWAYS
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#include "event_fd.h"
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#include <cutils/trace.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <utils/Trace.h>
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#include <atomic>
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#include <memory>
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#include <android-base/file.h>
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#include <android-base/logging.h>
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#include <android-base/stringprintf.h>
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#include "environment.h"
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#include "event_attr.h"
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#include "event_type.h"
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#include "perf_event.h"
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#include "utils.h"
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namespace simpleperf {
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static int perf_event_open(const perf_event_attr& attr, pid_t pid, int cpu, int group_fd,
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unsigned long flags) { // NOLINT
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return syscall(__NR_perf_event_open, &attr, pid, cpu, group_fd, flags);
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}
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std::unique_ptr<EventFd> EventFd::OpenEventFile(const perf_event_attr& attr, pid_t tid, int cpu,
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EventFd* group_event_fd,
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const std::string& event_name, bool report_error) {
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int group_fd = -1;
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if (group_event_fd != nullptr) {
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group_fd = group_event_fd->perf_event_fd_;
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}
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perf_event_attr real_attr = attr;
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if (attr.freq) {
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uint64_t max_sample_freq;
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if (GetMaxSampleFrequency(&max_sample_freq) && max_sample_freq < attr.sample_freq) {
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static bool warned = false;
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if (!warned) {
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warned = true;
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LOG(INFO) << "Adjust sample freq to max allowed sample freq " << max_sample_freq;
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}
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real_attr.sample_freq = max_sample_freq;
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}
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}
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int perf_event_fd = perf_event_open(real_attr, tid, cpu, group_fd, 0);
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if (perf_event_fd == -1) {
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if (report_error) {
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PLOG(ERROR) << "open perf_event_file (event " << event_name << ", tid " << tid << ", cpu "
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<< cpu << ", group_fd " << group_fd << ") failed";
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} else {
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PLOG(DEBUG) << "open perf_event_file (event " << event_name << ", tid " << tid << ", cpu "
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<< cpu << ", group_fd " << group_fd << ") failed";
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}
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return nullptr;
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}
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if (fcntl(perf_event_fd, F_SETFD, FD_CLOEXEC) == -1) {
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if (report_error) {
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PLOG(ERROR) << "fcntl(FD_CLOEXEC) for perf_event_file (event " << event_name << ", tid "
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<< tid << ", cpu " << cpu << ", group_fd " << group_fd << ") failed";
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} else {
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PLOG(DEBUG) << "fcntl(FD_CLOEXEC) for perf_event_file (event " << event_name << ", tid "
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<< tid << ", cpu " << cpu << ", group_fd " << group_fd << ") failed";
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}
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return nullptr;
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}
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return std::unique_ptr<EventFd>(new EventFd(real_attr, perf_event_fd, event_name, tid, cpu));
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}
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EventFd::~EventFd() {
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DestroyMappedBuffer();
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DestroyAuxBuffer();
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close(perf_event_fd_);
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}
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std::string EventFd::Name() const {
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return android::base::StringPrintf("perf_event_file(event %s, tid %d, cpu %d)",
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event_name_.c_str(), tid_, cpu_);
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}
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uint64_t EventFd::Id() const {
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if (id_ == 0) {
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PerfCounter counter;
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if (InnerReadCounter(&counter)) {
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id_ = counter.id;
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}
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}
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return id_;
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}
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bool EventFd::SetEnableEvent(bool enable) {
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int result = ioctl(perf_event_fd_, enable ? PERF_EVENT_IOC_ENABLE : PERF_EVENT_IOC_DISABLE, 0);
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if (result < 0) {
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PLOG(ERROR) << "ioctl(" << (enable ? "enable" : "disable") << ")" << Name() << " failed";
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return false;
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}
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return true;
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}
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bool EventFd::SetFilter(const std::string& filter) {
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bool success = ioctl(perf_event_fd_, PERF_EVENT_IOC_SET_FILTER, filter.c_str()) >= 0;
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if (!success) {
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PLOG(ERROR) << "failed to set filter";
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}
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return success;
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}
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bool EventFd::InnerReadCounter(PerfCounter* counter) const {
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CHECK(counter != nullptr);
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if (!android::base::ReadFully(perf_event_fd_, counter, sizeof(*counter))) {
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PLOG(ERROR) << "ReadCounter from " << Name() << " failed";
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return false;
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}
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return true;
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}
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bool EventFd::ReadCounter(PerfCounter* counter) {
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if (!InnerReadCounter(counter)) {
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return false;
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}
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// Trace is always available to systrace if enabled
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if (tid_ > 0) {
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ATRACE_INT64(
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android::base::StringPrintf("%s_tid%d_cpu%d", event_name_.c_str(), tid_, cpu_).c_str(),
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counter->value - last_counter_value_);
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} else {
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ATRACE_INT64(android::base::StringPrintf("%s_cpu%d", event_name_.c_str(), cpu_).c_str(),
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counter->value - last_counter_value_);
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}
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last_counter_value_ = counter->value;
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return true;
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}
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bool EventFd::CreateMappedBuffer(size_t mmap_pages, bool report_error) {
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CHECK(IsPowerOfTwo(mmap_pages));
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size_t page_size = sysconf(_SC_PAGE_SIZE);
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size_t mmap_len = (mmap_pages + 1) * page_size;
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void* mmap_addr = mmap(nullptr, mmap_len, PROT_READ | PROT_WRITE, MAP_SHARED, perf_event_fd_, 0);
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if (mmap_addr == MAP_FAILED) {
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bool is_perm_error = (errno == EPERM);
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if (report_error) {
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PLOG(ERROR) << "mmap(" << mmap_pages << ") failed for " << Name();
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} else {
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PLOG(DEBUG) << "mmap(" << mmap_pages << ") failed for " << Name();
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}
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if (report_error && is_perm_error) {
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LOG(ERROR) << "It seems the kernel doesn't allow allocating enough "
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<< "buffer for dumping samples, consider decreasing mmap pages(-m).";
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}
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return false;
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}
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mmap_addr_ = mmap_addr;
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mmap_len_ = mmap_len;
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mmap_metadata_page_ = reinterpret_cast<perf_event_mmap_page*>(mmap_addr_);
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mmap_data_buffer_ = reinterpret_cast<char*>(mmap_addr_) + page_size;
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mmap_data_buffer_size_ = mmap_len_ - page_size;
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return true;
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}
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bool EventFd::ShareMappedBuffer(const EventFd& event_fd, bool report_error) {
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CHECK(!HasMappedBuffer());
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CHECK(event_fd.HasMappedBuffer());
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int result = ioctl(perf_event_fd_, PERF_EVENT_IOC_SET_OUTPUT, event_fd.perf_event_fd_);
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if (result != 0) {
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if (report_error) {
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PLOG(ERROR) << "failed to share mapped buffer of " << event_fd.perf_event_fd_ << " with "
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<< perf_event_fd_;
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}
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return false;
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}
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return true;
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}
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void EventFd::DestroyMappedBuffer() {
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if (HasMappedBuffer()) {
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munmap(mmap_addr_, mmap_len_);
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mmap_addr_ = nullptr;
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mmap_len_ = 0;
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mmap_metadata_page_ = nullptr;
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mmap_data_buffer_ = nullptr;
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mmap_data_buffer_size_ = 0;
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}
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}
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std::vector<char> EventFd::GetAvailableMmapData() {
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size_t data_pos;
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size_t data_size = GetAvailableMmapDataSize(data_pos);
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std::vector<char> data(data_size);
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if (data_size > 0) {
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size_t copy_size = std::min(data_size, mmap_data_buffer_size_ - data_pos);
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memcpy(&data[0], mmap_data_buffer_ + data_pos, copy_size);
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if (copy_size < data_size) {
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memcpy(&data[copy_size], mmap_data_buffer_, data_size - copy_size);
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}
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DiscardMmapData(data_size);
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}
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return data;
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}
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size_t EventFd::GetAvailableMmapDataSize(size_t& data_pos) {
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// The mmap_data_buffer is used as a ring buffer between the kernel and
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// simpleperf. The kernel continuously writes records to the buffer, and
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// simpleperf continuously read records out.
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// _________________________________________
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// buffer | can write | can read | can write |
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// ^ ^
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// read_head write_head
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//
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// So simpleperf can read records in [read_head, write_head), and the kernel
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// can write records in [write_head, read_head). The kernel is responsible
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// for updating write_head, and simpleperf is responsible for updating
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// read_head.
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uint64_t write_head = mmap_metadata_page_->data_head;
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uint64_t read_head = mmap_metadata_page_->data_tail;
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// The kernel may decrease data_head temporarily (http://b/132446871), making
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// write_head < read_head. So check it to avoid available data size underflow.
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if (write_head <= read_head) {
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// No available data.
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return 0;
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}
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// rmb() used to ensure reading data after reading data_head.
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__sync_synchronize();
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data_pos = read_head & (mmap_data_buffer_size_ - 1);
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return write_head - read_head;
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}
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void EventFd::DiscardMmapData(size_t discard_size) {
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// mb() used to ensure finish reading data before writing data_tail.
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__sync_synchronize();
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mmap_metadata_page_->data_tail += discard_size;
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}
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bool EventFd::CreateAuxBuffer(size_t aux_buffer_size, bool report_error) {
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CHECK(HasMappedBuffer());
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CHECK(IsPowerOfTwo(aux_buffer_size));
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mmap_metadata_page_->aux_offset = mmap_len_;
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mmap_metadata_page_->aux_size = aux_buffer_size;
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mmap_metadata_page_->aux_head = 0;
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mmap_metadata_page_->aux_tail = 0;
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void* mmap_addr = mmap(nullptr, aux_buffer_size, PROT_READ | PROT_WRITE, MAP_SHARED,
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perf_event_fd_, mmap_metadata_page_->aux_offset);
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if (mmap_addr == MAP_FAILED) {
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if (report_error) {
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PLOG(ERROR) << "failed to mmap aux buffer of size " << aux_buffer_size << " for " << Name();
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} else {
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PLOG(DEBUG) << "failed to mmap aux buffer of size " << aux_buffer_size << " for " << Name();
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}
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return false;
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}
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aux_buffer_ = static_cast<char*>(mmap_addr);
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aux_buffer_size_ = aux_buffer_size;
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return true;
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}
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void EventFd::DestroyAuxBuffer() {
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if (HasAuxBuffer()) {
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munmap(aux_buffer_, aux_buffer_size_);
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aux_buffer_ = nullptr;
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aux_buffer_size_ = 0;
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}
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}
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uint64_t EventFd::GetAvailableAuxData(char** buf1, size_t* size1, char** buf2, size_t* size2) {
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// Aux buffer is similar to mapped_data_buffer. See comments in GetAvailableMmapData().
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uint64_t write_head = mmap_metadata_page_->aux_head;
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uint64_t read_head = mmap_metadata_page_->aux_tail;
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if (write_head <= read_head) {
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*size1 = *size2 = 0;
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return 0; // No available data.
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}
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// rmb() used to ensure reading data after reading aux_head.
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__sync_synchronize();
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size_t data_pos = read_head & (aux_buffer_size_ - 1);
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size_t data_size = write_head - read_head;
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*buf1 = aux_buffer_ + data_pos;
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if (data_size <= aux_buffer_size_ - data_pos) {
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*size1 = data_size;
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*size2 = 0;
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} else {
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*size1 = aux_buffer_size_ - data_pos;
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*buf2 = aux_buffer_;
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*size2 = data_size - *size1;
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}
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return read_head;
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}
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void EventFd::DiscardAuxData(size_t discard_size) {
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// mb() used to ensure finish reading data before writing aux_tail.
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__sync_synchronize();
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mmap_metadata_page_->aux_tail += discard_size;
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}
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bool EventFd::StartPolling(IOEventLoop& loop, const std::function<bool()>& callback) {
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ioevent_ref_ = loop.AddReadEvent(perf_event_fd_, callback);
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return ioevent_ref_ != nullptr;
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}
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bool EventFd::StopPolling() {
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return IOEventLoop::DelEvent(ioevent_ref_);
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}
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bool IsEventAttrSupported(const perf_event_attr& attr, const std::string& event_name) {
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return EventFd::OpenEventFile(attr, getpid(), -1, nullptr, event_name, false) != nullptr;
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}
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} // namespace simpleperf
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