| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| #define ATRACE_TAG ATRACE_TAG_ALWAYS |
| #include "event_fd.h" |
| |
| #include <fcntl.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <sys/ioctl.h> |
| #include <sys/mman.h> |
| #include <sys/syscall.h> |
| #include <sys/types.h> |
| #include <atomic> |
| #include <memory> |
| #include <cutils/trace.h> |
| #include <utils/Trace.h> |
| |
| #include <android-base/file.h> |
| #include <android-base/logging.h> |
| #include <android-base/stringprintf.h> |
| |
| #include "event_attr.h" |
| #include "event_type.h" |
| #include "perf_event.h" |
| #include "utils.h" |
| |
| static int perf_event_open(const perf_event_attr& attr, pid_t pid, int cpu, |
| int group_fd, unsigned long flags) { // NOLINT |
| return syscall(__NR_perf_event_open, &attr, pid, cpu, group_fd, flags); |
| } |
| |
| std::unique_ptr<EventFd> EventFd::OpenEventFile(const perf_event_attr& attr, |
| pid_t tid, int cpu, |
| EventFd* group_event_fd, |
| bool report_error) { |
| std::string event_name = GetEventNameByAttr(attr); |
| int group_fd = -1; |
| if (group_event_fd != nullptr) { |
| group_fd = group_event_fd->perf_event_fd_; |
| } |
| int perf_event_fd = perf_event_open(attr, tid, cpu, group_fd, 0); |
| if (perf_event_fd == -1) { |
| if (report_error) { |
| PLOG(ERROR) << "open perf_event_file (event " << event_name << ", tid " |
| << tid << ", cpu " << cpu << ", group_fd " << group_fd |
| << ") failed"; |
| } else { |
| PLOG(DEBUG) << "open perf_event_file (event " << event_name << ", tid " |
| << tid << ", cpu " << cpu << ", group_fd " << group_fd |
| << ") failed"; |
| } |
| return nullptr; |
| } |
| if (fcntl(perf_event_fd, F_SETFD, FD_CLOEXEC) == -1) { |
| if (report_error) { |
| PLOG(ERROR) << "fcntl(FD_CLOEXEC) for perf_event_file (event " |
| << event_name << ", tid " << tid << ", cpu " << cpu |
| << ", group_fd " << group_fd << ") failed"; |
| } else { |
| PLOG(DEBUG) << "fcntl(FD_CLOEXEC) for perf_event_file (event " |
| << event_name << ", tid " << tid << ", cpu " << cpu |
| << ", group_fd " << group_fd << ") failed"; |
| } |
| return nullptr; |
| } |
| return std::unique_ptr<EventFd>( |
| new EventFd(attr, perf_event_fd, event_name, tid, cpu)); |
| } |
| |
| EventFd::~EventFd() { |
| DestroyMappedBuffer(); |
| close(perf_event_fd_); |
| } |
| |
| std::string EventFd::Name() const { |
| return android::base::StringPrintf( |
| "perf_event_file(event %s, tid %d, cpu %d)", event_name_.c_str(), tid_, |
| cpu_); |
| } |
| |
| uint64_t EventFd::Id() const { |
| if (id_ == 0) { |
| PerfCounter counter; |
| if (ReadCounter(&counter)) { |
| id_ = counter.id; |
| } |
| } |
| return id_; |
| } |
| |
| bool EventFd::EnableEvent() { |
| int result = ioctl(perf_event_fd_, PERF_EVENT_IOC_ENABLE, 0); |
| if (result < 0) { |
| PLOG(ERROR) << "ioctl(enable) " << Name() << " failed"; |
| return false; |
| } |
| return true; |
| } |
| |
| bool EventFd::ReadCounter(PerfCounter* counter) const { |
| CHECK(counter != nullptr); |
| uint64_t pre_counter = counter->value; |
| if (!android::base::ReadFully(perf_event_fd_, counter, sizeof(*counter))) { |
| PLOG(ERROR) << "ReadCounter from " << Name() << " failed"; |
| return false; |
| } |
| // Trace is always available to systrace if enabled |
| if (tid_ > 0) { |
| ATRACE_INT64(android::base::StringPrintf( |
| "%s_tid%d_cpu%d", event_name_.c_str(), tid_, |
| cpu_).c_str(), counter->value - pre_counter); |
| } else { |
| ATRACE_INT64(android::base::StringPrintf( |
| "%s_cpu%d", event_name_.c_str(), |
| cpu_).c_str(), counter->value - pre_counter); |
| } |
| return true; |
| } |
| |
| bool EventFd::CreateMappedBuffer(size_t mmap_pages, bool report_error) { |
| CHECK(IsPowerOfTwo(mmap_pages)); |
| size_t page_size = sysconf(_SC_PAGE_SIZE); |
| size_t mmap_len = (mmap_pages + 1) * page_size; |
| void* mmap_addr = mmap(nullptr, mmap_len, PROT_READ | PROT_WRITE, MAP_SHARED, |
| perf_event_fd_, 0); |
| if (mmap_addr == MAP_FAILED) { |
| bool is_perm_error = (errno == EPERM); |
| if (report_error) { |
| PLOG(ERROR) << "mmap(" << mmap_pages << ") failed for " << Name(); |
| } else { |
| PLOG(DEBUG) << "mmap(" << mmap_pages << ") failed for " << Name(); |
| } |
| if (report_error && is_perm_error) { |
| LOG(ERROR) |
| << "It seems the kernel doesn't allow allocating enough " |
| << "buffer for dumping samples, consider decreasing mmap pages(-m)."; |
| } |
| return false; |
| } |
| mmap_addr_ = mmap_addr; |
| mmap_len_ = mmap_len; |
| mmap_metadata_page_ = reinterpret_cast<perf_event_mmap_page*>(mmap_addr_); |
| mmap_data_buffer_ = reinterpret_cast<char*>(mmap_addr_) + page_size; |
| mmap_data_buffer_size_ = mmap_len_ - page_size; |
| return true; |
| } |
| |
| bool EventFd::ShareMappedBuffer(const EventFd& event_fd, bool report_error) { |
| CHECK(!HasMappedBuffer()); |
| CHECK(event_fd.HasMappedBuffer()); |
| int result = |
| ioctl(perf_event_fd_, PERF_EVENT_IOC_SET_OUTPUT, event_fd.perf_event_fd_); |
| if (result != 0) { |
| if (report_error) { |
| PLOG(ERROR) << "failed to share mapped buffer of " |
| << event_fd.perf_event_fd_ << " with " << perf_event_fd_; |
| } |
| return false; |
| } |
| return true; |
| } |
| |
| void EventFd::DestroyMappedBuffer() { |
| if (HasMappedBuffer()) { |
| munmap(mmap_addr_, mmap_len_); |
| mmap_addr_ = nullptr; |
| mmap_len_ = 0; |
| mmap_metadata_page_ = nullptr; |
| mmap_data_buffer_ = nullptr; |
| mmap_data_buffer_size_ = 0; |
| } |
| } |
| |
| size_t EventFd::GetAvailableMmapData(std::vector<char>& buffer, size_t& buffer_pos) { |
| if (!HasMappedBuffer()) { |
| return 0; |
| } |
| // The mmap_data_buffer is used as a ring buffer between the kernel and |
| // simpleperf. The kernel continuously writes records to the buffer, and |
| // simpleperf continuously read records out. |
| // _________________________________________ |
| // buffer | can write | can read | can write | |
| // ^ ^ |
| // read_head write_head |
| // |
| // So simpleperf can read records in [read_head, write_head), and the kernel |
| // can write records in [write_head, read_head). The kernel is responsible |
| // for updating write_head, and simpleperf is responsible for updating |
| // read_head. |
| |
| size_t buf_mask = mmap_data_buffer_size_ - 1; |
| size_t write_head = |
| static_cast<size_t>(mmap_metadata_page_->data_head & buf_mask); |
| size_t read_head = |
| static_cast<size_t>(mmap_metadata_page_->data_tail & buf_mask); |
| |
| if (read_head == write_head) { |
| // No available data. |
| return 0; |
| } |
| size_t read_bytes; |
| if (read_head < write_head) { |
| read_bytes = write_head - read_head; |
| } else { |
| read_bytes = mmap_data_buffer_size_ - read_head + write_head; |
| } |
| // Extend the buffer if it is not big enough. |
| if (buffer.size() < buffer_pos + read_bytes) { |
| buffer.resize(buffer_pos + read_bytes); |
| } |
| |
| // rmb() used to ensure reading data after reading data_head. |
| __sync_synchronize(); |
| |
| // Copy records from mapped buffer. Note that records can be wrapped at the |
| // end of the mapped buffer. |
| char* to = &buffer[buffer_pos]; |
| if (read_head < write_head) { |
| char* from = mmap_data_buffer_ + read_head; |
| size_t n = write_head - read_head; |
| memcpy(to, from, n); |
| } else { |
| char* from = mmap_data_buffer_ + read_head; |
| size_t n = mmap_data_buffer_size_ - read_head; |
| memcpy(to, from, n); |
| to += n; |
| from = mmap_data_buffer_; |
| n = write_head; |
| memcpy(to, from, n); |
| } |
| buffer_pos += read_bytes; |
| DiscardMmapData(read_bytes); |
| return read_bytes; |
| } |
| |
| void EventFd::DiscardMmapData(size_t discard_size) { |
| // mb() used to ensure finish reading data before writing data_tail. |
| __sync_synchronize(); |
| mmap_metadata_page_->data_tail += discard_size; |
| } |
| |
| bool EventFd::StartPolling(IOEventLoop& loop, |
| const std::function<bool()>& callback) { |
| ioevent_ref_ = loop.AddReadEvent(perf_event_fd_, callback); |
| return ioevent_ref_ != nullptr; |
| } |
| |
| bool EventFd::StopPolling() { return IOEventLoop::DelEvent(ioevent_ref_); } |
| |
| bool IsEventAttrSupportedByKernel(perf_event_attr attr) { |
| auto event_fd = EventFd::OpenEventFile(attr, getpid(), -1, nullptr, false); |
| return event_fd != nullptr; |
| } |