| /* |
| * 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. |
| */ |
| |
| #include "event_fd.h" |
| |
| #include <fcntl.h> |
| #include <stdio.h> |
| #include <sys/ioctl.h> |
| #include <sys/mman.h> |
| #include <sys/syscall.h> |
| #include <sys/types.h> |
| #include <memory> |
| |
| #include <base/file.h> |
| #include <base/logging.h> |
| #include <base/stringprintf.h> |
| |
| #include "event_type.h" |
| #include "perf_event.h" |
| #include "utils.h" |
| |
| static int perf_event_open(perf_event_attr* attr, pid_t pid, int cpu, int group_fd, |
| unsigned long flags) { |
| return syscall(__NR_perf_event_open, attr, pid, cpu, group_fd, flags); |
| } |
| |
| std::unique_ptr<EventFd> EventFd::OpenEventFileForProcess(const perf_event_attr& attr, pid_t pid) { |
| return OpenEventFile(attr, pid, -1); |
| } |
| |
| std::unique_ptr<EventFd> EventFd::OpenEventFileForCpu(const perf_event_attr& attr, int cpu) { |
| return OpenEventFile(attr, -1, cpu); |
| } |
| |
| std::unique_ptr<EventFd> EventFd::OpenEventFile(const perf_event_attr& attr, pid_t pid, int cpu) { |
| perf_event_attr perf_attr = attr; |
| std::string event_name = "unknown event"; |
| const EventType* event_type = |
| EventTypeFactory::FindEventTypeByConfig(perf_attr.type, perf_attr.config); |
| if (event_type != nullptr) { |
| event_name = event_type->name; |
| } |
| int perf_event_fd = perf_event_open(&perf_attr, pid, cpu, -1, 0); |
| if (perf_event_fd == -1) { |
| // It depends whether the perf_event_file configuration is supported by the kernel and the |
| // machine. So fail to open the file is not an error. |
| PLOG(DEBUG) << "open perf_event_file (event " << event_name << ", pid " << pid << ", cpu " |
| << cpu << ") failed"; |
| return nullptr; |
| } |
| if (fcntl(perf_event_fd, F_SETFD, FD_CLOEXEC) == -1) { |
| PLOG(ERROR) << "fcntl(FD_CLOEXEC) for perf_event_file (event " << event_name << ", pid " << pid |
| << ", cpu " << cpu << ") failed"; |
| return nullptr; |
| } |
| return std::unique_ptr<EventFd>(new EventFd(perf_event_fd, event_name, pid, cpu)); |
| } |
| |
| EventFd::~EventFd() { |
| if (mmap_addr_ != nullptr) { |
| munmap(mmap_addr_, mmap_len_); |
| } |
| close(perf_event_fd_); |
| } |
| |
| std::string EventFd::Name() const { |
| return android::base::StringPrintf("perf_event_file(event %s, pid %d, cpu %d)", |
| event_name_.c_str(), pid_, 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::DisableEvent() { |
| int result = ioctl(perf_event_fd_, PERF_EVENT_IOC_DISABLE, 0); |
| if (result < 0) { |
| PLOG(ERROR) << "ioctl(disable) " << Name() << " failed"; |
| return false; |
| } |
| return true; |
| } |
| |
| bool EventFd::ReadCounter(PerfCounter* counter) const { |
| CHECK(counter != nullptr); |
| if (!android::base::ReadFully(perf_event_fd_, counter, sizeof(*counter))) { |
| PLOG(ERROR) << "ReadCounter from " << Name() << " failed"; |
| return false; |
| } |
| return true; |
| } |
| |
| bool EventFd::MmapContent(size_t mmap_pages) { |
| 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) { |
| PLOG(ERROR) << "mmap() failed for " << Name(); |
| 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; |
| } |
| |
| size_t EventFd::GetAvailableMmapData(char** pdata) { |
| // The mmap_data_buffer is used as a ring buffer like below. The kernel continuously writes |
| // records to the buffer, and the user continuously read records out. |
| // _________________________________________ |
| // buffer | can write | can read | can write | |
| // ^ ^ |
| // read_head write_head |
| // |
| // So the user 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 the user |
| // is responsible for updating read_head. |
| |
| uint64_t buf_mask = mmap_data_buffer_size_ - 1; |
| uint64_t write_head = mmap_metadata_page_->data_head & buf_mask; |
| uint64_t read_head = mmap_metadata_page_->data_tail & buf_mask; |
| |
| if (read_head == write_head) { |
| // No available data. |
| return 0; |
| } |
| |
| // Make sure we can see the data after the fence. |
| std::atomic_thread_fence(std::memory_order_acquire); |
| |
| *pdata = mmap_data_buffer_ + read_head; |
| if (read_head < write_head) { |
| return write_head - read_head; |
| } else { |
| return mmap_data_buffer_size_ - read_head; |
| } |
| } |
| |
| void EventFd::DiscardMmapData(size_t discard_size) { |
| mmap_metadata_page_->data_tail += discard_size; |
| } |
| |
| void EventFd::PreparePollForMmapData(pollfd* poll_fd) { |
| memset(poll_fd, 0, sizeof(pollfd)); |
| poll_fd->fd = perf_event_fd_; |
| poll_fd->events = POLLIN; |
| } |