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/*
* Copyright (C) 2019 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.
*/
#ifndef SRC_PROFILING_PERF_EVENT_READER_H_
#define SRC_PROFILING_PERF_EVENT_READER_H_
#include <linux/perf_event.h>
#include <stdint.h>
#include <sys/mman.h>
#include <sys/types.h>
#include "perfetto/ext/base/optional.h"
#include "perfetto/ext/base/scoped_file.h"
#include "perfetto/ext/tracing/core/basic_types.h"
#include "src/profiling/perf/event_config.h"
namespace perfetto {
namespace profiling {
class PerfRingBuffer {
public:
static base::Optional<PerfRingBuffer> Allocate(int perf_fd,
size_t data_page_count);
~PerfRingBuffer();
// move-only
PerfRingBuffer(const PerfRingBuffer&) = delete;
PerfRingBuffer& operator=(const PerfRingBuffer&) = delete;
PerfRingBuffer(PerfRingBuffer&& other) noexcept;
PerfRingBuffer& operator=(PerfRingBuffer&& other) noexcept;
char* ReadRecordNonconsuming();
void Consume(size_t bytes);
private:
PerfRingBuffer() = default;
bool valid() const { return metadata_page_ != nullptr; }
// Points at the start of the mmap'd region.
perf_event_mmap_page* metadata_page_ = nullptr;
// Size of the mmap'd region (1 metadata page + data_buf_sz_).
size_t mmap_sz_ = 0;
// mmap'd ring buffer
char* data_buf_ = nullptr;
size_t data_buf_sz_ = 0;
// When a record wraps around the ring buffer boundary, it is reconstructed in
// a contiguous form in this buffer. This allows us to always return a pointer
// to a contiguous record.
constexpr static size_t kMaxPerfRecordSize = 1 << 16; // max size 64k
alignas(uint64_t) char reconstructed_record_[kMaxPerfRecordSize];
};
struct ParsedSample {
uint32_t cpu = 0;
pid_t pid = 0;
pid_t tid = 0;
uint64_t timestamp = 0;
uint16_t cpu_mode = PERF_RECORD_MISC_CPUMODE_UNKNOWN;
std::unique_ptr<unwindstack::Regs> regs;
std::vector<char> stack;
};
class EventReader {
public:
// Allow base::Optional<EventReader> without making the constructor public.
template <typename EventReader, bool>
friend struct base::internal::OptionalStorageBase;
static base::Optional<EventReader> ConfigureEvents(
uint32_t cpu,
const EventConfig& event_cfg);
// Consumes records from the ring buffer until either encountering a sample,
// or catching up to the writer. The other record of interest
// (PERF_RECORD_LOST) is handled via the given callback.
base::Optional<ParsedSample> ReadUntilSample(
std::function<void(uint64_t)> lost_events_callback);
void PauseEvents();
uint32_t cpu() const { return cpu_; }
~EventReader() = default;
// move-only
EventReader(const EventReader&) = delete;
EventReader& operator=(const EventReader) = delete;
EventReader(EventReader&&) noexcept;
EventReader& operator=(EventReader&&) noexcept;
private:
EventReader(uint32_t cpu,
perf_event_attr event_attr,
base::ScopedFile perf_fd,
PerfRingBuffer ring_buffer);
ParsedSample ParseSampleRecord(uint32_t cpu, const char* record_start);
// All events are cpu-bound (thread-scoped events not supported).
const uint32_t cpu_;
const perf_event_attr event_attr_;
base::ScopedFile perf_fd_;
PerfRingBuffer ring_buffer_;
};
} // namespace profiling
} // namespace perfetto
#endif // SRC_PROFILING_PERF_EVENT_READER_H_