1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef SIMPLE_PERF_EVENT_FD_H_ 18 #define SIMPLE_PERF_EVENT_FD_H_ 19 20 #include <sys/types.h> 21 22 #include <memory> 23 #include <string> 24 #include <vector> 25 26 #include <android-base/macros.h> 27 28 #include "IOEventLoop.h" 29 #include "perf_event.h" 30 31 namespace simpleperf { 32 33 struct PerfCounter { 34 uint64_t value; // The value of the event specified by the perf_event_file. 35 uint64_t time_enabled; // The enabled time. 36 uint64_t time_running; // The running time. 37 uint64_t id; // The id of the perf_event_file. 38 }; 39 40 // EventFd represents an opened perf_event_file. 41 class EventFd { 42 public: 43 static std::unique_ptr<EventFd> OpenEventFile(const perf_event_attr& attr, pid_t tid, int cpu, 44 EventFd* group_event_fd, 45 const std::string& event_name, 46 bool report_error = true); 47 48 virtual ~EventFd(); 49 50 // Give information about this perf_event_file, like (event_name, tid, cpu). 51 std::string Name() const; 52 53 uint64_t Id() const; 54 ThreadId()55 pid_t ThreadId() const { return tid_; } 56 Cpu()57 int Cpu() const { return cpu_; } 58 attr()59 const perf_event_attr& attr() const { return attr_; } 60 61 // It tells the kernel to start counting and recording events specified by 62 // this file. 63 bool SetEnableEvent(bool enable); 64 bool SetFilter(const std::string& filter); 65 66 bool ReadCounter(PerfCounter* counter); 67 68 // Create mapped buffer used to receive records sent by the kernel. 69 // mmap_pages should be power of 2. 70 virtual bool CreateMappedBuffer(size_t mmap_pages, bool report_error); 71 72 // Share the mapped buffer used by event_fd. The two EventFds should monitor 73 // the same event on the same cpu, but have different thread ids. 74 bool ShareMappedBuffer(const EventFd& event_fd, bool report_error); 75 HasMappedBuffer()76 bool HasMappedBuffer() const { return mmap_data_buffer_size_ != 0; } GetMappedBuffer(size_t & buffer_size)77 char* GetMappedBuffer(size_t& buffer_size) { 78 buffer_size = mmap_data_buffer_size_; 79 return mmap_data_buffer_; 80 } 81 82 virtual void DestroyMappedBuffer(); 83 84 // Return available data in the kernel buffer. 85 std::vector<char> GetAvailableMmapData(); 86 // Return the size of available data in the buffer, and set data_pos to the first available data 87 // position in mmap_data_buffer_. 88 virtual size_t GetAvailableMmapDataSize(size_t& data_pos); 89 // Discard the size of the data we have read, so the kernel can reuse the space for new data. 90 virtual void DiscardMmapData(size_t discard_size); 91 92 // Manage the aux buffer, which receive auxiliary data sent by the kernel. 93 // aux_buffer_size: should be power of two, and mod PAGE_SIZE is zero. 94 virtual bool CreateAuxBuffer(size_t aux_buffer_size, bool report_error); HasAuxBuffer()95 bool HasAuxBuffer() const { return aux_buffer_size_ != 0; } 96 virtual void DestroyAuxBuffer(); 97 98 // Get available aux data, which can appear in one or two continuous buffers. 99 // buf1: return pointer to the first buffer 100 // size1: return data size in the first buffer 101 // buf2: return pointer to the second buffer 102 // size2: return data size in the second buffer 103 // Return value: return how many bytes of aux data has been read before. 104 virtual uint64_t GetAvailableAuxData(char** buf1, size_t* size1, char** buf2, size_t* size2); 105 virtual void DiscardAuxData(size_t discard_size); 106 107 // [callback] is called when there is data available in the mapped buffer. 108 virtual bool StartPolling(IOEventLoop& loop, const std::function<bool()>& callback); 109 virtual bool StopPolling(); 110 111 protected: EventFd(const perf_event_attr & attr,int perf_event_fd,const std::string & event_name,pid_t tid,int cpu)112 EventFd(const perf_event_attr& attr, int perf_event_fd, const std::string& event_name, pid_t tid, 113 int cpu) 114 : attr_(attr), 115 perf_event_fd_(perf_event_fd), 116 id_(0), 117 event_name_(event_name), 118 tid_(tid), 119 cpu_(cpu), 120 mmap_addr_(nullptr), 121 mmap_len_(0), 122 mmap_metadata_page_(nullptr), 123 mmap_data_buffer_(nullptr), 124 mmap_data_buffer_size_(0), 125 ioevent_ref_(nullptr), 126 last_counter_value_(0) {} 127 128 bool InnerReadCounter(PerfCounter* counter) const; 129 130 const perf_event_attr attr_; 131 int perf_event_fd_; 132 mutable uint64_t id_; 133 const std::string event_name_; 134 pid_t tid_; 135 int cpu_; 136 137 void* mmap_addr_; 138 size_t mmap_len_; 139 // the first page of mapped area, whose content can be changed by the kernel at any time 140 volatile perf_event_mmap_page* mmap_metadata_page_; 141 // starting from the second page of mapped area, containing records written by the kernel 142 char* mmap_data_buffer_; 143 size_t mmap_data_buffer_size_; 144 // receiving auxiliary data (like instruction tracing data generated by etm) from the kernel 145 char* aux_buffer_ = nullptr; 146 size_t aux_buffer_size_ = 0; 147 148 IOEventRef ioevent_ref_; 149 150 // Used by atrace to generate value difference between two ReadCounter() calls. 151 uint64_t last_counter_value_; 152 153 DISALLOW_COPY_AND_ASSIGN(EventFd); 154 }; 155 156 bool IsEventAttrSupported(const perf_event_attr& attr, const std::string& event_name); 157 158 } // namespace simpleperf 159 160 #endif // SIMPLE_PERF_EVENT_FD_H_ 161