1 /* 2 * Copyright (C) 2017 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 SRC_TRACED_PROBES_FTRACE_FTRACE_PROCFS_H_ 18 #define SRC_TRACED_PROBES_FTRACE_FTRACE_PROCFS_H_ 19 20 #include <memory> 21 #include <set> 22 #include <string> 23 #include <vector> 24 25 #include "perfetto/ext/base/scoped_file.h" 26 27 namespace perfetto { 28 29 class FtraceProcfs { 30 public: 31 static std::unique_ptr<FtraceProcfs> Create(const std::string& root); 32 static int g_kmesg_fd; 33 34 explicit FtraceProcfs(const std::string& root); 35 virtual ~FtraceProcfs(); 36 37 // Enable the event under with the given |group| and |name|. 38 bool EnableEvent(const std::string& group, const std::string& name); 39 40 // Disable the event under with the given |group| and |name|. 41 bool DisableEvent(const std::string& group, const std::string& name); 42 43 // Disable all events by writing to the global enable file. 44 bool DisableAllEvents(); 45 46 // Read the format for event with the given |group| and |name|. 47 // virtual for testing. 48 virtual std::string ReadEventFormat(const std::string& group, 49 const std::string& name) const; 50 51 virtual std::string ReadPageHeaderFormat() const; 52 53 // Read the "/per_cpu/cpuXX/stats" file for the given |cpu|. 54 std::string ReadCpuStats(size_t cpu) const; 55 56 // Set ftrace buffer size in pages. 57 // This size is *per cpu* so for the total size you have to multiply 58 // by the number of CPUs. 59 bool SetCpuBufferSizeInPages(size_t pages); 60 61 // Returns the number of CPUs. 62 // This will match the number of tracing/per_cpu/cpuXX directories. 63 size_t virtual NumberOfCpus() const; 64 65 // Clears the trace buffers for all CPUs. Blocks until this is done. 66 void ClearTrace(); 67 68 // Writes the string |str| as an event into the trace buffer. 69 bool WriteTraceMarker(const std::string& str); 70 71 // Enable tracing. 72 bool EnableTracing(); 73 74 // Disables tracing, does not clear the buffer. 75 bool DisableTracing(); 76 77 // Enables/disables tracing, does not clear the buffer. 78 bool SetTracingOn(bool enable); 79 80 // Returns true iff tracing is enabled. 81 // Necessarily racy: another program could enable/disable tracing at any 82 // point. 83 bool IsTracingEnabled(); 84 85 // Set the clock. |clock_name| should be one of the names returned by 86 // AvailableClocks. Setting the clock clears the buffer. 87 bool SetClock(const std::string& clock_name); 88 89 // Get the currently set clock. 90 std::string GetClock(); 91 92 // Get all the available clocks. 93 std::set<std::string> AvailableClocks(); 94 95 // Get all the enabled events. 96 virtual std::vector<std::string> ReadEnabledEvents(); 97 98 // Open the raw pipe for |cpu|. 99 virtual base::ScopedFile OpenPipeForCpu(size_t cpu); 100 101 virtual const std::set<std::string> GetEventNamesForGroup( 102 const std::string& path) const; 103 104 protected: 105 // virtual and protected for testing. 106 virtual bool WriteToFile(const std::string& path, const std::string& str); 107 virtual bool AppendToFile(const std::string& path, const std::string& str); 108 virtual bool ClearFile(const std::string& path); 109 virtual char ReadOneCharFromFile(const std::string& path); 110 virtual std::string ReadFileIntoString(const std::string& path) const; 111 112 private: 113 // Checks the trace file is present at the given root path. 114 static bool CheckRootPath(const std::string& root); 115 116 bool WriteNumberToFile(const std::string& path, size_t value); 117 118 const std::string root_; 119 }; 120 121 } // namespace perfetto 122 123 #endif // SRC_TRACED_PROBES_FTRACE_FTRACE_PROCFS_H_ 124