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 const char* const kTracingPaths[]; 32 33 // Tries creating an |FtraceProcfs| at the standard tracefs mount points. 34 // Takes an optional |instance_path| such as "instances/wifi/", in which case 35 // the returned object will be for that ftrace instance path. 36 static std::unique_ptr<FtraceProcfs> CreateGuessingMountPoint( 37 const std::string& instance_path = ""); 38 39 static std::unique_ptr<FtraceProcfs> Create(const std::string& root); 40 41 static int g_kmesg_fd; 42 43 explicit FtraceProcfs(const std::string& root); 44 virtual ~FtraceProcfs(); 45 46 // Set the filter for syscall events. If empty, clear the filter. 47 bool SetSyscallFilter(const std::set<size_t>& filter); 48 49 // Enable the event under with the given |group| and |name|. 50 bool EnableEvent(const std::string& group, const std::string& name); 51 52 // Disable the event under with the given |group| and |name|. 53 bool DisableEvent(const std::string& group, const std::string& name); 54 55 // Returns true if the event under the given |group| and |name| exists and its 56 // enable file is writeable. 57 bool IsEventAccessible(const std::string& group, const std::string& name); 58 59 // Disable all events by writing to the global enable file. 60 bool DisableAllEvents(); 61 62 // Read the format for event with the given |group| and |name|. 63 // virtual for testing. 64 virtual std::string ReadEventFormat(const std::string& group, 65 const std::string& name) const; 66 67 virtual std::string ReadPageHeaderFormat() const; 68 69 std::string GetCurrentTracer(); 70 // Sets the "current_tracer". Might fail with EBUSY if tracing pipes have 71 // already been opened for reading. 72 bool SetCurrentTracer(const std::string& tracer); 73 // Resets the "current_tracer" to "nop". 74 bool ResetCurrentTracer(); 75 bool AppendFunctionFilters(const std::vector<std::string>& filters); 76 bool ClearFunctionFilters(); 77 bool AppendFunctionGraphFilters(const std::vector<std::string>& filters); 78 bool ClearFunctionGraphFilters(); 79 80 // Get all triggers for event with the given |group| and |name|. 81 std::vector<std::string> ReadEventTriggers(const std::string& group, 82 const std::string& name) const; 83 84 // Create an event trigger for the given |group| and |name|. 85 bool CreateEventTrigger(const std::string& group, 86 const std::string& name, 87 const std::string& trigger); 88 89 // Remove an event trigger for the given |group| and |name|. 90 bool RemoveEventTrigger(const std::string& group, 91 const std::string& name, 92 const std::string& trigger); 93 94 // Remove all event trigger for the given |group| and |name|. 95 bool RemoveAllEventTriggers(const std::string& group, 96 const std::string& name); 97 98 // Sets up any associated event trigger before enabling the event 99 bool MaybeSetUpEventTriggers(const std::string& group, 100 const std::string& name); 101 102 // Tears down any associated event trigger after disabling the event 103 bool MaybeTearDownEventTriggers(const std::string& group, 104 const std::string& name); 105 106 // Returns true if rss_stat_throttled synthetic event is supported 107 bool SupportsRssStatThrottled(); 108 109 // Read the printk formats file. 110 std::string ReadPrintkFormats() const; 111 112 // Opens the "/per_cpu/cpuXX/stats" file for the given |cpu|. 113 base::ScopedFile OpenCpuStats(size_t cpu) const; 114 115 // Read the "/per_cpu/cpuXX/stats" file for the given |cpu|. 116 std::string ReadCpuStats(size_t cpu) const; 117 118 // Set ftrace buffer size in pages. 119 // This size is *per cpu* so for the total size you have to multiply 120 // by the number of CPUs. 121 bool SetCpuBufferSizeInPages(size_t pages); 122 123 // Returns the number of CPUs. 124 // This will match the number of tracing/per_cpu/cpuXX directories. 125 size_t virtual NumberOfCpus() const; 126 127 // Clears the trace buffers for all CPUs. Blocks until this is done. 128 void ClearTrace(); 129 130 // Clears the trace buffer for cpu. Blocks until this is done. 131 void ClearPerCpuTrace(size_t cpu); 132 133 // Writes the string |str| as an event into the trace buffer. 134 bool WriteTraceMarker(const std::string& str); 135 136 // Read tracing_on and return true if tracing_on is 1, otherwise return false. 137 bool GetTracingOn(); 138 139 // Write 1 to tracing_on if |on| is true, otherwise write 0. 140 bool SetTracingOn(bool on); 141 142 // Returns true if ftrace tracing is available. 143 // Ftrace tracing is available iff "/current_tracer" is "nop", indicates 144 // function tracing is not in use. Necessarily 145 // racy: another program could enable/disable tracing at any point. 146 bool IsTracingAvailable(); 147 148 // Set the clock. |clock_name| should be one of the names returned by 149 // AvailableClocks. Setting the clock clears the buffer. 150 bool SetClock(const std::string& clock_name); 151 152 // Get the currently set clock. 153 std::string GetClock(); 154 155 // Get all the available clocks. 156 std::set<std::string> AvailableClocks(); 157 158 // Get all the enabled events. 159 virtual std::vector<std::string> ReadEnabledEvents(); 160 161 // Open the raw pipe for |cpu|. 162 virtual base::ScopedFile OpenPipeForCpu(size_t cpu); 163 164 virtual const std::set<std::string> GetEventNamesForGroup( 165 const std::string& path) const; 166 167 // Returns the |id| for event with the given |group| and |name|. Returns 0 if 168 // the event doesn't exist, or its /id file could not be read. Not typically 169 // needed if already parsing the format file. 170 uint32_t ReadEventId(const std::string& group, const std::string& name) const; 171 GetRootPath()172 std::string GetRootPath() const { return root_; } 173 174 protected: 175 // virtual and protected for testing. 176 virtual bool WriteToFile(const std::string& path, const std::string& str); 177 virtual bool AppendToFile(const std::string& path, const std::string& str); 178 virtual bool ClearFile(const std::string& path); 179 virtual bool IsFileWriteable(const std::string& path); 180 virtual char ReadOneCharFromFile(const std::string& path); 181 virtual std::string ReadFileIntoString(const std::string& path) const; 182 183 private: 184 // Checks the trace file is present at the given root path. 185 static bool CheckRootPath(const std::string& root); 186 187 bool WriteNumberToFile(const std::string& path, size_t value); 188 189 const std::string root_; 190 }; 191 192 } // namespace perfetto 193 194 #endif // SRC_TRACED_PROBES_FTRACE_FTRACE_PROCFS_H_ 195