scripts/tracing/draw_functrace.py

   1 #!/usr/bin/python
   2 # SPDX-License-Identifier: GPL-2.0-only
   3
   4 """
   5 Copyright 2008 (c) Frederic Weisbecker <fweisbec@gmail.com>
   6
   7 This script parses a trace provided by the function tracer in
   8 kernel/trace/trace_functions.c
   9 The resulted trace is processed into a tree to produce a more human
  10 view of the call stack by drawing textual but hierarchical tree of
  11 calls. Only the functions's names and the the call time are provided.
  12
  13 Usage:
  14         Be sure that you have CONFIG_FUNCTION_TRACER
  15         # mount -t debugfs nodev /sys/kernel/debug
  16         # echo function > /sys/kernel/debug/tracing/current_tracer
  17         $ cat /sys/kernel/debug/tracing/trace_pipe > ~/raw_trace_func
  18         Wait some times but not too much, the script is a bit slow.
  19         Break the pipe (Ctrl + Z)
  20         $ scripts/draw_functrace.py < raw_trace_func > draw_functrace
  21         Then you have your drawn trace in draw_functrace
  22 """
  23
  24
  25 import sys, re
  26
  27 class CallTree:
  28         """ This class provides a tree representation of the functions
  29                 call stack. If a function has no parent in the kernel (interrupt,
  30                 syscall, kernel thread...) then it is attached to a virtual parent
  31                 called ROOT.
  32         """
  33         ROOT = None
  34
  35         def __init__(self, func, time = None, parent = None):
  36                 self._func = func
  37                 self._time = time
  38                 if parent is None:
  39                         self._parent = CallTree.ROOT
  40                 else:
  41                         self._parent = parent
  42                 self._children = []
  43
  44         def calls(self, func, calltime):
  45                 """ If a function calls another one, call this method to insert it
  46                         into the tree at the appropriate place.
  47                         @return: A reference to the newly created child node.
  48                 """
  49                 child = CallTree(func, calltime, self)
  50                 self._children.append(child)
  51                 return child
  52
  53         def getParent(self, func):
  54                 """ Retrieve the last parent of the current node that
  55                         has the name given by func. If this function is not
  56                         on a parent, then create it as new child of root
  57                         @return: A reference to the parent.
  58                 """
  59                 tree = self
  60                 while tree != CallTree.ROOT and tree._func != func:
  61                         tree = tree._parent
  62                 if tree == CallTree.ROOT:
  63                         child = CallTree.ROOT.calls(func, None)
  64                         return child
  65                 return tree
  66
  67         def __repr__(self):
  68                 return self.__toString("", True)
  69
  70         def __toString(self, branch, lastChild):
  71                 if self._time is not None:
  72                         s = "%s----%s (%s)\n" % (branch, self._func, self._time)
  73                 else:
  74                         s = "%s----%s\n" % (branch, self._func)
  75
  76                 i = 0
  77                 if lastChild:
  78                         branch = branch[:-1] + " "
  79                 while i < len(self._children):
  80                         if i != len(self._children) - 1:
  81                                 s += "%s" % self._children[i].__toString(branch +\
  82                                                                 "    |", False)
  83                         else:
  84                                 s += "%s" % self._children[i].__toString(branch +\
  85                                                                 "    |", True)
  86                         i += 1
  87                 return s
  88
  89 class BrokenLineException(Exception):
  90         """If the last line is not complete because of the pipe breakage,
  91            we want to stop the processing and ignore this line.
  92         """
  93         pass
  94
  95 class CommentLineException(Exception):
  96         """ If the line is a comment (as in the beginning of the trace file),
  97             just ignore it.
  98         """
  99         pass
 100
 101
 102 def parseLine(line):
 103         line = line.strip()
 104         if line.startswith("#"):
 105                 raise CommentLineException
 106         m = re.match("[^]]+?\\] +([0-9.]+): (\\w+) <-(\\w+)", line)
 107         if m is None:
 108                 raise BrokenLineException
 109         return (m.group(1), m.group(2), m.group(3))
 110
 111
 112 def main():
 113         CallTree.ROOT = CallTree("Root (Nowhere)", None, None)
 114         tree = CallTree.ROOT
 115
 116         for line in sys.stdin:
 117                 try:
 118                         calltime, callee, caller = parseLine(line)
 119                 except BrokenLineException:
 120                         break
 121                 except CommentLineException:
 122                         continue
 123                 tree = tree.getParent(caller)
 124                 tree = tree.calls(callee, calltime)
 125
 126         print(CallTree.ROOT)
 127
 128 if __name__ == "__main__":
 129         main()