tools/checkstack.py

   1 #!/usr/bin/env python
   2 # Script that tries to find how much stack space each function in an
   3 # object is using.
   4 #
   5 # Copyright (C) 2008  Kevin O'Connor <kevin@koconnor.net>
   6 #
   7 # This file may be distributed under the terms of the GNU GPLv3 license.
   8
   9 # Usage:
  10 #   objdump -m i386 -M i8086 -M suffix -d out/rom16.reloc.o | tools/checkstack.py
  11
  12 import sys
  13 import re
  14
  15 # Functions that change stacks
  16 STACKHOP = ['__send_disk_op']
  17 # List of functions we can assume are never called.
  18 #IGNORE = ['panic', '__dprintf']
  19 IGNORE = ['panic']
  20
  21 OUTPUTDESC = """
  22 #funcname1[preamble_stack_usage,max_usage_with_callers]:
  23 #    insn_addr:called_function [usage_at_call_point+caller_preamble,total_usage]
  24 #
  25 #funcname2[p,m,max_usage_to_yield_point]:
  26 #    insn_addr:called_function [u+c,t,usage_to_yield_point]
  27 """
  28
  29 # Find out maximum stack usage for a function
  30 def calcmaxstack(funcs, funcaddr):
  31     info = funcs[funcaddr]
  32     # Find max of all nested calls.
  33     maxusage = info[1]
  34     maxyieldusage = doesyield = 0
  35     if info[3] is not None:
  36         maxyieldusage = info[3]
  37         doesyield = 1
  38     info[2] = maxusage
  39     info[4] = info[3]
  40     seenbefore = {}
  41     totcalls = 0
  42     for insnaddr, calladdr, usage in info[6]:
  43         callinfo = funcs[calladdr]
  44         if callinfo[2] is None:
  45             calcmaxstack(funcs, calladdr)
  46         if callinfo[0] not in seenbefore:
  47             seenbefore[callinfo[0]] = 1
  48             totcalls += 1 + callinfo[5]
  49         funcnameroot = callinfo[0].split('.')[0]
  50         if funcnameroot in IGNORE:
  51             # This called function is ignored - don't contribute it to
  52             # the max stack.
  53             continue
  54         if funcnameroot in STACKHOP:
  55             if usage > maxusage:
  56                 maxusage = usage
  57             if callinfo[4] is not None:
  58                 doesyield = 1
  59                 if usage > maxyieldusage:
  60                     maxyieldusage = usage
  61             continue
  62         totusage = usage + callinfo[2]
  63         if totusage > maxusage:
  64             maxusage = totusage
  65         if callinfo[4] is not None:
  66             doesyield = 1
  67             totyieldusage = usage + callinfo[4]
  68             if totyieldusage > maxyieldusage:
  69                 maxyieldusage = totyieldusage
  70     info[2] = maxusage
  71     if doesyield:
  72         info[4] = maxyieldusage
  73     info[5] = totcalls
  74
  75 # Try to arrange output so that functions that call each other are
  76 # near each other.
  77 def orderfuncs(funcnames, availnames, funcs):
  78     l = [(availnames[name][5], name)
  79          for name in funcnames if name in availnames]
  80     l.sort()
  81     l.reverse()
  82     out = []
  83     while l:
  84         count, name = l.pop(0)
  85         if name not in availnames:
  86             continue
  87         callnames = [funcs[calls[1]][0] for calls in availnames[name][6]]
  88         del availnames[name]
  89         out = out + orderfuncs(callnames, availnames, funcs) + [name]
  90     return out
  91
  92 # Update function info with a found "yield" point.
  93 def noteYield(info, stackusage):
  94     prevyield = info[3]
  95     if prevyield is None or prevyield < stackusage:
  96         info[3] = stackusage
  97
  98 # Update function info with a found "call" point.
  99 def noteCall(info, subfuncs, insnaddr, calladdr, stackusage):
 100     if (calladdr, stackusage) in subfuncs:
 101         # Already noted a nearly identical call - ignore this one.
 102         return
 103     info[6].append((insnaddr, calladdr, stackusage))
 104     subfuncs[(calladdr, stackusage)] = 1
 105
 106 hex_s = r'[0-9a-f]+'
 107 re_func = re.compile(r'^(?P<funcaddr>' + hex_s + r') <(?P<func>.*)>:$')
 108 re_asm = re.compile(
 109     r'^[ ]*(?P<insnaddr>' + hex_s
 110     + r'):\t.*\t(addr32 )?(?P<insn>.+?)[ ]*((?P<calladdr>' + hex_s
 111     + r') <(?P<ref>.*)>)?$')
 112 re_usestack = re.compile(
 113     r'^(push[f]?[lw])|(sub.* [$](?P<num>0x' + hex_s + r'),%esp)$')
 114
 115 def calc():
 116     # funcs[funcaddr] = [funcname, basicstackusage, maxstackusage
 117     #                    , yieldusage, maxyieldusage, totalcalls
 118     #                    , [(insnaddr, calladdr, stackusage), ...]]
 119     funcs = {-1: ['<indirect>', 0, 0, None, None, 0, []]}
 120     cur = None
 121     atstart = 0
 122     stackusage = 0
 123
 124     # Parse input lines
 125     for line in sys.stdin.readlines():
 126         m = re_func.match(line)
 127         if m is not None:
 128             # Found function
 129             funcaddr = int(m.group('funcaddr'), 16)
 130             funcs[funcaddr] = cur = [m.group('func'), 0, None, None, None, 0, []]
 131             stackusage = 0
 132             atstart = 1
 133             subfuncs = {}
 134             continue
 135         m = re_asm.match(line)
 136         if m is not None:
 137             insn = m.group('insn')
 138
 139             im = re_usestack.match(insn)
 140             if im is not None:
 141                 if insn[:5] == 'pushl' or insn[:6] == 'pushfl':
 142                     stackusage += 4
 143                     continue
 144                 elif insn[:5] == 'pushw' or insn[:6] == 'pushfw':
 145                     stackusage += 2
 146                     continue
 147                 stackusage += int(im.group('num'), 16)
 148
 149             if atstart:
 150                 if insn == 'movl   %esp,%ebp':
 151                     # Still part of initial header
 152                     continue
 153                 cur[1] = stackusage
 154                 atstart = 0
 155
 156             insnaddr = m.group('insnaddr')
 157             calladdr = m.group('calladdr')
 158             if calladdr is None:
 159                 if insn[:6] == 'lcallw':
 160                     noteCall(cur, subfuncs, insnaddr, -1, stackusage + 4)
 161                     noteYield(cur, stackusage + 4)
 162                 elif insn[:3] == 'int':
 163                     noteCall(cur, subfuncs, insnaddr, -1, stackusage + 6)
 164                     noteYield(cur, stackusage + 6)
 165                 elif insn[:3] == 'sti':
 166                     noteYield(cur, stackusage)
 167                 else:
 168                     # misc instruction
 169                     continue
 170             else:
 171                 # Jump or call insn
 172                 calladdr = int(calladdr, 16)
 173                 ref = m.group('ref')
 174                 if '+' in ref:
 175                     # Inter-function jump.
 176                     pass
 177                 elif insn[:1] == 'j':
 178                     # Tail call
 179                     noteCall(cur, subfuncs, insnaddr, calladdr, 0)
 180                 elif insn[:5] == 'calll':
 181                     noteCall(cur, subfuncs, insnaddr, calladdr, stackusage + 4)
 182                 else:
 183                     print "unknown call", ref
 184                     noteCall(cur, subfuncs, insnaddr, calladdr, stackusage)
 185             # Reset stack usage to preamble usage
 186             stackusage = cur[1]
 187
 188         #print "other", repr(line)
 189
 190     # Calculate maxstackusage
 191     bynames = {}
 192     for funcaddr, info in funcs.items():
 193         bynames[info[0]] = info
 194         if info[2] is not None:
 195             continue
 196         calcmaxstack(funcs, funcaddr)
 197
 198     # Sort functions for output
 199     funcnames = bynames.keys()
 200     funcnames = orderfuncs(funcnames, bynames.copy(), funcs)
 201
 202     # Show all functions
 203     print OUTPUTDESC
 204     for funcname in funcnames:
 205         name, basicusage, maxusage, yieldusage, maxyieldusage, count, calls = \
 206             bynames[funcname]
 207         if maxusage == 0 and maxyieldusage is None:
 208             continue
 209         yieldstr = ""
 210         if maxyieldusage is not None:
 211             yieldstr = ",%d" % maxyieldusage
 212         print "\n%s[%d,%d%s]:" % (funcname, basicusage, maxusage, yieldstr)
 213         for insnaddr, calladdr, stackusage in calls:
 214             callinfo = funcs[calladdr]
 215             yieldstr = ""
 216             if callinfo[4] is not None:
 217                 yieldstr = ",%d" % (stackusage + callinfo[4])
 218             print "    %04s:%-40s [%d+%d,%d%s]" % (
 219                 insnaddr, callinfo[0], stackusage, callinfo[1]
 220                 , stackusage+callinfo[2], yieldstr)
 221
 222 def main():
 223     calc()
 224
 225 if __name__ == '__main__':
 226     main()