diff options
| -rw-r--r-- | TODO | 9 | ||||
| -rwxr-xr-x | tools/checkstack.py | 117 |
2 files changed, 120 insertions, 6 deletions
@@ -3,10 +3,9 @@ Split rombios32.c up into multiple files. Review changes committed to coreboot, virtualbox, qemu, kvm, and bochs cvs tip. -Alter ISRs so that they do not enable irqs. Only call out to other -bios functions after minimizing stack usage. - -Try to write a script to analyze stack usage of 16bit code. +Look into ways to reduce stack usage. Alter ISRs so that they do not +enable irqs. Only call out to other bios functions after minimizing +stack usage. Audit all sti/cli calls. Audit all call16 calls to make sure flags is setup properly with respect to irqs. @@ -14,8 +13,6 @@ setup properly with respect to irqs. Audit statements where a 32bit intermediary changes meaning of a 16bit comparison. -Look into ways to reduce stack usage. - Code assumes ebda segment is static - it doesn't read 0x40e. The __call16 code does a long jump to the interrupt trampolines - this diff --git a/tools/checkstack.py b/tools/checkstack.py new file mode 100755 index 0000000..9cd6b52 --- /dev/null +++ b/tools/checkstack.py @@ -0,0 +1,117 @@ +#!/usr/bin/env python +# Script that tries to find how much stack space each function in an +# object is using. +# +# Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net> +# +# This file may be distributed under the terms of the GNU GPLv3 license. + +# Usage: +# objdump -m i386 -M i8086 -M suffix -d out/rom16.o | tools/checkstack.py + +import sys +import re + +#IGNORE = ['screenc', 'bvprintf'] +IGNORE = ['screenc'] + +# Find out maximum stack usage for a function +def calcmaxstack(funcs, func): + info = funcs[func] + if func.split('.')[0] in IGNORE: + # Function is hardcoded to report 0 stack usage + info[1] = 0 + return + # Find max of all nested calls. + max = info[0] + for addr, callfname, usage in info[2]: + callinfo = funcs[callfname] + if callinfo[1] is None: + calcmaxstack(funcs, callfname) + totusage = usage + callinfo[1] + if totusage > max: + max = totusage + info[1] = max + +hex_s = r'[0-9a-f]+' +re_func = re.compile(r'^' + hex_s + r' <(?P<func>.*)>:$') +re_asm = re.compile( + r'^[ ]*(?P<addr>' + hex_s + r'):\t.*\t' + r'(?P<insn>[a-z0-9]+ [^<]*)( <(?P<ref>.*)>)?$') +re_usestack = re.compile( + r'^(push.*)|(sub.* [$](?P<num>0x' + hex_s + r'),%esp)$') + +def calc(): + # funcs = {funcname: [basicstackusage, maxstackusage + # , [(addr, callfname, stackusage), ...]] } + funcs = {} + cur = None + atstart = 0 + stackusage = 0 + + # Parse input lines + for line in sys.stdin.readlines(): + m = re_func.match(line) + if m is not None: + # Found function + cur = [0, None, []] + funcs[m.group('func')] = cur + stackusage = 0 + atstart = 1 + continue + m = re_asm.match(line) + if m is not None: + insn = m.group('insn') + + im = re_usestack.match(insn) + if im is not None: + if insn[:4] == 'push': + stackusage += 4 + continue + stackusage += int(im.group('num'), 16) + + if atstart: + cur[0] = stackusage + atstart = 0 + + ref = m.group('ref') + if ref is not None and '+' not in ref: + if insn[:1] == 'j': + # Tail call + stackusage = 0 + elif insn[:4] == 'call': + stackusage += 4 + else: + print "unknown call", ref + cur[2].append((m.group('addr'), ref, stackusage)) + # Reset stack usage to preamble usage + stackusage = cur[0] + + continue + + #print "other", repr(line) + + # Calculate maxstackusage + for func, info in funcs.items(): + if info[1] is not None: + continue + calcmaxstack(funcs, func) + + # Show all functions + funcnames = funcs.keys() + funcnames.sort() + for func in funcnames: + basicusage, maxusage, calls = funcs[func] + if maxusage == 0: + continue + print "\n%s[%d,%d]:" % (func, basicusage, maxusage) + for addr, callfname, stackusage in calls: + callinfo = funcs[callfname] + print " %04s:%-30s[%d+%d,%d]" % ( + addr, callfname, stackusage, callinfo[0], stackusage+callinfo[1]) + +def main(): + calc() + +if __name__ == '__main__': + main() |