blob: d0ca9a6505f907dcefd79d868d749cca41df541b [file] [log] [blame]
#!/usr/bin/env python
# Script to analyze code and arrange ld sections.
#
# Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import sys
# Align 'pos' to 'alignbytes' offset
def alignpos(pos, alignbytes):
mask = alignbytes - 1
return (pos + mask) & ~mask
# LD script headers/trailers
COMMONHEADER = """
/* DO NOT EDIT! This is an autogenerated file. See tools/layoutrom.py. */
OUTPUT_FORMAT("elf32-i386")
OUTPUT_ARCH("i386")
SECTIONS
{
"""
COMMONTRAILER = """
}
"""
######################################################################
# 16bit fixed address section fitting
######################################################################
# Get the maximum start position for a list of sections that end at an
# address.
def getSectionsStart(sections, endaddr, minalign=1):
totspace = 0
for size, align, name in sections:
if align > minalign:
minalign = align
totspace = alignpos(totspace, align) + size
return (endaddr - totspace) / minalign * minalign
# Write LD script includes for the given sections
def outSections(file, sections):
for size, align, name in sections:
file.write("*(%s)\n" % (name,))
# The 16bit code can't exceed 64K of space.
MAXPOS = 64*1024
# Layout the 16bit code. This ensures sections with fixed offset
# requirements are placed in the correct location. It also places the
# 16bit code as high as possible in the f-segment.
def doLayout16(sections, outname):
textsections = []
rodatasections = []
datasections = []
# fixedsections = [(addr, sectioninfo, extasectionslist), ...]
fixedsections = []
# canrelocate = [(sectioninfo, list), ...]
canrelocate = []
# Find desired sections.
for section in sections:
size, align, name = section
if name[:11] == '.fixedaddr.':
addr = int(name[11:], 16)
fixedsections.append((addr, section, []))
if align != 1:
print "Error: Fixed section %s has non-zero alignment (%d)" % (
name, align)
sys.exit(1)
if name[:6] == '.text.':
textsections.append(section)
canrelocate.append((section, textsections))
if name[:17] == '.rodata.__func__.' or name == '.rodata.str1.1':
rodatasections.append(section)
#canrelocate.append((section, rodatasections))
if name[:8] == '.data16.':
datasections.append(section)
#canrelocate.append((section, datasections))
# Find freespace in fixed address area
fixedsections.sort()
# fixedAddr = [(freespace, sectioninfo), ...]
fixedAddr = []
for i in range(len(fixedsections)):
fixedsectioninfo = fixedsections[i]
addr, section, extrasectionslist = fixedsectioninfo
if i == len(fixedsections) - 1:
nextaddr = MAXPOS
else:
nextaddr = fixedsections[i+1][0]
avail = nextaddr - addr - section[0]
fixedAddr.append((avail, fixedsectioninfo))
# Attempt to fit other sections into fixed area
fixedAddr.sort()
canrelocate.sort()
totalused = 0
for freespace, fixedsectioninfo in fixedAddr:
fixedaddr, fixedsection, extrasections = fixedsectioninfo
addpos = fixedaddr + fixedsection[0]
totalused += fixedsection[0]
nextfixedaddr = addpos + freespace
# print "Filling section %x uses %d, next=%x, available=%d" % (
# fixedaddr, fixedsection[0], nextfixedaddr, freespace)
while 1:
canfit = None
for fixedaddrinfo in canrelocate:
fitsection, inlist = fixedaddrinfo
fitsize, fitalign, fitname = fitsection
if addpos + fitsize > nextfixedaddr:
# Can't fit and nothing else will fit.
break
fitnextaddr = alignpos(addpos, fitalign) + fitsize
# print "Test %s - %x vs %x" % (
# fitname, fitnextaddr, nextfixedaddr)
if fitnextaddr > nextfixedaddr:
# This item can't fit.
continue
canfit = (fitnextaddr, fixedaddrinfo)
if canfit is None:
break
# Found a section that can fit.
fitnextaddr, fixedaddrinfo = canfit
canrelocate.remove(fixedaddrinfo)
fitsection, inlist = fixedaddrinfo
inlist.remove(fitsection)
extrasections.append(fitsection)
addpos = fitnextaddr
totalused += fitsection[0]
# print " Adding %s (size %d align %d) pos=%x avail=%d" % (
# fitsection[2], fitsection[0], fitsection[1]
# , fitnextaddr, nextfixedaddr - fitnextaddr)
firstfixed = fixedsections[0][0]
# Report stats
total = MAXPOS-firstfixed
slack = total - totalused
print ("Fixed space: 0x%x-0x%x total: %d slack: %d"
" Percent slack: %.1f%%" % (
firstfixed, MAXPOS, total, slack,
(float(slack) / total) * 100.0))
# Find start positions
text16_start = getSectionsStart(textsections, firstfixed)
data16_start = getSectionsStart(rodatasections + datasections, text16_start)
# Write header and regular sections
output = open(outname, 'wb')
output.write(COMMONHEADER + """
data16_start = 0x%x ;
.data16 data16_start : {
""" % data16_start)
outSections(output, datasections)
output.write("code16_rodata = . ;\n")
outSections(output, rodatasections)
output.write("""
}
text16_start = 0x%x ;
.text16 text16_start : {
""" % text16_start)
outSections(output, textsections)
# Write fixed sections
for addr, section, extrasections in fixedsections:
name = section[2]
output.write(". = ( 0x%x - text16_start ) ;\n" % (addr,))
output.write("*(%s)\n" % (name,))
for extrasection in extrasections:
output.write("*(%s)\n" % (extrasection[2],))
# Write trailer
output.write("""
text16_end = ABSOLUTE(.) ;
}
/* Discard regular data sections to force a link error if
* 16bit code attempts to access data not marked with VAR16
*/
/DISCARD/ : { *(.text*) *(.rodata*) *(.data*) *(.bss*) *(COMMON) }
""" + COMMONTRAILER)
return data16_start
######################################################################
# 32bit section outputting
######################################################################
# Return the subset of sections with a given name prefix
def getSectionsPrefix(sections, prefix):
lp = len(prefix)
out = []
for size, align, name in sections:
if name[:lp] == prefix:
out.append((size, align, name))
return out
# Layout the 32bit segmented code. This places the code as high as possible.
def doLayout32seg(sections, outname, endat):
# Find sections to output
textsections = getSectionsPrefix(sections, '.text.')
rodatasections = (getSectionsPrefix(sections, '.rodata.str1.1')
+ getSectionsPrefix(sections, '.rodata.__func__.'))
datasections = getSectionsPrefix(sections, '.data32seg.')
startat = getSectionsStart(
textsections + rodatasections + datasections, endat)
# Write sections
output = open(outname, 'wb')
output.write(COMMONHEADER + """
code32seg_start = 0x%x ;
.text32seg code32seg_start : {
freespace_end = . ;
""" % startat)
outSections(output, textsections)
output.write("code32seg_rodata = . ;\n")
outSections(output, rodatasections)
outSections(output, datasections)
output.write("""
code32seg_end = ABSOLUTE(.) ;
}
/DISCARD/ : { *(.text*) *(.rodata*) *(.data*) *(.bss*) *(COMMON) }
""" + COMMONTRAILER)
return startat
# Layout the 32bit flat code. This places the code as high as possible.
def doLayout32flat(sections, outname, endat):
endat += 0xf0000
# Find sections to output
textsections = getSectionsPrefix(sections, '.text.')
rodatasections = getSectionsPrefix(sections, '.rodata')
datasections = getSectionsPrefix(sections, '.data.')
bsssections = getSectionsPrefix(sections, '.bss.')
startat = getSectionsStart(
textsections + rodatasections + datasections + bsssections, endat, 512)
# Write sections
output = open(outname, 'wb')
output.write(COMMONHEADER + """
code32flat_start = 0x%x ;
.text32flat code32flat_start : {
""" % startat)
outSections(output, textsections)
output.write("code32_rodata = . ;\n")
outSections(output, rodatasections)
outSections(output, datasections)
outSections(output, bsssections)
output.write("""
freespace_start = . ;
code32flat_end = ABSOLUTE(.) ;
}
""" + COMMONTRAILER)
return startat
######################################################################
# Section garbage collection
######################################################################
def getSectionsList(info, names):
out = []
for i in info[0]:
size, align, section = i
if section not in names:
# print "gc", section
continue
out.append(i)
return out
# Find and keep the section associated with a symbol (if available).
def keepsymbol(symbol, infos, pos):
addr, section = infos[pos][1].get(symbol, (None, None))
if section is None or '*' in section or section[:9] == '.discard.':
return -1
keepsection(section, infos, pos)
return 0
# Note required section, and recursively set all referenced sections
# as required.
def keepsection(name, infos, pos=0):
if name in infos[pos][3]:
# Already kept - nothing to do.
return
infos[pos][3].append(name)
relocs = infos[pos][2].get(name)
if relocs is None:
return
# Keep all sections that this section points to
for symbol in relocs:
ret = keepsymbol(symbol, infos, pos)
if not ret:
continue
# Not in primary sections - it may be a cross 16/32 reference
ret = keepsymbol(symbol, infos, (pos+1)%3)
if not ret:
continue
ret = keepsymbol(symbol, infos, (pos+2)%3)
if not ret:
continue
# Determine which sections are actually referenced and need to be
# placed into the output file.
def gc(info16, info32seg, info32flat):
# infos = ((sections, symbols, relocs, keep sections), ...)
infos = ((info16[0], info16[1], info16[2], []),
(info32seg[0], info32seg[1], info32seg[2], []),
(info32flat[0], info32flat[1], info32flat[2], []))
# Start by keeping sections that are globally visible.
for size, align, section in info16[0]:
if section[:11] == '.fixedaddr.' or '.export.' in section:
keepsection(section, infos)
# Return sections found.
sections16 = getSectionsList(info16, infos[0][3])
sections32seg = getSectionsList(info32seg, infos[1][3])
sections32flat = getSectionsList(info32flat, infos[2][3])
return sections16, sections32seg, sections32flat
######################################################################
# Startup and input parsing
######################################################################
# Read in output from objdump
def parseObjDump(file):
# sections = [(size, align, section), ...]
sections = []
# symbols[symbol] = section
symbols = {}
# relocs[section] = [symbol, ...]
relocs = {}
state = None
for line in file.readlines():
line = line.rstrip()
if line == 'Sections:':
state = 'section'
continue
if line == 'SYMBOL TABLE:':
state = 'symbol'
continue
if line[:24] == 'RELOCATION RECORDS FOR [':
state = 'reloc'
relocsection = line[24:-2]
continue
if state == 'section':
try:
idx, name, size, vma, lma, fileoff, align = line.split()
if align[:3] != '2**':
continue
sections.append((int(size, 16), 2**int(align[3:]), name))
except:
pass
continue
if state == 'symbol':
try:
section, off, symbol = line[17:].split()
off = int(off, 16)
addr = int(line[:8], 16)
symbols[symbol] = addr, section
except:
pass
continue
if state == 'reloc':
try:
off, type, symbol = line.split()
off = int(off, 16)
relocs.setdefault(relocsection, []).append(symbol)
except:
pass
return sections, symbols, relocs
def main():
# Get output name
in16, in32seg, in32flat, out16, out32seg, out32flat = sys.argv[1:]
infile16 = open(in16, 'rb')
infile32seg = open(in32seg, 'rb')
infile32flat = open(in32flat, 'rb')
info16 = parseObjDump(infile16)
info32seg = parseObjDump(infile32seg)
info32flat = parseObjDump(infile32flat)
sections16, sections32seg, sections32flat = gc(info16, info32seg, info32flat)
start16 = doLayout16(sections16, out16)
start32seg = doLayout32seg(sections32seg, out32seg, start16)
doLayout32flat(sections32flat, out32flat, start32seg)
if __name__ == '__main__':
main()