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seabios/scripts/layoutrom.py

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#!/usr/bin/env python
# Script to analyze code and arrange ld sections.
#
# Copyright (C) 2008-2010 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import sys
# 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 = """
/* Discard regular data sections to force a link error if
* code attempts to access data not marked with VAR16 (or other
* appropriate macro)
*/
/DISCARD/ : {
*(.text*) *(.data*) *(.bss*) *(.rodata*)
*(COMMON) *(.discard*) *(.eh_frame) *(.note*)
}
}
"""
######################################################################
# Determine section locations
######################################################################
# Align 'pos' to 'alignbytes' offset
def alignpos(pos, alignbytes):
mask = alignbytes - 1
return (pos + mask) & ~mask
# Determine the final addresses for a list of sections that end at an
# address.
def setSectionsStart(sections, endaddr, minalign=1, segoffset=0):
totspace = 0
for section in sections:
if section.align > minalign:
minalign = section.align
totspace = alignpos(totspace, section.align) + section.size
startaddr = (endaddr - totspace) / minalign * minalign
curaddr = startaddr
for section in sections:
curaddr = alignpos(curaddr, section.align)
section.finalloc = curaddr
section.finalsegloc = curaddr - segoffset
curaddr += section.size
return startaddr, minalign
# The 16bit code can't exceed 64K of space.
BUILD_BIOS_ADDR = 0xf0000
BUILD_BIOS_SIZE = 0x10000
BUILD_ROM_START = 0xc0000
BUILD_LOWRAM_END = 0xa0000
# Space to reserve in f-segment for dynamic allocations
BUILD_MIN_BIOSTABLE = 2048
# 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 fitSections(sections, fillsections):
# fixedsections = [(addr, section), ...]
fixedsections = []
for section in sections:
if section.name.startswith('.fixedaddr.'):
addr = int(section.name[11:], 16)
section.finalloc = addr + BUILD_BIOS_ADDR
section.finalsegloc = addr
fixedsections.append((addr, section))
if section.align != 1:
print("Error: Fixed section %s has non-zero alignment (%d)" % (
section.name, section.align))
sys.exit(1)
fixedsections.sort()
firstfixed = fixedsections[0][0]
# Find freespace in fixed address area
# fixedAddr = [(freespace, section), ...]
fixedAddr = []
for i in range(len(fixedsections)):
fixedsectioninfo = fixedsections[i]
addr, section = fixedsectioninfo
if i == len(fixedsections) - 1:
nextaddr = BUILD_BIOS_SIZE
else:
nextaddr = fixedsections[i+1][0]
avail = nextaddr - addr - section.size
fixedAddr.append((avail, section))
fixedAddr.sort()
# Attempt to fit other sections into fixed area
canrelocate = [(section.size, section.align, section.name, section)
for section in fillsections]
canrelocate.sort()
canrelocate = [section for size, align, name, section in canrelocate]
totalused = 0
for freespace, fixedsection in fixedAddr:
addpos = fixedsection.finalsegloc + fixedsection.size
totalused += fixedsection.size
nextfixedaddr = addpos + freespace
# print("Filling section %x uses %d, next=%x, available=%d" % (
# fixedsection.finalloc, fixedsection.size, nextfixedaddr, freespace))
while 1:
canfit = None
for fitsection in canrelocate:
if addpos + fitsection.size > nextfixedaddr:
# Can't fit and nothing else will fit.
break
fitnextaddr = alignpos(addpos, fitsection.align) + fitsection.size
# print("Test %s - %x vs %x" % (
# fitsection.name, fitnextaddr, nextfixedaddr))
if fitnextaddr > nextfixedaddr:
# This item can't fit.
continue
canfit = (fitnextaddr, fitsection)
if canfit is None:
break
# Found a section that can fit.
fitnextaddr, fitsection = canfit
canrelocate.remove(fitsection)
fitsection.finalloc = addpos + BUILD_BIOS_ADDR
fitsection.finalsegloc = addpos
addpos = fitnextaddr
totalused += fitsection.size
# print(" Adding %s (size %d align %d) pos=%x avail=%d" % (
# fitsection[2], fitsection[0], fitsection[1]
# , fitnextaddr, nextfixedaddr - fitnextaddr))
# Report stats
total = BUILD_BIOS_SIZE-firstfixed
slack = total - totalused
print ("Fixed space: 0x%x-0x%x total: %d slack: %d"
" Percent slack: %.1f%%" % (
firstfixed, BUILD_BIOS_SIZE, total, slack,
(float(slack) / total) * 100.0))
return firstfixed + BUILD_BIOS_ADDR
# Return the subset of sections with a given category
def getSectionsCategory(sections, category):
return [section for section in sections if section.category == category]
# Return the subset of sections with a given name prefix
def getSectionsPrefix(sections, prefix):
return [section for section in sections
if section.name.startswith(prefix)]
# The sections (and associated information) to be placed in output rom
class LayoutInfo:
genreloc = None
sections16 = sec16_start = sec16_align = None
sections32seg = sec32seg_start = sec32seg_align = None
sections32flat = sec32flat_start = sec32flat_align = None
sections32init = sec32init_start = sec32init_align = None
sections32low = sec32low_start = sec32low_align = None
sections32fseg = sec32fseg_start = sec32fseg_align = None
zonefseg_start = zonefseg_end = None
final_readonly_start = None
zonelow_base = final_sec32low_start = None
exportsyms = varlowsyms = None
# Determine final memory addresses for sections
def doLayout(sections, config, genreloc):
li = LayoutInfo()
li.genreloc = genreloc
# Determine 16bit positions
li.sections16 = getSectionsCategory(sections, '16')
textsections = getSectionsPrefix(li.sections16, '.text.')
rodatasections = (
getSectionsPrefix(li.sections16, '.rodata.str1.1')
+ getSectionsPrefix(li.sections16, '.rodata.__func__.')
+ getSectionsPrefix(li.sections16, '.rodata.__PRETTY_FUNCTION__.'))
datasections = getSectionsPrefix(li.sections16, '.data16.')
fixedsections = getSectionsPrefix(li.sections16, '.fixedaddr.')
firstfixed = fitSections(fixedsections, textsections)
remsections = [s for s in textsections+rodatasections+datasections
if s.finalloc is None]
li.sec16_start, li.sec16_align = setSectionsStart(
remsections, firstfixed, segoffset=BUILD_BIOS_ADDR)
# Determine 32seg positions
li.sections32seg = getSectionsCategory(sections, '32seg')
textsections = getSectionsPrefix(li.sections32seg, '.text.')
rodatasections = (
getSectionsPrefix(li.sections32seg, '.rodata.str1.1')
+ getSectionsPrefix(li.sections32seg, '.rodata.__func__.')
+ getSectionsPrefix(li.sections32seg, '.rodata.__PRETTY_FUNCTION__.'))
datasections = getSectionsPrefix(li.sections32seg, '.data32seg.')
li.sec32seg_start, li.sec32seg_align = setSectionsStart(
textsections + rodatasections + datasections, li.sec16_start
, segoffset=BUILD_BIOS_ADDR)
# Determine "fseg memory" data positions
li.sections32fseg = getSectionsCategory(sections, '32fseg')
li.sec32fseg_start, li.sec32fseg_align = setSectionsStart(
li.sections32fseg, li.sec32seg_start, 16
, segoffset=BUILD_BIOS_ADDR)
# Determine 32flat runtime positions
li.sections32flat = getSectionsCategory(sections, '32flat')
textsections = getSectionsPrefix(li.sections32flat, '.text.')
rodatasections = getSectionsPrefix(li.sections32flat, '.rodata')
datasections = getSectionsPrefix(li.sections32flat, '.data.')
bsssections = getSectionsPrefix(li.sections32flat, '.bss.')
li.sec32flat_start, li.sec32flat_align = setSectionsStart(
textsections + rodatasections + datasections + bsssections
, li.sec32fseg_start, 16)
# Determine 32flat init positions
li.sections32init = getSectionsCategory(sections, '32init')
init32_textsections = getSectionsPrefix(li.sections32init, '.text.')
init32_rodatasections = getSectionsPrefix(li.sections32init, '.rodata')
init32_datasections = getSectionsPrefix(li.sections32init, '.data.')
init32_bsssections = getSectionsPrefix(li.sections32init, '.bss.')
li.sec32init_start, li.sec32init_align = setSectionsStart(
init32_textsections + init32_rodatasections
+ init32_datasections + init32_bsssections
, li.sec32flat_start, 16)
# Determine location of ZoneFSeg memory.
li.zonefseg_end = li.sec32flat_start
if not genreloc:
li.zonefseg_end = li.sec32init_start
li.zonefseg_start = BUILD_BIOS_ADDR
if li.zonefseg_start + BUILD_MIN_BIOSTABLE > li.zonefseg_end:
# Not enough ZoneFSeg space - force a minimum space.
li.zonefseg_end = li.sec32fseg_start
li.zonefseg_start = li.zonefseg_end - BUILD_MIN_BIOSTABLE
li.sec32flat_start, li.sec32flat_align = setSectionsStart(
textsections + rodatasections + datasections + bsssections
, li.zonefseg_start, 16)
li.sec32init_start, li.sec32init_align = setSectionsStart(
init32_textsections + init32_rodatasections
+ init32_datasections + init32_bsssections
, li.sec32flat_start, 16)
li.final_readonly_start = min(BUILD_BIOS_ADDR, li.sec32flat_start)
if not genreloc:
li.final_readonly_start = min(BUILD_BIOS_ADDR, li.sec32init_start)
# Determine "low memory" data positions
li.sections32low = getSectionsCategory(sections, '32low')
sec32low_end = li.sec32init_start
if config.get('CONFIG_MALLOC_UPPERMEMORY'):
final_sec32low_end = li.final_readonly_start
zonelow_base = final_sec32low_end - 64*1024
li.zonelow_base = max(BUILD_ROM_START, alignpos(zonelow_base, 2*1024))
else:
final_sec32low_end = BUILD_LOWRAM_END
li.zonelow_base = final_sec32low_end - 64*1024
relocdelta = final_sec32low_end - sec32low_end
li.sec32low_start, li.sec32low_align = setSectionsStart(
li.sections32low, sec32low_end, 16
, segoffset=li.zonelow_base - relocdelta)
li.final_sec32low_start = li.sec32low_start + relocdelta
# Print statistics
size16 = BUILD_BIOS_ADDR + BUILD_BIOS_SIZE - li.sec16_start
size32seg = li.sec16_start - li.sec32seg_start
size32fseg = li.sec32seg_start - li.sec32fseg_start
size32flat = li.sec32fseg_start - li.sec32flat_start
size32init = li.sec32flat_start - li.sec32init_start
sizelow = sec32low_end - li.sec32low_start
print("16bit size: %d" % size16)
print("32bit segmented size: %d" % size32seg)
print("32bit flat size: %d" % size32flat)
print("32bit flat init size: %d" % size32init)
print("Lowmem size: %d" % sizelow)
print("f-segment var size: %d" % size32fseg)
return li
######################################################################
# Linker script output
######################################################################
# Write LD script includes for the given cross references
def outXRefs(sections, useseg=0, exportsyms=[], forcedelta=0):
xrefs = dict([(symbol.name, symbol) for symbol in exportsyms])
out = ""
for section in sections:
for reloc in section.relocs:
symbol = reloc.symbol
if (symbol.section is not None
and (symbol.section.fileid != section.fileid
or symbol.name != reloc.symbolname)):
xrefs[reloc.symbolname] = symbol
for symbolname, symbol in xrefs.items():
loc = symbol.section.finalloc
if useseg:
loc = symbol.section.finalsegloc
out += "%s = 0x%x ;\n" % (symbolname, loc + forcedelta + symbol.offset)
return out
# Write LD script includes for the given sections using relative offsets
def outRelSections(sections, startsym, useseg=0):
sections = [(section.finalloc, section) for section in sections
if section.finalloc is not None]
sections.sort()
out = ""
for addr, section in sections:
loc = section.finalloc
if useseg:
loc = section.finalsegloc
out += ". = ( 0x%x - %s ) ;\n" % (loc, startsym)
if section.name == '.rodata.str1.1':
out += "_rodata = . ;\n"
out += "*(%s)\n" % (section.name,)
return out
# Build linker script output for a list of relocations.
def strRelocs(outname, outrel, relocs):
relocs.sort()
return (" %s_start = ABSOLUTE(.) ;\n" % (outname,)
+ "".join(["LONG(0x%x - %s)\n" % (pos, outrel)
for pos in relocs])
+ " %s_end = ABSOLUTE(.) ;\n" % (outname,))
# Find all relocations in the given sections with the given attributes
def getRelocs(sections, type=None, category=None, notcategory=None):
out = []
for section in sections:
for reloc in section.relocs:
if reloc.symbol.section is None:
continue
destcategory = reloc.symbol.section.category
if ((type is None or reloc.type == type)
and (category is None or destcategory == category)
and (notcategory is None or destcategory != notcategory)):
out.append(section.finalloc + reloc.offset)
return out
# Return the start address and minimum alignment for a set of sections
def getSectionsStart(sections, defaddr=0):
return min([section.finalloc for section in sections
if section.finalloc is not None] or [defaddr])
# Output the linker scripts for all required sections.
def writeLinkerScripts(li, out16, out32seg, out32flat):
# Write 16bit linker script
out = outXRefs(li.sections16, useseg=1) + """
zonelow_base = 0x%x ;
_zonelow_seg = 0x%x ;
code16_start = 0x%x ;
.text16 code16_start : {
%s
}
""" % (li.zonelow_base,
li.zonelow_base / 16,
li.sec16_start - BUILD_BIOS_ADDR,
outRelSections(li.sections16, 'code16_start', useseg=1))
outfile = open(out16, 'wb')
outfile.write(COMMONHEADER + out + COMMONTRAILER)
outfile.close()
# Write 32seg linker script
out = outXRefs(li.sections32seg, useseg=1) + """
code32seg_start = 0x%x ;
.text32seg code32seg_start : {
%s
}
""" % (li.sec32seg_start - BUILD_BIOS_ADDR,
outRelSections(li.sections32seg, 'code32seg_start', useseg=1))
outfile = open(out32seg, 'wb')
outfile.write(COMMONHEADER + out + COMMONTRAILER)
outfile.close()
# Write 32flat linker script
sections32all = (li.sections32flat + li.sections32init + li.sections32fseg)
sec32all_start = li.sec32low_start
relocstr = ""
if li.genreloc:
# Generate relocations
absrelocs = getRelocs(
li.sections32init, type='R_386_32', category='32init')
relrelocs = getRelocs(
li.sections32init, type='R_386_PC32', notcategory='32init')
initrelocs = getRelocs(
li.sections32flat + li.sections32low + li.sections16
+ li.sections32seg + li.sections32fseg, category='32init')
relocstr = (strRelocs("_reloc_abs", "code32init_start", absrelocs)
+ strRelocs("_reloc_rel", "code32init_start", relrelocs)
+ strRelocs("_reloc_init", "code32flat_start", initrelocs))
numrelocs = len(absrelocs + relrelocs + initrelocs)
sec32all_start -= numrelocs * 4
out = outXRefs(li.sections32low, exportsyms=li.varlowsyms
, forcedelta=li.final_sec32low_start-li.sec32low_start)
out += outXRefs(sections32all, exportsyms=li.exportsyms) + """
_reloc_min_align = 0x%x ;
zonefseg_start = 0x%x ;
zonefseg_end = 0x%x ;
zonelow_base = 0x%x ;
final_varlow_start = 0x%x ;
final_readonly_start = 0x%x ;
code32flat_start = 0x%x ;
.text code32flat_start : {
%s
varlow_start = ABSOLUTE(.) ;
%s
varlow_end = ABSOLUTE(.) ;
code32init_start = ABSOLUTE(.) ;
%s
code32init_end = ABSOLUTE(.) ;
%s
%s
. = ( 0x%x - code32flat_start ) ;
*(.text32seg)
. = ( 0x%x - code32flat_start ) ;
*(.text16)
code32flat_end = ABSOLUTE(.) ;
} :text
""" % (li.sec32init_align,
li.zonefseg_start,
li.zonefseg_end,
li.zonelow_base,
li.final_sec32low_start,
li.final_readonly_start,
sec32all_start,
relocstr,
outRelSections(li.sections32low, 'code32flat_start'),
outRelSections(li.sections32init, 'code32flat_start'),
outRelSections(li.sections32flat, 'code32flat_start'),
outRelSections(li.sections32fseg, 'code32flat_start'),
li.sec32seg_start,
li.sec16_start)
out = COMMONHEADER + out + COMMONTRAILER + """
ENTRY(entry_elf)
PHDRS
{
text PT_LOAD AT ( code32flat_start ) ;
}
"""
outfile = open(out32flat, 'wb')
outfile.write(out)
outfile.close()
######################################################################
# Detection of init code
######################################################################
def markRuntime(section, sections, chain=[]):
if (section is None or not section.keep or section.category is not None
or '.init.' in section.name or section.fileid != '32flat'):
return
if '.data.varinit.' in section.name:
print("ERROR: %s is VARVERIFY32INIT but used from %s" % (
section.name, chain))
sys.exit(1)
section.category = '32flat'
# Recursively mark all sections this section points to
for reloc in section.relocs:
markRuntime(reloc.symbol.section, sections, chain + [section.name])
def findInit(sections):
# Recursively find and mark all "runtime" sections.
for section in sections:
if ('.data.varlow.' in section.name or '.data.varfseg.' in section.name
or '.runtime.' in section.name or '.export.' in section.name):
markRuntime(section, sections)
for section in sections:
if section.category is not None:
continue
if section.fileid == '32flat':
section.category = '32init'
else:
section.category = section.fileid
######################################################################
# Section garbage collection
######################################################################
CFUNCPREFIX = [('_cfunc16_', 0), ('_cfunc32seg_', 1), ('_cfunc32flat_', 2)]
# Find and keep the section associated with a symbol (if available).
def keepsymbol(reloc, infos, pos, isxref):
symbolname = reloc.symbolname
mustbecfunc = 0
for symprefix, needpos in CFUNCPREFIX:
if symbolname.startswith(symprefix):
if needpos != pos:
return -1
symbolname = symbolname[len(symprefix):]
mustbecfunc = 1
break
symbol = infos[pos][1].get(symbolname)
if (symbol is None or symbol.section is None
or symbol.section.name.startswith('.discard.')):
return -1
isdestcfunc = (symbol.section.name.startswith('.text.')
and not symbol.section.name.startswith('.text.asm.'))
if ((mustbecfunc and not isdestcfunc)
or (not mustbecfunc and isdestcfunc and isxref)):
return -1
reloc.symbol = symbol
keepsection(symbol.section, infos, pos)
return 0
# Note required section, and recursively set all referenced sections
# as required.
def keepsection(section, infos, pos=0):
if section.keep:
# Already kept - nothing to do.
return
section.keep = 1
# Keep all sections that this section points to
for reloc in section.relocs:
ret = keepsymbol(reloc, infos, pos, 0)
if not ret:
continue
# Not in primary sections - it may be a cross 16/32 reference
ret = keepsymbol(reloc, infos, (pos+1)%3, 1)
if not ret:
continue
ret = keepsymbol(reloc, infos, (pos+2)%3, 1)
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 = ((sections16, symbols16), (sect32seg, sym32seg)
# , (sect32flat, sym32flat))
infos = (info16, info32seg, info32flat)
# Start by keeping sections that are globally visible.
for section in info16[0]:
if section.name.startswith('.fixedaddr.') or '.export.' in section.name:
keepsection(section, infos)
return [section for section in info16[0]+info32seg[0]+info32flat[0]
if section.keep]
######################################################################
# Startup and input parsing
######################################################################
class Section:
name = size = alignment = fileid = relocs = None
finalloc = finalsegloc = category = keep = None
class Reloc:
offset = type = symbolname = symbol = None
class Symbol:
name = offset = section = None
# Read in output from objdump
def parseObjDump(file, fileid):
# sections = [section, ...]
sections = []
sectionmap = {}
# symbols[symbolname] = symbol
symbols = {}
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.startswith('RELOCATION RECORDS FOR ['):
sectionname = line[24:-2]
if sectionname.startswith('.debug_'):
# Skip debugging sections (to reduce parsing time)
state = None
continue
state = 'reloc'
relocsection = sectionmap[sectionname]
continue
if state == 'section':
try:
idx, name, size, vma, lma, fileoff, align = line.split()
if align[:3] != '2**':
continue
section = Section()
section.name = name
section.size = int(size, 16)
section.align = 2**int(align[3:])
section.fileid = fileid
section.relocs = []
sections.append(section)
sectionmap[name] = section
except ValueError:
pass
continue
if state == 'symbol':
try:
parts = line[17:].split()
if len(parts) == 3:
sectionname, size, name = parts
elif len(parts) == 4 and parts[2] == '.hidden':
sectionname, size, hidden, name = parts
else:
continue
symbol = Symbol()
symbol.size = int(size, 16)
symbol.offset = int(line[:8], 16)
symbol.name = name
symbol.section = sectionmap.get(sectionname)
symbols[name] = symbol
except ValueError:
pass
continue
if state == 'reloc':
try:
off, type, symbolname = line.split()
reloc = Reloc()
reloc.offset = int(off, 16)
reloc.type = type
reloc.symbolname = symbolname
reloc.symbol = symbols.get(symbolname)
if reloc.symbol is None:
# Some binutils (2.20.1) give section name instead
# of a symbol - create a dummy symbol.
reloc.symbol = symbol = Symbol()
symbol.size = 0
symbol.offset = 0
symbol.name = symbolname
symbol.section = sectionmap.get(symbolname)
symbols[symbolname] = symbol
relocsection.relocs.append(reloc)
except ValueError:
pass
return sections, symbols
# Parser for constants in simple C header files.
def scanconfig(file):
f = open(file, 'rb')
opts = {}
for l in f.readlines():
parts = l.split()
if len(parts) != 3:
continue
if parts[0] != '#define':
continue
value = parts[2]
if value.isdigit() or (value.startswith('0x') and value[2:].isdigit()):
value = int(value, 0)
opts[parts[1]] = value
return opts
def main():
# Get output name
in16, in32seg, in32flat, cfgfile, out16, out32seg, out32flat = sys.argv[1:]
# Read in the objdump information
infile16 = open(in16, 'rb')
infile32seg = open(in32seg, 'rb')
infile32flat = open(in32flat, 'rb')
# infoX = (sections, symbols)
info16 = parseObjDump(infile16, '16')
info32seg = parseObjDump(infile32seg, '32seg')
info32flat = parseObjDump(infile32flat, '32flat')
# Read kconfig config file
config = scanconfig(cfgfile)
# Figure out which sections to keep.
sections = gc(info16, info32seg, info32flat)
# Separate 32bit flat into runtime and init parts
findInit(sections)
# Note "low memory" and "fseg memory" parts
for section in getSectionsPrefix(sections, '.data.varlow.'):
section.category = '32low'
for section in getSectionsPrefix(sections, '.data.varfseg.'):
section.category = '32fseg'
# Determine the final memory locations of each kept section.
genreloc = '_reloc_abs_start' in info32flat[1]
li = doLayout(sections, config, genreloc)
# Exported symbols
li.exportsyms = [symbol for symbol in info16[1].values()
if (symbol.section is not None
and '.export.' in symbol.section.name
and symbol.name != symbol.section.name)]
li.varlowsyms = [symbol for symbol in info32flat[1].values()
if (symbol.section is not None
and symbol.section.finalloc is not None
and '.data.varlow.' in symbol.section.name
and symbol.name != symbol.section.name)]
# Write out linker script files.
writeLinkerScripts(li, out16, out32seg, out32flat)
if __name__ == '__main__':
main()
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