#!/usr/bin/env python
# Script to analyze code and arrange ld sections.
#
# Copyright (C) 2008-2014 Kevin O'Connor <kevin@koconnor.net>
#
# This file may be distributed under the terms of the GNU GPLv3 license.
import operator
import sys
# LD script headers/trailers
COMMONHEADER = """
/* DO NOT EDIT! This is an autogenerated file. See scripts/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 = int((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(key=operator.itemgetter(0))
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(key=operator.itemgetter(0))
# 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 fileid
def getSectionsFileid(sections, fileid):
return [section for section in sections if section.fileid == fileid]
# 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:
sections = None
config = None
genreloc = None
sec32init_start = sec32init_end = sec32init_align = None
sec32low_start = sec32low_end = None
zonelow_base = final_sec32low_start = None
zonefseg_start = zonefseg_end = None
final_readonly_start = None
varlowsyms = entrysym = None
# Determine final memory addresses for sections
def doLayout(sections, config, genreloc):
li = LayoutInfo()
li.config = config
li.sections = sections
li.genreloc = genreloc
# Determine 16bit positions
sections16 = getSectionsCategory(sections, '16')
textsections = getSectionsPrefix(sections16, '.text.')
rodatasections = getSectionsPrefix(sections16, '.rodata')
datasections = getSectionsPrefix(sections16, '.data16.')
fixedsections = getSectionsCategory(sections, 'fixed')
firstfixed = fitSections(fixedsections, textsections)
remsections = [s for s in textsections+rodatasections+datasections
if s.finalloc is None]
sec16_start, sec16_align = setSectionsStart(
remsections, firstfixed, segoffset=BUILD_BIOS_ADDR)
# Determine 32seg positions
sections32seg = getSectionsCategory(sections, '32seg')
textsections = getSectionsPrefix(sections32seg, '.text.')
rodatasections = getSectionsPrefix(sections32seg, '.rodata')
datasections = getSectionsPrefix(sections32seg, '.data32seg.')
sec32seg_start, sec32seg_align = setSectionsStart(
textsections + rodatasections + datasections, sec16_start
, segoffset=BUILD_BIOS_ADDR)
# Determine 32bit "fseg memory" data positions
sections32textfseg = getSectionsCategory(sections, '32textfseg')
sec32textfseg_start, sec32textfseg_align = setSectionsStart(
sections32textfseg, sec32seg_start, 16)
sections32fseg = getSectionsCategory(sections, '32fseg')
sec32fseg_start, sec32fseg_align = setSectionsStart(
sections32fseg, sec32textfseg_start, 16
, segoffset=BUILD_BIOS_ADDR)
# Determine 32flat runtime positions
sections32flat = getSectionsCategory(sections, '32flat')
textsections = getSectionsPrefix(sections32flat, '.text.')
rodatasections = getSectionsPrefix(sections32flat, '.rodata')
datasections = getSectionsPrefix(sections32flat, '.data.')
bsssections = getSectionsPrefix(sections32flat, '.bss.')
sec32flat_start, sec32flat_align = setSectionsStart(
textsections + rodatasections + datasections + bsssections
, sec32fseg_start, 16)
# Determine 32flat init positions
sections32init = getSectionsCategory(sections, '32init')
init32_textsections = getSectionsPrefix(sections32init, '.text.')
init32_rodatasections = getSectionsPrefix(sections32init, '.rodata')
init32_datasections = getSectionsPrefix(sections32init, '.data.')
init32_bsssections = getSectionsPrefix(sections32init, '.bss.')
sec32init_start, sec32init_align = setSectionsStart(
init32_textsections + init32_rodatasections
+ init32_datasections + init32_bsssections
, sec32flat_start, 16)
# Determine location of ZoneFSeg memory.
zonefseg_end = sec32flat_start
if not genreloc:
zonefseg_end = sec32init_start
zonefseg_start = BUILD_BIOS_ADDR
if zonefseg_start + BUILD_MIN_BIOSTABLE > zonefseg_end:
# Not enough ZoneFSeg space - force a minimum space.
zonefseg_end = sec32fseg_start
zonefseg_start = zonefseg_end - BUILD_MIN_BIOSTABLE
sec32flat_start, sec32flat_align = setSectionsStart(
textsections + rodatasections + datasections + bsssections
, zonefseg_start, 16)
sec32init_start, sec32init_align = setSectionsStart(
init32_textsections + init32_rodatasections
+ init32_datasections + init32_bsssections
, sec32flat_start, 16)
li.sec32init_start = sec32init_start
li.sec32init_end = sec32flat_start
li.sec32init_align = sec32init_align
final_readonly_start = min(BUILD_BIOS_ADDR, sec32flat_start)
if not genreloc:
final_readonly_start = min(BUILD_BIOS_ADDR, sec32init_start)
li.zonefseg_start = zonefseg_start
li.zonefseg_end = zonefseg_end
li.final_readonly_start = final_readonly_start
# Determine "low memory" data positions
sections32low = getSectionsCategory(sections, '32low')
sec32low_end = sec32init_start
if config.get('CONFIG_MALLOC_UPPERMEMORY'):
final_sec32low_end = final_readonly_start
zonelow_base = final_sec32low_end - 64*1024
zonelow_base = max(BUILD_ROM_START, alignpos(zonelow_base, 2*1024))
else:
final_sec32low_end = BUILD_LOWRAM_END
zonelow_base = final_sec32low_end - 64*1024
relocdelta = final_sec32low_end - sec32low_end
li.sec32low_start, li.sec32low_align = setSectionsStart(
sections32low, sec32low_end, 16
, segoffset=zonelow_base - relocdelta)
li.sec32low_end = sec32low_end
li.zonelow_base = zonelow_base
li.final_sec32low_start = li.sec32low_start + relocdelta
# Print statistics
size16 = BUILD_BIOS_ADDR + BUILD_BIOS_SIZE - sec16_start
size32seg = sec16_start - sec32seg_start
size32textfseg = sec32seg_start - sec32textfseg_start
size32fseg = sec32textfseg_start - sec32fseg_start
size32flat = sec32fseg_start - sec32flat_start
size32init = sec32flat_start - sec32init_start
sizelow = li.sec32low_end - li.sec32low_start
print("16bit size: %d" % size16)
print("32bit segmented size: %d" % size32seg)
print("32bit flat size: %d" % (size32flat + size32textfseg))
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
def outSections(sections, useseg=0):
out = ""
for section in sections:
loc = section.finalloc
if useseg:
loc = section.finalsegloc
out += "%s 0x%x : { *(%s) }\n" % (section.name, loc, section.name)
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(key=operator.itemgetter(0))
out = ""
for addr, section in sections:
loc = section.finalloc
if useseg:
loc = section.finalsegloc
out += ". = ( 0x%x - %s ) ;\n" % (loc, startsym)
if section.name in ('.rodata.str1.1', '.rodata'):
out += "_rodata%s = . ;\n" % (section.fileid,)
out += "*%s.*(%s)\n" % (section.fileid, 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 relocations to the given sections
def getRelocs(sections, tosection, type=None):
return [section.finalloc + reloc.offset
for section in sections
for reloc in section.relocs
if (reloc.symbol.section in tosection
and (type is None or reloc.type == type))]
# Output the linker scripts for all required sections.
def writeLinkerScripts(li, out16, out32seg, out32flat):
# Write 16bit linker script
filesections16 = getSectionsFileid(li.sections, '16')
out = outXRefs(filesections16, useseg=1) + """
zonelow_base = 0x%x ;
_zonelow_seg = 0x%x ;
%s
""" % (li.zonelow_base,
int(li.zonelow_base / 16),
outSections(filesections16, useseg=1))
outfile = open(out16, 'w')
outfile.write(COMMONHEADER + out + COMMONTRAILER)
outfile.close()
# Write 32seg linker script
filesections32seg = getSectionsFileid(li.sections, '32seg')
out = (outXRefs(filesections32seg, useseg=1)
+ outSections(filesections32seg, useseg=1))
outfile = open(out32seg, 'w')
outfile.write(COMMONHEADER + out + COMMONTRAILER)
outfile.close()
# Write 32flat linker script
sec32all_start = li.sec32low_start
relocstr = ""
if li.genreloc:
# Generate relocations
initsections = dict([
(s, 1) for s in getSectionsCategory(li.sections, '32init')])
noninitsections = dict([(s, 1) for s in li.sections
if s not in initsections])
absrelocs = getRelocs(initsections, initsections, type='R_386_32')
relrelocs = getRelocs(initsections, noninitsections, type='R_386_PC32')
initrelocs = getRelocs(noninitsections, initsections)
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
filesections32flat = getSectionsFileid(li.sections, '32flat')
out = outXRefs([], exportsyms=li.varlowsyms
, forcedelta=li.final_sec32low_start-li.sec32low_start)
multiboot_header = ""
if li.config.get('CONFIG_MULTIBOOT'):
multiboot_header = "LONG(0x1BADB002) LONG(0) LONG(-0x1BADB002)"
sec32all_start -= 3 * 4
out += outXRefs(filesections32flat, exportsyms=[li.entrysym]) + """
_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 ;
varlow_start = 0x%x ;
varlow_end = 0x%x ;
code32init_start = 0x%x ;
code32init_end = 0x%x ;
code32flat_start = 0x%x ;
.text code32flat_start : {
%s
%s
%s
code32flat_end = ABSOLUTE(.) ;
} :text
""" % (li.sec32init_align,
li.zonefseg_start,
li.zonefseg_end,
li.zonelow_base,
li.final_sec32low_start,
li.final_readonly_start,
li.sec32low_start,
li.sec32low_end,
li.sec32init_start,
li.sec32init_end,
sec32all_start,
multiboot_header,
relocstr,
outRelSections(li.sections, 'code32flat_start'))
out = COMMONHEADER + out + COMMONTRAILER + """
ENTRY(%s)
PHDRS
{
text PT_LOAD AT ( code32flat_start ) ;
}
""" % (li.entrysym.name,)
outfile = open(out32flat, 'w')
outfile.write(out)
outfile.close()
######################################################################
# Detection of unused sections and init sections
######################################################################
# Visit all sections reachable from a given set of start sections
def findReachable(anchorsections, checkreloc, data):
anchorsections = dict([(section, []) for section in anchorsections])
pending = list(anchorsections)
while pending:
section = pending.pop()
for reloc in section.relocs:
chain = anchorsections[section] + [section.name]
if not checkreloc(reloc, section, data, chain):
continue
nextsection = reloc.symbol.section
if nextsection not in anchorsections:
anchorsections[nextsection] = chain
pending.append(nextsection)
return anchorsections
# Find "runtime" sections (ie, not init only sections).
def checkRuntime(reloc, rsection, data, chain):
section = reloc.symbol.section
if section is None or '.init.' in section.name:
return 0
if '.data.varinit.' in section.name:
print("ERROR: %s is VARVERIFY32INIT but used from %s" % (
section.name, chain))
sys.exit(1)
return 1
# Find and keep the section associated with a symbol (if available).
def checkKeepSym(reloc, syms, fileid, isxref):
symbolname = reloc.symbolname
mustbecfunc = symbolname.startswith('_cfunc')
if mustbecfunc:
symprefix = '_cfunc' + fileid + '_'
if not symbolname.startswith(symprefix):
return 0
symbolname = symbolname[len(symprefix):]
symbol = syms.get(symbolname)
if (symbol is None or symbol.section is None
or symbol.section.name.startswith('.discard.')):
return 0
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 0
reloc.symbol = symbol
return 1
# Resolve a relocation and check if it should be kept in the final binary.
def checkKeep(reloc, section, symbols, chain):
ret = checkKeepSym(reloc, symbols[section.fileid], section.fileid, 0)
if ret:
return ret
# Not in primary sections - it may be a cross 16/32 reference
for fileid in ('16', '32seg', '32flat'):
if fileid != section.fileid:
ret = checkKeepSym(reloc, symbols[fileid], fileid, 1)
if ret:
return ret
return 0
######################################################################
# Startup and input parsing
######################################################################
class Section:
name = size = alignment = fileid = relocs = None
finalloc = finalsegloc = category = 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, 'r')
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, 'r')
infile32seg = open(in32seg, 'r')
infile32flat = open(in32flat, 'r')
# 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.
allsections = info16[0] + info32seg[0] + info32flat[0]
symbols = {'16': info16[1], '32seg': info32seg[1], '32flat': info32flat[1]}
if config.get('CONFIG_COREBOOT'):
entrysym = symbols['16'].get('entry_elf')
elif config.get('CONFIG_CSM'):
entrysym = symbols['16'].get('entry_csm')
else:
entrysym = symbols['16'].get('reset_vector')
anchorsections = [entrysym.section] + [
section for section in allsections
if section.name.startswith('.fixedaddr.')]
keepsections = findReachable(anchorsections, checkKeep, symbols)
sections = [section for section in allsections if section in keepsections]
# Separate 32bit flat into runtime, init, and special variable parts
anchorsections = [
section for section in sections
if ('.data.varlow.' in section.name or '.data.varfseg.' in section.name
or '.fixedaddr.' in section.name or '.runtime.' in section.name)]
runtimesections = findReachable(anchorsections, checkRuntime, None)
for section in sections:
if section.name.startswith('.data.varlow.'):
section.category = '32low'
elif section.name.startswith('.data.varfseg.'):
section.category = '32fseg'
elif section.name.startswith('.text.32fseg.'):
section.category = '32textfseg'
elif section.name.startswith('.fixedaddr.'):
section.category = 'fixed'
elif section.fileid == '32flat' and section not in runtimesections:
section.category = '32init'
else:
section.category = section.fileid
# Determine the final memory locations of each kept section.
genreloc = '_reloc_abs_start' in symbols['32flat']
li = doLayout(sections, config, genreloc)
# Exported symbols
li.varlowsyms = [symbol for symbol in symbols['32flat'].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)]
li.entrysym = entrysym
# Write out linker script files.
writeLinkerScripts(li, out16, out32seg, out32flat)
if __name__ == '__main__':
main()