2 # Script to analyze code and arrange ld sections.
4 # Copyright (C) 2008 Kevin O'Connor <kevin@koconnor.net>
6 # This file may be distributed under the terms of the GNU GPLv3 license.
10 # Align 'pos' to 'alignbytes' offset
11 def alignpos(pos, alignbytes):
13 return (pos + mask) & ~mask
15 # LD script headers/trailers
17 /* DO NOT EDIT! This is an autogenerated file. See tools/layoutrom.py. */
18 OUTPUT_FORMAT("elf32-i386")
28 ######################################################################
29 # 16bit fixed address section fitting
30 ######################################################################
32 # Get the maximum start position for a list of sections that end at an
34 def getSectionsStart(sections, endaddr, minalign=1):
36 for size, align, name in sections:
39 totspace = alignpos(totspace, align) + size
40 return (endaddr - totspace) / minalign * minalign
42 # Write LD script includes for the given sections
43 def outSections(file, sections):
44 for size, align, name in sections:
45 file.write("*(%s)\n" % (name,))
47 # The 16bit code can't exceed 64K of space.
50 # Layout the 16bit code. This ensures sections with fixed offset
51 # requirements are placed in the correct location. It also places the
52 # 16bit code as high as possible in the f-segment.
53 def doLayout16(sections, outname):
57 # fixedsections = [(addr, sectioninfo, extasectionslist), ...]
59 # canrelocate = [(sectioninfo, list), ...]
62 # Find desired sections.
63 for section in sections:
64 size, align, name = section
65 if name[:11] == '.fixedaddr.':
66 addr = int(name[11:], 16)
67 fixedsections.append((addr, section, []))
69 print "Error: Fixed section %s has non-zero alignment (%d)" % (
72 if name[:6] == '.text.':
73 textsections.append(section)
74 canrelocate.append((section, textsections))
75 if name[:17] == '.rodata.__func__.' or name == '.rodata.str1.1':
76 rodatasections.append(section)
77 #canrelocate.append((section, rodatasections))
78 if name[:8] == '.data16.':
79 datasections.append(section)
80 #canrelocate.append((section, datasections))
82 # Find freespace in fixed address area
84 # fixedAddr = [(freespace, sectioninfo), ...]
86 for i in range(len(fixedsections)):
87 fixedsectioninfo = fixedsections[i]
88 addr, section, extrasectionslist = fixedsectioninfo
89 if i == len(fixedsections) - 1:
92 nextaddr = fixedsections[i+1][0]
93 avail = nextaddr - addr - section[0]
94 fixedAddr.append((avail, fixedsectioninfo))
96 # Attempt to fit other sections into fixed area
100 for freespace, fixedsectioninfo in fixedAddr:
101 fixedaddr, fixedsection, extrasections = fixedsectioninfo
102 addpos = fixedaddr + fixedsection[0]
103 totalused += fixedsection[0]
104 nextfixedaddr = addpos + freespace
105 # print "Filling section %x uses %d, next=%x, available=%d" % (
106 # fixedaddr, fixedsection[0], nextfixedaddr, freespace)
109 for fixedaddrinfo in canrelocate:
110 fitsection, inlist = fixedaddrinfo
111 fitsize, fitalign, fitname = fitsection
112 if addpos + fitsize > nextfixedaddr:
113 # Can't fit and nothing else will fit.
115 fitnextaddr = alignpos(addpos, fitalign) + fitsize
116 # print "Test %s - %x vs %x" % (
117 # fitname, fitnextaddr, nextfixedaddr)
118 if fitnextaddr > nextfixedaddr:
119 # This item can't fit.
121 canfit = (fitnextaddr, fixedaddrinfo)
124 # Found a section that can fit.
125 fitnextaddr, fixedaddrinfo = canfit
126 canrelocate.remove(fixedaddrinfo)
127 fitsection, inlist = fixedaddrinfo
128 inlist.remove(fitsection)
129 extrasections.append(fitsection)
131 totalused += fitsection[0]
132 # print " Adding %s (size %d align %d) pos=%x avail=%d" % (
133 # fitsection[2], fitsection[0], fitsection[1]
134 # , fitnextaddr, nextfixedaddr - fitnextaddr)
135 firstfixed = fixedsections[0][0]
138 total = MAXPOS-firstfixed
139 slack = total - totalused
140 print ("Fixed space: 0x%x-0x%x total: %d slack: %d"
141 " Percent slack: %.1f%%" % (
142 firstfixed, MAXPOS, total, slack,
143 (float(slack) / total) * 100.0))
145 # Find start positions
146 text16_start = getSectionsStart(textsections, firstfixed)
147 data16_start = getSectionsStart(rodatasections + datasections, text16_start)
149 # Write header and regular sections
150 output = open(outname, 'wb')
151 output.write(COMMONHEADER + """
152 data16_start = 0x%x ;
153 .data16 data16_start : {
156 outSections(output, datasections)
157 output.write("code16_rodata = . ;\n")
158 outSections(output, rodatasections)
162 text16_start = 0x%x ;
163 .text16 text16_start : {
165 outSections(output, textsections)
167 # Write fixed sections
168 for addr, section, extrasections in fixedsections:
170 output.write(". = ( 0x%x - text16_start ) ;\n" % (addr,))
171 output.write("*(%s)\n" % (name,))
172 for extrasection in extrasections:
173 output.write("*(%s)\n" % (extrasection[2],))
177 text16_end = ABSOLUTE(.) ;
180 /* Discard regular data sections to force a link error if
181 * 16bit code attempts to access data not marked with VAR16
183 /DISCARD/ : { *(.text*) *(.rodata*) *(.data*) *(.bss*) *(COMMON) }
189 ######################################################################
190 # 32bit section outputting
191 ######################################################################
193 # Return the subset of sections with a given name prefix
194 def getSectionsPrefix(sections, prefix):
197 for size, align, name in sections:
198 if name[:lp] == prefix:
199 out.append((size, align, name))
202 # Layout the 32bit code. This places the code as high as possible.
203 def doLayout32(sections, outname, start16):
205 # Find sections to output
206 textsections = getSectionsPrefix(sections, '.text.')
207 rodatasections = getSectionsPrefix(sections, '.rodata')
208 datasections = getSectionsPrefix(sections, '.data.')
209 bsssections = getSectionsPrefix(sections, '.bss.')
210 start32 = getSectionsStart(
211 textsections + rodatasections + datasections + bsssections, start16, 512)
214 output = open(outname, 'wb')
215 output.write(COMMONHEADER + """
217 code32_start = ABSOLUTE(.) ;
220 outSections(output, textsections)
221 output.write("code32_rodata = . ;\n")
222 outSections(output, rodatasections)
223 outSections(output, datasections)
224 outSections(output, bsssections)
227 freespace_start = . ;
228 code32_end = ABSOLUTE(.) ;
233 ######################################################################
234 # Section garbage collection
235 ######################################################################
237 # Note required section, and recursively set all referenced sections
239 def keepsection(name, pri, alt):
241 # Already kept - nothing to do.
244 relocs = pri[2].get(name)
247 # Keep all sections that this section points to
248 for symbol in relocs:
249 addr, section = pri[1].get(symbol, (None, None))
250 if (section is not None and '*' not in section
251 and section[:9] != '.discard.'):
252 keepsection(section, pri, alt)
254 # Not in primary sections - it may be a cross 16/32 reference
255 addr, section = alt[1].get(symbol, (None, None))
256 if section is not None and '*' not in section:
257 keepsection(section, alt, pri)
259 # Determine which sections are actually referenced and need to be
260 # placed into the output file.
261 def gc(info16, info32):
262 # pri = (sections, symbols, relocs, keep sections)
263 pri = (info16[0], info16[1], info16[2], [])
264 alt = (info32[0], info32[1], info32[2], [])
265 # Start by keeping sections that are globally visible.
266 for size, align, section in info16[0]:
267 if section[:11] == '.fixedaddr.' or '.export.' in section:
268 keepsection(section, pri, alt)
269 # Return sections found.
271 for info in info16[0]:
272 size, align, section = info
273 if section not in pri[3]:
274 # print "gc16", section
276 sections16.append(info)
278 for info in info32[0]:
279 size, align, section = info
280 if section not in alt[3]:
281 # print "gc32", section
283 sections32.append(info)
284 return sections16, sections32
287 ######################################################################
288 # Startup and input parsing
289 ######################################################################
291 # Read in output from objdump
292 def parseObjDump(file):
293 # sections = [(size, align, section), ...]
295 # symbols[symbol] = section
297 # relocs[section] = [symbol, ...]
301 for line in file.readlines():
303 if line == 'Sections:':
306 if line == 'SYMBOL TABLE:':
309 if line[:24] == 'RELOCATION RECORDS FOR [':
311 relocsection = line[24:-2]
314 if state == 'section':
316 idx, name, size, vma, lma, fileoff, align = line.split()
317 if align[:3] != '2**':
319 sections.append((int(size, 16), 2**int(align[3:]), name))
323 if state == 'symbol':
325 section, off, symbol = line[17:].split()
327 addr = int(line[:8], 16)
328 symbols[symbol] = addr, section
334 off, type, symbol = line.split()
336 relocs.setdefault(relocsection, []).append(symbol)
339 return sections, symbols, relocs
343 in16, in32, out16, out32 = sys.argv[1:]
345 infile16 = open(in16, 'rb')
346 infile32 = open(in32, 'rb')
348 info16 = parseObjDump(infile16)
349 info32 = parseObjDump(infile32)
351 sections16, sections32 = gc(info16, info32)
353 start16 = doLayout16(sections16, out16)
354 doLayout32(sections32, out32, start16)
356 if __name__ == '__main__':