From: Kevin O'Connor <kevin@koconnor.net>
Date: Wed, 15 Sep 2010 04:26:19 +0000 (-0400)
Subject: Enhance build to emit relocation information.
X-Git-Url: http://wien.tomnetworks.com/gitweb/?a=commitdiff_plain;h=402fd9cba09e1885f3ee136e279223d2bd83049a;p=seabios.git

Enhance build to emit relocation information.

Add support for determining which relocations need to be adjusted to
relocate the "32bit flat init" code.  Place those relocations in the
output object.
---

diff --git a/tools/layoutrom.py b/tools/layoutrom.py
index ca8cb3c..7eca502 100755
--- a/tools/layoutrom.py
+++ b/tools/layoutrom.py
@@ -241,7 +241,7 @@ def getSectionsFile(sections, fileid, defaddr=0):
     return sections, pos
 
 # Layout the 32bit segmented code.  This places the code as high as possible.
-def writeLinkerScripts(sections, entrysym, out16, out32seg, out32flat):
+def writeLinkerScripts(sections, entrysym, genreloc, out16, out32seg, out32flat):
     # Write 16bit linker script
     sections16, code16_start = getSectionsFile(sections, '16')
     output = open(out16, 'wb')
@@ -274,15 +274,26 @@ def writeLinkerScripts(sections, entrysym, out16, out32seg, out32flat):
     # Write 32flat linker script
     sections32flat, code32flat_start = getSectionsFile(
         sections, '32flat', code32seg_start)
+    relocstr = ""
+    relocminalign = 0
+    if genreloc:
+        # Generate relocations
+        relocstr, size, relocminalign = genRelocs(sections)
+        code32flat_start -= size
     output = open(out32flat, 'wb')
     output.write(COMMONHEADER
                  + outXRefs(sections32flat) + """
     %s = 0x%x ;
+    _reloc_min_align = 0x%x ;
     code32flat_start = 0x%x ;
     .text code32flat_start : {
 """ % (entrysym.name,
        entrysym.section.finalloc + entrysym.offset + BUILD_BIOS_ADDR,
-       code32flat_start)
+       relocminalign, code32flat_start)
+                 + relocstr
+                 + """
+        code32init_start = ABSOLUTE(.) ;
+"""
                  + outRelSections(getSectionsPrefix(sections32flat, '32init', '')
                                   , 'code32flat_start')
                  + """
@@ -313,6 +324,51 @@ PHDRS
 # Detection of init code
 ######################################################################
 
+# Determine init section relocations
+def genRelocs(sections):
+    absrelocs = []
+    relrelocs = []
+    initrelocs = []
+    minalign = 16
+    for section in sections:
+        if section.category == '32init' and section.align > minalign:
+            minalign = section.align
+        for reloc in section.relocs:
+            symbol = reloc.symbol
+            if symbol.section is None:
+                continue
+            relocpos = section.finalloc + reloc.offset
+            if (reloc.type == 'R_386_32' and section.category == '32init'
+                and symbol.section.category == '32init'):
+                # Absolute relocation
+                absrelocs.append(relocpos)
+            elif (reloc.type == 'R_386_PC32' and section.category == '32init'
+                  and symbol.section.category != '32init'):
+                # Relative relocation
+                relrelocs.append(relocpos)
+            elif (section.category != '32init'
+                  and symbol.section.category == '32init'):
+                # Relocation to the init section
+                if section.fileid in ('16', '32seg'):
+                    relocpos += BUILD_BIOS_ADDR
+                initrelocs.append(relocpos)
+    absrelocs.sort()
+    relrelocs.sort()
+    initrelocs.sort()
+    out = ("        _reloc_abs_start = ABSOLUTE(.) ;\n"
+           + "".join(["LONG(0x%x - code32init_start)\n" % (pos,)
+                      for pos in absrelocs])
+           + "        _reloc_abs_end = ABSOLUTE(.) ;\n"
+           + "        _reloc_rel_start = ABSOLUTE(.) ;\n"
+           + "".join(["LONG(0x%x - code32init_start)\n" % (pos,)
+                      for pos in relrelocs])
+           + "        _reloc_rel_end = ABSOLUTE(.) ;\n"
+           + "        _reloc_init_start = ABSOLUTE(.) ;\n"
+           + "".join(["LONG(0x%x - code32flat_start)\n" % (pos,)
+                      for pos in initrelocs])
+           + "        _reloc_init_end = ABSOLUTE(.) ;\n")
+    return out, len(absrelocs + relrelocs + initrelocs) * 4, minalign
+
 def markRuntime(section, sections):
     if (section is None or not section.keep or section.category is not None
         or '.init.' in section.name or section.fileid != '32flat'):
@@ -490,7 +546,8 @@ def main():
 
     # Write out linker script files.
     entrysym = info16[1]['post32']
-    writeLinkerScripts(sections, entrysym, out16, out32seg, out32flat)
+    genreloc = '_reloc_abs_start' in info32flat[1]
+    writeLinkerScripts(sections, entrysym, genreloc, out16, out32seg, out32flat)
 
 if __name__ == '__main__':
     main()