[Wisp-cvs] wisp/users/dig makehello.py,1.18,1.19 elf.py,1.16,1.17
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[Wisp-cvs] wisp/users/dig makehello.py,1.18,1.19 elf.py,1.16,1.17
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From: <di...@us...> - 2003-04-08 21:19:11
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Update of /cvsroot/wisp/wisp/users/dig
In directory sc8-pr-cvs1:/tmp/cvs-serv9820
Modified Files:
makehello.py elf.py
Log Message:
moved make_ELF32_executable from makehello.py to elf.py
Index: makehello.py
===================================================================
RCS file: /cvsroot/wisp/wisp/users/dig/makehello.py,v
retrieving revision 1.18
retrieving revision 1.19
diff -u -d -r1.18 -r1.19
--- makehello.py 3 Apr 2003 09:12:02 -0000 1.18
+++ makehello.py 8 Apr 2003 21:19:05 -0000 1.19
@@ -33,156 +33,8 @@
data.place_symbol('&message')
data.emit_string('Hello, world!\n')
-def infer_by_prefix (name, dict):
- for l in range(len(name), -1, -1):
- prefix = name[:l]
- try: return dict[prefix]
- except: pass
- return None
-def guess_shtype (name):
- return infer_by_prefix(name, {'': SHT.PROGBITS,
- '.bss': SHT.NOBITS,
- '.dynstr': SHT.STRTAB,
- '.note': SHT.NOTE,
- '.shstrtab': SHT.STRTAB,
- '.symstr': SHT.STRTAB,
- '.symtab': SHT.SYMTAB,
- })
-def guess_ptype (name):
- return infer_by_prefix(name, {'': PT.LOAD,
- '.note': PT.NOTE})
-def guess_flags (name):
- return infer_by_prefix(name, {'': 'rw--',
- '.bss': 'rw--',
- '.comment': '----',
- '.data': 'rw--',
- '.debug': '----',
- '.dynstr': 'a--s',
- '.line': '----',
- '.note': '----',
- '.rodata': 'r---',
- '.shstrtab': '---s',
- '.symstr': 'a--s',
- '.text': 'r-x-'})
-def guess_shflags (name):
- flags = guess_flags(name)
- sh_flags = 0
- if 'r' in flags or 'a' in flags: sh_flags |= SHF.ALLOC
- if 'w' in flags: sh_flags |= SHF.ALLOC | SHF.WRITE
- if 'x' in flags: sh_flags |= SHF.ALLOC | SHF.EXECINSTR
- if 's' in flags: sh_flags |= SHF.STRINGS
- return sh_flags
-def guess_pflags (name):
- flags = guess_flags(name)
- p_flags = 0
- if 'r' in flags: p_flags |= PF.R
- if 'w' in flags: p_flags |= PF.W
- if 'x' in flags: p_flags |= PF.X
- return p_flags
-
-def make_executable (text = None, data = None,
- memory_bottom = 0x08048000,
- want_symbols = 1):
- # Will set given sections' origins.
-
- sections = {}
- sections['.text'] = code
- sections['.data'] = data
-
- binary = Linkie('<')
- memory_boundary = memory_bottom # must be at page boundary
- binary.paste(0, make_ELF32_header('<'))
- binary.place_symbol('#elf/type', ET.EXEC)
- binary.place_symbol('#elf/machine', EM.I386)
- binary.place_symbol('#elf/flags', 0) # no flags for ia386
-
- shentnames = ['.text', '.data']
- if want_symbols: shentnames += ['.symstr', '.symtab']
- shentnames.append('.shstrtab')
-
- sections['.shstrtab'] = Linkie('<')
- sections['.shstrtab'].emit_byte(0)
-
- if want_symbols:
- sections['.symstr'] = Linkie('<')
- sections['.symstr'].emit_byte(0)
-
- sections['.symtab'] = Linkie('<')
- sections['.symtab'].align(4)
- sections['.symtab'].emit_string('\0' * 16)
-
- phentnames = []
- for name in shentnames:
- if guess_pflags(name) <> 0:
- phentnames.append(name)
- sections['.shstrtab'].place_symbol('#.shstrtab/strings/' + name)
- sections['.shstrtab'].emit_string(name)
- sections['.shstrtab'].emit_byte(0)
-
- program_header_table = make_ELF32_phtable('<', phentnames)
- binary.paste(-4, program_header_table)
-
- for name in shentnames:
- section = sections[name]
- p_flags = guess_pflags(name)
- alignment = section.get_alignment()
- binary.place_symbol('#' + name + '/sh_align', alignment)
-
- if p_flags <> 0:
- binary.place_symbol('#' + name + '/p_align', 0x1000)
- binary.align(min(alignment, 0x1000))
- else:
- # No program header entry => not loaded
- # thusly no larger alignment necessary.
- binary.align(min(alignment, 4))
-
- offset = binary.filesz()
-
- if p_flags <> 0:
- address = memory_boundary | (offset & 0xFFF)
- # take into account alignments larger than a page
- address = (address + alignment - 1) & ~(alignment - 1)
- binary.place_symbol('#' + name + '/p_flags', guess_pflags(name))
- binary.place_symbol('#' + name + '/p_type', guess_ptype(name))
- section.set_origin(address)
- binary.place_symbol('&' + name, address)
- else:
- address = None
-
- binary.place_symbol('#' + name + '/memsz', section.memsz())
- binary.place_symbol('#' + name + '/filesz', section.filesz())
- binary.place_symbol('#' + name + '/sh_size', section.filesz())
- binary.place_symbol('#' + name + '/sh_type', guess_shtype(name))
- binary.place_symbol('#' + name + '/sh_info', 0)
- if name == '.symtab': sh_link = shentnames.index('.symstr') + 1
- else: sh_link = SHN.UNDEF
- binary.place_symbol('#' + name + '/sh_link', sh_link)
- binary.place_symbol('#' + name + '/sh_entsize', 0)
- binary.place_symbol('#' + name + '/sh_flags', guess_shflags(name))
-
- # alignment has been processed already
- binary.place_symbol('!' + name)
- binary.paste(-1, section)
- if want_symbols:
- symtab = sections['.symtab']
- symstr = sections['.symstr']
- for symbol, value in section.get_symbols():
- if symbol[0] == '&': # only process memory references
- emit_ELF32_symtab_entry(symtab, symstr, symbol, value,
- shentnames.index(name) + 1)
-
- memory_boundary += section.memsz()
- memory_boundary = (memory_boundary + 0xFFF) & ~0xFFF
-
- # create section header table
- section_header_table = make_ELF32_shtable('<', shentnames)
- binary.paste(-4, section_header_table)
- binary.place_symbol('#elf/shstrndx', shentnames.index('.shstrtab') + 1)
- binary.link()
- return binary
-
print 'With symbols'
-hello = make_executable(text = code, data = data)
+hello = make_ELF32_executable(text = code, data = data, want_symbols = 1)
hello.dump()
f = open('hello', 'w')
@@ -190,7 +42,7 @@
f.close()
print 'Without symbols'
-hellowosym = make_executable(text = code, data = data, want_symbols = 0)
+hellowosym = make_ELF32_executable(text = code, data = data, want_symbols = 0)
hellowosym.dump()
f = open('hellowosym', 'w')
Index: elf.py
===================================================================
RCS file: /cvsroot/wisp/wisp/users/dig/elf.py,v
retrieving revision 1.16
retrieving revision 1.17
diff -u -d -r1.16 -r1.17
--- elf.py 3 Apr 2003 09:12:01 -0000 1.16
+++ elf.py 8 Apr 2003 21:19:06 -0000 1.17
@@ -406,12 +406,160 @@
symtab.emit_byte(0) # st_other; reserved
symtab.emit_wyde(section)
+def infer_by_prefix (name, dict):
+ for l in range(len(name), -1, -1):
+ prefix = name[:l]
+ try: return dict[prefix]
+ except: pass
+ return None
+
+def guess_ELF32_shtype (name):
+ return infer_by_prefix(name, {'': SHT.PROGBITS,
+ '.bss': SHT.NOBITS,
+ '.dynstr': SHT.STRTAB,
+ '.note': SHT.NOTE,
+ '.shstrtab': SHT.STRTAB,
+ '.symstr': SHT.STRTAB,
+ '.symtab': SHT.SYMTAB,
+ })
+
+def guess_ELF32_ptype (name):
+ return infer_by_prefix(name, {'': PT.LOAD,
+ '.note': PT.NOTE})
+
+def guess_ELF32_flags (name):
+ return infer_by_prefix(name, {'': 'rw--',
+ '.bss': 'rw--',
+ '.comment': '----',
+ '.data': 'rw--',
+ '.debug': '----',
+ '.dynstr': 'a--s',
+ '.line': '----',
+ '.note': '----',
+ '.rodata': 'r---',
+ '.shstrtab': '---s',
+ '.symstr': 'a--s',
+ '.text': 'r-x-'})
+
+def guess_ELF32_shflags (name):
+ flags = guess_ELF32_flags(name)
+ sh_flags = 0
+ if 'r' in flags or 'a' in flags: sh_flags |= SHF.ALLOC
+ if 'w' in flags: sh_flags |= SHF.ALLOC | SHF.WRITE
+ if 'x' in flags: sh_flags |= SHF.ALLOC | SHF.EXECINSTR
+ if 's' in flags: sh_flags |= SHF.STRINGS
+ return sh_flags
+
+def guess_ELF32_pflags (name):
+ flags = guess_ELF32_flags(name)
+ p_flags = 0
+ if 'r' in flags: p_flags |= PF.R
+ if 'w' in flags: p_flags |= PF.W
+ if 'x' in flags: p_flags |= PF.X
+ return p_flags
+
+def make_ELF32_executable (text = None, data = None,
+ memory_bottom = 0x08048000,
+ want_symbols = 0):
+ # Will set given sections' origins.
+
+ sections = {}
+ sections['.text'] = text
+ sections['.data'] = data
+
+ binary = Linkie('<')
+ memory_boundary = memory_bottom # must be at page boundary
+ binary.paste(0, make_ELF32_header('<'))
+ binary.place_symbol('#elf/type', ET.EXEC)
+ binary.place_symbol('#elf/machine', EM.I386)
+ binary.place_symbol('#elf/flags', 0) # no flags for ia386
+
+ shentnames = ['.text', '.data']
+ if want_symbols: shentnames += ['.symstr', '.symtab']
+ shentnames.append('.shstrtab')
+
+ sections['.shstrtab'] = Linkie('<')
+ sections['.shstrtab'].emit_byte(0)
+
+ if want_symbols:
+ sections['.symstr'] = Linkie('<')
+ sections['.symstr'].emit_byte(0)
+
+ sections['.symtab'] = Linkie('<')
+ sections['.symtab'].align(4)
+ sections['.symtab'].emit_string('\0' * 16)
+
+ phentnames = []
+ for name in shentnames:
+ if guess_ELF32_pflags(name) <> 0:
+ phentnames.append(name)
+ sections['.shstrtab'].place_symbol('#.shstrtab/strings/' + name)
+ sections['.shstrtab'].emit_string(name)
+ sections['.shstrtab'].emit_byte(0)
+
+ program_header_table = make_ELF32_phtable('<', phentnames)
+ binary.paste(-4, program_header_table)
+
+ for name in shentnames:
+ section = sections[name]
+ p_flags = guess_ELF32_pflags(name)
+ alignment = section.get_alignment()
+ binary.place_symbol('#' + name + '/sh_align', alignment)
+
+ if p_flags <> 0:
+ binary.place_symbol('#' + name + '/p_align', 0x1000)
+ binary.align(min(alignment, 0x1000))
+ else:
+ # No program header entry => not loaded
+ # thusly no larger alignment necessary.
+ binary.align(min(alignment, 4))
+
+ offset = binary.filesz()
+
+ if p_flags <> 0:
+ address = memory_boundary | (offset & 0xFFF)
+ # take into account alignments larger than a page
+ address = (address + alignment - 1) & ~(alignment - 1)
+ binary.place_symbol('#' + name + '/p_flags', guess_ELF32_pflags(name))
+ binary.place_symbol('#' + name + '/p_type', guess_ELF32_ptype(name))
+ section.set_origin(address)
+ binary.place_symbol('&' + name, address)
+ else:
+ address = None
+
+ binary.place_symbol('#' + name + '/memsz', section.memsz())
+ binary.place_symbol('#' + name + '/filesz', section.filesz())
+ binary.place_symbol('#' + name + '/sh_size', section.filesz())
+ binary.place_symbol('#' + name + '/sh_type', guess_ELF32_shtype(name))
+ binary.place_symbol('#' + name + '/sh_info', 0)
+ if name == '.symtab': sh_link = shentnames.index('.symstr') + 1
+ else: sh_link = SHN.UNDEF
+ binary.place_symbol('#' + name + '/sh_link', sh_link)
+ binary.place_symbol('#' + name + '/sh_entsize', 0)
+ binary.place_symbol('#' + name + '/sh_flags', guess_ELF32_shflags(name))
+
+ # alignment has been processed already
+ binary.place_symbol('!' + name)
+ binary.paste(-1, section)
+ if want_symbols:
+ symtab = sections['.symtab']
+ symstr = sections['.symstr']
+ for symbol, value in section.get_symbols():
+ if symbol[0] == '&': # only process memory references
+ emit_ELF32_symtab_entry(symtab, symstr, symbol, value,
+ shentnames.index(name) + 1)
+
+ memory_boundary += section.memsz()
+ memory_boundary = (memory_boundary + 0xFFF) & ~0xFFF
+
+ # create section header table
+ section_header_table = make_ELF32_shtable('<', shentnames)
+ binary.paste(-4, section_header_table)
+ binary.place_symbol('#elf/shstrndx', shentnames.index('.shstrtab') + 1)
+ binary.link()
+ return binary
+
# Thoughts of generating ELF32 files
# * In ELF parlance, linker notes are called relocations.
# We need to solve relocations only when generating an
# executable file.
-# * ELF symbols are defined relative to their corresponding sections'
-# origins. Basically, a symbol's value consists of two parts:
-# reference to its section and its location inside the section.
-# * We'll need some symbols to represent offsets in the generated
-# file. It's probably best to treat them as ELF absolute symbols.
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