objdump.py

#
# Copyright 2020, Data61, CSIRO (ABN 41 687 119 230)
#
# SPDX-License-Identifier: BSD-2-Clause
#

# parsing code for objdump files. used on a symtab dump to build a python
# symbol table and on a disassembly of the .rodata section to build a
# summary of the read-only data

import re

def build_syms (symtab):
	syms = {}
	for line in symtab:
		bits = line.split ()
		try:
			addr = int (bits[0], 16)
			size = int (bits[-2], 16)
			section = bits[-3]
			syms[bits[-1]] = (addr, size, section)
		except ValueError:
			pass
		except IndexError:
			pass

	sections = {}
	for (addr, size, section) in syms.itervalues ():
		if not size:
			continue
		(start, end) = sections.get (section, (addr, addr))
		start = min (addr, start)
		end = max (addr + size - 1, end)
		sections[section] = (start, end)

	return (syms, sections)

def install_syms (symtab):
	(syms, sects) = build_syms (symtab)
	import target_objects
	target_objects.symbols.update (syms)
	target_objects.sections.update (sects)

is_rodata_line = re.compile('^\s*[0-9a-fA-F]+:\s+[0-9a-fA-F]+\s+')

def build_rodata (rodata_stream, rodata_ranges = [('Section', '.rodata')]):
	from syntax import structs, fresh_name, Struct, mk_word32
	import syntax
	from target_objects import symbols, sections, trace

	act_rodata_ranges = []
	for (kind, nm) in rodata_ranges:
		if kind == 'Symbol':
			(addr, size, _) = symbols[nm]
			act_rodata_ranges.append ((addr, addr + size - 1))
		elif kind == 'Section':
			if nm in sections:
				act_rodata_ranges.append (sections[nm])
			else:
				# it's reasonable to supply .rodata as the
				# expected section only for it to be missing
				trace ('No %r section in objdump.' % nm)
		else:
			assert kind in ['Symbol', 'Section'], rodata_ranges

	comb_ranges = []
	for (start, end) in sorted (act_rodata_ranges):
		if comb_ranges and comb_ranges[-1][1] + 1 == start:
			(start, _) = comb_ranges[-1]
			comb_ranges[-1] = (start, end)
		else:
			comb_ranges.append ((start, end))

	rodata = {}
	for line in rodata_stream:
		if not is_rodata_line.match (line):
			continue
		bits = line.split ()
		(addr, v) = (int (bits[0][:-1], 16), int (bits[1], 16))
		if [1 for (start, end) in comb_ranges
				if start <= addr and addr <= end]:
			assert addr % 4 == 0, addr
			rodata[addr] = v

	if len (comb_ranges) == 1:
		rodata_names = ['rodata_struct']
	else:
		rodata_names = ['rodata_struct_%d' % (i + 1)
			for (i, _) in enumerate (comb_ranges)]

	rodata_ptrs = []
	for ((start, end), name) in zip (comb_ranges, rodata_names):
		struct_name = fresh_name (name, structs)
		struct = Struct (struct_name, (end - start) + 1, 1)
		structs[struct_name] = struct
		typ = syntax.get_global_wrapper (struct.typ)
		rodata_ptrs.append ((mk_word32 (start), typ))

	return (rodata, comb_ranges, rodata_ptrs)

def install_rodata (rodata_stream, rodata_ranges = [('Section', '.rodata')]):
	import target_objects
	rodata = build_rodata (rodata_stream, rodata_ranges)
	target_objects.rodata[:] = rodata

# the prunes file isn't really an objdump file, but this seems the best place

non_var_re = re.compile('[(),\s\[\]]+')

def parse_prunes (prune_stream):
	prunes = {}
	for l in prune_stream:
		[lname, rhs] = l.split ('from [')
		bits = lname.split ()
		assert bits[:3] == ['Pruned', 'inputs', 'of']
		name = bits[3]
		[lvars, rvars] = rhs.split ('] to [')
		lvars = [v for v in non_var_re.split (lvars) if v]
		rvars = [v for v in non_var_re.split (rvars) if v]
		if not (lvars[-2:] == ['dm', 'm']
				and rvars[-2:] == ['dm', 'm']):
			continue
		lvars = lvars[:-2]
		rvars = rvars[:-2]
		prunes['DecompiledFuns.' + name + '_step'] = (lvars, rvars)
	return prunes

# likewise the signatures produced by the c-parser

def parse_sigs (sig_stream):
	sigs = {}
	for l in sig_stream:
		bits = l.split ()
		if not bits:
			continue
		ret = int (bits[0])
		nm = bits[1]
		args = [int(bit) for bit in bits[2:]]
		sigs[nm] = (args, ret)
	return sigs