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Diffstat (limited to 'tools/binman/elf.py')
-rw-r--r-- | tools/binman/elf.py | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/tools/binman/elf.py b/tools/binman/elf.py new file mode 100644 index 00000000000..80ff2253f03 --- /dev/null +++ b/tools/binman/elf.py @@ -0,0 +1,129 @@ +# Copyright (c) 2016 Google, Inc +# Written by Simon Glass <sjg@chromium.org> +# +# SPDX-License-Identifier: GPL-2.0+ +# +# Handle various things related to ELF images +# + +from collections import namedtuple, OrderedDict +import command +import os +import re +import struct + +import tools + +# This is enabled from control.py +debug = False + +Symbol = namedtuple('Symbol', ['section', 'address', 'size', 'weak']) + + +def GetSymbols(fname, patterns): + """Get the symbols from an ELF file + + Args: + fname: Filename of the ELF file to read + patterns: List of regex patterns to search for, each a string + + Returns: + None, if the file does not exist, or Dict: + key: Name of symbol + value: Hex value of symbol + """ + stdout = command.Output('objdump', '-t', fname, raise_on_error=False) + lines = stdout.splitlines() + if patterns: + re_syms = re.compile('|'.join(patterns)) + else: + re_syms = None + syms = {} + syms_started = False + for line in lines: + if not line or not syms_started: + if 'SYMBOL TABLE' in line: + syms_started = True + line = None # Otherwise code coverage complains about 'continue' + continue + if re_syms and not re_syms.search(line): + continue + + space_pos = line.find(' ') + value, rest = line[:space_pos], line[space_pos + 1:] + flags = rest[:7] + parts = rest[7:].split() + section, size = parts[:2] + if len(parts) > 2: + name = parts[2] + syms[name] = Symbol(section, int(value, 16), int(size,16), + flags[1] == 'w') + return syms + +def GetSymbolAddress(fname, sym_name): + """Get a value of a symbol from an ELF file + + Args: + fname: Filename of the ELF file to read + patterns: List of regex patterns to search for, each a string + + Returns: + Symbol value (as an integer) or None if not found + """ + syms = GetSymbols(fname, [sym_name]) + sym = syms.get(sym_name) + if not sym: + return None + return sym.address + +def LookupAndWriteSymbols(elf_fname, entry, image): + """Replace all symbols in an entry with their correct values + + The entry contents is updated so that values for referenced symbols will be + visible at run time. This is done by finding out the symbols positions in + the entry (using the ELF file) and replacing them with values from binman's + data structures. + + Args: + elf_fname: Filename of ELF image containing the symbol information for + entry + entry: Entry to process + image: Image which can be used to lookup symbol values + """ + fname = tools.GetInputFilename(elf_fname) + syms = GetSymbols(fname, ['image', 'binman']) + if not syms: + return + base = syms.get('__image_copy_start') + if not base: + return + for name, sym in syms.iteritems(): + if name.startswith('_binman'): + msg = ("Image '%s': Symbol '%s'\n in entry '%s'" % + (image.GetPath(), name, entry.GetPath())) + offset = sym.address - base.address + if offset < 0 or offset + sym.size > entry.contents_size: + raise ValueError('%s has offset %x (size %x) but the contents ' + 'size is %x' % (entry.GetPath(), offset, + sym.size, entry.contents_size)) + if sym.size == 4: + pack_string = '<I' + elif sym.size == 8: + pack_string = '<Q' + else: + raise ValueError('%s has size %d: only 4 and 8 are supported' % + (msg, sym.size)) + + # Look up the symbol in our entry tables. + value = image.LookupSymbol(name, sym.weak, msg) + if value is not None: + value += base.address + else: + value = -1 + pack_string = pack_string.lower() + value_bytes = struct.pack(pack_string, value) + if debug: + print('%s:\n insert %s, offset %x, value %x, length %d' % + (msg, name, offset, value, len(value_bytes))) + entry.data = (entry.data[:offset] + value_bytes + + entry.data[offset + sym.size:]) |