u-boot/tools/binman/elf.py
Simon Glass 3ab9598df7 binman: Rename 'position' to 'offset'
After some thought, I believe there is an unfortunate naming flaw in
binman. Entries have a position and size, but now that we support
hierarchical sections it is unclear whether a position should be an
absolute position within the image, or a relative position within its
parent section.

At present 'position' actually means the relative position. This indicates
a need for an 'image position' for code that wants to find the location of
an entry without having to do calculations back through parents to
discover this image position.

A better name for the current 'position' or 'pos' is 'offset'. It is not
always an absolute position, but it is always an offset from its parent
offset.

It is unfortunate to rename this concept now, 18 months after binman was
introduced. However I believe it is the right thing to do. The impact is
mostly limited to binman itself and a few changes to in-tree users to
binman:

   tegra
   sunxi
   x86

The change makes old binman definitions (e.g. downstream or out-of-tree)
incompatible if they use the 'pos = <...>' property. Later work will
adjust binman to generate an error when it is used.

Signed-off-by: Simon Glass <sjg@chromium.org>
2018-08-01 16:30:06 -06:00

130 lines
4.3 KiB
Python

# SPDX-License-Identifier: GPL-2.0+
# Copyright (c) 2016 Google, Inc
# Written by Simon Glass <sjg@chromium.org>
#
# 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')
# Sort dict by address
return OrderedDict(sorted(syms.iteritems(), key=lambda x: x[1].address))
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, section):
"""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 offsets 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
section: Section 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 = ("Section '%s': Symbol '%s'\n in entry '%s'" %
(section.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 = section.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:])