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7c15013639
A recent change adjusted the symbol calculation to work on x86 but broke
it for Tegra. In fact this is because they have different needs.
On x86 devices the code is linked to a ROM address and the end-at-4gb
property is used for the image. In this case there is no need to add the
base address of the image, since the base address is already built into
the offset and image-pos properties.
On other devices we must add the base address since the offsets start at
zero.
In addition the base address is currently added to the 'offset' and 'size'
values. It should in fact only be added to 'image-pos', since 'offset' is
relative to its parent and 'size' is not actually an address. This code
should have been adjusted when support for 'image-pos' and 'size' was
added, but it was not.
To correct these problems:
- move the code that handles adding the base address to section.py, which
can check the end-at-4gb property and which property
(offset/size/image-pos) is being read
- add the base address only when needed (only for image-pos and not if the
image uses end-at-4gb)
- add a note to the documentation
- add a separate test to cover x86 behaviour
Fixes: 15c981cc (binman: Correct symbol calculation with non-zero image base)
Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@nvidia.com>
302 lines
9.8 KiB
Python
302 lines
9.8 KiB
Python
# SPDX-License-Identifier: GPL-2.0+
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# Copyright (c) 2016 Google, Inc
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# Written by Simon Glass <sjg@chromium.org>
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#
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# Handle various things related to ELF images
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#
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from __future__ import print_function
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from collections import namedtuple, OrderedDict
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import command
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import io
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import os
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import re
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import shutil
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import struct
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import tempfile
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import tools
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import tout
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ELF_TOOLS = True
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try:
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from elftools.elf.elffile import ELFFile
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from elftools.elf.sections import SymbolTableSection
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except: # pragma: no cover
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ELF_TOOLS = False
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Symbol = namedtuple('Symbol', ['section', 'address', 'size', 'weak'])
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# Information about an ELF file:
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# data: Extracted program contents of ELF file (this would be loaded by an
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# ELF loader when reading this file
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# load: Load address of code
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# entry: Entry address of code
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# memsize: Number of bytes in memory occupied by loading this ELF file
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ElfInfo = namedtuple('ElfInfo', ['data', 'load', 'entry', 'memsize'])
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def GetSymbols(fname, patterns):
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"""Get the symbols from an ELF file
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Args:
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fname: Filename of the ELF file to read
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patterns: List of regex patterns to search for, each a string
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Returns:
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None, if the file does not exist, or Dict:
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key: Name of symbol
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value: Hex value of symbol
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"""
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stdout = tools.Run('objdump', '-t', fname)
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lines = stdout.splitlines()
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if patterns:
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re_syms = re.compile('|'.join(patterns))
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else:
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re_syms = None
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syms = {}
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syms_started = False
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for line in lines:
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if not line or not syms_started:
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if 'SYMBOL TABLE' in line:
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syms_started = True
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line = None # Otherwise code coverage complains about 'continue'
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continue
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if re_syms and not re_syms.search(line):
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continue
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space_pos = line.find(' ')
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value, rest = line[:space_pos], line[space_pos + 1:]
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flags = rest[:7]
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parts = rest[7:].split()
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section, size = parts[:2]
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if len(parts) > 2:
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name = parts[2] if parts[2] != '.hidden' else parts[3]
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syms[name] = Symbol(section, int(value, 16), int(size,16),
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flags[1] == 'w')
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# Sort dict by address
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return OrderedDict(sorted(syms.items(), key=lambda x: x[1].address))
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def GetSymbolAddress(fname, sym_name):
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"""Get a value of a symbol from an ELF file
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Args:
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fname: Filename of the ELF file to read
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patterns: List of regex patterns to search for, each a string
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Returns:
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Symbol value (as an integer) or None if not found
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"""
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syms = GetSymbols(fname, [sym_name])
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sym = syms.get(sym_name)
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if not sym:
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return None
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return sym.address
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def LookupAndWriteSymbols(elf_fname, entry, section):
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"""Replace all symbols in an entry with their correct values
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The entry contents is updated so that values for referenced symbols will be
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visible at run time. This is done by finding out the symbols offsets in the
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entry (using the ELF file) and replacing them with values from binman's data
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structures.
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Args:
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elf_fname: Filename of ELF image containing the symbol information for
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entry
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entry: Entry to process
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section: Section which can be used to lookup symbol values
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"""
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fname = tools.GetInputFilename(elf_fname)
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syms = GetSymbols(fname, ['image', 'binman'])
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if not syms:
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return
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base = syms.get('__image_copy_start')
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if not base:
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return
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for name, sym in syms.items():
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if name.startswith('_binman'):
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msg = ("Section '%s': Symbol '%s'\n in entry '%s'" %
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(section.GetPath(), name, entry.GetPath()))
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offset = sym.address - base.address
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if offset < 0 or offset + sym.size > entry.contents_size:
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raise ValueError('%s has offset %x (size %x) but the contents '
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'size is %x' % (entry.GetPath(), offset,
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sym.size, entry.contents_size))
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if sym.size == 4:
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pack_string = '<I'
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elif sym.size == 8:
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pack_string = '<Q'
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else:
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raise ValueError('%s has size %d: only 4 and 8 are supported' %
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(msg, sym.size))
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# Look up the symbol in our entry tables.
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value = section.LookupSymbol(name, sym.weak, msg, base.address)
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if value is None:
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value = -1
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pack_string = pack_string.lower()
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value_bytes = struct.pack(pack_string, value)
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tout.Debug('%s:\n insert %s, offset %x, value %x, length %d' %
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(msg, name, offset, value, len(value_bytes)))
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entry.data = (entry.data[:offset] + value_bytes +
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entry.data[offset + sym.size:])
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def MakeElf(elf_fname, text, data):
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"""Make an elf file with the given data in a single section
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The output file has a several section including '.text' and '.data',
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containing the info provided in arguments.
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Args:
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elf_fname: Output filename
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text: Text (code) to put in the file's .text section
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data: Data to put in the file's .data section
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"""
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outdir = tempfile.mkdtemp(prefix='binman.elf.')
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s_file = os.path.join(outdir, 'elf.S')
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# Spilt the text into two parts so that we can make the entry point two
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# bytes after the start of the text section
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text_bytes1 = ['\t.byte\t%#x' % tools.ToByte(byte) for byte in text[:2]]
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text_bytes2 = ['\t.byte\t%#x' % tools.ToByte(byte) for byte in text[2:]]
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data_bytes = ['\t.byte\t%#x' % tools.ToByte(byte) for byte in data]
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with open(s_file, 'w') as fd:
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print('''/* Auto-generated C program to produce an ELF file for testing */
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.section .text
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.code32
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.globl _start
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.type _start, @function
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%s
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_start:
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%s
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.ident "comment"
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.comm fred,8,4
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.section .empty
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.globl _empty
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_empty:
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.byte 1
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.globl ernie
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.data
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.type ernie, @object
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.size ernie, 4
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ernie:
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%s
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''' % ('\n'.join(text_bytes1), '\n'.join(text_bytes2), '\n'.join(data_bytes)),
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file=fd)
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lds_file = os.path.join(outdir, 'elf.lds')
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# Use a linker script to set the alignment and text address.
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with open(lds_file, 'w') as fd:
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print('''/* Auto-generated linker script to produce an ELF file for testing */
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PHDRS
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{
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text PT_LOAD ;
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data PT_LOAD ;
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empty PT_LOAD FLAGS ( 6 ) ;
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note PT_NOTE ;
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}
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SECTIONS
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{
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. = 0xfef20000;
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ENTRY(_start)
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.text . : SUBALIGN(0)
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{
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*(.text)
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} :text
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.data : {
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*(.data)
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} :data
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_bss_start = .;
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.empty : {
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*(.empty)
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} :empty
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/DISCARD/ : {
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*(.note.gnu.property)
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}
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.note : {
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*(.comment)
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} :note
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.bss _bss_start (OVERLAY) : {
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*(.bss)
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}
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}
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''', file=fd)
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# -static: Avoid requiring any shared libraries
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# -nostdlib: Don't link with C library
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# -Wl,--build-id=none: Don't generate a build ID, so that we just get the
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# text section at the start
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# -m32: Build for 32-bit x86
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# -T...: Specifies the link script, which sets the start address
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stdout = command.Output('cc', '-static', '-nostdlib', '-Wl,--build-id=none',
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'-m32','-T', lds_file, '-o', elf_fname, s_file)
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shutil.rmtree(outdir)
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def DecodeElf(data, location):
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"""Decode an ELF file and return information about it
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Args:
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data: Data from ELF file
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location: Start address of data to return
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Returns:
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ElfInfo object containing information about the decoded ELF file
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"""
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file_size = len(data)
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with io.BytesIO(data) as fd:
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elf = ELFFile(fd)
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data_start = 0xffffffff;
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data_end = 0;
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mem_end = 0;
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virt_to_phys = 0;
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for i in range(elf.num_segments()):
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segment = elf.get_segment(i)
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if segment['p_type'] != 'PT_LOAD' or not segment['p_memsz']:
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skipped = 1 # To make code-coverage see this line
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continue
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start = segment['p_paddr']
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mend = start + segment['p_memsz']
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rend = start + segment['p_filesz']
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data_start = min(data_start, start)
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data_end = max(data_end, rend)
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mem_end = max(mem_end, mend)
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if not virt_to_phys:
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virt_to_phys = segment['p_paddr'] - segment['p_vaddr']
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output = bytearray(data_end - data_start)
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for i in range(elf.num_segments()):
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segment = elf.get_segment(i)
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if segment['p_type'] != 'PT_LOAD' or not segment['p_memsz']:
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skipped = 1 # To make code-coverage see this line
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continue
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start = segment['p_paddr']
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offset = 0
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if start < location:
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offset = location - start
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start = location
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# A legal ELF file can have a program header with non-zero length
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# but zero-length file size and a non-zero offset which, added
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# together, are greater than input->size (i.e. the total file size).
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# So we need to not even test in the case that p_filesz is zero.
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# Note: All of this code is commented out since we don't have a test
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# case for it.
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size = segment['p_filesz']
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#if not size:
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#continue
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#end = segment['p_offset'] + segment['p_filesz']
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#if end > file_size:
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#raise ValueError('Underflow copying out the segment. File has %#x bytes left, segment end is %#x\n',
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#file_size, end)
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output[start - data_start:start - data_start + size] = (
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segment.data()[offset:])
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return ElfInfo(output, data_start, elf.header['e_entry'] + virt_to_phys,
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mem_end - data_start)
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