| # 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 __future__ import print_function |
| |
| from collections import namedtuple, OrderedDict |
| import command |
| import io |
| import os |
| import re |
| import shutil |
| import struct |
| import tempfile |
| |
| import tools |
| import tout |
| |
| ELF_TOOLS = True |
| try: |
| from elftools.elf.elffile import ELFFile |
| from elftools.elf.sections import SymbolTableSection |
| except: # pragma: no cover |
| ELF_TOOLS = False |
| |
| Symbol = namedtuple('Symbol', ['section', 'address', 'size', 'weak']) |
| |
| # Information about an ELF file: |
| # data: Extracted program contents of ELF file (this would be loaded by an |
| # ELF loader when reading this file |
| # load: Load address of code |
| # entry: Entry address of code |
| # memsize: Number of bytes in memory occupied by loading this ELF file |
| ElfInfo = namedtuple('ElfInfo', ['data', 'load', 'entry', 'memsize']) |
| |
| |
| 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.items(), 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.items(): |
| 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) |
| tout.Debug('%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:]) |
| |
| def MakeElf(elf_fname, text, data): |
| """Make an elf file with the given data in a single section |
| |
| The output file has a several section including '.text' and '.data', |
| containing the info provided in arguments. |
| |
| Args: |
| elf_fname: Output filename |
| text: Text (code) to put in the file's .text section |
| data: Data to put in the file's .data section |
| """ |
| outdir = tempfile.mkdtemp(prefix='binman.elf.') |
| s_file = os.path.join(outdir, 'elf.S') |
| |
| # Spilt the text into two parts so that we can make the entry point two |
| # bytes after the start of the text section |
| text_bytes1 = ['\t.byte\t%#x' % tools.ToByte(byte) for byte in text[:2]] |
| text_bytes2 = ['\t.byte\t%#x' % tools.ToByte(byte) for byte in text[2:]] |
| data_bytes = ['\t.byte\t%#x' % tools.ToByte(byte) for byte in data] |
| with open(s_file, 'w') as fd: |
| print('''/* Auto-generated C program to produce an ELF file for testing */ |
| |
| .section .text |
| .code32 |
| .globl _start |
| .type _start, @function |
| %s |
| _start: |
| %s |
| .ident "comment" |
| |
| .comm fred,8,4 |
| |
| .section .empty |
| .globl _empty |
| _empty: |
| .byte 1 |
| |
| .globl ernie |
| .data |
| .type ernie, @object |
| .size ernie, 4 |
| ernie: |
| %s |
| ''' % ('\n'.join(text_bytes1), '\n'.join(text_bytes2), '\n'.join(data_bytes)), |
| file=fd) |
| lds_file = os.path.join(outdir, 'elf.lds') |
| |
| # Use a linker script to set the alignment and text address. |
| with open(lds_file, 'w') as fd: |
| print('''/* Auto-generated linker script to produce an ELF file for testing */ |
| |
| PHDRS |
| { |
| text PT_LOAD ; |
| data PT_LOAD ; |
| empty PT_LOAD FLAGS ( 6 ) ; |
| note PT_NOTE ; |
| } |
| |
| SECTIONS |
| { |
| . = 0xfef20000; |
| ENTRY(_start) |
| .text . : SUBALIGN(0) |
| { |
| *(.text) |
| } :text |
| .data : { |
| *(.data) |
| } :data |
| _bss_start = .; |
| .empty : { |
| *(.empty) |
| } :empty |
| .note : { |
| *(.comment) |
| } :note |
| .bss _bss_start (OVERLAY) : { |
| *(.bss) |
| } |
| } |
| ''', file=fd) |
| # -static: Avoid requiring any shared libraries |
| # -nostdlib: Don't link with C library |
| # -Wl,--build-id=none: Don't generate a build ID, so that we just get the |
| # text section at the start |
| # -m32: Build for 32-bit x86 |
| # -T...: Specifies the link script, which sets the start address |
| stdout = command.Output('cc', '-static', '-nostdlib', '-Wl,--build-id=none', |
| '-m32','-T', lds_file, '-o', elf_fname, s_file) |
| shutil.rmtree(outdir) |
| |
| def DecodeElf(data, location): |
| """Decode an ELF file and return information about it |
| |
| Args: |
| data: Data from ELF file |
| location: Start address of data to return |
| |
| Returns: |
| ElfInfo object containing information about the decoded ELF file |
| """ |
| file_size = len(data) |
| with io.BytesIO(data) as fd: |
| elf = ELFFile(fd) |
| data_start = 0xffffffff; |
| data_end = 0; |
| mem_end = 0; |
| virt_to_phys = 0; |
| |
| for i in range(elf.num_segments()): |
| segment = elf.get_segment(i) |
| if segment['p_type'] != 'PT_LOAD' or not segment['p_memsz']: |
| skipped = 1 # To make code-coverage see this line |
| continue |
| start = segment['p_paddr'] |
| mend = start + segment['p_memsz'] |
| rend = start + segment['p_filesz'] |
| data_start = min(data_start, start) |
| data_end = max(data_end, rend) |
| mem_end = max(mem_end, mend) |
| if not virt_to_phys: |
| virt_to_phys = segment['p_paddr'] - segment['p_vaddr'] |
| |
| output = bytearray(data_end - data_start) |
| for i in range(elf.num_segments()): |
| segment = elf.get_segment(i) |
| if segment['p_type'] != 'PT_LOAD' or not segment['p_memsz']: |
| skipped = 1 # To make code-coverage see this line |
| continue |
| start = segment['p_paddr'] |
| offset = 0 |
| if start < location: |
| offset = location - start |
| start = location |
| # A legal ELF file can have a program header with non-zero length |
| # but zero-length file size and a non-zero offset which, added |
| # together, are greater than input->size (i.e. the total file size). |
| # So we need to not even test in the case that p_filesz is zero. |
| # Note: All of this code is commented out since we don't have a test |
| # case for it. |
| size = segment['p_filesz'] |
| #if not size: |
| #continue |
| #end = segment['p_offset'] + segment['p_filesz'] |
| #if end > file_size: |
| #raise ValueError('Underflow copying out the segment. File has %#x bytes left, segment end is %#x\n', |
| #file_size, end) |
| output[start - data_start:start - data_start + size] = ( |
| segment.data()[offset:]) |
| return ElfInfo(output, data_start, elf.header['e_entry'] + virt_to_phys, |
| mem_end - data_start) |
