diff options
Diffstat (limited to 'tools/binman/elf.py')
| -rw-r--r-- | tools/binman/elf.py | 174 |
1 files changed, 174 insertions, 0 deletions
diff --git a/tools/binman/elf.py b/tools/binman/elf.py index 828681d76d..8147b3437d 100644 --- a/tools/binman/elf.py +++ b/tools/binman/elf.py @@ -5,19 +5,39 @@ # 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 +ELF_TOOLS = True +try: + from elftools.elf.elffile import ELFFile + from elftools.elf.sections import SymbolTableSection +except: # pragma: no cover + ELF_TOOLS = False + # This is enabled from control.py debug = 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 @@ -128,3 +148,157 @@ def LookupAndWriteSymbols(elf_fname, entry, section): (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) |