199 lines
6.8 KiB
Python
199 lines
6.8 KiB
Python
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#!/usr/bin/env python
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"""
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Run gdb to disassemble a function, feed the bytes to 'llvm-mc -disassemble' command,
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and display the disassembly result.
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"""
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import os
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import sys
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from optparse import OptionParser
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def is_exe(fpath):
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"""Check whether fpath is an executable."""
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return os.path.isfile(fpath) and os.access(fpath, os.X_OK)
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def which(program):
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"""Find the full path to a program, or return None."""
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fpath, fname = os.path.split(program)
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if fpath:
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if is_exe(program):
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return program
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else:
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for path in os.environ["PATH"].split(os.pathsep):
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exe_file = os.path.join(path, program)
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if is_exe(exe_file):
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return exe_file
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return None
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def do_llvm_mc_disassembly(gdb_commands, gdb_options, exe, func, mc, mc_options):
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from cStringIO import StringIO
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import pexpect
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gdb_prompt = "\r\n\(gdb\) "
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gdb = pexpect.spawn(('gdb %s' % gdb_options) if gdb_options else 'gdb')
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# Turn on logging for what gdb sends back.
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gdb.logfile_read = sys.stdout
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gdb.expect(gdb_prompt)
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# See if there any extra command(s) to execute before we issue the file command.
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for cmd in gdb_commands:
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gdb.sendline(cmd)
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gdb.expect(gdb_prompt)
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# Now issue the file command.
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gdb.sendline('file %s' % exe)
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gdb.expect(gdb_prompt)
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# Send the disassemble command.
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gdb.sendline('disassemble %s' % func)
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gdb.expect(gdb_prompt)
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# Get the output from gdb.
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gdb_output = gdb.before
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# Use StringIO to record the memory dump as well as the gdb assembler code.
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mc_input = StringIO()
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# These keep track of the states of our simple gdb_output parser.
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prev_line = None
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prev_addr = None
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curr_addr = None
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addr_diff = 0
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looking = False
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for line in gdb_output.split(os.linesep):
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if line.startswith('Dump of assembler code'):
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looking = True
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continue
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if line.startswith('End of assembler dump.'):
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looking = False
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prev_addr = curr_addr
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if mc_options and mc_options.find('arm') != -1:
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addr_diff = 4
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if mc_options and mc_options.find('thumb') != -1:
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# It is obviously wrong to assume the last instruction of the
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# function has two bytes.
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# FIXME
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addr_diff = 2
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if looking and line.startswith('0x'):
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# It's an assembler code dump.
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prev_addr = curr_addr
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curr_addr = line.split(None, 1)[0]
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if prev_addr and curr_addr:
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addr_diff = int(curr_addr, 16) - int(prev_addr, 16)
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if prev_addr and addr_diff > 0:
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# Feed the examining memory command to gdb.
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gdb.sendline('x /%db %s' % (addr_diff, prev_addr))
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gdb.expect(gdb_prompt)
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x_output = gdb.before
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# Get the last output line from the gdb examine memory command,
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# split the string into a 3-tuple with separator '>:' to handle
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# objc method names.
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memory_dump = x_output.split(os.linesep)[-1].partition('>:')[2].strip()
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#print "\nbytes:", memory_dump
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disasm_str = prev_line.partition('>:')[2]
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print >> mc_input, '%s # %s' % (memory_dump, disasm_str)
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# We're done with the processing. Assign the current line to be prev_line.
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prev_line = line
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# Close the gdb session now that we are done with it.
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gdb.sendline('quit')
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gdb.expect(pexpect.EOF)
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gdb.close()
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# Write the memory dump into a file.
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with open('disasm-input.txt', 'w') as f:
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f.write(mc_input.getvalue())
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mc_cmd = '%s -disassemble %s disasm-input.txt' % (mc, mc_options)
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print "\nExecuting command:", mc_cmd
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os.system(mc_cmd)
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# And invoke llvm-mc with the just recorded file.
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#mc = pexpect.spawn('%s -disassemble %s disasm-input.txt' % (mc, mc_options))
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#mc.logfile_read = sys.stdout
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#print "mc:", mc
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#mc.close()
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def main():
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# This is to set up the Python path to include the pexpect-2.4 dir.
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# Remember to update this when/if things change.
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scriptPath = sys.path[0]
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sys.path.append(os.path.join(scriptPath, os.pardir, os.pardir, 'test', 'pexpect-2.4'))
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parser = OptionParser(usage="""\
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Run gdb to disassemble a function, feed the bytes to 'llvm-mc -disassemble' command,
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and display the disassembly result.
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Usage: %prog [options]
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""")
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parser.add_option('-C', '--gdb-command',
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type='string', action='append', metavar='COMMAND',
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default=[], dest='gdb_commands',
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help='Command(s) gdb executes after starting up (can be empty)')
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parser.add_option('-O', '--gdb-options',
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type='string', action='store',
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dest='gdb_options',
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help="""The options passed to 'gdb' command if specified.""")
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parser.add_option('-e', '--executable',
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type='string', action='store',
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dest='executable',
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help="""The executable to do disassembly on.""")
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parser.add_option('-f', '--function',
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type='string', action='store',
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dest='function',
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help="""The function name (could be an address to gdb) for disassembly.""")
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parser.add_option('-m', '--llvm-mc',
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type='string', action='store',
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dest='llvm_mc',
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help="""The llvm-mc executable full path, if specified.
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Otherwise, it must be present in your PATH environment.""")
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parser.add_option('-o', '--options',
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type='string', action='store',
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dest='llvm_mc_options',
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help="""The options passed to 'llvm-mc -disassemble' command if specified.""")
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opts, args = parser.parse_args()
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gdb_commands = opts.gdb_commands
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gdb_options = opts.gdb_options
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if not opts.executable:
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parser.print_help()
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sys.exit(1)
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executable = opts.executable
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if not opts.function:
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parser.print_help()
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sys.exit(1)
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function = opts.function
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llvm_mc = opts.llvm_mc if opts.llvm_mc else which('llvm-mc')
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if not llvm_mc:
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parser.print_help()
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sys.exit(1)
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# This is optional. For example:
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# --options='-triple=arm-apple-darwin -debug-only=arm-disassembler'
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llvm_mc_options = opts.llvm_mc_options
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# We have parsed the options.
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print "gdb commands:", gdb_commands
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print "gdb options:", gdb_options
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print "executable:", executable
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print "function:", function
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print "llvm-mc:", llvm_mc
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print "llvm-mc options:", llvm_mc_options
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do_llvm_mc_disassembly(gdb_commands, gdb_options, executable, function, llvm_mc, llvm_mc_options)
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if __name__ == '__main__':
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main()
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