dm3xx_encode_usb_hardcoder.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

""" Dji DM3xx DaVinci encode_usb binary hard-coded values editor.

The tool can parse encode_usb ELF file from Dji Firmware module for
TI DM3xx DaVinci Media Processor.
It finds certain hard-coded values in the binary data, and allows
exporting or importing them.

Only 'setValue' element in the exported file is really changeable,
all the other data is just informational. This includes `maxValue` and
`minValue` - they don't do anything and changing them in the JSON file
will not influence update operation.

Exported values:

og_hardcoded.p3x_dm3xx.startup_encrypt_check_always_pass -

  The binary does encryption check at startup by sending encrypt request
  to camera (m0100) and comparing result with same data encrypted locally.
  If the comparison fails (which means encryption keys are different),
  the binary will continously retry encryption, generating considerable
  CPU load and degrading video compression to 8FPS due to that.
  This option, when set to 1, prevents the continous loop by always setting
  encryption check status to "passed".

  Here's an example DaVinci console log when there is no issue with encryption:
  ```
  Entry Encrypt qury mode
  [...]
  Encrypt passed!
  ```
  The second line should show within 100 lines after first one. If it never
  shows, then there is an issue which results in continous retries.

"""

# Copyright (C) 2016,2017 Mefistotelis <mefistotelis@gmail.com>
# Copyright (C) 2018 Original Gangsters <https://dji-rev.slack.com/>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

__version__ = "0.0.2"
__author__ = "Mefistotelis @ Original Gangsters"
__license__ = "GPL"

import sys
import argparse
import os
import re
import io
import enum
import json

sys.path.insert(0, './')
from amba_sys_hardcoder import eprint, elf_march_to_asm_config, \
  armfw_elf_whole_section_search, armfw_elf_match_to_public_values, \
  armfw_elf_paramvals_extract_list, armfw_elf_get_value_update_bytes, \
  armfw_elf_paramvals_get_depend_list, armfw_elf_publicval_update, \
  armfw_elf_paramvals_update_list, armfw_elf_generic_objdump, \
  armfw_asm_search_strings_to_re_list, armfw_elf_paramvals_export_json, \
  armfw_elf_paramvals_export_simple_list, armfw_elf_paramvals_export_mapfile, \
  VarType, DataVariety, CodeVariety


def startup_encrypt_check_always_pass_params_update(asm_arch, elf_sections, re_list, glob_params_list, var_info, new_var_nativ):
    """ Callback function to prepare 'startup_encrypt_check_always_pass' value change.
    Sets global params required for the switch.
    """
    glob_re = glob_params_list[var_info['cfunc_name']+'..re']['value']
    glob_re_size = glob_params_list[var_info['cfunc_name']+'..re_size']['value']
    var_encryptThrFxn = glob_params_list['encryptThrFxn']
    if new_var_nativ == 1:
        # Set variables requires to change original into encpass
        patterns = re_func_encryptThrFxn_encpass
        re_lines, re_labels = armfw_asm_search_strings_to_re_list(patterns['re'])
        # First variable
        var_bPassedEnc_name = 's_bPassedEnc'
        var_bPassedEnc = glob_params_list['Encrypt_Request.s_bPassedEnc'].copy()
        var_bPassedEnc['cfunc_name'] = var_info['cfunc_name']
        var_bPassedEnc['name'] = var_bPassedEnc['cfunc_name']+'.'+var_bPassedEnc_name
        var_bPassedEnc['line'] = None
        var_bPassedEnc['address'] = None
        var_bPassedEnc['value'] = None
        for ln_num, ln_regex in enumerate(re_lines):
            re_line = re.search(r'^.+P<'+var_bPassedEnc_name+'>.+$', ln_regex)
            if re_line:
                var_bPassedEnc['line'] = ln_num
                var_bPassedEnc['address'] = var_encryptThrFxn['address'] + sum(glob_re_size[0:ln_num])
                break
        # Second variable
        var_bPassedEnc_p_name = 's_bPassedEnc_p'
        var_bPassedEnc_p = {'str_value': "", 'value': 0x0, 'address': None, 'line': None, 'cfunc_name': var_info['cfunc_name']}
        var_bPassedEnc_p['value'] = glob_params_list['Encrypt_Request.s_bPassedEnc']['value']
        var_bPassedEnc_p['name'] = var_bPassedEnc['cfunc_name']+'.'+var_bPassedEnc_p_name
        var_bPassedEnc_p.update(patterns['vars'][var_bPassedEnc_p_name])
        for ln_num, ln_regex in enumerate(re_lines):
            re_line = re.search(r'^.+P<'+var_bPassedEnc_p_name+'>.+$', ln_regex)
            if re_line:
                var_bPassedEnc_p['line'] = ln_num
                var_bPassedEnc_p['address'] = var_encryptThrFxn['address'] + sum(glob_re_size[0:ln_num])
                break
        # Make var_bPassedEnc point to var_bPassedEnc_p
        var_bPassedEnc['value'] = var_bPassedEnc_p['address'] # var_encryptThrFxn['value'] + 13*4
        # Store both variables
        glob_params_list[var_bPassedEnc['name']] = var_bPassedEnc
        glob_params_list[var_bPassedEnc_p['name']] = var_bPassedEnc_p
    else:
        # Set variables requires to change encpass back to original
        pass


re_func_encryptThrFxn_original = {
'name': "encryptThrFxn-original",
'version': "P3X_FW_V01.07",
're': """
encryptThrFxn:
  push	{fp, lr}
  add	fp, sp, #4
  sub	sp, sp, #0x10
  str	r0, \[fp, #-0x10\]
  ldr	r0, \[pc, #(?P<cstr_ent_query_md>[0-9a-fx]+)\]
  bl	#(?P<puts>[0-9a-fx]+)
loc_label1:
  mov	r0, #1
  bl	#(?P<Encrypt_Request>[0-9a-fx]+)
  mov	r3, r0
  str	r3, \[fp, #-8\]
  ldr	r3, \[fp, #-8\]
  cmp	r3, #0
  bne	#(?P<loc_label2>[0-9a-fx]+)
  mov	r0, #1
  bl	#(?P<sleep>[0-9a-fx]+)
  b	#(?P<loc_label1>[0-9a-fx]+)
loc_label2:
  ldr	r0, \[pc, #(?P<cstr_enc_pass>[0-9a-fx]+)\]
  bl	#(?P<puts>[0-9a-fx]+)
  sub	sp, fp, #4
  pop	{fp, pc}
""",
'vars': {
  'encryptThrFxn':	{'type': VarType.DIRECT_LINE_OF_CODE, 'variety': CodeVariety.FUNCTION},
  'startup_encrypt_check_always_pass':	{'type': VarType.DETACHED_DATA, 'variety': DataVariety.INT8_T,
    'public': "og_hardcoded.p3x_dm3xx", 'minValue': "0", 'maxValue': "1", 'defaultValue': "0", 'setValue': "0",
    'custom_params_callback': startup_encrypt_check_always_pass_params_update,
    'description': "Set startup encryption test as passed even if it did not; 0-repeat forever on fail,1-force pass"},
  'cstr_ent_query_md':	{'type': VarType.RELATIVE_ADDR_TO_PTR_TO_GLOBAL_DATA, 'baseaddr': "PC+", 'variety': DataVariety.CHAR, 'array': "null_term"},
  'cstr_enc_pass':	{'type': VarType.RELATIVE_ADDR_TO_PTR_TO_GLOBAL_DATA, 'baseaddr': "PC+", 'variety': DataVariety.CHAR, 'array': "null_term"},
  'loc_label1':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label2':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'puts':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'sleep':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'Encrypt_Request':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
},
}

re_func_encryptThrFxn_encpass = {
'name': "encryptThrFxn-encpass",
'version': "P3X_FW_V01.07",
're': """
encryptThrFxn:
  push	{fp, lr}
  add	fp, sp, #4
  sub	sp, sp, #0x10
  str	r0, \[fp, #-0x10\]
  ldr	r0, \[pc, #(?P<cstr_ent_query_md>[0-9a-fx]+)\]
  bl	#(?P<puts>[0-9a-fx]+)
loc_label1:
  mov	r0, #1
  bl	#(?P<Encrypt_Request>[0-9a-fx]+)
  mov	r3, #1
  ldr	r0, \[pc, #(?P<s_bPassedEnc>[0-9a-fx]+)\]
  strb	r3, \[r0\]
  cmp	r3, #0
  b	#(?P<loc_label2>[0-9a-fx]+)
  dcd	(?P<s_bPassedEnc_p>[0-9a-fx]+)
  bl	#(?P<sleep>[0-9a-fx]+)
  b	#(?P<loc_label1>[0-9a-fx]+)
loc_label2:
  ldr	r0, \[pc, #(?P<cstr_enc_pass>[0-9a-fx]+)\]
  bl	#(?P<puts>[0-9a-fx]+)
  sub	sp, fp, #4
  pop	{fp, pc}
""",
'vars': {
  'encryptThrFxn':	{'type': VarType.DIRECT_LINE_OF_CODE, 'variety': CodeVariety.FUNCTION},
  'startup_encrypt_check_always_pass':	{'type': VarType.DETACHED_DATA, 'variety': DataVariety.INT8_T,
    'public': "og_hardcoded.p3x_dm3xx", 'minValue': "0", 'maxValue': "1", 'defaultValue': "0", 'setValue': "1",
    'custom_params_callback': startup_encrypt_check_always_pass_params_update,
    'description': "Set startup encryption test as passed even if it did not; 0-repeat forever on fail,1-force pass"},
  'cstr_ent_query_md':	{'type': VarType.RELATIVE_ADDR_TO_PTR_TO_GLOBAL_DATA, 'baseaddr': "PC+", 'variety': DataVariety.CHAR, 'array': "null_term"},
  'cstr_enc_pass':	{'type': VarType.RELATIVE_ADDR_TO_PTR_TO_GLOBAL_DATA, 'baseaddr': "PC+", 'variety': DataVariety.CHAR, 'array': "null_term"},
  'loc_label1':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label2':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'puts':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'sleep':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'Encrypt_Request':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  's_bPassedEnc':		{'type': VarType.RELATIVE_ADDR_TO_PTR_TO_GLOBAL_DATA, 'baseaddr': "PC+", 'variety': DataVariety.UINT32_T},
  's_bPassedEnc_p':	{'type': VarType.ABSOLUTE_ADDR_TO_GLOBAL_DATA, 'variety': DataVariety.UINT32_T},
},
}

re_func_Encrypt_Request = {
'name': "Encrypt_Request",
'version': "P3X_FW_V01.07",
're': """
Encrypt_Request:
  push	{fp, lr}
  add	fp, sp, #4
  sub	sp, sp, #0x360
  str	r0, \[fp, #-0x350\]
  sub	r3, fp, #0x300
  mov	r0, r3
  mov	r1, #0x20
  bl	#(?P<GetRandomData>[0-9a-fx]+)
  sub	r3, fp, #0x34c
  mov	r0, r3
  mov	r1, #0
  mov	r2, #8
  bl	#(?P<memset>[0-9a-fx]+)
  mov	r3, #8
  strb	r3, \[fp, #-0x34c\]
  mov	r3, #1
  strb	r3, \[fp, #-0x34b\]
  mov	r3, #2
  strb	r3, \[fp, #-0x34a\]
  mov	r3, #0
  strb	r3, \[fp, #-0x349\]
  mov	r3, #0x30
  strb	r3, \[fp, #-0x348\]
  mov	r3, #0
  strb	r3, \[fp, #-0x347\]
  bl	#(?P<Enc_Serial_Get_CurSeq>[0-9a-fx]+)
  mov	r3, r0
  mov	r2, r3
  ldr	r3, \[pc, #0x284\]
  sub	r1, fp, #4
  strh	r2, \[r1, r3\]
  sub	r3, fp, #0x140
  str	r3, \[fp, #-0x10\]
  ldr	r2, \[fp, #-0x10\]
  mov	r3, #4
  strb	r3, \[r2\]
  ldr	r3, \[fp, #-0x10\]
  add	r3, r3, #1
  str	r3, \[fp, #-0x10\]
  ldr	r2, \[fp, #-0x10\]
  mov	r3, #8
  strb	r3, \[r2\]
  ldr	r3, \[fp, #-0x10\]
  add	r3, r3, #1
  str	r3, \[fp, #-0x10\]
  sub	r3, fp, #0x300
  ldr	r0, \[fp, #-0x10\]
  mov	r1, r3
  mov	r2, #0x20
  bl	#(?P<memcpy>[0-9a-fx]+)
  ldr	r3, \[fp, #-0x10\]
  add	r3, r3, #0x20
  str	r3, \[fp, #-0x10\]
  ldr	r2, \[fp, #-0x10\]
  sub	r3, fp, #0x140
  rsb	r3, r3, r2
  str	r3, \[fp, #-0x14\]
  mov	r3, #0
  str	r3, \[fp, #-8\]
  b	#(?P<loc_label02>[0-9a-fx]+)
  sub	r2, fp, #0x34c
  sub	r1, fp, #0x140
  sub	r3, fp, #0x26c
  str	r3, \[sp\]
  sub	r3, fp, #0x344
  str	r3, \[sp, #4\]
  mov	r3, #0x12c
  str	r3, \[sp, #8\]
  mov	r0, r2
  ldr	r2, \[fp, #-0x14\]
  mov	r3, #0x3e8
  bl	#(?P<Enc_Serial_SendWaitAck>[0-9a-fx]+)
  mov	r3, r0
  cmp	r3, #0
  beq	#(?P<loc_label03>[0-9a-fx]+)
  ldr	r3, \[fp, #-8\]
  add	r3, r3, #1
  str	r3, \[fp, #-8\]
  ldr	r2, \[fp, #-8\]
  ldr	r3, \[fp, #-0x350\]
  cmp	r2, r3
  blo	#(?P<loc_label01>[0-9a-fx]+)
  ldr	r2, \[fp, #-8\]
  ldr	r3, \[fp, #-0x350\]
  cmp	r2, r3
  blo	#(?P<loc_label04>[0-9a-fx]+)
  mov	r3, #0
  str	r3, \[fp, #-0x354\]
  b	#(?P<loc_label10>[0-9a-fx]+)
  ldr	r3, \[fp, #-0x344\]
  cmp	r3, #0x3a
  bhi	#(?P<loc_label05>[0-9a-fx]+)
  mov	r1, #0
  str	r1, \[fp, #-0x354\]
  b	#(?P<loc_label10>[0-9a-fx]+)
  sub	r3, fp, #0x26c
  str	r3, \[fp, #-0x10\]
  ldr	r3, \[fp, #-0x10\]
  ldrb	r3, \[r3\]
  cmp	r3, #0
  moveq	r3, #0
  movne	r3, #1
  and	r2, r3, #0xff
  ldr	r3, \[fp, #-0x10\]
  add	r3, r3, #1
  str	r3, \[fp, #-0x10\]
  cmp	r2, #0
  beq	#(?P<loc_label06>[0-9a-fx]+)
  mov	r3, #0
  str	r3, \[fp, #-0x354\]
  b	#(?P<loc_label10>[0-9a-fx]+)
  sub	r3, fp, #0x320
  mov	r0, r3
  mov	r1, #0x20
  ldr	r2, \[pc, #(?P<cstr_fname_key>[0-9a-fx]+)\]
  bl	#(?P<AesDecryptFromFile>[0-9a-fx]+)
  mov	r3, r0
  cmp	r3, #0
  beq	#(?P<loc_label07>[0-9a-fx]+)
  mov	r1, #0
  str	r1, \[fp, #-0x354\]
  b	#(?P<loc_label10>[0-9a-fx]+)
  sub	r3, fp, #0x340
  sub	r2, fp, #0x320
  sub	ip, fp, #0x300
  mov	r0, r3
  mov	r1, #2
  mov	r3, ip
  bl	#(?P<CalMac>[0-9a-fx]+)
  sub	r3, fp, #0x340
  mov	r0, r3
  ldr	r1, \[fp, #-0x10\]
  mov	r2, #0x20
  bl	#(?P<memcmp>[0-9a-fx]+)
  mov	r3, r0
  cmp	r3, #0
  beq	#(?P<loc_label08>[0-9a-fx]+)
  mov	r3, #0
  str	r3, \[fp, #-0x354\]
  b	#(?P<loc_label10>[0-9a-fx]+)
  ldr	r3, \[fp, #-0x10\]
  add	r3, r3, #0x20
  str	r3, \[fp, #-0x10\]
  sub	r3, fp, #0x2d0
  str	r3, \[fp, #-0xc\]
  ldr	r0, \[fp, #-0xc\]
  ldr	r1, \[fp, #-0x10\]
  mov	r2, #0xa
  bl	#(?P<memcpy>[0-9a-fx]+)
  ldr	r3, \[fp, #-0xc\]
  add	r3, r3, #0xa
  str	r3, \[fp, #-0xc\]
  ldr	r3, \[fp, #-0x10\]
  add	r3, r3, #0xa
  str	r3, \[fp, #-0x10\]
  sub	r3, fp, #0x320
  ldr	r0, \[fp, #-0xc\]
  mov	r1, r3
  mov	r2, #0x20
  bl	#(?P<memcpy>[0-9a-fx]+)
  ldr	r3, \[fp, #-0xc\]
  add	r3, r3, #0x20
  str	r3, \[fp, #-0xc\]
  ldr	r2, \[fp, #-0xc\]
  sub	r3, fp, #0x2d0
  rsb	r3, r3, r2
  mov	r1, r3
  sub	r3, fp, #0x2d0
  sub	r2, fp, #0x2e0
  mov	r0, r3
  bl	#(?P<CalMD5>[0-9a-fx]+)
  sub	r3, fp, #0x2e0
  mov	r0, r3
  ldr	r1, \[fp, #-0x10\]
  mov	r2, #0x10
  bl	#(?P<memcmp>[0-9a-fx]+)
  mov	r3, r0
  cmp	r3, #0
  beq	#(?P<loc_label09>[0-9a-fx]+)
  mov	r1, #0
  str	r1, \[fp, #-0x354\]
  b	#(?P<loc_label10>[0-9a-fx]+)
  ldr	r3, \[pc, #(?P<s_bPassedEnc>[0-9a-fx]+)\]
  mov	r2, #1
  strb	r2, \[r3\]
  mov	r3, #1
  str	r3, \[fp, #-0x354\]
  ldr	r3, \[fp, #-0x354\]
  mov	r0, r3
  sub	sp, fp, #4
  pop	{fp, pc}
""",
'vars': {
  'Encrypt_Request':	{'type': VarType.DIRECT_LINE_OF_CODE, 'variety': CodeVariety.FUNCTION},
  'cstr_fname_key':	{'type': VarType.RELATIVE_ADDR_TO_PTR_TO_GLOBAL_DATA, 'baseaddr': "PC+", 'variety': DataVariety.CHAR, 'array': "null_term"},
  'loc_label01':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label02':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label03':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label04':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label05':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label06':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label07':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label08':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label09':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'loc_label10':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.CHUNK},
  'puts':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'memset':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'memcpy':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'memcmp':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'sleep':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'GetRandomData':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'Enc_Serial_Get_CurSeq':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'Enc_Serial_SendWaitAck':	{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'AesDecryptFromFile':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'CalMac':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  'CalMD5':		{'type': VarType.ABSOLUTE_ADDR_TO_CODE, 'variety': CodeVariety.FUNCTION},
  's_bPassedEnc':		{'type': VarType.RELATIVE_ADDR_TO_PTR_TO_GLOBAL_DATA, 'baseaddr': "PC+", 'variety': DataVariety.UINT32_T},
},
}

re_general_list = [
  {'sect': ".text", 'func': re_func_encryptThrFxn_original,},
  {'sect': ".text", 'func': re_func_encryptThrFxn_encpass,},
  {'sect': ".text", 'func': re_func_Encrypt_Request,},
]


def armfw_elf_dm3xxvals_list(po, elffh):
    params_list, _, _, _, _, _ = armfw_elf_paramvals_extract_list(po, elffh, re_general_list, 'arm')
    # print list of parameter values
    armfw_elf_paramvals_export_simple_list(po, params_list, sys.stdout)


def armfw_elf_dm3xxvals_mapfile(po, elffh):
    _, params_list, elf_sections, _, _, asm_arch = \
      armfw_elf_paramvals_extract_list(po, elffh, re_general_list, 'arm')
    armfw_elf_paramvals_export_mapfile(po, params_list, elf_sections, asm_arch, sys.stdout)


def armfw_elf_dm3xxvals_extract(po, elffh):
    """ Extracts all values from firmware to JSON format text file.
    """
    params_list, _, _, _, _, _ = armfw_elf_paramvals_extract_list(po, elffh, re_general_list, 'arm')
    if len(params_list) <= 0:
        raise ValueError("No known values found in ELF file.")
    if not po.dry_run:
        valfile = open(po.valfile, "w")
    else:
        valfile = io.StringIO()
    armfw_elf_paramvals_export_json(po, params_list, valfile)
    valfile.close()


def armfw_elf_dm3xxvals_update(po, elffh):
    """ Updates all hardcoded values in firmware from JSON format text file.
    """
    pub_params_list, glob_params_list, elf_sections, cs, elfobj, asm_arch = \
      armfw_elf_paramvals_extract_list(po, elffh, re_general_list, 'arm')
    if len(pub_params_list) <= 0:
        raise ValueError("No known values found in ELF file.")
    with open(po.valfile) as valfile:
        nxparams_list = json.load(valfile)
    # Change section data buffers to bytearrays, so we can change them easily
    for section_name, section in elf_sections.items():
        section['data'] = bytearray(section['data'])
    update_count = armfw_elf_paramvals_update_list(po, asm_arch, re_general_list, pub_params_list, glob_params_list, elf_sections, nxparams_list)
    if (po.verbose > 0):
        print("{:s}: Updated {:d} out of {:d} hardcoded values"
          .format(po.elffile,update_count,len(pub_params_list)))
    # Now update the ELF file
    for section_name, section in elf_sections.items():
        elfsect = elfobj.get_section_by_name(section_name)
        elfsect.set_data(section['data'])
        elfobj.set_section_by_name(section_name, elfsect)
    if not po.dry_run:
        elfobj.write_changes()


def main():
    """ Main executable function.

    Its task is to parse command line options and call a function which performs requested command.
    """
    parser = argparse.ArgumentParser(description=__doc__.split('.')[0])

    parser.add_argument('-e', '--elffile', type=str, required=True,
          help="Input ELF firmware file name")

    parser.add_argument('-o', '--valfile', type=str,
          help="Values list JSON file name")

    parser.add_argument('--dry-run', action='store_true',
          help="Do not write any files or do permanent changes")

    parser.add_argument('-v', '--verbose', action='count', default=0,
          help="Increases verbosity level; max level is set by -vvv")

    subparser = parser.add_mutually_exclusive_group(required=True)

    subparser.add_argument('-l', '--list', action='store_true',
          help="list values stored in the firmware")

    subparser.add_argument('-x', '--extract', action='store_true',
          help="Extract values to infos json text file")

    subparser.add_argument('-u', '--update', action='store_true',
          help="Update values in binary fw from infos text file")

    subparser.add_argument('-d', '--objdump', action='store_true',
          help="display asm like slightly primitive objdump")

    subparser.add_argument('--mapfile', action='store_true',
          help="export known symbols to map file")

    subparser.add_argument('--version', action='version', version="%(prog)s {version} by {author}"
            .format(version=__version__, author=__author__),
          help="Display version information and exit")

    po = parser.parse_args()

    po.basename = os.path.splitext(os.path.basename(po.elffile))[0]

    if len(po.elffile) > 0 and (po.valfile is None or len(po.valfile) == 0):
        po.valfile = po.basename + ".json"

    if po.objdump:
        if (po.verbose > 0):
            print("{}: Opening for objdump".format(po.elffile))
        with open(po.elffile, 'rb') as elffh:
            armfw_elf_generic_objdump(po, elffh)

    elif po.list:
        if (po.verbose > 0):
            print("{}: Opening for list".format(po.elffile))
        with open(po.elffile, 'rb') as elffh:
            armfw_elf_dm3xxvals_list(po, elffh)

    elif po.mapfile:
        if (po.verbose > 0):
            print("{}: Opening for mapfile generation".format(po.elffile))
        with open(po.elffile, 'rb') as elffh:
            armfw_elf_dm3xxvals_mapfile(po, elffh)

    elif po.extract:
        if (po.verbose > 0):
            print("{}: Opening for extract".format(po.elffile))
        with open(po.elffile, 'rb') as elffh:
            armfw_elf_dm3xxvals_extract(po, elffh)

    elif po.update:
        if (po.verbose > 0):
            print("{}: Opening for update".format(po.elffile))
        with open(po.elffile, 'r+b') as elffh:
            armfw_elf_dm3xxvals_update(po, elffh)

    else:
        raise NotImplementedError("Unsupported command.")


if __name__ == '__main__':
    try:
        main()
    except Exception as ex:
        eprint("Error: "+str(ex))
        if 0: raise
        sys.exit(10)