scripts: Add elf_helper.py
This patch adds a python helper library that encapsulates the ELF processing being done across multiple scripts. Users of this script will be converted over in a following patch. Signed-off-by: Andy Gross <andy.gross@linaro.org>
This commit is contained in:
Andy Gross
Andrew Boie
parent
18560a01a4
commit
826389ab7f
1 changed files with 522 additions and 0 deletions
522
scripts/elf_helper.py
Normal file
522
scripts/elf_helper.py
Normal file
|
|
@ -0,0 +1,522 @@
|
|||
#!/usr/bin/env python3
|
||||
#
|
||||
# Copyright (c) 2017-2018 Linaro
|
||||
#
|
||||
# SPDX-License-Identifier: Apache-2.0
|
||||
|
||||
import sys
|
||||
import argparse
|
||||
import pprint
|
||||
import os
|
||||
import struct
|
||||
from distutils.version import LooseVersion
|
||||
|
||||
import elftools
|
||||
from elftools.elf.elffile import ELFFile
|
||||
from elftools.dwarf import descriptions
|
||||
from elftools.elf.sections import SymbolTableSection
|
||||
|
||||
if LooseVersion(elftools.__version__) < LooseVersion('0.24'):
|
||||
sys.stderr.write("pyelftools is out of date, need version 0.24 or later\n")
|
||||
sys.exit(1)
|
||||
|
||||
|
||||
def subsystem_to_enum(subsys):
|
||||
return "K_OBJ_DRIVER_" + subsys[:-11].upper()
|
||||
|
||||
|
||||
def kobject_to_enum(ko):
|
||||
return "K_OBJ_" + ko[2:].upper()
|
||||
|
||||
|
||||
DW_OP_addr = 0x3
|
||||
DW_OP_fbreg = 0x91
|
||||
STACK_TYPE = "_k_thread_stack_element"
|
||||
thread_counter = 0
|
||||
|
||||
# Global type environment. Populated by pass 1.
|
||||
type_env = {}
|
||||
kobjects = {}
|
||||
subsystems = {}
|
||||
|
||||
# --- debug stuff ---
|
||||
|
||||
scr = os.path.basename(sys.argv[0])
|
||||
|
||||
# --- type classes ----
|
||||
|
||||
|
||||
class KobjectInstance:
|
||||
def __init__(self, type_obj, addr):
|
||||
global thread_counter
|
||||
|
||||
self.addr = addr
|
||||
self.type_obj = type_obj
|
||||
|
||||
# Type name determined later since drivers needs to look at the
|
||||
# API struct address
|
||||
self.type_name = None
|
||||
|
||||
if self.type_obj.name == "k_thread":
|
||||
# Assign an ID for this thread object, used to track its
|
||||
# permissions to other kernel objects
|
||||
self.data = thread_counter
|
||||
thread_counter = thread_counter + 1
|
||||
else:
|
||||
self.data = 0
|
||||
|
||||
|
||||
class KobjectType:
|
||||
def __init__(self, offset, name, size, api=False):
|
||||
self.name = name
|
||||
self.size = size
|
||||
self.offset = offset
|
||||
self.api = api
|
||||
|
||||
def __repr__(self):
|
||||
return "<kobject %s>" % self.name
|
||||
|
||||
def has_kobject(self):
|
||||
return True
|
||||
|
||||
def get_kobjects(self, addr):
|
||||
return {addr: KobjectInstance(self, addr)}
|
||||
|
||||
|
||||
class ArrayType:
|
||||
def __init__(self, offset, elements, member_type):
|
||||
self.elements = elements
|
||||
self.member_type = member_type
|
||||
self.offset = offset
|
||||
|
||||
def __repr__(self):
|
||||
return "<array of %d, size %d>" % (self.member_type, self.num_members)
|
||||
|
||||
def has_kobject(self):
|
||||
if self.member_type not in type_env:
|
||||
return False
|
||||
|
||||
return type_env[self.member_type].has_kobject()
|
||||
|
||||
def get_kobjects(self, addr):
|
||||
mt = type_env[self.member_type]
|
||||
|
||||
# Stacks are arrays of _k_stack_element_t but we want to treat
|
||||
# the whole array as one kernel object (a thread stack)
|
||||
# Data value gets set to size of entire region
|
||||
if isinstance(mt, KobjectType) and mt.name == STACK_TYPE:
|
||||
# An array of stacks appears as a multi-dimensional array.
|
||||
# The last size is the size of each stack. We need to track
|
||||
# each stack within the array, not as one huge stack object.
|
||||
*dimensions, stacksize = self.elements
|
||||
num_members = 1
|
||||
for e in dimensions:
|
||||
num_members = num_members * e
|
||||
|
||||
ret = {}
|
||||
for i in range(num_members):
|
||||
a = addr + (i * stacksize)
|
||||
o = mt.get_kobjects(a)
|
||||
o[a].data = stacksize
|
||||
ret.update(o)
|
||||
return ret
|
||||
|
||||
objs = {}
|
||||
|
||||
# Multidimensional array flattened out
|
||||
num_members = 1
|
||||
for e in self.elements:
|
||||
num_members = num_members * e
|
||||
|
||||
for i in range(num_members):
|
||||
objs.update(mt.get_kobjects(addr + (i * mt.size)))
|
||||
return objs
|
||||
|
||||
|
||||
class AggregateTypeMember:
|
||||
def __init__(self, offset, member_name, member_type, member_offset):
|
||||
self.member_name = member_name
|
||||
self.member_type = member_type
|
||||
self.member_offset = member_offset
|
||||
|
||||
def __repr__(self):
|
||||
return "<member %s, type %d, offset %d>" % (
|
||||
self.member_name, self.member_type, self.member_offset)
|
||||
|
||||
def has_kobject(self):
|
||||
if self.member_type not in type_env:
|
||||
return False
|
||||
|
||||
return type_env[self.member_type].has_kobject()
|
||||
|
||||
def get_kobjects(self, addr):
|
||||
mt = type_env[self.member_type]
|
||||
return mt.get_kobjects(addr + self.member_offset)
|
||||
|
||||
|
||||
class ConstType:
|
||||
def __init__(self, child_type):
|
||||
self.child_type = child_type
|
||||
|
||||
def __repr__(self):
|
||||
return "<const %d>" % self.child_type
|
||||
|
||||
def has_kobject(self):
|
||||
if self.child_type not in type_env:
|
||||
return False
|
||||
|
||||
return type_env[self.child_type].has_kobject()
|
||||
|
||||
def get_kobjects(self, addr):
|
||||
return type_env[self.child_type].get_kobjects(addr)
|
||||
|
||||
|
||||
class AggregateType:
|
||||
def __init__(self, offset, name, size):
|
||||
self.name = name
|
||||
self.size = size
|
||||
self.offset = offset
|
||||
self.members = []
|
||||
|
||||
def add_member(self, member):
|
||||
self.members.append(member)
|
||||
|
||||
def __repr__(self):
|
||||
return "<struct %s, with %s>" % (self.name, self.members)
|
||||
|
||||
def has_kobject(self):
|
||||
result = False
|
||||
|
||||
bad_members = []
|
||||
|
||||
for member in self.members:
|
||||
if member.has_kobject():
|
||||
result = True
|
||||
else:
|
||||
bad_members.append(member)
|
||||
# Don't need to consider this again, just remove it
|
||||
|
||||
for bad_member in bad_members:
|
||||
self.members.remove(bad_member)
|
||||
|
||||
return result
|
||||
|
||||
def get_kobjects(self, addr):
|
||||
objs = {}
|
||||
for member in self.members:
|
||||
objs.update(member.get_kobjects(addr))
|
||||
return objs
|
||||
|
||||
|
||||
# --- helper functions for getting data from DIEs ---
|
||||
|
||||
def die_get_name(die):
|
||||
if 'DW_AT_name' not in die.attributes:
|
||||
return None
|
||||
return die.attributes["DW_AT_name"].value.decode("utf-8")
|
||||
|
||||
|
||||
def die_get_type_offset(die):
|
||||
if 'DW_AT_type' not in die.attributes:
|
||||
return 0
|
||||
|
||||
return die.attributes["DW_AT_type"].value + die.cu.cu_offset
|
||||
|
||||
|
||||
def die_get_byte_size(die):
|
||||
if 'DW_AT_byte_size' not in die.attributes:
|
||||
return 0
|
||||
|
||||
return die.attributes["DW_AT_byte_size"].value
|
||||
|
||||
|
||||
def analyze_die_struct(die):
|
||||
name = die_get_name(die) or "<anon>"
|
||||
offset = die.offset
|
||||
size = die_get_byte_size(die)
|
||||
|
||||
# Incomplete type
|
||||
if not size:
|
||||
return
|
||||
|
||||
if name in kobjects:
|
||||
type_env[offset] = KobjectType(offset, name, size)
|
||||
elif name in subsystems:
|
||||
type_env[offset] = KobjectType(offset, name, size, api=True)
|
||||
else:
|
||||
at = AggregateType(offset, name, size)
|
||||
type_env[offset] = at
|
||||
|
||||
for child in die.iter_children():
|
||||
if child.tag != "DW_TAG_member":
|
||||
continue
|
||||
child_type = die_get_type_offset(child)
|
||||
member_offset = \
|
||||
child.attributes["DW_AT_data_member_location"].value
|
||||
cname = die_get_name(child) or "<anon>"
|
||||
m = AggregateTypeMember(child.offset, cname, child_type,
|
||||
member_offset)
|
||||
at.add_member(m)
|
||||
|
||||
return
|
||||
|
||||
|
||||
def analyze_die_const(die):
|
||||
type_offset = die_get_type_offset(die)
|
||||
if not type_offset:
|
||||
return
|
||||
|
||||
type_env[die.offset] = ConstType(type_offset)
|
||||
|
||||
|
||||
def analyze_die_array(die):
|
||||
type_offset = die_get_type_offset(die)
|
||||
elements = []
|
||||
|
||||
for child in die.iter_children():
|
||||
if child.tag != "DW_TAG_subrange_type":
|
||||
continue
|
||||
if "DW_AT_upper_bound" not in child.attributes:
|
||||
continue
|
||||
|
||||
ub = child.attributes["DW_AT_upper_bound"]
|
||||
if not ub.form.startswith("DW_FORM_data"):
|
||||
continue
|
||||
|
||||
elements.append(ub.value + 1)
|
||||
|
||||
if not elements:
|
||||
return
|
||||
|
||||
type_env[die.offset] = ArrayType(die.offset, elements, type_offset)
|
||||
|
||||
|
||||
def addr_deref(elf, addr):
|
||||
for section in elf.iter_sections():
|
||||
start = section['sh_addr']
|
||||
end = start + section['sh_size']
|
||||
|
||||
if addr >= start and addr < end:
|
||||
data = section.data()
|
||||
offset = addr - start
|
||||
return struct.unpack("<I" if elf.little_endian else ">I",
|
||||
data[offset:offset + 4])[0]
|
||||
|
||||
return 0
|
||||
|
||||
|
||||
def device_get_api_addr(elf, addr):
|
||||
return addr_deref(elf, addr + 4)
|
||||
|
||||
|
||||
def get_filename_lineno(die):
|
||||
lp_header = die.dwarfinfo.line_program_for_CU(die.cu).header
|
||||
files = lp_header["file_entry"]
|
||||
includes = lp_header["include_directory"]
|
||||
|
||||
fileinfo = files[die.attributes["DW_AT_decl_file"].value - 1]
|
||||
filename = fileinfo.name.decode("utf-8")
|
||||
filedir = includes[fileinfo.dir_index - 1].decode("utf-8")
|
||||
|
||||
path = os.path.join(filedir, filename)
|
||||
lineno = die.attributes["DW_AT_decl_line"].value
|
||||
return (path, lineno)
|
||||
|
||||
|
||||
class ElfHelper:
|
||||
|
||||
def __init__(self, filename, verbose, kobjs, subs):
|
||||
self.verbose = verbose
|
||||
self.fp = open(filename, "rb")
|
||||
self.elf = ELFFile(self.fp)
|
||||
self.little_endian = self.elf.little_endian
|
||||
global kobjects
|
||||
global subsystems
|
||||
kobjects = kobjs
|
||||
subsystems = subs
|
||||
|
||||
def find_kobjects(self, syms):
|
||||
if not self.elf.has_dwarf_info():
|
||||
sys.stderr.write("ELF file has no DWARF information\n")
|
||||
sys.exit(1)
|
||||
|
||||
kram_start = syms["__kernel_ram_start"]
|
||||
kram_end = syms["__kernel_ram_end"]
|
||||
krom_start = syms["_image_rom_start"]
|
||||
krom_end = syms["_image_rom_end"]
|
||||
|
||||
di = self.elf.get_dwarf_info()
|
||||
|
||||
variables = []
|
||||
|
||||
# Step 1: collect all type information.
|
||||
for CU in di.iter_CUs():
|
||||
CU_path = CU.get_top_DIE().get_full_path()
|
||||
lp = di.line_program_for_CU(CU)
|
||||
|
||||
for idx, die in enumerate(CU.iter_DIEs()):
|
||||
# Unions are disregarded, kernel objects should never be union
|
||||
# members since the memory is not dedicated to that object and
|
||||
# could be something else
|
||||
if die.tag == "DW_TAG_structure_type":
|
||||
analyze_die_struct(die)
|
||||
elif die.tag == "DW_TAG_const_type":
|
||||
analyze_die_const(die)
|
||||
elif die.tag == "DW_TAG_array_type":
|
||||
analyze_die_array(die)
|
||||
elif die.tag == "DW_TAG_variable":
|
||||
variables.append(die)
|
||||
|
||||
# Step 2: filter type_env to only contain kernel objects, or structs
|
||||
# and arrays of kernel objects
|
||||
bad_offsets = []
|
||||
for offset, type_object in type_env.items():
|
||||
if not type_object.has_kobject():
|
||||
bad_offsets.append(offset)
|
||||
|
||||
for offset in bad_offsets:
|
||||
del type_env[offset]
|
||||
|
||||
# Step 3: Now that we know all the types we are looking for, examine
|
||||
# all variables
|
||||
all_objs = {}
|
||||
|
||||
# Gross hack, see below
|
||||
work_q_found = False
|
||||
|
||||
for die in variables:
|
||||
name = die_get_name(die)
|
||||
if not name:
|
||||
continue
|
||||
|
||||
type_offset = die_get_type_offset(die)
|
||||
|
||||
# Is this a kernel object, or a structure containing kernel
|
||||
# objects?
|
||||
if type_offset not in type_env:
|
||||
continue
|
||||
|
||||
if "DW_AT_declaration" in die.attributes:
|
||||
# FIXME: why does k_sys_work_q not resolve an address in the
|
||||
# DWARF data??? Every single instance it finds is an extern
|
||||
# definition but not the actual instance in system_work_q.c
|
||||
# Is there something weird about how lib-y stuff is linked?
|
||||
if name == "k_sys_work_q" and not work_q_found and \
|
||||
name in syms:
|
||||
addr = syms[name]
|
||||
work_q_found = True
|
||||
else:
|
||||
continue
|
||||
else:
|
||||
if "DW_AT_location" not in die.attributes:
|
||||
self.debug_die(
|
||||
die,
|
||||
"No location information for object '%s'; possibly"
|
||||
" stack allocated" % name)
|
||||
continue
|
||||
|
||||
loc = die.attributes["DW_AT_location"]
|
||||
if loc.form != "DW_FORM_exprloc" and \
|
||||
loc.form != "DW_FORM_block1":
|
||||
self.debug_die(
|
||||
die,
|
||||
"kernel object '%s' unexpected location format" %
|
||||
name)
|
||||
continue
|
||||
|
||||
opcode = loc.value[0]
|
||||
if opcode != DW_OP_addr:
|
||||
|
||||
# Check if frame pointer offset DW_OP_fbreg
|
||||
if opcode == DW_OP_fbreg:
|
||||
self.debug_die(die, "kernel object '%s' found on stack" %
|
||||
name)
|
||||
else:
|
||||
self.debug_die(
|
||||
die,
|
||||
"kernel object '%s' unexpected exprloc opcode %s" %
|
||||
(name, hex(opcode)))
|
||||
continue
|
||||
|
||||
addr = (loc.value[1] | (loc.value[2] << 8) |
|
||||
(loc.value[3] << 16) | (loc.value[4] << 24))
|
||||
|
||||
if addr == 0:
|
||||
# Never linked; gc-sections deleted it
|
||||
continue
|
||||
|
||||
if ((addr < kram_start or addr >= kram_end) and
|
||||
(addr < krom_start or addr >= krom_end)):
|
||||
|
||||
self.debug_die(die,
|
||||
"object '%s' found in invalid location %s"
|
||||
% (name, hex(addr)))
|
||||
continue
|
||||
|
||||
type_obj = type_env[type_offset]
|
||||
objs = type_obj.get_kobjects(addr)
|
||||
all_objs.update(objs)
|
||||
|
||||
self.debug("symbol '%s' at %s contains %d object(s)" % (name,
|
||||
hex(addr), len(objs)))
|
||||
|
||||
# Step 4: objs is a dictionary mapping variable memory addresses to
|
||||
# their associated type objects. Now that we have seen all variables
|
||||
# and can properly look up API structs, convert this into a dictionary
|
||||
# mapping variables to the C enumeration of what kernel object type it
|
||||
# is.
|
||||
ret = {}
|
||||
for addr, ko in all_objs.items():
|
||||
# API structs don't get into the gperf table
|
||||
if ko.type_obj.api:
|
||||
continue
|
||||
|
||||
if ko.type_obj.name != "device":
|
||||
# Not a device struct so we immediately know its type
|
||||
ko.type_name = kobject_to_enum(ko.type_obj.name)
|
||||
ret[addr] = ko
|
||||
continue
|
||||
|
||||
# Device struct. Need to get the address of its API struct,
|
||||
# if it has one.
|
||||
apiaddr = device_get_api_addr(self.elf, addr)
|
||||
if apiaddr not in all_objs:
|
||||
# API struct does not correspond to a known subsystem, skip it
|
||||
continue
|
||||
|
||||
apiobj = all_objs[apiaddr]
|
||||
ko.type_name = subsystem_to_enum(apiobj.type_obj.name)
|
||||
ret[addr] = ko
|
||||
|
||||
self.debug("found %d kernel object instances total" % len(ret))
|
||||
return ret
|
||||
|
||||
def get_symbols(self):
|
||||
for section in self.elf.iter_sections():
|
||||
if isinstance(section, SymbolTableSection):
|
||||
return {self.sym.name: self.sym.entry.st_value
|
||||
for self.sym in section.iter_symbols()}
|
||||
|
||||
raise LookupError("Could not find symbol table")
|
||||
|
||||
def debug(self, text):
|
||||
if not self.verbose:
|
||||
return
|
||||
sys.stdout.write(scr + ": " + text + "\n")
|
||||
|
||||
def error(self, text):
|
||||
sys.stderr.write("%s ERROR: %s\n" % (scr, text))
|
||||
sys.exit(1)
|
||||
|
||||
def debug_die(self, die, text):
|
||||
fn, ln = get_filename_lineno(die)
|
||||
|
||||
self.debug(str(die))
|
||||
self.debug("File '%s', line %d:" % (fn, ln))
|
||||
self.debug(" %s" % text)
|
||||
|
||||
def get_thread_counter(self):
|
||||
return thread_counter
|
||||
|
||||
if __name__ == '__main__':
|
||||
sys.exit(main(sys.argv))
|
||||
Loading…
Add table
Add a link
Reference in a new issue