547 lines
16 KiB
Python
547 lines
16 KiB
Python
#!/usr/bin/env python3
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#
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# Copyright (c) 2017-2018 Linaro
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#
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# SPDX-License-Identifier: Apache-2.0
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import sys
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import argparse
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import pprint
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import os
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import struct
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from distutils.version import LooseVersion
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import elftools
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from elftools.elf.elffile import ELFFile
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from elftools.dwarf import descriptions
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from elftools.elf.sections import SymbolTableSection
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if LooseVersion(elftools.__version__) < LooseVersion('0.24'):
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sys.stderr.write("pyelftools is out of date, need version 0.24 or later\n")
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sys.exit(1)
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def subsystem_to_enum(subsys):
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return "K_OBJ_DRIVER_" + subsys[:-11].upper()
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def kobject_to_enum(kobj):
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if kobj.startswith("k_") or kobj.startswith("_k_"):
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name = kobj[2:]
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else:
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name = kobj
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return "K_OBJ_%s" % name.upper()
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DW_OP_addr = 0x3
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DW_OP_fbreg = 0x91
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STACK_TYPE = "_k_thread_stack_element"
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thread_counter = 0
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# Global type environment. Populated by pass 1.
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type_env = {}
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extern_env = {}
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kobjects = {}
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subsystems = {}
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# --- debug stuff ---
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scr = os.path.basename(sys.argv[0])
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# --- type classes ----
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class KobjectInstance:
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def __init__(self, type_obj, addr):
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global thread_counter
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self.addr = addr
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self.type_obj = type_obj
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# Type name determined later since drivers needs to look at the
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# API struct address
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self.type_name = None
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if self.type_obj.name == "k_thread":
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# Assign an ID for this thread object, used to track its
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# permissions to other kernel objects
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self.data = thread_counter
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thread_counter = thread_counter + 1
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else:
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self.data = 0
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class KobjectType:
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def __init__(self, offset, name, size, api=False):
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self.name = name
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self.size = size
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self.offset = offset
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self.api = api
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def __repr__(self):
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return "<kobject %s>" % self.name
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def has_kobject(self):
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return True
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def get_kobjects(self, addr):
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return {addr: KobjectInstance(self, addr)}
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class ArrayType:
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def __init__(self, offset, elements, member_type):
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self.elements = elements
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self.member_type = member_type
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self.offset = offset
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def __repr__(self):
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return "<array of %d, size %d>" % (self.member_type, self.num_members)
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def has_kobject(self):
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if self.member_type not in type_env:
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return False
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return type_env[self.member_type].has_kobject()
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def get_kobjects(self, addr):
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mt = type_env[self.member_type]
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# Stacks are arrays of _k_stack_element_t but we want to treat
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# the whole array as one kernel object (a thread stack)
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# Data value gets set to size of entire region
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if isinstance(mt, KobjectType) and mt.name == STACK_TYPE:
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# An array of stacks appears as a multi-dimensional array.
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# The last size is the size of each stack. We need to track
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# each stack within the array, not as one huge stack object.
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*dimensions, stacksize = self.elements
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num_members = 1
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for e in dimensions:
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num_members = num_members * e
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ret = {}
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for i in range(num_members):
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a = addr + (i * stacksize)
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o = mt.get_kobjects(a)
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o[a].data = stacksize
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ret.update(o)
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return ret
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objs = {}
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# Multidimensional array flattened out
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num_members = 1
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for e in self.elements:
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num_members = num_members * e
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for i in range(num_members):
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objs.update(mt.get_kobjects(addr + (i * mt.size)))
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return objs
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class AggregateTypeMember:
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def __init__(self, offset, member_name, member_type, member_offset):
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self.member_name = member_name
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self.member_type = member_type
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if isinstance(member_offset, list):
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# DWARF v2, location encoded as set of operations
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# only "DW_OP_plus_uconst" with ULEB128 argument supported
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if member_offset[0]==0x23:
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self.member_offset = member_offset[1] & 0x7f
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for i in range(1, len(member_offset)-1):
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if (member_offset[i] & 0x80):
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self.member_offset += (member_offset[i+1] & 0x7f) << i*7
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else:
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debug_die("not yet supported location operation")
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else:
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self.member_offset = member_offset
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def __repr__(self):
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return "<member %s, type %d, offset %d>" % (
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self.member_name, self.member_type, self.member_offset)
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def has_kobject(self):
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if self.member_type not in type_env:
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return False
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return type_env[self.member_type].has_kobject()
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def get_kobjects(self, addr):
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mt = type_env[self.member_type]
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return mt.get_kobjects(addr + self.member_offset)
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class ConstType:
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def __init__(self, child_type):
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self.child_type = child_type
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def __repr__(self):
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return "<const %d>" % self.child_type
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def has_kobject(self):
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if self.child_type not in type_env:
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return False
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return type_env[self.child_type].has_kobject()
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def get_kobjects(self, addr):
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return type_env[self.child_type].get_kobjects(addr)
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class AggregateType:
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def __init__(self, offset, name, size):
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self.name = name
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self.size = size
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self.offset = offset
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self.members = []
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def add_member(self, member):
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self.members.append(member)
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def __repr__(self):
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return "<struct %s, with %s>" % (self.name, self.members)
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def has_kobject(self):
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result = False
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bad_members = []
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for member in self.members:
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if member.has_kobject():
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result = True
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else:
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bad_members.append(member)
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# Don't need to consider this again, just remove it
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for bad_member in bad_members:
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self.members.remove(bad_member)
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return result
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def get_kobjects(self, addr):
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objs = {}
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for member in self.members:
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objs.update(member.get_kobjects(addr))
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return objs
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# --- helper functions for getting data from DIEs ---
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def die_get_spec(die):
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if 'DW_AT_specification' not in die.attributes:
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return None
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spec_val = die.attributes["DW_AT_specification"].value
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# offset of the DW_TAG_variable for the extern declaration
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offset = spec_val + die.cu.cu_offset
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return extern_env.get(offset)
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def die_get_name(die):
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if 'DW_AT_name' not in die.attributes:
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die = die_get_spec(die)
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if not die:
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return None
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return die.attributes["DW_AT_name"].value.decode("utf-8")
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def die_get_type_offset(die):
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if 'DW_AT_type' not in die.attributes:
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die = die_get_spec(die)
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if not die:
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return None
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return die.attributes["DW_AT_type"].value + die.cu.cu_offset
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def die_get_byte_size(die):
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if 'DW_AT_byte_size' not in die.attributes:
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return 0
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return die.attributes["DW_AT_byte_size"].value
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def analyze_die_struct(die):
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name = die_get_name(die) or "<anon>"
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offset = die.offset
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size = die_get_byte_size(die)
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# Incomplete type
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if not size:
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return
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if name in kobjects:
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type_env[offset] = KobjectType(offset, name, size)
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elif name in subsystems:
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type_env[offset] = KobjectType(offset, name, size, api=True)
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else:
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at = AggregateType(offset, name, size)
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type_env[offset] = at
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for child in die.iter_children():
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if child.tag != "DW_TAG_member":
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continue
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child_type = die_get_type_offset(child)
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member_offset = \
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child.attributes["DW_AT_data_member_location"].value
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cname = die_get_name(child) or "<anon>"
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m = AggregateTypeMember(child.offset, cname, child_type,
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member_offset)
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at.add_member(m)
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return
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def analyze_die_const(die):
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type_offset = die_get_type_offset(die)
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if not type_offset:
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return
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type_env[die.offset] = ConstType(type_offset)
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def analyze_die_array(die):
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type_offset = die_get_type_offset(die)
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elements = []
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for child in die.iter_children():
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if child.tag != "DW_TAG_subrange_type":
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continue
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if "DW_AT_upper_bound" not in child.attributes:
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continue
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ub = child.attributes["DW_AT_upper_bound"]
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if not ub.form.startswith("DW_FORM_data"):
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continue
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elements.append(ub.value + 1)
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if not elements:
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return
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type_env[die.offset] = ArrayType(die.offset, elements, type_offset)
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def addr_deref(elf, addr):
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for section in elf.iter_sections():
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start = section['sh_addr']
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end = start + section['sh_size']
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if addr >= start and addr < end:
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data = section.data()
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offset = addr - start
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return struct.unpack("<I" if elf.little_endian else ">I",
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data[offset:offset + 4])[0]
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return 0
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def device_get_api_addr(elf, addr):
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return addr_deref(elf, addr + 4)
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def get_filename_lineno(die):
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lp_header = die.dwarfinfo.line_program_for_CU(die.cu).header
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files = lp_header["file_entry"]
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includes = lp_header["include_directory"]
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fileinfo = files[die.attributes["DW_AT_decl_file"].value - 1]
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filename = fileinfo.name.decode("utf-8")
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filedir = includes[fileinfo.dir_index - 1].decode("utf-8")
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path = os.path.join(filedir, filename)
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lineno = die.attributes["DW_AT_decl_line"].value
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return (path, lineno)
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class ElfHelper:
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def __init__(self, filename, verbose, kobjs, subs):
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self.verbose = verbose
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self.fp = open(filename, "rb")
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self.elf = ELFFile(self.fp)
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self.little_endian = self.elf.little_endian
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global kobjects
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global subsystems
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kobjects = kobjs
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subsystems = subs
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def find_kobjects(self, syms):
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if not self.elf.has_dwarf_info():
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sys.stderr.write("ELF file has no DWARF information\n")
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sys.exit(1)
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kram_start = syms["__kernel_ram_start"]
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kram_end = syms["__kernel_ram_end"]
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krom_start = syms["_image_rom_start"]
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krom_end = syms["_image_rom_end"]
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di = self.elf.get_dwarf_info()
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variables = []
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# Step 1: collect all type information.
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for CU in di.iter_CUs():
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CU_path = CU.get_top_DIE().get_full_path()
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lp = di.line_program_for_CU(CU)
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for idx, die in enumerate(CU.iter_DIEs()):
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# Unions are disregarded, kernel objects should never be union
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# members since the memory is not dedicated to that object and
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# could be something else
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if die.tag == "DW_TAG_structure_type":
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analyze_die_struct(die)
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elif die.tag == "DW_TAG_const_type":
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analyze_die_const(die)
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elif die.tag == "DW_TAG_array_type":
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analyze_die_array(die)
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elif die.tag == "DW_TAG_variable":
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variables.append(die)
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# Step 2: filter type_env to only contain kernel objects, or structs
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# and arrays of kernel objects
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bad_offsets = []
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for offset, type_object in type_env.items():
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if not type_object.has_kobject():
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bad_offsets.append(offset)
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for offset in bad_offsets:
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del type_env[offset]
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# Step 3: Now that we know all the types we are looking for, examine
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# all variables
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all_objs = {}
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for die in variables:
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name = die_get_name(die)
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if not name:
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continue
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type_offset = die_get_type_offset(die)
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# Is this a kernel object, or a structure containing kernel
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# objects?
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if type_offset not in type_env:
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continue
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if "DW_AT_declaration" in die.attributes:
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# Extern declaration, only used indirectly
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extern_env[die.offset] = die
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continue
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if "DW_AT_location" not in die.attributes:
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self.debug_die(
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die,
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"No location information for object '%s'; possibly"
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" stack allocated" % name)
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continue
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loc = die.attributes["DW_AT_location"]
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if loc.form != "DW_FORM_exprloc" and \
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loc.form != "DW_FORM_block1":
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self.debug_die(
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die,
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"kernel object '%s' unexpected location format" %
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name)
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continue
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opcode = loc.value[0]
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if opcode != DW_OP_addr:
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# Check if frame pointer offset DW_OP_fbreg
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if opcode == DW_OP_fbreg:
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self.debug_die(die, "kernel object '%s' found on stack" %
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name)
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else:
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self.debug_die(
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die,
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"kernel object '%s' unexpected exprloc opcode %s" %
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(name, hex(opcode)))
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continue
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addr = (loc.value[1] | (loc.value[2] << 8) |
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(loc.value[3] << 16) | (loc.value[4] << 24))
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if addr == 0:
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# Never linked; gc-sections deleted it
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continue
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if ((addr < kram_start or addr >= kram_end) and
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(addr < krom_start or addr >= krom_end)):
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self.debug_die(die,
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"object '%s' found in invalid location %s"
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% (name, hex(addr)))
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continue
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type_obj = type_env[type_offset]
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objs = type_obj.get_kobjects(addr)
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all_objs.update(objs)
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self.debug("symbol '%s' at %s contains %d object(s)" % (name,
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hex(addr), len(objs)))
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# Step 4: objs is a dictionary mapping variable memory addresses to
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# their associated type objects. Now that we have seen all variables
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# and can properly look up API structs, convert this into a dictionary
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# mapping variables to the C enumeration of what kernel object type it
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# is.
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ret = {}
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for addr, ko in all_objs.items():
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# API structs don't get into the gperf table
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if ko.type_obj.api:
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continue
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if ko.type_obj.name != "device":
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# Not a device struct so we immediately know its type
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ko.type_name = kobject_to_enum(ko.type_obj.name)
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ret[addr] = ko
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continue
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# Device struct. Need to get the address of its API struct,
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# if it has one.
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apiaddr = device_get_api_addr(self.elf, addr)
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if apiaddr not in all_objs:
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# API struct does not correspond to a known subsystem, skip it
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continue
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apiobj = all_objs[apiaddr]
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ko.type_name = subsystem_to_enum(apiobj.type_obj.name)
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ret[addr] = ko
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self.debug("found %d kernel object instances total" % len(ret))
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return ret
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def get_symbols(self):
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for section in self.elf.iter_sections():
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if isinstance(section, SymbolTableSection):
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return {self.sym.name: self.sym.entry.st_value
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for self.sym in section.iter_symbols()}
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raise LookupError("Could not find symbol table")
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def debug(self, text):
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if not self.verbose:
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return
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sys.stdout.write(scr + ": " + text + "\n")
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def error(self, text):
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sys.stderr.write("%s ERROR: %s\n" % (scr, text))
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sys.exit(1)
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def debug_die(self, die, text):
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fn, ln = get_filename_lineno(die)
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self.debug(str(die))
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self.debug("File '%s', line %d:" % (fn, ln))
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self.debug(" %s" % text)
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def get_thread_counter(self):
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return thread_counter
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if __name__ == '__main__':
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sys.exit(main(sys.argv))
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