zephyr/scripts/elf_helper.py
Andrew Boie 577d5ddba4 userspace: fix kobj detection declared extern
If a variable is declared extern first, the name and type
information is stored in a special DW_DIE_variable which
is then referenced by the actual instances via the
tag DW_AT_specification.

We now place extern variable instances in an extern environment
and use this data to fetch the name/type of the instances,
which do not have it (which is why they were being skipped).

As it turns out, the gross hack for the system workqueue was
due to this problem because of the extern declaration in
kernel.h.

Fixes: #6992

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
2018-05-16 17:00:27 -07:00

531 lines
15 KiB
Python

#!/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sys.stderr.write("pyelftools is out of date, need version 0.24 or later\n")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 = {}
extern_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_spec(die):
if 'DW_AT_specification' not in die.attributes:
return None
spec_val = die.attributes["DW_AT_specification"].value
# offset of the DW_TAG_variable for the extern declaration
offset = spec_val + die.cu.cu_offset
return extern_env.get(offset)
def die_get_name(die):
if 'DW_AT_name' not in die.attributes:
die = die_get_spec(die)
if not die:
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:
die = die_get_spec(die)
if not die:
return None
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 = {}
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:
# Extern declaration, only used indirectly
extern_env[die.offset] = die
continue
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))