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kdump: initial basic target
This module contains the bare minimum to load an x86_64 kernel crash dump and populate the thread list with thread info and stacks. Signed-off-by: Jeff Mahoney <[email protected]>
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‎crash/__init__.py‎

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#!/usr/bin/env python
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# vim:set shiftwidth=4 softtabstop=4 expandtab textwidth=79:

‎crash/kdump/__init__.py‎

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#!/usr/bin/env python
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# vim:set shiftwidth=4 softtabstop=4 expandtab textwidth=79:

‎crash/kdump/target.py‎

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#!/usr/bin/env python
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# vim:set shiftwidth=4 softtabstop=4 expandtab textwidth=79:
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import gdb
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from kdumpfile import kdumpfile
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from util import list_for_each_entry
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from kdumpfile.exceptions import *
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#arch = "i386:x86-64"
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#
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#setup = {
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# 'i386:x86-64' : setup_thread_amd64,
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#}
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ulong_type = gdb.lookup_type('unsigned long')
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rip = gdb.lookup_minimal_symbol("thread_return").value()
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def setup_thread_amd64(thread, task):
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rsp = task['thread']['sp'].cast(ulong_type.pointer())
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rbp = rsp.dereference().cast(ulong_type.pointer())
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rbx = (rbp - 1).dereference()
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r12 = (rbp - 2).dereference()
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r13 = (rbp - 3).dereference()
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r14 = (rbp - 4).dereference()
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r15 = (rbp - 5).dereference()
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# The two pushes that don't have CFI info
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# rsp += 2
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# ex = in_exception_stack(rsp)
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# if ex:
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# print "EXCEPTION STACK: pid %d" % task['pid']
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thread.registers['rsp'].value = rsp
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thread.registers['rbp'].value = rbp
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thread.registers['rip'].value = rip
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thread.registers['rbx'].value = rbx
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thread.registers['r12'].value = r12
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thread.registers['r13'].value = r13
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thread.registers['r14'].value = r14
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thread.registers['r15'].value = r15
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thread.registers['cs'].value = 2*8
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thread.registers['ss'].value = 3*8
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def symbol_func(symname):
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ms = gdb.lookup_minimal_symbol(symname)
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if not ms:
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print ("Cannot lookup symbol %s" % symname)
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raise RuntimeError("Cannot lookup symbol %s" % symname)
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return long(ms.value())
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class Target(gdb.Target):
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def __init__(self, fil):
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if isinstance(fil, str):
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fil = file(fil)
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self.fil = fil
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print "kdump (%s)" % fil
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self.kdump = kdumpfile(fil)
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self.kdump.symbol_func = symbol_func
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self.kdump.vtop_init()
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super(Target, self).__init__()
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gdb.execute('set print thread-events 0')
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self.setup_tasks()
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def setup_tasks(self):
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init_task = gdb.lookup_global_symbol('init_task')
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task_list = init_task.value()['tasks']
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self.pid_to_task_struct = {}
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for task in list_for_each_entry(task_list, init_task.type, 'tasks'):
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thread = gdb.selected_inferior().new_thread((1, task['pid'], 0), task)
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thread.name = task['comm'].string()
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gdb.selected_inferior().executing = False
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def to_xfer_partial(self, obj, annex, readbuf, writebuf, offset, ln):
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ret = -1
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if obj == self.TARGET_OBJECT_MEMORY:
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try:
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r = self.kdump.read (self.kdump.KDUMP_KVADDR, offset, ln)
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readbuf[:] = r
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ret = ln
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except EOFException, e:
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raise gdb.TargetXferEof(str(e))
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except NoDataException, e:
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raise gdb.TargetXferUnavailable(str(e))
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else:
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raise IOError("Unknown obj type")
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return ret
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def to_thread_alive(self, ptid):
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return 1
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def to_pid_to_str(self, ptid):
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return "pid %d" % ptid[1]
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def to_fetch_registers(self, register):
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thread = gdb.selected_thread()
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setup_thread_amd64(thread, thread.info)
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return True
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def to_prepare_to_store(self, thread):
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pass
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# We don't need to store anything; The regcache is already written.
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def to_store_registers(self, thread):
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pass
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def to_has_execution(self, ptid):
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return False

‎crash/kdump/util.py‎

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#!/usr/bin/env python
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# vim:set shiftwidth=4 softtabstop=4 expandtab textwidth=79:
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import gdb
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charp = gdb.lookup_type('char').pointer()
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def resolve_type(val):
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if isinstance(val, str):
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gdbtype = gdb.lookup_gdbtype(val)
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elif isinstance(val, gdb.Value):
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gdbtype = val.gdbtype
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else:
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gdbtype = val
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return gdbtype
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def offsetof(val, member):
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gdbtype = resolve_type(val)
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if not isinstance(val, gdb.Type):
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raise TypeError("offsetof requires gdb.Type or a string/value that can be used to lookup a gdb.Type")
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return gdbtype[member].bitpos >> 3
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def container_of(val, gdbtype, member):
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gdbtype = resolve_type(gdbtype)
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offset = offsetof(gdbtype, member)
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return (val.cast(charp) - offset).cast(gdbtype.pointer()).dereference()
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list_head_type = gdb.lookup_type("struct list_head")
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def list_for_each(list_head):
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if list_head.type == list_head_type.pointer():
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list_head = list_head.dereference()
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elif list_head.type != list_head_type:
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raise gdb.GdbError("Must be struct list_head not %s" % list_head.type)
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node = list_head['next'].dereference()
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while node.address != list_head.address:
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yield node.address
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node = node['next'].dereference()
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def list_for_each_entry(list_head, gdbtype, member):
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for node in list_for_each(list_head):
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if node.type != list_head_type.pointer():
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raise TypeError("Type %s found. Expected struct list_head *." % node.type)
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yield container_of(node, gdbtype, member)
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def per_cpu(symbol, cpu):
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if isinstance(symbol, str):
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symbol = gdb.lookup_global_symbol(symbol).value()
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elif isinstance(symbol, gdb.Symbol):
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symbol = symbol.value()
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else:
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raise TypeError("Must be string or gdb.Symbol")
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percpu_addr = symbol.address.cast(charp) + per_cpu_offset[cpu]
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return percpu_addr.cast(symbol.type.pointer()).dereference()

‎setup.py‎

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#!/usr/bin/env python
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# vim:set shiftwidth=4 softtabstop=4 expandtab textwidth=79:
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from setuptools import setup, find_packages
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setup(
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name = "crash",
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version = "0.1",
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packages = find_packages(),
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package_data = {
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'' : [ "*.dist" "*.txt" ],
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},
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install_requires = [],
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author = "Jeff Mahoney",
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author_email = "[email protected]",
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description = "Python Linux Kernel Crash dump forensic tools",
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license = "GPL v2 only",
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)

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