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#!/usr/bin/python
# GDB debugging support
#
# Copyright 2012 Red Hat, Inc. and/or its affiliates
#
# Authors:
# Avi Kivity <avi@redhat.com>
#
# This work is licensed under the terms of the GNU GPL, version 2. See
# the COPYING file in the top-level directory.
#
# Contributions after 2012-01-13 are licensed under the terms of the
# GNU GPL, version 2 or (at your option) any later version.
import gdb
import os, sys
# Annoyingly, gdb doesn't put the directory of scripts onto the
# module search path. Do it manually.
sys.path.append(os.path.dirname(__file__))
from qemugdb import mtree
def get_fs_base():
'''Fetch %fs base value using arch_prctl(ARCH_GET_FS)'''
# %rsp - 120 is scratch space according to the SystemV ABI
old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
gdb.execute('call arch_prctl(0x1003, $rsp - 120)', False, True)
fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True)
return fs_base
def get_glibc_pointer_guard():
'''Fetch glibc pointer guard value'''
fs_base = get_fs_base()
return gdb.parse_and_eval('*(uint64_t*)((uint64_t)%s + 0x30)' % fs_base)
def glibc_ptr_demangle(val, pointer_guard):
'''Undo effect of glibc's PTR_MANGLE()'''
return gdb.parse_and_eval('(((uint64_t)%s >> 0x11) | ((uint64_t)%s << (64 - 0x11))) ^ (uint64_t)%s' % (val, val, pointer_guard))
def bt_jmpbuf(jmpbuf):
'''Backtrace a jmpbuf'''
JB_RBX = 0
JB_RBP = 1
JB_R12 = 2
JB_R13 = 3
JB_R14 = 4
JB_R15 = 5
JB_RSP = 6
JB_PC = 7
old_rbx = gdb.parse_and_eval('(uint64_t)$rbx')
old_rbp = gdb.parse_and_eval('(uint64_t)$rbp')
old_rsp = gdb.parse_and_eval('(uint64_t)$rsp')
old_r12 = gdb.parse_and_eval('(uint64_t)$r12')
old_r13 = gdb.parse_and_eval('(uint64_t)$r13')
old_r14 = gdb.parse_and_eval('(uint64_t)$r14')
old_r15 = gdb.parse_and_eval('(uint64_t)$r15')
old_rip = gdb.parse_and_eval('(uint64_t)$rip')
pointer_guard = get_glibc_pointer_guard()
gdb.execute('set $rbx = %s' % jmpbuf[JB_RBX])
gdb.execute('set $rbp = %s' % glibc_ptr_demangle(jmpbuf[JB_RBP], pointer_guard))
gdb.execute('set $rsp = %s' % glibc_ptr_demangle(jmpbuf[JB_RSP], pointer_guard))
gdb.execute('set $r12 = %s' % jmpbuf[JB_R12])
gdb.execute('set $r13 = %s' % jmpbuf[JB_R13])
gdb.execute('set $r14 = %s' % jmpbuf[JB_R14])
gdb.execute('set $r15 = %s' % jmpbuf[JB_R15])
gdb.execute('set $rip = %s' % glibc_ptr_demangle(jmpbuf[JB_PC], pointer_guard))
gdb.execute('bt')
gdb.execute('set $rbx = %s' % old_rbx)
gdb.execute('set $rbp = %s' % old_rbp)
gdb.execute('set $rsp = %s' % old_rsp)
gdb.execute('set $r12 = %s' % old_r12)
gdb.execute('set $r13 = %s' % old_r13)
gdb.execute('set $r14 = %s' % old_r14)
gdb.execute('set $r15 = %s' % old_r15)
gdb.execute('set $rip = %s' % old_rip)
class QemuCommand(gdb.Command):
'''Prefix for QEMU debug support commands'''
def __init__(self):
gdb.Command.__init__(self, 'qemu', gdb.COMMAND_DATA,
gdb.COMPLETE_NONE, True)
class CoroutineCommand(gdb.Command):
'''Display coroutine backtrace'''
def __init__(self):
gdb.Command.__init__(self, 'qemu coroutine', gdb.COMMAND_DATA,
gdb.COMPLETE_NONE)
def invoke(self, arg, from_tty):
argv = gdb.string_to_argv(arg)
if len(argv) != 1:
gdb.write('usage: qemu coroutine <coroutine-pointer>\n')
return
coroutine_pointer = gdb.parse_and_eval(argv[0]).cast(gdb.lookup_type('CoroutineUContext').pointer())
bt_jmpbuf(coroutine_pointer['env']['__jmpbuf'])
QemuCommand()
CoroutineCommand()
mtree.MtreeCommand()
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