1#!/usr/bin/python 2 3# GDB debugging support 4# 5# Copyright 2012 Red Hat, Inc. and/or its affiliates 6# 7# Authors: 8# Avi Kivity <avi@redhat.com> 9# 10# This work is licensed under the terms of the GNU GPL, version 2. See 11# the COPYING file in the top-level directory. 12# 13# Contributions after 2012-01-13 are licensed under the terms of the 14# GNU GPL, version 2 or (at your option) any later version. 15 16 17import gdb 18 19import os, sys 20 21# Annoyingly, gdb doesn't put the directory of scripts onto the 22# module search path. Do it manually. 23 24sys.path.append(os.path.dirname(__file__)) 25 26from qemugdb import mtree 27 28def get_fs_base(): 29 '''Fetch %fs base value using arch_prctl(ARCH_GET_FS)''' 30 # %rsp - 120 is scratch space according to the SystemV ABI 31 old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)') 32 gdb.execute('call arch_prctl(0x1003, $rsp - 120)', False, True) 33 fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)') 34 gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True) 35 return fs_base 36 37def get_glibc_pointer_guard(): 38 '''Fetch glibc pointer guard value''' 39 fs_base = get_fs_base() 40 return gdb.parse_and_eval('*(uint64_t*)((uint64_t)%s + 0x30)' % fs_base) 41 42def glibc_ptr_demangle(val, pointer_guard): 43 '''Undo effect of glibc's PTR_MANGLE()''' 44 return gdb.parse_and_eval('(((uint64_t)%s >> 0x11) | ((uint64_t)%s << (64 - 0x11))) ^ (uint64_t)%s' % (val, val, pointer_guard)) 45 46def bt_jmpbuf(jmpbuf): 47 '''Backtrace a jmpbuf''' 48 JB_RBX = 0 49 JB_RBP = 1 50 JB_R12 = 2 51 JB_R13 = 3 52 JB_R14 = 4 53 JB_R15 = 5 54 JB_RSP = 6 55 JB_PC = 7 56 57 old_rbx = gdb.parse_and_eval('(uint64_t)$rbx') 58 old_rbp = gdb.parse_and_eval('(uint64_t)$rbp') 59 old_rsp = gdb.parse_and_eval('(uint64_t)$rsp') 60 old_r12 = gdb.parse_and_eval('(uint64_t)$r12') 61 old_r13 = gdb.parse_and_eval('(uint64_t)$r13') 62 old_r14 = gdb.parse_and_eval('(uint64_t)$r14') 63 old_r15 = gdb.parse_and_eval('(uint64_t)$r15') 64 old_rip = gdb.parse_and_eval('(uint64_t)$rip') 65 66 pointer_guard = get_glibc_pointer_guard() 67 gdb.execute('set $rbx = %s' % jmpbuf[JB_RBX]) 68 gdb.execute('set $rbp = %s' % glibc_ptr_demangle(jmpbuf[JB_RBP], pointer_guard)) 69 gdb.execute('set $rsp = %s' % glibc_ptr_demangle(jmpbuf[JB_RSP], pointer_guard)) 70 gdb.execute('set $r12 = %s' % jmpbuf[JB_R12]) 71 gdb.execute('set $r13 = %s' % jmpbuf[JB_R13]) 72 gdb.execute('set $r14 = %s' % jmpbuf[JB_R14]) 73 gdb.execute('set $r15 = %s' % jmpbuf[JB_R15]) 74 gdb.execute('set $rip = %s' % glibc_ptr_demangle(jmpbuf[JB_PC], pointer_guard)) 75 76 gdb.execute('bt') 77 78 gdb.execute('set $rbx = %s' % old_rbx) 79 gdb.execute('set $rbp = %s' % old_rbp) 80 gdb.execute('set $rsp = %s' % old_rsp) 81 gdb.execute('set $r12 = %s' % old_r12) 82 gdb.execute('set $r13 = %s' % old_r13) 83 gdb.execute('set $r14 = %s' % old_r14) 84 gdb.execute('set $r15 = %s' % old_r15) 85 gdb.execute('set $rip = %s' % old_rip) 86 87class QemuCommand(gdb.Command): 88 '''Prefix for QEMU debug support commands''' 89 def __init__(self): 90 gdb.Command.__init__(self, 'qemu', gdb.COMMAND_DATA, 91 gdb.COMPLETE_NONE, True) 92 93class CoroutineCommand(gdb.Command): 94 '''Display coroutine backtrace''' 95 def __init__(self): 96 gdb.Command.__init__(self, 'qemu coroutine', gdb.COMMAND_DATA, 97 gdb.COMPLETE_NONE) 98 99 def invoke(self, arg, from_tty): 100 argv = gdb.string_to_argv(arg) 101 if len(argv) != 1: 102 gdb.write('usage: qemu coroutine <coroutine-pointer>\n') 103 return 104 105 coroutine_pointer = gdb.parse_and_eval(argv[0]).cast(gdb.lookup_type('CoroutineUContext').pointer()) 106 bt_jmpbuf(coroutine_pointer['env']['__jmpbuf']) 107 108QemuCommand() 109CoroutineCommand() 110mtree.MtreeCommand() 111