scripts/qemu-gdb.py

   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
  17 import gdb
  18
  19 def isnull(ptr):
  20     return ptr == gdb.Value(0).cast(ptr.type)
  21
  22 def int128(p):
  23     return long(p['lo']) + (long(p['hi']) << 64)
  24
  25 def get_fs_base():
  26     '''Fetch %fs base value using arch_prctl(ARCH_GET_FS)'''
  27     # %rsp - 120 is scratch space according to the SystemV ABI
  28     old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
  29     gdb.execute('call arch_prctl(0x1003, $rsp - 120)', False, True)
  30     fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
  31     gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True)
  32     return fs_base
  33
  34 def get_glibc_pointer_guard():
  35     '''Fetch glibc pointer guard value'''
  36     fs_base = get_fs_base()
  37     return gdb.parse_and_eval('*(uint64_t*)((uint64_t)%s + 0x30)' % fs_base)
  38
  39 def glibc_ptr_demangle(val, pointer_guard):
  40     '''Undo effect of glibc's PTR_MANGLE()'''
  41     return gdb.parse_and_eval('(((uint64_t)%s >> 0x11) | ((uint64_t)%s << (64 - 0x11))) ^ (uint64_t)%s' % (val, val, pointer_guard))
  42
  43 def bt_jmpbuf(jmpbuf):
  44     '''Backtrace a jmpbuf'''
  45     JB_RBX  = 0
  46     JB_RBP  = 1
  47     JB_R12  = 2
  48     JB_R13  = 3
  49     JB_R14  = 4
  50     JB_R15  = 5
  51     JB_RSP  = 6
  52     JB_PC   = 7
  53
  54     old_rbx = gdb.parse_and_eval('(uint64_t)$rbx')
  55     old_rbp = gdb.parse_and_eval('(uint64_t)$rbp')
  56     old_rsp = gdb.parse_and_eval('(uint64_t)$rsp')
  57     old_r12 = gdb.parse_and_eval('(uint64_t)$r12')
  58     old_r13 = gdb.parse_and_eval('(uint64_t)$r13')
  59     old_r14 = gdb.parse_and_eval('(uint64_t)$r14')
  60     old_r15 = gdb.parse_and_eval('(uint64_t)$r15')
  61     old_rip = gdb.parse_and_eval('(uint64_t)$rip')
  62
  63     pointer_guard = get_glibc_pointer_guard()
  64     gdb.execute('set $rbx = %s' % jmpbuf[JB_RBX])
  65     gdb.execute('set $rbp = %s' % glibc_ptr_demangle(jmpbuf[JB_RBP], pointer_guard))
  66     gdb.execute('set $rsp = %s' % glibc_ptr_demangle(jmpbuf[JB_RSP], pointer_guard))
  67     gdb.execute('set $r12 = %s' % jmpbuf[JB_R12])
  68     gdb.execute('set $r13 = %s' % jmpbuf[JB_R13])
  69     gdb.execute('set $r14 = %s' % jmpbuf[JB_R14])
  70     gdb.execute('set $r15 = %s' % jmpbuf[JB_R15])
  71     gdb.execute('set $rip = %s' % glibc_ptr_demangle(jmpbuf[JB_PC], pointer_guard))
  72
  73     gdb.execute('bt')
  74
  75     gdb.execute('set $rbx = %s' % old_rbx)
  76     gdb.execute('set $rbp = %s' % old_rbp)
  77     gdb.execute('set $rsp = %s' % old_rsp)
  78     gdb.execute('set $r12 = %s' % old_r12)
  79     gdb.execute('set $r13 = %s' % old_r13)
  80     gdb.execute('set $r14 = %s' % old_r14)
  81     gdb.execute('set $r15 = %s' % old_r15)
  82     gdb.execute('set $rip = %s' % old_rip)
  83
  84 class QemuCommand(gdb.Command):
  85     '''Prefix for QEMU debug support commands'''
  86     def __init__(self):
  87         gdb.Command.__init__(self, 'qemu', gdb.COMMAND_DATA,
  88                              gdb.COMPLETE_NONE, True)
  89
  90 class CoroutineCommand(gdb.Command):
  91     '''Display coroutine backtrace'''
  92     def __init__(self):
  93         gdb.Command.__init__(self, 'qemu coroutine', gdb.COMMAND_DATA,
  94                              gdb.COMPLETE_NONE)
  95
  96     def invoke(self, arg, from_tty):
  97         argv = gdb.string_to_argv(arg)
  98         if len(argv) != 1:
  99             gdb.write('usage: qemu coroutine <coroutine-pointer>\n')
 100             return
 101
 102         coroutine_pointer = gdb.parse_and_eval(argv[0]).cast(gdb.lookup_type('CoroutineUContext').pointer())
 103         bt_jmpbuf(coroutine_pointer['env']['__jmpbuf'])
 104
 105 class MtreeCommand(gdb.Command):
 106     '''Display the memory tree hierarchy'''
 107     def __init__(self):
 108         gdb.Command.__init__(self, 'qemu mtree', gdb.COMMAND_DATA,
 109                              gdb.COMPLETE_NONE)
 110         self.queue = []
 111     def invoke(self, arg, from_tty):
 112         self.seen = set()
 113         self.queue_root('address_space_memory')
 114         self.queue_root('address_space_io')
 115         self.process_queue()
 116     def queue_root(self, varname):
 117         ptr = gdb.parse_and_eval(varname)['root']
 118         self.queue.append(ptr)
 119     def process_queue(self):
 120         while self.queue:
 121             ptr = self.queue.pop(0)
 122             if long(ptr) in self.seen:
 123                 continue
 124             self.print_item(ptr)
 125     def print_item(self, ptr, offset = gdb.Value(0), level = 0):
 126         self.seen.add(long(ptr))
 127         addr = ptr['addr']
 128         addr += offset
 129         size = int128(ptr['size'])
 130         alias = ptr['alias']
 131         klass = ''
 132         if not isnull(alias):
 133             klass = ' (alias)'
 134         elif not isnull(ptr['ops']):
 135             klass = ' (I/O)'
 136         elif bool(ptr['ram']):
 137             klass = ' (RAM)'
 138         gdb.write('%s%016x-%016x %s%s (@ %s)\n'
 139                   % ('  ' * level,
 140                      long(addr),
 141                      long(addr + (size - 1)),
 142                      ptr['name'].string(),
 143                      klass,
 144                      ptr,
 145                      ),
 146                   gdb.STDOUT)
 147         if not isnull(alias):
 148             gdb.write('%s    alias: %s@%016x (@ %s)\n' %
 149                       ('  ' * level,
 150                        alias['name'].string(),
 151                        ptr['alias_offset'],
 152                        alias,
 153                        ),
 154                       gdb.STDOUT)
 155             self.queue.append(alias)
 156         subregion = ptr['subregions']['tqh_first']
 157         level += 1
 158         while not isnull(subregion):
 159             self.print_item(subregion, addr, level)
 160             subregion = subregion['subregions_link']['tqe_next']
 161
 162 QemuCommand()
 163 CoroutineCommand()
 164 MtreeCommand()