scripts/qemugdb/coroutine.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 import gdb
  17
  18 def get_fs_base():
  19     '''Fetch %fs base value using arch_prctl(ARCH_GET_FS)'''
  20     # %rsp - 120 is scratch space according to the SystemV ABI
  21     old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
  22     gdb.execute('call arch_prctl(0x1003, $rsp - 120)', False, True)
  23     fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
  24     gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True)
  25     return fs_base
  26
  27 def get_glibc_pointer_guard():
  28     '''Fetch glibc pointer guard value'''
  29     fs_base = get_fs_base()
  30     return gdb.parse_and_eval('*(uint64_t*)((uint64_t)%s + 0x30)' % fs_base)
  31
  32 def glibc_ptr_demangle(val, pointer_guard):
  33     '''Undo effect of glibc's PTR_MANGLE()'''
  34     return gdb.parse_and_eval('(((uint64_t)%s >> 0x11) | ((uint64_t)%s << (64 - 0x11))) ^ (uint64_t)%s' % (val, val, pointer_guard))
  35
  36 def bt_jmpbuf(jmpbuf):
  37     '''Backtrace a jmpbuf'''
  38     JB_RBX  = 0
  39     JB_RBP  = 1
  40     JB_R12  = 2
  41     JB_R13  = 3
  42     JB_R14  = 4
  43     JB_R15  = 5
  44     JB_RSP  = 6
  45     JB_PC   = 7
  46
  47     old_rbx = gdb.parse_and_eval('(uint64_t)$rbx')
  48     old_rbp = gdb.parse_and_eval('(uint64_t)$rbp')
  49     old_rsp = gdb.parse_and_eval('(uint64_t)$rsp')
  50     old_r12 = gdb.parse_and_eval('(uint64_t)$r12')
  51     old_r13 = gdb.parse_and_eval('(uint64_t)$r13')
  52     old_r14 = gdb.parse_and_eval('(uint64_t)$r14')
  53     old_r15 = gdb.parse_and_eval('(uint64_t)$r15')
  54     old_rip = gdb.parse_and_eval('(uint64_t)$rip')
  55
  56     pointer_guard = get_glibc_pointer_guard()
  57     gdb.execute('set $rbx = %s' % jmpbuf[JB_RBX])
  58     gdb.execute('set $rbp = %s' % glibc_ptr_demangle(jmpbuf[JB_RBP], pointer_guard))
  59     gdb.execute('set $rsp = %s' % glibc_ptr_demangle(jmpbuf[JB_RSP], pointer_guard))
  60     gdb.execute('set $r12 = %s' % jmpbuf[JB_R12])
  61     gdb.execute('set $r13 = %s' % jmpbuf[JB_R13])
  62     gdb.execute('set $r14 = %s' % jmpbuf[JB_R14])
  63     gdb.execute('set $r15 = %s' % jmpbuf[JB_R15])
  64     gdb.execute('set $rip = %s' % glibc_ptr_demangle(jmpbuf[JB_PC], pointer_guard))
  65
  66     gdb.execute('bt')
  67
  68     gdb.execute('set $rbx = %s' % old_rbx)
  69     gdb.execute('set $rbp = %s' % old_rbp)
  70     gdb.execute('set $rsp = %s' % old_rsp)
  71     gdb.execute('set $r12 = %s' % old_r12)
  72     gdb.execute('set $r13 = %s' % old_r13)
  73     gdb.execute('set $r14 = %s' % old_r14)
  74     gdb.execute('set $r15 = %s' % old_r15)
  75     gdb.execute('set $rip = %s' % old_rip)
  76
  77
  78 class CoroutineCommand(gdb.Command):
  79     '''Display coroutine backtrace'''
  80     def __init__(self):
  81         gdb.Command.__init__(self, 'qemu coroutine', gdb.COMMAND_DATA,
  82                              gdb.COMPLETE_NONE)
  83
  84     def invoke(self, arg, from_tty):
  85         argv = gdb.string_to_argv(arg)
  86         if len(argv) != 1:
  87             gdb.write('usage: qemu coroutine <coroutine-pointer>\n')
  88             return
  89
  90         coroutine_pointer = gdb.parse_and_eval(argv[0]).cast(gdb.lookup_type('CoroutineUContext').pointer())
  91         bt_jmpbuf(coroutine_pointer['env']['__jmpbuf'])