qemu

FORK: QEMU emulator
git clone https://git.neptards.moe/neptards/qemu.git
Log | Files | Refs | Submodules | LICENSE

coroutine.py (4464B)

      1 #
      2 # GDB debugging support
      3 #
      4 # Copyright 2012 Red Hat, Inc. and/or its affiliates
      5 #
      6 # Authors:
      7 #  Avi Kivity <avi@redhat.com>
      8 #
      9 # This work is licensed under the terms of the GNU GPL, version 2
     10 # or later.  See the COPYING file in the top-level directory.
     11 
     12 import gdb
     13 
     14 VOID_PTR = gdb.lookup_type('void').pointer()
     15 
     16 def get_fs_base():
     17     '''Fetch %fs base value using arch_prctl(ARCH_GET_FS).  This is
     18        pthread_self().'''
     19     # %rsp - 120 is scratch space according to the SystemV ABI
     20     old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
     21     gdb.execute('call (int)arch_prctl(0x1003, $rsp - 120)', False, True)
     22     fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)')
     23     gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True)
     24     return fs_base
     25 
     26 def pthread_self():
     27     '''Fetch pthread_self() from the glibc start_thread function.'''
     28     f = gdb.newest_frame()
     29     while f.name() != 'start_thread':
     30         f = f.older()
     31         if f is None:
     32             return get_fs_base()
     33 
     34     try:
     35         return f.read_var("arg")
     36     except ValueError:
     37         return get_fs_base()
     38 
     39 def get_glibc_pointer_guard():
     40     '''Fetch glibc pointer guard value'''
     41     fs_base = pthread_self()
     42     return gdb.parse_and_eval('*(uint64_t*)((uint64_t)%s + 0x30)' % fs_base)
     43 
     44 def glibc_ptr_demangle(val, pointer_guard):
     45     '''Undo effect of glibc's PTR_MANGLE()'''
     46     return gdb.parse_and_eval('(((uint64_t)%s >> 0x11) | ((uint64_t)%s << (64 - 0x11))) ^ (uint64_t)%s' % (val, val, pointer_guard))
     47 
     48 def get_jmpbuf_regs(jmpbuf):
     49     JB_RBX  = 0
     50     JB_RBP  = 1
     51     JB_R12  = 2
     52     JB_R13  = 3
     53     JB_R14  = 4
     54     JB_R15  = 5
     55     JB_RSP  = 6
     56     JB_PC   = 7
     57 
     58     pointer_guard = get_glibc_pointer_guard()
     59     return {'rbx': jmpbuf[JB_RBX],
     60         'rbp': glibc_ptr_demangle(jmpbuf[JB_RBP], pointer_guard),
     61         'rsp': glibc_ptr_demangle(jmpbuf[JB_RSP], pointer_guard),
     62         'r12': jmpbuf[JB_R12],
     63         'r13': jmpbuf[JB_R13],
     64         'r14': jmpbuf[JB_R14],
     65         'r15': jmpbuf[JB_R15],
     66         'rip': glibc_ptr_demangle(jmpbuf[JB_PC], pointer_guard) }
     67 
     68 def bt_jmpbuf(jmpbuf):
     69     '''Backtrace a jmpbuf'''
     70     regs = get_jmpbuf_regs(jmpbuf)
     71     old = dict()
     72 
     73     # remember current stack frame and select the topmost
     74     # so that register modifications don't wreck it
     75     selected_frame = gdb.selected_frame()
     76     gdb.newest_frame().select()
     77 
     78     for i in regs:
     79         old[i] = gdb.parse_and_eval('(uint64_t)$%s' % i)
     80 
     81     for i in regs:
     82         gdb.execute('set $%s = %s' % (i, regs[i]))
     83 
     84     gdb.execute('bt')
     85 
     86     for i in regs:
     87         gdb.execute('set $%s = %s' % (i, old[i]))
     88 
     89     selected_frame.select()
     90 
     91 def co_cast(co):
     92     return co.cast(gdb.lookup_type('CoroutineUContext').pointer())
     93 
     94 def coroutine_to_jmpbuf(co):
     95     coroutine_pointer = co_cast(co)
     96     return coroutine_pointer['env']['__jmpbuf']
     97 
     98 
     99 class CoroutineCommand(gdb.Command):
    100     '''Display coroutine backtrace'''
    101     def __init__(self):
    102         gdb.Command.__init__(self, 'qemu coroutine', gdb.COMMAND_DATA,
    103                              gdb.COMPLETE_NONE)
    104 
    105     def invoke(self, arg, from_tty):
    106         argv = gdb.string_to_argv(arg)
    107         if len(argv) != 1:
    108             gdb.write('usage: qemu coroutine <coroutine-pointer>\n')
    109             return
    110 
    111         bt_jmpbuf(coroutine_to_jmpbuf(gdb.parse_and_eval(argv[0])))
    112 
    113 class CoroutineBt(gdb.Command):
    114     '''Display backtrace including coroutine switches'''
    115     def __init__(self):
    116         gdb.Command.__init__(self, 'qemu bt', gdb.COMMAND_STACK,
    117                              gdb.COMPLETE_NONE)
    118 
    119     def invoke(self, arg, from_tty):
    120 
    121         gdb.execute("bt")
    122 
    123         if gdb.parse_and_eval("qemu_in_coroutine()") == False:
    124             return
    125 
    126         co_ptr = gdb.parse_and_eval("qemu_coroutine_self()")
    127 
    128         while True:
    129             co = co_cast(co_ptr)
    130             co_ptr = co["base"]["caller"]
    131             if co_ptr == 0:
    132                 break
    133             gdb.write("Coroutine at " + str(co_ptr) + ":\n")
    134             bt_jmpbuf(coroutine_to_jmpbuf(co_ptr))
    135 
    136 class CoroutineSPFunction(gdb.Function):
    137     def __init__(self):
    138         gdb.Function.__init__(self, 'qemu_coroutine_sp')
    139 
    140     def invoke(self, addr):
    141         return get_jmpbuf_regs(coroutine_to_jmpbuf(addr))['rsp'].cast(VOID_PTR)
    142 
    143 class CoroutinePCFunction(gdb.Function):
    144     def __init__(self):
    145         gdb.Function.__init__(self, 'qemu_coroutine_pc')
    146 
    147     def invoke(self, addr):
    148         return get_jmpbuf_regs(coroutine_to_jmpbuf(addr))['rip'].cast(VOID_PTR)