cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

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
     12import gdb
     13
     14VOID_PTR = gdb.lookup_type('void').pointer()
     15
     16def 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
     26def 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
     39def 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
     44def 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
     48def 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
     68def 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
     91def co_cast(co):
     92    return co.cast(gdb.lookup_type('CoroutineUContext').pointer())
     93
     94def coroutine_to_jmpbuf(co):
     95    coroutine_pointer = co_cast(co)
     96    return coroutine_pointer['env']['__jmpbuf']
     97
     98
     99class 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
    113class 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
    136class 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
    143class 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)