| #!/usr/bin/python |
| |
| # GDB debugging support |
| # |
| # Copyright 2012 Red Hat, Inc. and/or its affiliates |
| # |
| # Authors: |
| # Avi Kivity <avi@redhat.com> |
| # |
| # This work is licensed under the terms of the GNU GPL, version 2. See |
| # the COPYING file in the top-level directory. |
| # |
| # Contributions after 2012-01-13 are licensed under the terms of the |
| # GNU GPL, version 2 or (at your option) any later version. |
| |
| import gdb |
| |
| VOID_PTR = gdb.lookup_type('void').pointer() |
| |
| def get_fs_base(): |
| '''Fetch %fs base value using arch_prctl(ARCH_GET_FS). This is |
| pthread_self().''' |
| # %rsp - 120 is scratch space according to the SystemV ABI |
| old = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)') |
| gdb.execute('call arch_prctl(0x1003, $rsp - 120)', False, True) |
| fs_base = gdb.parse_and_eval('*(uint64_t*)($rsp - 120)') |
| gdb.execute('set *(uint64_t*)($rsp - 120) = %s' % old, False, True) |
| return fs_base |
| |
| def pthread_self(): |
| '''Fetch pthread_self() from the glibc start_thread function.''' |
| f = gdb.newest_frame() |
| while f.name() != 'start_thread': |
| f = f.older() |
| if f is None: |
| return get_fs_base() |
| |
| try: |
| return f.read_var("arg") |
| except ValueError: |
| return get_fs_base() |
| |
| def get_glibc_pointer_guard(): |
| '''Fetch glibc pointer guard value''' |
| fs_base = pthread_self() |
| return gdb.parse_and_eval('*(uint64_t*)((uint64_t)%s + 0x30)' % fs_base) |
| |
| def glibc_ptr_demangle(val, pointer_guard): |
| '''Undo effect of glibc's PTR_MANGLE()''' |
| return gdb.parse_and_eval('(((uint64_t)%s >> 0x11) | ((uint64_t)%s << (64 - 0x11))) ^ (uint64_t)%s' % (val, val, pointer_guard)) |
| |
| def get_jmpbuf_regs(jmpbuf): |
| JB_RBX = 0 |
| JB_RBP = 1 |
| JB_R12 = 2 |
| JB_R13 = 3 |
| JB_R14 = 4 |
| JB_R15 = 5 |
| JB_RSP = 6 |
| JB_PC = 7 |
| |
| pointer_guard = get_glibc_pointer_guard() |
| return {'rbx': jmpbuf[JB_RBX], |
| 'rbp': glibc_ptr_demangle(jmpbuf[JB_RBP], pointer_guard), |
| 'rsp': glibc_ptr_demangle(jmpbuf[JB_RSP], pointer_guard), |
| 'r12': jmpbuf[JB_R12], |
| 'r13': jmpbuf[JB_R13], |
| 'r14': jmpbuf[JB_R14], |
| 'r15': jmpbuf[JB_R15], |
| 'rip': glibc_ptr_demangle(jmpbuf[JB_PC], pointer_guard) } |
| |
| def bt_jmpbuf(jmpbuf): |
| '''Backtrace a jmpbuf''' |
| regs = get_jmpbuf_regs(jmpbuf) |
| old = dict() |
| |
| for i in regs: |
| old[i] = gdb.parse_and_eval('(uint64_t)$%s' % i) |
| |
| for i in regs: |
| gdb.execute('set $%s = %s' % (i, regs[i])) |
| |
| gdb.execute('bt') |
| |
| for i in regs: |
| gdb.execute('set $%s = %s' % (i, old[i])) |
| |
| def coroutine_to_jmpbuf(co): |
| coroutine_pointer = co.cast(gdb.lookup_type('CoroutineUContext').pointer()) |
| return coroutine_pointer['env']['__jmpbuf'] |
| |
| |
| class CoroutineCommand(gdb.Command): |
| '''Display coroutine backtrace''' |
| def __init__(self): |
| gdb.Command.__init__(self, 'qemu coroutine', gdb.COMMAND_DATA, |
| gdb.COMPLETE_NONE) |
| |
| def invoke(self, arg, from_tty): |
| argv = gdb.string_to_argv(arg) |
| if len(argv) != 1: |
| gdb.write('usage: qemu coroutine <coroutine-pointer>\n') |
| return |
| |
| bt_jmpbuf(coroutine_to_jmpbuf(gdb.parse_and_eval(argv[0]))) |
| |
| class CoroutineSPFunction(gdb.Function): |
| def __init__(self): |
| gdb.Function.__init__(self, 'qemu_coroutine_sp') |
| |
| def invoke(self, addr): |
| return get_jmpbuf_regs(coroutine_to_jmpbuf(addr))['rsp'].cast(VOID_PTR) |
| |
| class CoroutinePCFunction(gdb.Function): |
| def __init__(self): |
| gdb.Function.__init__(self, 'qemu_coroutine_pc') |
| |
| def invoke(self, addr): |
| return get_jmpbuf_regs(coroutine_to_jmpbuf(addr))['rip'].cast(VOID_PTR) |