## gdb helper commands and functions for Linux kernel debugging##  kernel log buffer dump## Copyright (c) Siemens AG, 2011, 2012## Authors:#  Jan Kiszka <jan.kiszka@siemens.com>## This work is licensed under the terms of the GNU GPL version 2.# import gdbimport sys from linux import utils  class LxDmesg(gdb.Command):    """Print Linux kernel log buffer."""     def __init__(self):        super(LxDmesg, self).__init__("lx-dmesg", gdb.COMMAND_DATA)     def invoke(self, arg, from_tty):        log_buf_addr = int(str(gdb.parse_and_eval(            "(void *)'printk.c'::log_buf")).split()[0], 16)        log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx"))        log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx"))        log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len"))         inf = gdb.inferiors()[0]        start = log_buf_addr + log_first_idx        if log_first_idx < log_next_idx:            log_buf_2nd_half = -1            length = log_next_idx - log_first_idx            log_buf = utils.read_memoryview(inf, start, length).tobytes()        else:            log_buf_2nd_half = log_buf_len - log_first_idx            a = utils.read_memoryview(inf, start, log_buf_2nd_half)            b = utils.read_memoryview(inf, log_buf_addr, log_next_idx)            log_buf = a.tobytes() + b.tobytes()         pos = 0        while pos < log_buf.__len__():            length = utils.read_u16(log_buf[pos + 8:pos + 10])            if length == 0:                if log_buf_2nd_half == -1:                    gdb.write("Corrupted log buffer!\n")                    break                pos = log_buf_2nd_half                continue             text_len = utils.read_u16(log_buf[pos + 10:pos + 12])            text = log_buf[pos + 16:pos + 16 + text_len].decode(                encoding='utf8', errors='replace')            time_stamp = utils.read_u64(log_buf[pos:pos + 8])             for line in text.splitlines():                msg = u"[{time:12.6f}] {line}\n".format(                    time=time_stamp / 1000000000.0,                    line=line)                # With python2 gdb.write will attempt to convert unicode to                # ascii and might fail so pass an utf8-encoded str instead.                if sys.hexversion < 0x03000000:                    msg = msg.encode(encoding='utf8', errors='replace')                gdb.write(msg)             pos += length  LxDmesg()