scripts/gdb: add lx-dmesg command

#

# 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 gdb

import string

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("log_buf")).split()[0], 16)

        log_first_idx = int(gdb.parse_and_eval("log_first_idx"))

        log_next_idx = int(gdb.parse_and_eval("log_next_idx"))

        log_buf_len = int(gdb.parse_and_eval("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 = inf.read_memory(start, length)

        else:

            log_buf_2nd_half = log_buf_len - log_first_idx

            log_buf = inf.read_memory(start, log_buf_2nd_half) + \

                inf.read_memory(log_buf_addr, log_next_idx)

        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])

            time_stamp = utils.read_u64(log_buf[pos:pos + 8])

            for line in log_buf[pos + 16:pos + 16 + text_len].splitlines():

                gdb.write("[{time:12.6f}] {line}\n".format(

                    time=time_stamp / 1000000000.0,

                    line=line))

            pos += length

LxDmesg()

    import linux.utils

    import linux.symbols

    import linux.modules

    import linux.dmesg