1#
2# gdb helper commands and functions for Linux kernel debugging
3#
4#  kernel log buffer dump
5#
6# Copyright (c) Siemens AG, 2011, 2012
7#
8# Authors:
9#  Jan Kiszka <jan.kiszka@siemens.com>
10#
11# This work is licensed under the terms of the GNU GPL version 2.
12#
13
14import gdb
15
16from linux import utils
17
18
19class LxDmesg(gdb.Command):
20    """Print Linux kernel log buffer."""
21
22    def __init__(self):
23        super(LxDmesg, self).__init__("lx-dmesg", gdb.COMMAND_DATA)
24
25    def invoke(self, arg, from_tty):
26        log_buf_addr = int(str(gdb.parse_and_eval("log_buf")).split()[0], 16)
27        log_first_idx = int(gdb.parse_and_eval("log_first_idx"))
28        log_next_idx = int(gdb.parse_and_eval("log_next_idx"))
29        log_buf_len = int(gdb.parse_and_eval("log_buf_len"))
30
31        inf = gdb.inferiors()[0]
32        start = log_buf_addr + log_first_idx
33        if log_first_idx < log_next_idx:
34            log_buf_2nd_half = -1
35            length = log_next_idx - log_first_idx
36            log_buf = inf.read_memory(start, length)
37        else:
38            log_buf_2nd_half = log_buf_len - log_first_idx
39            log_buf = inf.read_memory(start, log_buf_2nd_half) + \
40                inf.read_memory(log_buf_addr, log_next_idx)
41
42        pos = 0
43        while pos < log_buf.__len__():
44            length = utils.read_u16(log_buf[pos + 8:pos + 10])
45            if length == 0:
46                if log_buf_2nd_half == -1:
47                    gdb.write("Corrupted log buffer!\n")
48                    break
49                pos = log_buf_2nd_half
50                continue
51
52            text_len = utils.read_u16(log_buf[pos + 10:pos + 12])
53            text = log_buf[pos + 16:pos + 16 + text_len]
54            time_stamp = utils.read_u64(log_buf[pos:pos + 8])
55
56            for line in memoryview(text).tobytes().splitlines():
57                gdb.write("[{time:12.6f}] {line}\n".format(
58                    time=time_stamp / 1000000000.0,
59                    line=line))
60
61            pos += length
62
63
64LxDmesg()
65