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#
# 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 sys
from linux import utils
printk_log_type = utils.CachedType("struct printk_log")
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()
length_offset = printk_log_type.get_type()['len'].bitpos // 8
text_len_offset = printk_log_type.get_type()['text_len'].bitpos // 8
time_stamp_offset = printk_log_type.get_type()['ts_nsec'].bitpos // 8
text_offset = printk_log_type.get_type().sizeof
pos = 0
while pos < log_buf.__len__():
length = utils.read_u16(log_buf, pos + length_offset)
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 + text_len_offset)
text_start = pos + text_offset
text = log_buf[text_start:text_start + text_len].decode(
encoding='utf8', errors='replace')
time_stamp = utils.read_u64(log_buf, pos + time_stamp_offset)
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()
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