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( 27 "'printk.c'::log_buf")).split()[0], 16) 28 log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx")) 29 log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx")) 30 log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len")) 31 32 inf = gdb.inferiors()[0] 33 start = log_buf_addr + log_first_idx 34 if log_first_idx < log_next_idx: 35 log_buf_2nd_half = -1 36 length = log_next_idx - log_first_idx 37 log_buf = utils.read_memoryview(inf, start, length).tobytes() 38 else: 39 log_buf_2nd_half = log_buf_len - log_first_idx 40 a = utils.read_memoryview(inf, start, log_buf_2nd_half) 41 b = utils.read_memoryview(inf, log_buf_addr, log_next_idx) 42 log_buf = a.tobytes() + b.tobytes() 43 44 pos = 0 45 while pos < log_buf.__len__(): 46 length = utils.read_u16(log_buf[pos + 8:pos + 10]) 47 if length == 0: 48 if log_buf_2nd_half == -1: 49 gdb.write("Corrupted log buffer!\n") 50 break 51 pos = log_buf_2nd_half 52 continue 53 54 text_len = utils.read_u16(log_buf[pos + 10:pos + 12]) 55 text = log_buf[pos + 16:pos + 16 + text_len].decode() 56 time_stamp = utils.read_u64(log_buf[pos:pos + 8]) 57 58 for line in text.splitlines(): 59 gdb.write("[{time:12.6f}] {line}\n".format( 60 time=time_stamp / 1000000000.0, 61 line=line)) 62 63 pos += length 64 65 66LxDmesg() 67