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 15import sys 16 17from linux import utils 18 19printk_log_type = utils.CachedType("struct printk_log") 20 21 22class LxDmesg(gdb.Command): 23 """Print Linux kernel log buffer.""" 24 25 def __init__(self): 26 super(LxDmesg, self).__init__("lx-dmesg", gdb.COMMAND_DATA) 27 28 def invoke(self, arg, from_tty): 29 log_buf_addr = int(str(gdb.parse_and_eval( 30 "(void *)'printk.c'::log_buf")).split()[0], 16) 31 log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx")) 32 log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx")) 33 log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len")) 34 35 inf = gdb.inferiors()[0] 36 start = log_buf_addr + log_first_idx 37 if log_first_idx < log_next_idx: 38 log_buf_2nd_half = -1 39 length = log_next_idx - log_first_idx 40 log_buf = utils.read_memoryview(inf, start, length).tobytes() 41 else: 42 log_buf_2nd_half = log_buf_len - log_first_idx 43 a = utils.read_memoryview(inf, start, log_buf_2nd_half) 44 b = utils.read_memoryview(inf, log_buf_addr, log_next_idx) 45 log_buf = a.tobytes() + b.tobytes() 46 47 length_offset = printk_log_type.get_type()['len'].bitpos // 8 48 text_len_offset = printk_log_type.get_type()['text_len'].bitpos // 8 49 time_stamp_offset = printk_log_type.get_type()['ts_nsec'].bitpos // 8 50 text_offset = printk_log_type.get_type().sizeof 51 52 pos = 0 53 while pos < log_buf.__len__(): 54 length = utils.read_u16(log_buf, pos + length_offset) 55 if length == 0: 56 if log_buf_2nd_half == -1: 57 gdb.write("Corrupted log buffer!\n") 58 break 59 pos = log_buf_2nd_half 60 continue 61 62 text_len = utils.read_u16(log_buf, pos + text_len_offset) 63 text_start = pos + text_offset 64 text = log_buf[text_start:text_start + text_len].decode( 65 encoding='utf8', errors='replace') 66 time_stamp = utils.read_u64(log_buf, pos + time_stamp_offset) 67 68 for line in text.splitlines(): 69 msg = u"[{time:12.6f}] {line}\n".format( 70 time=time_stamp / 1000000000.0, 71 line=line) 72 # With python2 gdb.write will attempt to convert unicode to 73 # ascii and might fail so pass an utf8-encoded str instead. 74 if sys.hexversion < 0x03000000: 75 msg = msg.encode(encoding='utf8', errors='replace') 76 gdb.write(msg) 77 78 pos += length 79 80 81LxDmesg() 82