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 19 20class LxDmesg(gdb.Command): 21 """Print Linux kernel log buffer.""" 22 23 def __init__(self): 24 super(LxDmesg, self).__init__("lx-dmesg", gdb.COMMAND_DATA) 25 26 def invoke(self, arg, from_tty): 27 log_buf_addr = int(str(gdb.parse_and_eval( 28 "(void *)'printk.c'::log_buf")).split()[0], 16) 29 log_first_idx = int(gdb.parse_and_eval("'printk.c'::log_first_idx")) 30 log_next_idx = int(gdb.parse_and_eval("'printk.c'::log_next_idx")) 31 log_buf_len = int(gdb.parse_and_eval("'printk.c'::log_buf_len")) 32 33 inf = gdb.inferiors()[0] 34 start = log_buf_addr + log_first_idx 35 if log_first_idx < log_next_idx: 36 log_buf_2nd_half = -1 37 length = log_next_idx - log_first_idx 38 log_buf = utils.read_memoryview(inf, start, length).tobytes() 39 else: 40 log_buf_2nd_half = log_buf_len - log_first_idx 41 a = utils.read_memoryview(inf, start, log_buf_2nd_half) 42 b = utils.read_memoryview(inf, log_buf_addr, log_next_idx) 43 log_buf = a.tobytes() + b.tobytes() 44 45 pos = 0 46 while pos < log_buf.__len__(): 47 length = utils.read_u16(log_buf[pos + 8:pos + 10]) 48 if length == 0: 49 if log_buf_2nd_half == -1: 50 gdb.write("Corrupted log buffer!\n") 51 break 52 pos = log_buf_2nd_half 53 continue 54 55 text_len = utils.read_u16(log_buf[pos + 10:pos + 12]) 56 text = log_buf[pos + 16:pos + 16 + text_len].decode( 57 encoding='utf8', errors='replace') 58 time_stamp = utils.read_u64(log_buf[pos:pos + 8]) 59 60 for line in text.splitlines(): 61 msg = u"[{time:12.6f}] {line}\n".format( 62 time=time_stamp / 1000000000.0, 63 line=line) 64 # With python2 gdb.write will attempt to convert unicode to 65 # ascii and might fail so pass an utf8-encoded str instead. 66 if sys.hexversion < 0x03000000: 67 msg = msg.encode(encoding='utf8', errors='replace') 68 gdb.write(msg) 69 70 pos += length 71 72 73LxDmesg() 74