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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153## 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 gdbimport sys
from linux import utils
printk_info_type = utils.CachedType("struct printk_info")prb_data_blk_lpos_type = utils.CachedType("struct prb_data_blk_lpos")prb_desc_type = utils.CachedType("struct prb_desc")prb_desc_ring_type = utils.CachedType("struct prb_desc_ring")prb_data_ring_type = utils.CachedType("struct prb_data_ring")printk_ringbuffer_type = utils.CachedType("struct printk_ringbuffer")
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): inf = gdb.inferiors()[0]
# read in prb structure prb_addr = int(str(gdb.parse_and_eval("(void *)'printk.c'::prb")).split()[0], 16) sz = printk_ringbuffer_type.get_type().sizeof prb = utils.read_memoryview(inf, prb_addr, sz).tobytes()
# read in descriptor ring structure off = printk_ringbuffer_type.get_type()['desc_ring'].bitpos // 8 addr = prb_addr + off sz = prb_desc_ring_type.get_type().sizeof desc_ring = utils.read_memoryview(inf, addr, sz).tobytes()
# read in descriptor count, size, and address off = prb_desc_ring_type.get_type()['count_bits'].bitpos // 8 desc_ring_count = 1 << utils.read_u32(desc_ring, off) desc_sz = prb_desc_type.get_type().sizeof off = prb_desc_ring_type.get_type()['descs'].bitpos // 8 desc_addr = utils.read_ulong(desc_ring, off)
# read in info size and address info_sz = printk_info_type.get_type().sizeof off = prb_desc_ring_type.get_type()['infos'].bitpos // 8 info_addr = utils.read_ulong(desc_ring, off)
# read in text data ring structure off = printk_ringbuffer_type.get_type()['text_data_ring'].bitpos // 8 addr = prb_addr + off sz = prb_data_ring_type.get_type().sizeof text_data_ring = utils.read_memoryview(inf, addr, sz).tobytes()
# read in text data size and address off = prb_data_ring_type.get_type()['size_bits'].bitpos // 8 text_data_sz = 1 << utils.read_u32(text_data_ring, off) off = prb_data_ring_type.get_type()['data'].bitpos // 8 text_data_addr = utils.read_ulong(text_data_ring, off)
sv_off = prb_desc_type.get_type()['state_var'].bitpos // 8
off = prb_desc_type.get_type()['text_blk_lpos'].bitpos // 8 begin_off = off + (prb_data_blk_lpos_type.get_type()['begin'].bitpos // 8) next_off = off + (prb_data_blk_lpos_type.get_type()['next'].bitpos // 8)
ts_off = printk_info_type.get_type()['ts_nsec'].bitpos // 8 len_off = printk_info_type.get_type()['text_len'].bitpos // 8
# definitions from kernel/printk/printk_ringbuffer.h desc_committed = 1 desc_finalized = 2 desc_sv_bits = utils.get_long_type().sizeof * 8 desc_flags_shift = desc_sv_bits - 2 desc_flags_mask = 3 << desc_flags_shift desc_id_mask = ~desc_flags_mask
# read in tail and head descriptor ids off = prb_desc_ring_type.get_type()['tail_id'].bitpos // 8 tail_id = utils.read_atomic_long(desc_ring, off) off = prb_desc_ring_type.get_type()['head_id'].bitpos // 8 head_id = utils.read_atomic_long(desc_ring, off)
did = tail_id while True: ind = did % desc_ring_count desc_off = desc_sz * ind info_off = info_sz * ind
desc = utils.read_memoryview(inf, desc_addr + desc_off, desc_sz).tobytes()
# skip non-committed record state = 3 & (utils.read_atomic_long(desc, sv_off) >> desc_flags_shift) if state != desc_committed and state != desc_finalized: if did == head_id: break did = (did + 1) & desc_id_mask continue
begin = utils.read_ulong(desc, begin_off) % text_data_sz end = utils.read_ulong(desc, next_off) % text_data_sz
info = utils.read_memoryview(inf, info_addr + info_off, info_sz).tobytes()
# handle data-less record if begin & 1 == 1: text = "" else: # handle wrapping data block if begin > end: begin = 0
# skip over descriptor id text_start = begin + utils.get_long_type().sizeof
text_len = utils.read_u16(info, len_off)
# handle truncated message if end - text_start < text_len: text_len = end - text_start
text_data = utils.read_memoryview(inf, text_data_addr + text_start, text_len).tobytes() text = text_data[0:text_len].decode(encoding='utf8', errors='replace')
time_stamp = utils.read_u64(info, ts_off)
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)
if did == head_id: break did = (did + 1) & desc_id_mask
LxDmesg()