diff options
Diffstat (limited to 'scripts/gdb/linux/dmesg.py')
| -rw-r--r-- | scripts/gdb/linux/dmesg.py | 152 |
1 files changed, 152 insertions, 0 deletions
diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py new file mode 100644 index 000000000..c771831eb --- /dev/null +++ b/scripts/gdb/linux/dmesg.py @@ -0,0 +1,152 @@ +# +# 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_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() |