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10dcb06d40
Rather than deriving the state by evaluating bits within the flags area of the state variable, assign the states explicit values and set those values in the flags area. Introduce macros to make it simple to read and write state values for the state variable. Although the functionality is preserved, the binary representation for the states is changed. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-5-john.ogness@linutronix.de
147 lines
5.5 KiB
Python
147 lines
5.5 KiB
Python
#
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# gdb helper commands and functions for Linux kernel debugging
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#
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# kernel log buffer dump
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#
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# Copyright (c) Siemens AG, 2011, 2012
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#
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# Authors:
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# Jan Kiszka <jan.kiszka@siemens.com>
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#
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# This work is licensed under the terms of the GNU GPL version 2.
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#
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import gdb
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import sys
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from linux import utils
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printk_info_type = utils.CachedType("struct printk_info")
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prb_data_blk_lpos_type = utils.CachedType("struct prb_data_blk_lpos")
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prb_desc_type = utils.CachedType("struct prb_desc")
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prb_desc_ring_type = utils.CachedType("struct prb_desc_ring")
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prb_data_ring_type = utils.CachedType("struct prb_data_ring")
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printk_ringbuffer_type = utils.CachedType("struct printk_ringbuffer")
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atomic_long_type = utils.CachedType("atomic_long_t")
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class LxDmesg(gdb.Command):
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"""Print Linux kernel log buffer."""
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def __init__(self):
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super(LxDmesg, self).__init__("lx-dmesg", gdb.COMMAND_DATA)
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def invoke(self, arg, from_tty):
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inf = gdb.inferiors()[0]
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# read in prb structure
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prb_addr = int(str(gdb.parse_and_eval("(void *)'printk.c'::prb")).split()[0], 16)
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sz = printk_ringbuffer_type.get_type().sizeof
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prb = utils.read_memoryview(inf, prb_addr, sz).tobytes()
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# read in descriptor ring structure
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off = printk_ringbuffer_type.get_type()['desc_ring'].bitpos // 8
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addr = prb_addr + off
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sz = prb_desc_ring_type.get_type().sizeof
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desc_ring = utils.read_memoryview(inf, addr, sz).tobytes()
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# read in descriptor array
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off = prb_desc_ring_type.get_type()['count_bits'].bitpos // 8
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desc_ring_count = 1 << utils.read_u32(desc_ring, off)
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desc_sz = prb_desc_type.get_type().sizeof
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off = prb_desc_ring_type.get_type()['descs'].bitpos // 8
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addr = utils.read_ulong(desc_ring, off)
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descs = utils.read_memoryview(inf, addr, desc_sz * desc_ring_count).tobytes()
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# read in text data ring structure
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off = printk_ringbuffer_type.get_type()['text_data_ring'].bitpos // 8
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addr = prb_addr + off
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sz = prb_data_ring_type.get_type().sizeof
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text_data_ring = utils.read_memoryview(inf, addr, sz).tobytes()
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# read in text data
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off = prb_data_ring_type.get_type()['size_bits'].bitpos // 8
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text_data_sz = 1 << utils.read_u32(text_data_ring, off)
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off = prb_data_ring_type.get_type()['data'].bitpos // 8
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addr = utils.read_ulong(text_data_ring, off)
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text_data = utils.read_memoryview(inf, addr, text_data_sz).tobytes()
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counter_off = atomic_long_type.get_type()['counter'].bitpos // 8
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sv_off = prb_desc_type.get_type()['state_var'].bitpos // 8
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off = prb_desc_type.get_type()['text_blk_lpos'].bitpos // 8
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begin_off = off + (prb_data_blk_lpos_type.get_type()['begin'].bitpos // 8)
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next_off = off + (prb_data_blk_lpos_type.get_type()['next'].bitpos // 8)
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off = prb_desc_type.get_type()['info'].bitpos // 8
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ts_off = off + printk_info_type.get_type()['ts_nsec'].bitpos // 8
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len_off = off + printk_info_type.get_type()['text_len'].bitpos // 8
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# definitions from kernel/printk/printk_ringbuffer.h
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desc_committed = 1
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desc_sv_bits = utils.get_long_type().sizeof * 8
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desc_flags_shift = desc_sv_bits - 2
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desc_flags_mask = 3 << desc_flags_shift
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desc_id_mask = ~desc_flags_mask
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# read in tail and head descriptor ids
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off = prb_desc_ring_type.get_type()['tail_id'].bitpos // 8
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tail_id = utils.read_u64(desc_ring, off + counter_off)
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off = prb_desc_ring_type.get_type()['head_id'].bitpos // 8
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head_id = utils.read_u64(desc_ring, off + counter_off)
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did = tail_id
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while True:
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ind = did % desc_ring_count
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desc_off = desc_sz * ind
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# skip non-committed record
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state = 3 & (utils.read_u64(descs, desc_off + sv_off +
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counter_off) >> desc_flags_shift)
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if state != desc_committed:
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if did == head_id:
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break
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did = (did + 1) & desc_id_mask
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continue
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begin = utils.read_ulong(descs, desc_off + begin_off) % text_data_sz
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end = utils.read_ulong(descs, desc_off + next_off) % text_data_sz
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# handle data-less record
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if begin & 1 == 1:
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text = ""
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else:
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# handle wrapping data block
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if begin > end:
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begin = 0
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# skip over descriptor id
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text_start = begin + utils.get_long_type().sizeof
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text_len = utils.read_u16(descs, desc_off + len_off)
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# handle truncated message
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if end - text_start < text_len:
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text_len = end - text_start
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text = text_data[text_start:text_start + text_len].decode(
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encoding='utf8', errors='replace')
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time_stamp = utils.read_u64(descs, desc_off + ts_off)
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for line in text.splitlines():
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msg = u"[{time:12.6f}] {line}\n".format(
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time=time_stamp / 1000000000.0,
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line=line)
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# With python2 gdb.write will attempt to convert unicode to
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# ascii and might fail so pass an utf8-encoded str instead.
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if sys.hexversion < 0x03000000:
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msg = msg.encode(encoding='utf8', errors='replace')
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gdb.write(msg)
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if did == head_id:
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break
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did = (did + 1) & desc_id_mask
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LxDmesg()
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