Commit ca210ba3 authored by Joel Colledge's avatar Joel Colledge Committed by Linus Torvalds
Browse files

scripts/gdb: fix lx-dmesg when CONFIG_PRINTK_CALLER is set 

When CONFIG_PRINTK_CALLER is set, struct printk_log contains an
additional member caller_id.  This affects the offset of the log text.
Account for this by using the type information from gdb to determine all
the offsets instead of using hardcoded values.

This fixes following error:

  (gdb) lx-dmesg
  Python Exception <class 'ValueError'> embedded null character:
  Error occurred in Python command: embedded null character

The read_u* utility functions now take an offset argument to make them
easier to use.

Link: http://lkml.kernel.org/r/20191011142500.2339-1-joel.colledge@linbit.com


Signed-off-by: default avatarJoel Colledge <joel.colledge@linbit.com>
Reviewed-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: Leonard Crestez <leonard.crestez@nxp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 96c804a6

scripts/gdb/linux/dmesg.py

+12 −4
Original line number Diff line number Diff line
@@ -16,6 +16,8 @@ import sys 


from linux import utils



printk_log_type = utils.CachedType("struct printk_log")





class LxDmesg(gdb.Command):

    """Print Linux kernel log buffer."""
@@ -42,9 +44,14 @@ class LxDmesg(gdb.Command): 
            b = utils.read_memoryview(inf, log_buf_addr, log_next_idx)

            log_buf = a.tobytes() + b.tobytes()



        length_offset = printk_log_type.get_type()['len'].bitpos // 8

        text_len_offset = printk_log_type.get_type()['text_len'].bitpos // 8

        time_stamp_offset = printk_log_type.get_type()['ts_nsec'].bitpos // 8

        text_offset = printk_log_type.get_type().sizeof



        pos = 0

        while pos < log_buf.__len__():

            length = utils.read_u16(log_buf[pos + 8:pos + 10])

            length = utils.read_u16(log_buf, pos + length_offset)

            if length == 0:

                if log_buf_2nd_half == -1:

                    gdb.write("Corrupted log buffer!\n")
@@ -52,10 +59,11 @@ class LxDmesg(gdb.Command): 
                pos = log_buf_2nd_half

                continue



            text_len = utils.read_u16(log_buf[pos + 10:pos + 12])

            text = log_buf[pos + 16:pos + 16 + text_len].decode(

            text_len = utils.read_u16(log_buf, pos + text_len_offset)

            text_start = pos + text_offset

            text = log_buf[text_start:text_start + text_len].decode(

                encoding='utf8', errors='replace')

            time_stamp = utils.read_u64(log_buf[pos:pos + 8])

            time_stamp = utils.read_u64(log_buf, pos + time_stamp_offset)



            for line in text.splitlines():

                msg = u"[{time:12.6f}] {line}\n".format(

scripts/gdb/linux/utils.py

+13 −12
Original line number Diff line number Diff line
@@ -92,15 +92,16 @@ def read_memoryview(inf, start, length): 
    return memoryview(inf.read_memory(start, length))





def read_u16(buffer):

def read_u16(buffer, offset):

    buffer_val = buffer[offset:offset + 2]

    value = [0, 0]



    if type(buffer[0]) is str:

        value[0] = ord(buffer[0])

        value[1] = ord(buffer[1])

    if type(buffer_val[0]) is str:

        value[0] = ord(buffer_val[0])

        value[1] = ord(buffer_val[1])

    else:

        value[0] = buffer[0]

        value[1] = buffer[1]

        value[0] = buffer_val[0]

        value[1] = buffer_val[1]



    if get_target_endianness() == LITTLE_ENDIAN:

        return value[0] + (value[1] << 8)
@@ -108,18 +109,18 @@ def read_u16(buffer): 
        return value[1] + (value[0] << 8)





def read_u32(buffer):

def read_u32(buffer, offset):

    if get_target_endianness() == LITTLE_ENDIAN:

        return read_u16(buffer[0:2]) + (read_u16(buffer[2:4]) << 16)

        return read_u16(buffer, offset) + (read_u16(buffer, offset + 2) << 16)

    else:

        return read_u16(buffer[2:4]) + (read_u16(buffer[0:2]) << 16)

        return read_u16(buffer, offset + 2) + (read_u16(buffer, offset) << 16)





def read_u64(buffer):

def read_u64(buffer, offset):

    if get_target_endianness() == LITTLE_ENDIAN:

        return read_u32(buffer[0:4]) + (read_u32(buffer[4:8]) << 32)

        return read_u32(buffer, offset) + (read_u32(buffer, offset + 4) << 32)

    else:

        return read_u32(buffer[4:8]) + (read_u32(buffer[0:4]) << 32)

        return read_u32(buffer, offset + 4) + (read_u32(buffer, offset) << 32)





target_arch = None

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