The patch titled
Subject: scripts/gdb: fix lx-dmesg when CONFIG_PRINTK_CALLER is set
has been added to the -mm tree. Its filename is
scripts-gdb-fix-lx-dmesg-when-config_printk_caller-is-set.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/scripts-gdb-fix-lx-dmesg-when-config_printk_caller-is-set.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/scripts-gdb-fix-lx-dmesg-when-config_printk_caller-is-set.patch
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------------------------------------------------------
From: Joel Colledge <joel.colledge@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: Joel Colledge <joel.colledge@xxxxxxxxxx>
Reviewed-by: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
Cc: Kieran Bingham <kbingham@xxxxxxxxxx>
Cc: Leonard Crestez <leonard.crestez@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
scripts/gdb/linux/dmesg.py | 16 ++++++++++++----
scripts/gdb/linux/utils.py | 25 +++++++++++++------------
2 files changed, 25 insertions(+), 16 deletions(-)
--- a/scripts/gdb/linux/dmesg.py~scripts-gdb-fix-lx-dmesg-when-config_printk_caller-is-set
+++ a/scripts/gdb/linux/dmesg.py
@@ -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(
--- a/scripts/gdb/linux/utils.py~scripts-gdb-fix-lx-dmesg-when-config_printk_caller-is-set
+++ a/scripts/gdb/linux/utils.py
@@ -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
_
Patches currently in -mm which might be from joel.colledge@xxxxxxxxxx are
scripts-gdb-fix-lx-dmesg-when-config_printk_caller-is-set.patch
