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Subject[PATCH v6 11/21] scripts/gdb: Add lx-dmesg command
Date
This pokes into the log buffer of the debugged kernel, dumping it to the
gdb console. Helping in case the target should or can no longer execute
dmesg itself.

CC: Kay Sievers <kay@vrfy.org>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
scripts/gdb/linux/dmesg.py | 64 ++++++++++++++++++++++++++++++++++++++++++++++
scripts/gdb/vmlinux-gdb.py | 1 +
2 files changed, 65 insertions(+)
create mode 100644 scripts/gdb/linux/dmesg.py

diff --git a/scripts/gdb/linux/dmesg.py b/scripts/gdb/linux/dmesg.py
new file mode 100644
index 0000000..7650f24
--- /dev/null
+++ b/scripts/gdb/linux/dmesg.py
@@ -0,0 +1,64 @@
+#
+# 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 string
+
+from linux import utils
+
+
+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):
+ log_buf_addr = int(str(gdb.parse_and_eval("log_buf")).split()[0], 16)
+ log_first_idx = int(gdb.parse_and_eval("log_first_idx"))
+ log_next_idx = int(gdb.parse_and_eval("log_next_idx"))
+ log_buf_len = int(gdb.parse_and_eval("log_buf_len"))
+
+ inf = gdb.inferiors()[0]
+ start = log_buf_addr + log_first_idx
+ if log_first_idx < log_next_idx:
+ log_buf_2nd_half = -1
+ length = log_next_idx - log_first_idx
+ log_buf = inf.read_memory(start, length)
+ else:
+ log_buf_2nd_half = log_buf_len - log_first_idx
+ log_buf = inf.read_memory(start, log_buf_2nd_half) + \
+ inf.read_memory(log_buf_addr, log_next_idx)
+
+ pos = 0
+ while pos < log_buf.__len__():
+ length = utils.read_u16(log_buf[pos + 8:pos + 10])
+ if length == 0:
+ if log_buf_2nd_half == -1:
+ gdb.write("Corrupted log buffer!\n")
+ break
+ pos = log_buf_2nd_half
+ continue
+
+ text_len = utils.read_u16(log_buf[pos + 10:pos + 12])
+ time_stamp = utils.read_u64(log_buf[pos:pos + 8])
+
+ for line in log_buf[pos + 16:pos + 16 + text_len].splitlines():
+ gdb.write("[{time:12.6f}] {line}\n".format(
+ time=time_stamp / 1000000000.0,
+ line=line))
+
+ pos += length
+
+
+LxDmesg()
diff --git a/scripts/gdb/vmlinux-gdb.py b/scripts/gdb/vmlinux-gdb.py
index cf2e716..fa66d23 100644
--- a/scripts/gdb/vmlinux-gdb.py
+++ b/scripts/gdb/vmlinux-gdb.py
@@ -25,3 +25,4 @@ else:
import linux.utils
import linux.symbols
import linux.modules
+ import linux.dmesg
--
1.8.1.1.298.ge7eed54


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