From 8512f116fc5de214fd73cacf474b3109323a5754 Mon Sep 17 00:00:00 2001
From: Douglas RAILLARD <douglas.raillard@arm.com>
Date: Thu, 14 Mar 2019 15:32:31 +0000
Subject: [PATCH] trace: Add DmesgCollector
Allows collecting dmesg output and parses it for easy filtering.
---
devlib/trace/dmesg.py | 187 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 187 insertions(+)
create mode 100644 devlib/trace/dmesg.py
diff --git a/devlib/trace/dmesg.py b/devlib/trace/dmesg.py
new file mode 100644
index 0000000..a9f80c7
--- /dev/null
+++ b/devlib/trace/dmesg.py
@@ -0,0 +1,187 @@
+# Copyright 2019 ARM Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+from __future__ import division
+import re
+from itertools import takewhile
+from datetime import timedelta
+
+from devlib.trace import TraceCollector
+
+
+class KernelLogEntry(object):
+ """
+ Entry of the kernel ring buffer.
+
+ :param facility: facility the entry comes from
+ :type facility: str
+
+ :param level: log level
+ :type level: str
+
+ :param timestamp: Timestamp of the entry
+ :type timestamp: datetime.timedelta
+
+ :param msg: Content of the entry
+ :type msg: str
+ """
+
+ _TIMESTAMP_MSG_REGEX = re.compile(r'\[(.*?)\] (.*)')
+
+ def __init__(self, facility, level, timestamp, msg):
+ self.facility = facility
+ self.level = level
+ self.timestamp = timestamp
+ self.msg = msg
+
+ @classmethod
+ def from_str(cls, line):
+ """
+ Parses a "dmesg --decode" output line, formatted as following:
+ kern :err : [3618282.310743] nouveau 0000:01:00.0: systemd-logind[988]: nv50cal_space: -16
+
+ Or the more basic output:
+ [3618282.310743] nouveau 0000:01:00.0: systemd-logind[988]: nv50cal_space: -16
+
+ """
+
+ def parse_timestamp_msg(line):
+ match = cls._TIMESTAMP_MSG_REGEX.match(line.strip())
+ if not match:
+ raise ValueError('dmesg entry format not recognized: {}'.format(line))
+ timestamp, msg = match.groups()
+ return timestamp, msg
+
+ # If we can parse the timestamp directly, that is a basic line
+ try:
+ timestamp, msg = parse_timestamp_msg(line)
+ except ValueError:
+ facility, level, remainder = line.split(':', 2)
+ timestamp, msg = parse_timestamp_msg(remainder)
+ facility = facility.strip()
+ level = level.strip()
+ else:
+ facility = None
+ level = None
+
+ return cls(
+ facility=facility,
+ level=level,
+ timestamp=timedelta(seconds=float(timestamp.strip())),
+ msg=msg.strip(),
+ )
+
+ def __str__(self):
+ if self.facility and self.level:
+ prefix = '{facility}:{level}:'.format(
+ facility=self.facility,
+ level=self.level,
+ )
+ else:
+ prefix = ''
+
+ return '{prefix}[{timestamp}] {msg}'.format(
+ timestamp=self.timestamp.total_seconds(),
+ msg=self.msg,
+ prefix=prefix,
+ )
+
+
+class DmesgCollector(TraceCollector):
+ """
+ Dmesg output collector.
+
+ :param level: Minimum log level to enable. All levels that are more
+ critical will be collected as well.
+ :type level: str
+
+ :param facility: Facility to record, see dmesg --help for the list.
+ :type level: str
+
+ .. warning:: If BusyBox dmesg is used, facility and level will be ignored,
+ and the parsed entries will also lack that information.
+ """
+
+ # taken from "dmesg --help"
+ # This list needs to be ordered by priority
+ LOG_LEVELS = [
+ "emerg", # system is unusable
+ "alert", # action must be taken immediately
+ "crit", # critical conditions
+ "err", # error conditions
+ "warn", # warning conditions
+ "notice", # normal but significant condition
+ "info", # informational
+ "debug", # debug-level messages
+ ]
+
+ def __init__(self, target, level=LOG_LEVELS[-1], facility='kern'):
+ super(DmesgCollector, self).__init__(target)
+
+ if level not in self.LOG_LEVELS:
+ raise ValueError('level needs to be one of: {}'.format(
+ ', '.join(self.LOG_LEVELS)
+ ))
+ self.level = level
+
+ # Check if dmesg is the BusyBox one, or the one from util-linux.
+ # Note: BusyBox dmesg does not support -h, but will still print the
+ # help with an exit code of 1
+ self.basic_dmesg = 'BusyBox' in self.target.execute('dmesg -h',
+ check_exit_code=False)
+ self.reset()
+
+ @property
+ def entries(self):
+ return self._parse_entries(self.dmesg_out)
+
+ @classmethod
+ def _parse_entries(cls, dmesg_out):
+ if not dmesg_out:
+ return []
+ else:
+ return [
+ KernelLogEntry.from_str(line)
+ for line in dmesg_out.splitlines()
+ ]
+
+ def reset(self):
+ self.dmesg_out = None
+
+ def start(self):
+ self.reset()
+ # Empty the dmesg ring buffer
+ self.target.execute('dmesg -c')
+
+ def stop(self):
+ levels_list = list(takewhile(
+ lambda level: level != self.level,
+ self.LOG_LEVELS
+ ))
+ levels_list.append(self.level)
+ if self.basic_dmesg:
+ cmd = 'dmesg'
+ else:
+ cmd = 'dmesg --facility={facility} --force-prefix --decode --level={levels}'.format(
+ levels=','.join(levels_list),
+ facility=self.facility,
+ )
+
+ self.dmesg_out = self.target.execute(cmd)
+
+ def get_trace(self, outfile):
+ with open(outfile, 'wt') as f:
+ f.write(self.dmesg_out + '\n')
+