cachepc-qemu

Fork of AMDESE/qemu with changes for cachepc side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-qemu
Log | Files | Refs | Submodules | LICENSE | sfeed.txt

kvm_flightrecorder (3642B)

      1#!/usr/bin/env python3
      2#
      3# KVM Flight Recorder - ring buffer tracing script
      4#
      5# Copyright (C) 2012 IBM Corp
      6#
      7# Author: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
      8#
      9# This script provides a command-line interface to kvm ftrace and is designed
     10# to be used as a flight recorder that is always running.  To start in-memory
     11# recording:
     12#
     13# sudo kvm_flightrecorder start 8192  # 8 MB per-cpu ring buffers
     14#
     15# The per-cpu ring buffer size can be given in KB as an optional argument to
     16# the 'start' subcommand.
     17#
     18# To stop the flight recorder:
     19#
     20# sudo kvm_flightrecorder stop
     21#
     22# To dump the contents of the flight recorder (this can be done when the
     23# recorder is stopped or while it is running):
     24#
     25# sudo kvm_flightrecorder dump >/path/to/dump.txt
     26#
     27# To observe the trace while it is running, use the 'tail' subcommand:
     28#
     29# sudo kvm_flightrecorder tail
     30#
     31# Note that the flight recorder may impact overall system performance by
     32# consuming CPU cycles.  No disk I/O is performed since the ring buffer holds a
     33# fixed-size in-memory trace.
     34
     35import sys
     36import os
     37
     38tracing_dir = '/sys/kernel/debug/tracing'
     39
     40def trace_path(*args):
     41    return os.path.join(tracing_dir, *args)
     42
     43def write_file(path, data):
     44    open(path, 'wb').write(data)
     45
     46def enable_event(subsystem, event, enable):
     47    write_file(trace_path('events', subsystem, event, 'enable'), '1' if enable else '0')
     48
     49def enable_subsystem(subsystem, enable):
     50    write_file(trace_path('events', subsystem, 'enable'), '1' if enable else '0')
     51
     52def start_tracing():
     53    enable_subsystem('kvm', True)
     54    write_file(trace_path('tracing_on'), '1')
     55
     56def stop_tracing():
     57    write_file(trace_path('tracing_on'), '0')
     58    enable_subsystem('kvm', False)
     59    write_file(trace_path('events', 'enable'), '0')
     60    write_file(trace_path('current_tracer'), 'nop')
     61
     62def dump_trace():
     63    tracefile = open(trace_path('trace'), 'r')
     64    try:
     65        lines = True
     66        while lines:
     67            lines = tracefile.readlines(64 * 1024)
     68            sys.stdout.writelines(lines)
     69    except KeyboardInterrupt:
     70        pass
     71
     72def tail_trace():
     73    try:
     74        for line in open(trace_path('trace_pipe'), 'r'):
     75            sys.stdout.write(line)
     76    except KeyboardInterrupt:
     77        pass
     78
     79def usage():
     80    print('Usage: %s start [buffer_size_kb] | stop | dump | tail' % sys.argv[0])
     81    print('Control the KVM flight recorder tracing.')
     82    sys.exit(0)
     83
     84def main():
     85    if len(sys.argv) < 2:
     86        usage()
     87
     88    cmd = sys.argv[1]
     89    if cmd == '--version':
     90        print('kvm_flightrecorder version 1.0')
     91        sys.exit(0)
     92
     93    if not os.path.isdir(tracing_dir):
     94        print('Unable to tracing debugfs directory, try:')
     95        print('mount -t debugfs none /sys/kernel/debug')
     96        sys.exit(1)
     97    if not os.access(tracing_dir, os.W_OK):
     98        print('Unable to write to tracing debugfs directory, please run as root')
     99        sys.exit(1)
    100
    101    if cmd == 'start':
    102        stop_tracing() # clean up first
    103
    104        if len(sys.argv) == 3:
    105            try:
    106                buffer_size_kb = int(sys.argv[2])
    107            except ValueError:
    108                print('Invalid per-cpu trace buffer size in KB')
    109                sys.exit(1)
    110            write_file(trace_path('buffer_size_kb'), str(buffer_size_kb))
    111            print('Per-CPU ring buffer size set to %d KB' % buffer_size_kb)
    112
    113        start_tracing()
    114        print('KVM flight recorder enabled')
    115    elif cmd == 'stop':
    116        stop_tracing()
    117        print('KVM flight recorder disabled')
    118    elif cmd == 'dump':
    119        dump_trace()
    120    elif cmd == 'tail':
    121        tail_trace()
    122    else:
    123        usage()
    124
    125if __name__ == '__main__':
    126    sys.exit(main())