#!/bin/sh

#
# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (c) 2020 Peter Holm
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
# ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
# FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
# DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
# OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
# OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
# SUCH DAMAGE.
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# 20200224 13:05:04 all (1/1): systrace.sh
# [ thread pid 64171 tid 100708 ]
# Stopped at      sdt_modevent+0x1c1:     int     $3
# db>

# markj@ wrote:
# I think I see the problem now.  It should happen if you:
# 1. load systrace.ko
# 2. enable some system call probes, and disable them again
# 3. unload systrace.ko
# 4. load some unrelated module
# 5. goto 1
#
# In particular, if systrace.ko is loaded at different addresses each
# time, we'll end up calling a stale function pointer.

# https://people.freebsd.org/~pho/stress/log/mark137.txt

[ `id -u ` -ne 0 ] && echo "Must be root!" && exit 1
. ../default.cfg

dtrace -n 'dtrace:::BEGIN { exit(0); }' > /dev/null 2>&1 || exit 0
for i in `jot 2`; do
	sleep 4 & pid=$!
	dtrace -w -n 'syscall::*read:entry,syscall::*write:entry {\
	    @rw[execname,probefunc] = count(); }' -p $pid > /dev/null 2>&1
	wait $pid
	kldstat | grep -q dtraceall.ko && kldunload dtraceall.ko

	mount -t tmpfs dummy $mntpoint && umount $mntpoint
done
kldstat | grep -q tmpfs && kldunload tmpfs.ko
exit 0