freebsd-dev/sys/kern/kern_dtrace.c
Mateusz Guzik 9d68f7741f systrace: track it like sdt probes
While here predict false.

Note the code is wrong (regardless of this change). Dereference of the
pointer can race with module unload. A fix would set the probe to a
nop stub instead of NULL.
2018-04-27 15:16:34 +00:00

130 lines
3.6 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* Copyright (c) 2007-2008 John Birrell <jb@FreeBSD.org>
* All rights reserved.
*
* 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.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_kdb.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/eventhandler.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/proc.h>
#include <sys/dtrace_bsd.h>
#include <sys/sysctl.h>
#include <sys/sysent.h>
#define KDTRACE_PROC_SIZE 64
#define KDTRACE_THREAD_SIZE 256
FEATURE(kdtrace_hooks,
"Kernel DTrace hooks which are required to load DTrace kernel modules");
static MALLOC_DEFINE(M_KDTRACE, "kdtrace", "DTrace hooks");
/* Hooks used in the machine-dependent trap handlers. */
dtrace_trap_func_t dtrace_trap_func;
dtrace_doubletrap_func_t dtrace_doubletrap_func;
dtrace_pid_probe_ptr_t dtrace_pid_probe_ptr;
dtrace_return_probe_ptr_t dtrace_return_probe_ptr;
bool __read_frequently systrace_enabled;
systrace_probe_func_t systrace_probe_func;
/* Return the DTrace process data size compiled in the kernel hooks. */
size_t
kdtrace_proc_size()
{
return (KDTRACE_PROC_SIZE);
}
static void
kdtrace_proc_ctor(void *arg __unused, struct proc *p)
{
p->p_dtrace = malloc(KDTRACE_PROC_SIZE, M_KDTRACE, M_WAITOK|M_ZERO);
}
static void
kdtrace_proc_dtor(void *arg __unused, struct proc *p)
{
if (p->p_dtrace != NULL) {
free(p->p_dtrace, M_KDTRACE);
p->p_dtrace = NULL;
}
}
/* Return the DTrace thread data size compiled in the kernel hooks. */
size_t
kdtrace_thread_size()
{
return (KDTRACE_THREAD_SIZE);
}
static void
kdtrace_thread_ctor(void *arg __unused, struct thread *td)
{
td->td_dtrace = malloc(KDTRACE_THREAD_SIZE, M_KDTRACE, M_WAITOK|M_ZERO);
}
static void
kdtrace_thread_dtor(void *arg __unused, struct thread *td)
{
if (td->td_dtrace != NULL) {
free(td->td_dtrace, M_KDTRACE);
td->td_dtrace = NULL;
}
}
/*
* Initialise the kernel DTrace hooks.
*/
static void
init_dtrace(void *dummy __unused)
{
EVENTHANDLER_REGISTER(process_ctor, kdtrace_proc_ctor, NULL,
EVENTHANDLER_PRI_ANY);
EVENTHANDLER_REGISTER(process_dtor, kdtrace_proc_dtor, NULL,
EVENTHANDLER_PRI_ANY);
EVENTHANDLER_REGISTER(thread_ctor, kdtrace_thread_ctor, NULL,
EVENTHANDLER_PRI_ANY);
EVENTHANDLER_REGISTER(thread_dtor, kdtrace_thread_dtor, NULL,
EVENTHANDLER_PRI_ANY);
}
SYSINIT(kdtrace, SI_SUB_KDTRACE, SI_ORDER_FIRST, init_dtrace, NULL);