kern_dtrace.c revision 219028 
1/*-
2 * Copyright (c) 2007-2008 John Birrell <jb@FreeBSD.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/kern/kern_dtrace.c 219028 2011-02-25 10:11:01Z netchild $");
29
30#include "opt_kdb.h"
31
32#include <sys/param.h>
33#include <sys/systm.h>
34#include <sys/eventhandler.h>
35#include <sys/kdb.h>
36#include <sys/kernel.h>
37#include <sys/malloc.h>
38#include <sys/proc.h>
39#include <sys/dtrace_bsd.h>
40#include <sys/sysctl.h>
41
42#define KDTRACE_PROC_SIZE	64
43#define	KDTRACE_THREAD_SIZE	256
44
45FEATURE(kdtrace_hooks,
46    "Kernel DTrace hooks which are required to load DTrace kernel modules");
47
48MALLOC_DEFINE(M_KDTRACE, "kdtrace", "DTrace hooks");
49
50/* Return the DTrace process data size compiled in the kernel hooks. */
51size_t
52kdtrace_proc_size()
53{
54
55	return (KDTRACE_PROC_SIZE);
56}
57
58static void
59kdtrace_proc_ctor(void *arg __unused, struct proc *p)
60{
61
62	p->p_dtrace = malloc(KDTRACE_PROC_SIZE, M_KDTRACE, M_WAITOK|M_ZERO);
63}
64
65static void
66kdtrace_proc_dtor(void *arg __unused, struct proc *p)
67{
68
69	if (p->p_dtrace != NULL) {
70		free(p->p_dtrace, M_KDTRACE);
71		p->p_dtrace = NULL;
72	}
73}
74
75/* Return the DTrace thread data size compiled in the kernel hooks. */
76size_t
77kdtrace_thread_size()
78{
79
80	return (KDTRACE_THREAD_SIZE);
81}
82
83static void
84kdtrace_thread_ctor(void *arg __unused, struct thread *td)
85{
86
87	td->td_dtrace = malloc(KDTRACE_THREAD_SIZE, M_KDTRACE, M_WAITOK|M_ZERO);
88}
89
90static void
91kdtrace_thread_dtor(void *arg __unused, struct thread *td)
92{
93
94	if (td->td_dtrace != NULL) {
95		free(td->td_dtrace, M_KDTRACE);
96		td->td_dtrace = NULL;
97	}
98}
99
100/*
101 *  Initialise the kernel DTrace hooks.
102 */
103static void
104init_dtrace(void *dummy __unused)
105{
106
107	EVENTHANDLER_REGISTER(process_ctor, kdtrace_proc_ctor, NULL,
108	    EVENTHANDLER_PRI_ANY);
109	EVENTHANDLER_REGISTER(process_dtor, kdtrace_proc_dtor, NULL,
110	    EVENTHANDLER_PRI_ANY);
111	EVENTHANDLER_REGISTER(thread_ctor, kdtrace_thread_ctor, NULL,
112	    EVENTHANDLER_PRI_ANY);
113	EVENTHANDLER_REGISTER(thread_dtor, kdtrace_thread_dtor, NULL,
114	    EVENTHANDLER_PRI_ANY);
115}
116
117SYSINIT(kdtrace, SI_SUB_KDTRACE, SI_ORDER_FIRST, init_dtrace, NULL);
118