kern_dtrace.c revision 179090 
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 179090 2008-05-18 19:43:52Z jb $");
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
41#define KDTRACE_PROC_SIZE	64
42#define KDTRACE_PROC_ZERO	8
43#define	KDTRACE_THREAD_SIZE	256
44#define	KDTRACE_THREAD_ZERO	64
45
46MALLOC_DEFINE(M_KDTRACE, "kdtrace", "DTrace hooks");
47
48/* Return the DTrace process data size compiled in the kernel hooks. */
49size_t
50kdtrace_proc_size()
51{
52	return(KDTRACE_PROC_SIZE);
53}
54
55static void
56kdtrace_proc_ctor(void *arg __unused, struct proc *p)
57{
58	p->p_dtrace = malloc(KDTRACE_PROC_SIZE, M_KDTRACE, M_WAITOK);
59
60	bzero(p->p_dtrace, KDTRACE_PROC_ZERO);
61}
62
63static void
64kdtrace_proc_dtor(void *arg __unused, struct proc *p)
65{
66	if (p->p_dtrace != NULL) {
67		free(p->p_dtrace, M_KDTRACE);
68		p->p_dtrace = NULL;
69	}
70}
71
72/* Return the DTrace thread data size compiled in the kernel hooks. */
73size_t
74kdtrace_thread_size()
75{
76	return(KDTRACE_THREAD_SIZE);
77}
78
79static void
80kdtrace_thread_ctor(void *arg __unused, struct thread *td)
81{
82	td->td_dtrace = malloc(KDTRACE_THREAD_SIZE, M_KDTRACE, M_WAITOK);
83
84	bzero(td->td_dtrace, KDTRACE_THREAD_ZERO);
85}
86
87static void
88kdtrace_thread_dtor(void *arg __unused, struct thread *td)
89{
90	if (td->td_dtrace != NULL) {
91		free(td->td_dtrace, M_KDTRACE);
92		td->td_dtrace = NULL;
93	}
94}
95
96/*
97 *  Initialise the kernel DTrace hooks.
98 */
99static void
100init_dtrace(void *dummy __unused)
101{
102	EVENTHANDLER_REGISTER(process_ctor, kdtrace_proc_ctor, NULL, EVENTHANDLER_PRI_ANY);
103	EVENTHANDLER_REGISTER(process_dtor, kdtrace_proc_dtor, NULL, EVENTHANDLER_PRI_ANY);
104	EVENTHANDLER_REGISTER(thread_ctor, kdtrace_thread_ctor, NULL, EVENTHANDLER_PRI_ANY);
105	EVENTHANDLER_REGISTER(thread_dtor, kdtrace_thread_dtor, NULL, EVENTHANDLER_PRI_ANY);
106}
107
108SYSINIT(kdtrace, SI_SUB_KDTRACE, SI_ORDER_FIRST, init_dtrace, NULL);
109
110#ifndef KDB
111/*
112 * This is a stub for the kernel debugger for the DTrace actions to call
113 * when the kernel has been built without KDB.
114 */
115void
116kdb_enter(const char *why, const char *msg)
117{
118	printf("Cannot enter kernel debugger - No KDB in kernel.\n%s - %s\n", why, msg);
119}
120#endif
121