xref: /freebsd/sys/kern/kern_dtrace.c (revision 9a14aa017b21c292740c00ee098195cd46642730)
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("$FreeBSD$");
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 
45 FEATURE(kdtrace_hooks,
46     "Kernel DTrace hooks which are required to load DTrace kernel modules");
47 
48 static MALLOC_DEFINE(M_KDTRACE, "kdtrace", "DTrace hooks");
49 
50 /* Return the DTrace process data size compiled in the kernel hooks. */
51 size_t
52 kdtrace_proc_size()
53 {
54 
55 	return (KDTRACE_PROC_SIZE);
56 }
57 
58 static void
59 kdtrace_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 
65 static void
66 kdtrace_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. */
76 size_t
77 kdtrace_thread_size()
78 {
79 
80 	return (KDTRACE_THREAD_SIZE);
81 }
82 
83 static void
84 kdtrace_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 
90 static void
91 kdtrace_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  */
103 static void
104 init_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 
117 SYSINIT(kdtrace, SI_SUB_KDTRACE, SI_ORDER_FIRST, init_dtrace, NULL);
118