1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1988 AT&T	*/
28/*	  All Rights Reserved	*/
29
30
31/*
32 * #pragma ident	"@(#)instr_size.c	1.14	05/07/08 SMI"
33 */
34
35#include <sys/dtrace.h>
36#include <sys/dtrace_glue.h>
37
38#include <sys/dis_tables.h>
39
40/*
41 * This subsystem (with the minor exception of the instr_size() function) is
42 * is called from DTrace probe context.  This imposes several requirements on
43 * the implementation:
44 *
45 * 1. External subsystems and functions may not be referenced.  The one current
46 *    exception is for cmn_err, but only to signal the detection of table
47 *    errors.  Assuming the tables are correct, no combination of input is to
48 *    trigger a cmn_err call.
49 *
50 * 2. These functions can't be allowed to be traced.  To prevent this,
51 *    all functions in the probe path (everything except instr_size()) must
52 *    have names that begin with "dtrace_".
53 */
54
55typedef enum dis_isize {
56	DIS_ISIZE_INSTR,
57	DIS_ISIZE_OPERAND
58} dis_isize_t;
59
60
61/*
62 * get a byte from instruction stream
63 */
64static int
65dtrace_dis_get_byte(void *p)
66{
67	int ret;
68	uchar_t **instr = p;
69
70	ret = **instr;
71	*instr += 1;
72
73	return (ret);
74}
75
76/*
77 * Returns either the size of a given instruction, in bytes, or the size of that
78 * instruction's memory access (if any), depending on the value of `which'.
79 * If a programming error in the tables is detected, the system will panic to
80 * ease diagnosis.  Invalid instructions will not be flagged.  They will appear
81 * to have an instruction size between 1 and the actual size, and will be
82 * reported as having no memory impact.
83 */
84/* ARGSUSED2 */
85static int
86dtrace_dis_isize(uchar_t *instr, dis_isize_t which, model_t model, int *rmindex)
87{
88	int sz;
89	dis86_t	x;
90	uint_t mode = SIZE32;
91
92	mode = (model == DATAMODEL_LP64) ? SIZE64 : SIZE32;
93
94	x.d86_data = (void **)&instr;
95	x.d86_get_byte = dtrace_dis_get_byte;
96	x.d86_check_func = NULL;
97
98	if (dtrace_disx86(&x, mode) != 0)
99		return (-1);
100
101	if (which == DIS_ISIZE_INSTR)
102		sz = x.d86_len;		/* length of the instruction */
103	else
104		sz = x.d86_memsize;	/* length of memory operand */
105
106	if (rmindex != NULL)
107		*rmindex = x.d86_rmindex;
108	return (sz);
109}
110
111int
112dtrace_instr_size_isa(uchar_t *instr, model_t model, int *rmindex)
113{
114	return (dtrace_dis_isize(instr, DIS_ISIZE_INSTR, model, rmindex));
115}
116
117int
118dtrace_instr_size(uchar_t *instr)
119{
120	return (dtrace_dis_isize(instr, DIS_ISIZE_INSTR, DATAMODEL_NATIVE,
121	    NULL));
122}
123
124#if !defined(__APPLE__)
125/*ARGSUSED*/
126int
127instr_size(struct regs *rp, caddr_t *addrp, enum seg_rw rw)
128{
129	uchar_t instr[16];	/* maximum size instruction */
130	caddr_t pc = (caddr_t)rp->r_pc;
131
132	(void) copyin_nowatch(pc, (caddr_t)instr, sizeof (instr));
133
134	return (dtrace_dis_isize(instr,
135	    rw == S_EXEC ? DIS_ISIZE_INSTR : DIS_ISIZE_OPERAND,
136	    curproc->p_model, NULL));
137}
138#endif /* __APPLE__ */
139