instr_size.c revision 179237 
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 * $FreeBSD: head/sys/cddl/dev/dtrace/i386/instr_size.c 179237 2008-05-23 05:59:42Z jb $
23 */
24/*
25 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
26 * Use is subject to license terms.
27 */
28
29/*	Copyright (c) 1988 AT&T	*/
30/*	  All Rights Reserved	*/
31
32
33#if defined(sun)
34#pragma ident	"@(#)instr_size.c	1.14	05/07/08 SMI"
35#endif
36
37#include <sys/types.h>
38#include <sys/param.h>
39#include <sys/proc.h>
40#if defined(sun)
41#include <sys/cmn_err.h>
42#include <sys/archsystm.h>
43#include <sys/copyops.h>
44#include <vm/seg_enum.h>
45#include <sys/privregs.h>
46#else
47typedef	u_int			model_t;
48#define	DATAMODEL_NATIVE	0
49int dtrace_instr_size(uchar_t *);
50#endif
51
52#include <dis_tables.h>
53
54/*
55 * This subsystem (with the minor exception of the instr_size() function) is
56 * is called from DTrace probe context.  This imposes several requirements on
57 * the implementation:
58 *
59 * 1. External subsystems and functions may not be referenced.  The one current
60 *    exception is for cmn_err, but only to signal the detection of table
61 *    errors.  Assuming the tables are correct, no combination of input is to
62 *    trigger a cmn_err call.
63 *
64 * 2. These functions can't be allowed to be traced.  To prevent this,
65 *    all functions in the probe path (everything except instr_size()) must
66 *    have names that begin with "dtrace_".
67 */
68
69typedef enum dis_isize {
70	DIS_ISIZE_INSTR,
71	DIS_ISIZE_OPERAND
72} dis_isize_t;
73
74
75/*
76 * get a byte from instruction stream
77 */
78static int
79dtrace_dis_get_byte(void *p)
80{
81	int ret;
82	uchar_t **instr = p;
83
84	ret = **instr;
85	*instr += 1;
86
87	return (ret);
88}
89
90/*
91 * Returns either the size of a given instruction, in bytes, or the size of that
92 * instruction's memory access (if any), depending on the value of `which'.
93 * If a programming error in the tables is detected, the system will panic to
94 * ease diagnosis.  Invalid instructions will not be flagged.  They will appear
95 * to have an instruction size between 1 and the actual size, and will be
96 * reported as having no memory impact.
97 */
98/* ARGSUSED2 */
99static int
100dtrace_dis_isize(uchar_t *instr, dis_isize_t which, model_t model, int *rmindex)
101{
102	int sz;
103	dis86_t	x;
104	uint_t mode = SIZE32;
105
106#if defined(sun)
107	mode = (model == DATAMODEL_LP64) ? SIZE64 : SIZE32;
108#endif
109
110	x.d86_data = (void **)&instr;
111	x.d86_get_byte = dtrace_dis_get_byte;
112	x.d86_check_func = NULL;
113
114	if (dtrace_disx86(&x, mode) != 0)
115		return (-1);
116
117	if (which == DIS_ISIZE_INSTR)
118		sz = x.d86_len;		/* length of the instruction */
119	else
120		sz = x.d86_memsize;	/* length of memory operand */
121
122	if (rmindex != NULL)
123		*rmindex = x.d86_rmindex;
124	return (sz);
125}
126
127int
128dtrace_instr_size(uchar_t *instr)
129{
130	return (dtrace_dis_isize(instr, DIS_ISIZE_INSTR, DATAMODEL_NATIVE,
131	    NULL));
132}
133