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	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	#include <sys/dtrace.h>
	31	#include <sys/dtrace_glue.h>
	32
	33	#include <sys/dis_tables.h>
	34
	35	/*
	36	* This subsystem (with the minor exception of the instr_size() function) is
	37	* is called from DTrace probe context. This imposes several requirements on
	38	* the implementation:
	39	*
	40	* 1. External subsystems and functions may not be referenced. The one current
	41	* exception is for cmn_err, but only to signal the detection of table
	42	* errors. Assuming the tables are correct, no combination of input is to
	43	* trigger a cmn_err call.
	44	*
	45	* 2. These functions can't be allowed to be traced. To prevent this,
	46	* all functions in the probe path (everything except instr_size()) must
	47	* have names that begin with "dtrace_".
	48	*/
	49
	50	typedef enum dis_isize {
	51	DIS_ISIZE_INSTR,
	52	DIS_ISIZE_OPERAND
	53	} dis_isize_t;
	54
	55
	56	/*
	57	* get a byte from instruction stream
	58	*/
	59	static int
	60	dtrace_dis_get_byte(void *p)
	61	{
	62	int ret;
	63	uchar_t **instr = p;
	64
	65	ret = **instr;
	66	*instr += 1;
	67
	68	return (ret);
	69	}
	70
	71	/*
	72	* Returns either the size of a given instruction, in bytes, or the size of that
	73	* instruction's memory access (if any), depending on the value of `which'.
	74	* If a programming error in the tables is detected, the system will panic to
	75	* ease diagnosis. Invalid instructions will not be flagged. They will appear
	76	* to have an instruction size between 1 and the actual size, and will be
	77	* reported as having no memory impact.
	78	*/
	79	/* ARGSUSED2 */
	80	static __attribute__((noinline)) int
	81	dtrace_dis_isize(uchar_t instr, dis_isize_t which, model_t model, int rmindex)
	82	{
	83	int sz;
	84	dis86_t x;
	85	uint_t mode = SIZE32;
	86
	87	mode = (model == DATAMODEL_LP64) ? SIZE64 : SIZE32;
	88
	89	x.d86_data = (void **)&instr;
	90	x.d86_get_byte = dtrace_dis_get_byte;
	91	x.d86_check_func = NULL;
	92
	93	if (dtrace_disx86(&x, mode) != 0)
	94	return (-1);
	95
	96	if (which == DIS_ISIZE_INSTR)
	97	sz = x.d86_len; /* length of the instruction */
	98	else
	99	sz = x.d86_memsize; /* length of memory operand */
	100
	101	if (rmindex != NULL)
	102	*rmindex = x.d86_rmindex;
	103	return (sz);
	104	}
	105
	106	int
	107	dtrace_instr_size_isa(uchar_t instr, model_t model, int rmindex)
	108	{
	109	return (dtrace_dis_isize(instr, DIS_ISIZE_INSTR, model, rmindex));
	110	}
	111
	112	int
	113	dtrace_instr_size(uchar_t *instr)
	114	{
	115	return (dtrace_dis_isize(instr, DIS_ISIZE_INSTR, DATAMODEL_NATIVE,
	116	NULL));
	117	}