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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
	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
	55	typedef 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	*/
	64	static int
	65	dtrace_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 */
	85	static int
	86	dtrace_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
	111	int
	112	dtrace_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
	117	int
	118	dtrace_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/
	126	int
	127	instr_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__ */