bsd/dev/i386/instr_size.c

   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 }