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 #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 }