usr/src/uts/i86pc/os/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 #pragma ident   "%Z%%M% %I%     %E% SMI"
  32
  33 #include <sys/proc.h>
  34 #include <sys/param.h>
  35 #include <sys/cmn_err.h>
  36 #include <sys/archsystm.h>
  37 #include <sys/copyops.h>
  38 #include <vm/seg_enum.h>
  39 #include <sys/privregs.h>
  40
  41 #include <dis_tables.h>
  42
  43 /*
  44  * This subsystem (with the minor exception of the instr_size() function) is
  45  * is called from DTrace probe context.  This imposes several requirements on
  46  * the implementation:
  47  *
  48  * 1. External subsystems and functions may not be referenced.  The one current
  49  *    exception is for cmn_err, but only to signal the detection of table
  50  *    errors.  Assuming the tables are correct, no combination of input is to
  51  *    trigger a cmn_err call.
  52  *
  53  * 2. These functions can't be allowed to be traced.  To prevent this,
  54  *    all functions in the probe path (everything except instr_size()) must
  55  *    have names that begin with "dtrace_".
  56  */
  57
  58 typedef enum dis_isize {
  59         DIS_ISIZE_INSTR,
  60         DIS_ISIZE_OPERAND
  61 } dis_isize_t;
  62
  63
  64 /*
  65  * get a byte from instruction stream
  66  */
  67 static int
  68 dtrace_dis_get_byte(void *p)
  69 {
  70         int ret;
  71         uchar_t **instr = p;
  72
  73         ret = **instr;
  74         *instr += 1;
  75
  76         return (ret);
  77 }
  78
  79 /*
  80  * Returns either the size of a given instruction, in bytes, or the size of that
  81  * instruction's memory access (if any), depending on the value of `which'.
  82  * If a programming error in the tables is detected, the system will panic to
  83  * ease diagnosis.  Invalid instructions will not be flagged.  They will appear
  84  * to have an instruction size between 1 and the actual size, and will be
  85  * reported as having no memory impact.
  86  */
  87 /* ARGSUSED2 */
  88 static int
  89 dtrace_dis_isize(uchar_t *instr, dis_isize_t which, model_t model, int *rmindex)
  90 {
  91         int sz;
  92         dis86_t x;
  93         uint_t mode = SIZE32;
  94
  95         mode = (model == DATAMODEL_LP64) ? SIZE64 : SIZE32;
  96
  97         x.d86_data = (void **)&instr;
  98         x.d86_get_byte = dtrace_dis_get_byte;
  99         x.d86_check_func = NULL;
 100
 101         if (dtrace_disx86(&x, mode) != 0)
 102                 return (-1);
 103
 104         if (which == DIS_ISIZE_INSTR)
 105                 sz = x.d86_len;         /* length of the instruction */
 106         else
 107                 sz = x.d86_memsize;     /* length of memory operand */
 108
 109         if (rmindex != NULL)
 110                 *rmindex = x.d86_rmindex;
 111         return (sz);
 112 }
 113
 114 int
 115 dtrace_instr_size_isa(uchar_t *instr, model_t model, int *rmindex)
 116 {
 117         return (dtrace_dis_isize(instr, DIS_ISIZE_INSTR, model, rmindex));
 118 }
 119
 120 int
 121 dtrace_instr_size(uchar_t *instr)
 122 {
 123         return (dtrace_dis_isize(instr, DIS_ISIZE_INSTR, DATAMODEL_NATIVE,
 124             NULL));
 125 }
 126
 127 /*ARGSUSED*/
 128 int
 129 instr_size(struct regs *rp, caddr_t *addrp, enum seg_rw rw)
 130 {
 131         uchar_t instr[16];      /* maximum size instruction */
 132         caddr_t pc = (caddr_t)rp->r_pc;
 133
 134         (void) copyin_nowatch(pc, (caddr_t)instr, sizeof (instr));
 135
 136         return (dtrace_dis_isize(instr,
 137             rw == S_EXEC ? DIS_ISIZE_INSTR : DIS_ISIZE_OPERAND,
 138             curproc->p_model, NULL));
 139 }