usr/src/lib/libdtrace/common/dt_regset.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 /*
  24  * Copyright 2003 Sun Microsystems, Inc.  All rights reserved.
  25  * Use is subject to license terms.
  26  */
  27
  28 /*
  29  * Copyright (c) 2012 by Delphix. All rights reserved.
  30  */
  31
  32 #include <sys/types.h>
  33 #include <sys/bitmap.h>
  34 #include <assert.h>
  35 #include <strings.h>
  36 #include <stdlib.h>
  37
  38 #include <dt_regset.h>
  39 #include <dt_impl.h>
  40
  41 dt_regset_t *
  42 dt_regset_create(ulong_t nregs)
  43 {
  44         ulong_t n = BT_BITOUL(nregs);
  45         dt_regset_t *drp = malloc(sizeof (dt_regset_t));
  46
  47         if (drp == NULL)
  48                 return (NULL);
  49
  50         drp->dr_bitmap = malloc(sizeof (ulong_t) * n);
  51         drp->dr_size = nregs;
  52
  53         if (drp->dr_bitmap == NULL) {
  54                 dt_regset_destroy(drp);
  55                 return (NULL);
  56         }
  57
  58         bzero(drp->dr_bitmap, sizeof (ulong_t) * n);
  59         return (drp);
  60 }
  61
  62 void
  63 dt_regset_destroy(dt_regset_t *drp)
  64 {
  65         free(drp->dr_bitmap);
  66         free(drp);
  67 }
  68
  69 void
  70 dt_regset_reset(dt_regset_t *drp)
  71 {
  72         bzero(drp->dr_bitmap, sizeof (ulong_t) * BT_BITOUL(drp->dr_size));
  73 }
  74
  75 void
  76 dt_regset_assert_free(dt_regset_t *drp)
  77 {
  78         int reg;
  79         boolean_t fail = B_FALSE;
  80         for (reg = 0; reg < drp->dr_size; reg++) {
  81                 if (BT_TEST(drp->dr_bitmap, reg) != 0)  {
  82                         dt_dprintf("%%r%d was left allocated\n", reg);
  83                         fail = B_TRUE;
  84                 }
  85         }
  86
  87         /*
  88          * We set this during dtest runs to check for register leaks.
  89          */
  90         if (fail && getenv("DTRACE_DEBUG_REGSET") != NULL)
  91                 abort();
  92 }
  93
  94 int
  95 dt_regset_alloc(dt_regset_t *drp)
  96 {
  97         ulong_t nbits = drp->dr_size - 1;
  98         ulong_t maxw = nbits >> BT_ULSHIFT;
  99         ulong_t wx;
 100
 101         for (wx = 0; wx <= maxw; wx++) {
 102                 if (drp->dr_bitmap[wx] != ~0UL)
 103                         break;
 104         }
 105
 106         if (wx <= maxw) {
 107                 ulong_t maxb = (wx == maxw) ? nbits & BT_ULMASK : BT_NBIPUL - 1;
 108                 ulong_t word = drp->dr_bitmap[wx];
 109                 ulong_t bit, bx;
 110                 int reg;
 111
 112                 for (bit = 1, bx = 0; bx <= maxb; bx++, bit <<= 1) {
 113                         if ((word & bit) == 0) {
 114                                 reg = (int)((wx << BT_ULSHIFT) | bx);
 115                                 BT_SET(drp->dr_bitmap, reg);
 116                                 return (reg);
 117                         }
 118                 }
 119         }
 120
 121         xyerror(D_NOREG, "Insufficient registers to generate code");
 122         /*NOTREACHED*/
 123         return (-1);
 124 }
 125
 126 void
 127 dt_regset_free(dt_regset_t *drp, int reg)
 128 {
 129         assert(reg >= 0 && reg < drp->dr_size);
 130         assert(BT_TEST(drp->dr_bitmap, reg) != 0);
 131         BT_CLEAR(drp->dr_bitmap, reg);
 132 }