usr/src/uts/common/os/id32.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 2004 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 #pragma ident   "%Z%%M% %I%     %E% SMI"
  28
  29 #include <sys/vmem.h>
  30 #include <sys/kmem.h>
  31 #include <sys/param.h>
  32 #include <sys/sysmacros.h>
  33 #include <sys/cmn_err.h>
  34 #include <vm/seg_kmem.h>
  35
  36 static vmem_t *id32_arena;
  37 static kmem_cache_t *id32_cache;
  38
  39 #define ID32_BITS       5
  40 #define ID32_ALIGN      (1 << ID32_BITS)
  41 #define ID32_MOD        (ID32_ALIGN - 1)
  42
  43 #if defined(__amd64)
  44 /*
  45  * For amd64 the 32 bit id is the offset of the entry in the arena.
  46  */
  47 extern char *heap_core_base;
  48 #define ID32_ENCODE(x)  (((x) - (uintptr_t)heap_core_base) | \
  49         ((((x) - (uintptr_t)heap_core_base) % ID32_MOD)) + 1)
  50 #define ID32_DECODE(x)  (P2ALIGN((x), (uintptr_t)ID32_ALIGN) + \
  51         (uintptr_t)heap_core_base)
  52 #define ID32_VALID(x)   (ID32_ENCODE(ID32_DECODE(x)) == (x))
  53 #else   /* __amd64 */
  54 /*
  55  * All other architectures use the 32 bit pointer value for the 32 bit id.
  56  */
  57 #define ID32_ENCODE(x)  (((x) | ((x) % ID32_MOD)) + 1)
  58 #define ID32_DECODE(x)  P2ALIGN((x), ID32_ALIGN)
  59 #define ID32_VALID(x)   (ID32_ENCODE(ID32_DECODE(x)) == (x))
  60 #endif  /* __amd64 */
  61
  62 void
  63 id32_init(void)
  64 {
  65         id32_arena = vmem_create("id32", NULL, 0, PAGESIZE,
  66             segkmem_alloc, segkmem_free, heap32_arena, 0, VM_SLEEP);
  67
  68         id32_cache = kmem_cache_create("id32_cache", ID32_ALIGN, ID32_ALIGN,
  69             NULL, NULL, NULL, NULL, id32_arena, 0);
  70 }
  71
  72 /*
  73  * Return a 32-bit identifier for the specified pointer.
  74  */
  75 uint32_t
  76 id32_alloc(void *ptr, int kmflag)
  77 {
  78         void **hent = kmem_cache_alloc(id32_cache, kmflag);
  79         uintptr_t id;
  80
  81         if (hent == NULL)
  82                 return (0);
  83
  84         *hent = ptr;
  85         id = ID32_ENCODE((uintptr_t)hent);
  86         ASSERT64(id <= UINT32_MAX);
  87         return ((uint32_t)id);
  88 }
  89
  90 /*
  91  * Free a 32-bit ID.
  92  */
  93 void
  94 id32_free(uint32_t id)
  95 {
  96         if (!ID32_VALID(id)) {
  97                 cmn_err(CE_WARN, "id32_free(%x): bad ID rejected\n", id);
  98                 return;
  99         }
 100
 101         kmem_cache_free(id32_cache, (void *)(uintptr_t)ID32_DECODE(id));
 102 }
 103
 104 /*
 105  * Return the pointer described by a 32-bit ID, or NULL if the ID is bad.
 106  */
 107 void *
 108 id32_lookup(uint32_t id)
 109 {
 110         if (!ID32_VALID(id)) {
 111                 cmn_err(CE_WARN, "id32_lookup(%x): bad ID rejected\n", id);
 112                 return (NULL);
 113         }
 114
 115         return (((void **)(uintptr_t)ID32_DECODE(id))[0]);
 116 }