xref: /illumos-gate/usr/src/uts/common/os/id32.c (revision 2d6eb4a5e0a47d30189497241345dc5466bb68ab)
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 #include <sys/vmem.h>
28 #include <sys/kmem.h>
29 #include <sys/param.h>
30 #include <sys/sysmacros.h>
31 #include <sys/cmn_err.h>
32 #include <vm/seg_kmem.h>
33 
34 static vmem_t *id32_arena;
35 static kmem_cache_t *id32_cache;
36 
37 #define	ID32_BITS	5
38 #define	ID32_ALIGN	(1 << ID32_BITS)
39 #define	ID32_MOD	(ID32_ALIGN - 1)
40 
41 #if defined(__amd64)
42 /*
43  * For amd64 the 32 bit id is the offset of the entry in the arena.
44  */
45 extern char *heap_core_base;
46 #define	ID32_ENCODE(x)	(((x) - (uintptr_t)heap_core_base) | \
47 	((((x) - (uintptr_t)heap_core_base) % ID32_MOD)) + 1)
48 #define	ID32_DECODE(x)	(P2ALIGN((x), (uintptr_t)ID32_ALIGN) + \
49 	(uintptr_t)heap_core_base)
50 #define	ID32_VALID(x)	(ID32_ENCODE(ID32_DECODE(x)) == (x))
51 #else	/* __amd64 */
52 /*
53  * All other architectures use the 32 bit pointer value for the 32 bit id.
54  */
55 #define	ID32_ENCODE(x)	(((x) | ((x) % ID32_MOD)) + 1)
56 #define	ID32_DECODE(x)	P2ALIGN((x), ID32_ALIGN)
57 #define	ID32_VALID(x)	(ID32_ENCODE(ID32_DECODE(x)) == (x))
58 #endif	/* __amd64 */
59 
60 void
id32_init(void)61 id32_init(void)
62 {
63 	id32_arena = vmem_create("id32", NULL, 0, PAGESIZE,
64 	    segkmem_alloc, segkmem_free, heap32_arena, 0, VM_SLEEP);
65 
66 	id32_cache = kmem_cache_create("id32_cache", ID32_ALIGN, ID32_ALIGN,
67 	    NULL, NULL, NULL, NULL, id32_arena, 0);
68 }
69 
70 /*
71  * Return a 32-bit identifier for the specified pointer.
72  */
73 uint32_t
id32_alloc(void * ptr,int kmflag)74 id32_alloc(void *ptr, int kmflag)
75 {
76 	void **hent = kmem_cache_alloc(id32_cache, kmflag);
77 	uintptr_t id;
78 
79 	if (hent == NULL)
80 		return (0);
81 
82 	*hent = ptr;
83 	id = ID32_ENCODE((uintptr_t)hent);
84 	ASSERT64(id <= UINT32_MAX);
85 	return ((uint32_t)id);
86 }
87 
88 /*
89  * Free a 32-bit ID.
90  */
91 void
id32_free(uint32_t id)92 id32_free(uint32_t id)
93 {
94 	if (!ID32_VALID(id)) {
95 		cmn_err(CE_WARN, "id32_free(%x): bad ID rejected\n", id);
96 		return;
97 	}
98 
99 	kmem_cache_free(id32_cache, (void *)(uintptr_t)ID32_DECODE(id));
100 }
101 
102 /*
103  * Return the pointer described by a 32-bit ID, or NULL if the ID is bad.
104  */
105 void *
id32_lookup(uint32_t id)106 id32_lookup(uint32_t id)
107 {
108 	if (!ID32_VALID(id)) {
109 		cmn_err(CE_WARN, "id32_lookup(%x): bad ID rejected\n", id);
110 		return (NULL);
111 	}
112 
113 	return (((void **)(uintptr_t)ID32_DECODE(id))[0]);
114 }
115