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 (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22 /*
23 * Copyright 2006 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/stropts.h>
30 #include <sys/isa_defs.h>
31 #include <sys/nvpair.h>
32 #include <sys/sysmacros.h>
33 #if defined(_KERNEL) && !defined(_BOOT)
34 #include <sys/varargs.h>
35 #else
36 #include <stdarg.h>
37 #include <strings.h>
38 #endif
39
40 /*
41 * This allocator is very simple.
42 * - it uses a pre-allocated buffer for memory allocations.
43 * - it does _not_ free memory in the pre-allocated buffer.
44 *
45 * The reason for the selected implemention is simplicity.
46 * This allocator is designed for the usage in interrupt context when
47 * the caller may not wait for free memory.
48 */
49
50 /* pre-allocated buffer for memory allocations */
51 typedef struct nvbuf {
52 uintptr_t nvb_buf; /* address of pre-allocated buffer */
53 uintptr_t nvb_lim; /* limit address in the buffer */
54 uintptr_t nvb_cur; /* current address in the buffer */
55 } nvbuf_t;
56
57 /*
58 * Initialize the pre-allocated buffer allocator. The caller needs to supply
59 *
60 * buf address of pre-allocated buffer
61 * bufsz size of pre-allocated buffer
62 *
63 * nv_fixed_init() calculates the remaining members of nvbuf_t.
64 */
65 static int
nv_fixed_init(nv_alloc_t * nva,va_list valist)66 nv_fixed_init(nv_alloc_t *nva, va_list valist)
67 {
68 uintptr_t base = va_arg(valist, uintptr_t);
69 uintptr_t lim = base + va_arg(valist, size_t);
70 nvbuf_t *nvb = (nvbuf_t *)P2ROUNDUP(base, sizeof (uintptr_t));
71
72 if (base == 0 || (uintptr_t)&nvb[1] > lim)
73 return (EINVAL);
74
75 nvb->nvb_buf = (uintptr_t)&nvb[0];
76 nvb->nvb_cur = (uintptr_t)&nvb[1];
77 nvb->nvb_lim = lim;
78 nva->nva_arg = nvb;
79
80 return (0);
81 }
82
83 static void *
nv_fixed_alloc(nv_alloc_t * nva,size_t size)84 nv_fixed_alloc(nv_alloc_t *nva, size_t size)
85 {
86 nvbuf_t *nvb = nva->nva_arg;
87 uintptr_t new = nvb->nvb_cur;
88
89 if (size == 0 || new + size > nvb->nvb_lim)
90 return (NULL);
91
92 nvb->nvb_cur = P2ROUNDUP(new + size, sizeof (uintptr_t));
93
94 return ((void *)new);
95 }
96
97 /*ARGSUSED*/
98 static void
nv_fixed_free(nv_alloc_t * nva,void * buf,size_t size)99 nv_fixed_free(nv_alloc_t *nva, void *buf, size_t size)
100 {
101 /* don't free memory in the pre-allocated buffer */
102 }
103
104 static void
nv_fixed_reset(nv_alloc_t * nva)105 nv_fixed_reset(nv_alloc_t *nva)
106 {
107 nvbuf_t *nvb = nva->nva_arg;
108
109 nvb->nvb_cur = (uintptr_t)&nvb[1];
110 }
111
112 const nv_alloc_ops_t nv_fixed_ops_def = {
113 nv_fixed_init, /* nv_ao_init() */
114 NULL, /* nv_ao_fini() */
115 nv_fixed_alloc, /* nv_ao_alloc() */
116 nv_fixed_free, /* nv_ao_free() */
117 nv_fixed_reset /* nv_ao_reset() */
118 };
119
120 const nv_alloc_ops_t *nv_fixed_ops = &nv_fixed_ops_def;
121