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 https://opensource.org/licenses/CDDL-1.0.
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 #include <sys/isa_defs.h>
28 #include <sys/nvpair.h>
29 #include <sys/sysmacros.h>
30
31 /*
32 * This allocator is very simple.
33 * - it uses a pre-allocated buffer for memory allocations.
34 * - it does _not_ free memory in the pre-allocated buffer.
35 *
36 * The reason for the selected implementation is simplicity.
37 * This allocator is designed for the usage in interrupt context when
38 * the caller may not wait for free memory.
39 */
40
41 /* pre-allocated buffer for memory allocations */
42 typedef struct nvbuf {
43 uintptr_t nvb_buf; /* address of pre-allocated buffer */
44 uintptr_t nvb_lim; /* limit address in the buffer */
45 uintptr_t nvb_cur; /* current address in the buffer */
46 } nvbuf_t;
47
48 /*
49 * Initialize the pre-allocated buffer allocator. The caller needs to supply
50 *
51 * buf address of pre-allocated buffer
52 * bufsz size of pre-allocated buffer
53 *
54 * nv_fixed_init() calculates the remaining members of nvbuf_t.
55 */
56 static int
nv_fixed_init(nv_alloc_t * nva,va_list valist)57 nv_fixed_init(nv_alloc_t *nva, va_list valist)
58 {
59 uintptr_t base = va_arg(valist, uintptr_t);
60 uintptr_t lim = base + va_arg(valist, size_t);
61 nvbuf_t *nvb = (nvbuf_t *)P2ROUNDUP(base, sizeof (uintptr_t));
62
63 if (base == 0 || (uintptr_t)&nvb[1] > lim)
64 return (EINVAL);
65
66 nvb->nvb_buf = (uintptr_t)&nvb[0];
67 nvb->nvb_cur = (uintptr_t)&nvb[1];
68 nvb->nvb_lim = lim;
69 nva->nva_arg = nvb;
70
71 return (0);
72 }
73
74 static void *
nv_fixed_alloc(nv_alloc_t * nva,size_t size)75 nv_fixed_alloc(nv_alloc_t *nva, size_t size)
76 {
77 nvbuf_t *nvb = nva->nva_arg;
78 uintptr_t new = nvb->nvb_cur;
79
80 if (size == 0 || new + size > nvb->nvb_lim)
81 return (NULL);
82
83 nvb->nvb_cur = P2ROUNDUP(new + size, sizeof (uintptr_t));
84
85 return ((void *)new);
86 }
87
88 static void
nv_fixed_free(nv_alloc_t * nva,void * buf,size_t size)89 nv_fixed_free(nv_alloc_t *nva, void *buf, size_t size)
90 {
91 /* don't free memory in the pre-allocated buffer */
92 (void) nva, (void) buf, (void) size;
93 }
94
95 static void
nv_fixed_reset(nv_alloc_t * nva)96 nv_fixed_reset(nv_alloc_t *nva)
97 {
98 nvbuf_t *nvb = nva->nva_arg;
99
100 nvb->nvb_cur = (uintptr_t)&nvb[1];
101 }
102
103 static const nv_alloc_ops_t nv_fixed_ops_def = {
104 .nv_ao_init = nv_fixed_init,
105 .nv_ao_fini = NULL,
106 .nv_ao_alloc = nv_fixed_alloc,
107 .nv_ao_free = nv_fixed_free,
108 .nv_ao_reset = nv_fixed_reset
109 };
110
111 const nv_alloc_ops_t *const nv_fixed_ops = &nv_fixed_ops_def;
112
113 #if defined(_KERNEL)
114 EXPORT_SYMBOL(nv_fixed_ops);
115 #endif
116