1 // SPDX-License-Identifier: CDDL-1.0
2 /*
3 * CDDL HEADER START
4 *
5 * The contents of this file are subject to the terms of the
6 * Common Development and Distribution License (the "License").
7 * You may not use this file except in compliance with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or https://opensource.org/licenses/CDDL-1.0.
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 2006 Sun Microsystems, Inc. All rights reserved.
25 * Use is subject to license terms.
26 */
27
28 #include <sys/isa_defs.h>
29 #include <sys/nvpair.h>
30 #include <sys/sysmacros.h>
31
32 /*
33 * This allocator is very simple.
34 * - it uses a pre-allocated buffer for memory allocations.
35 * - it does _not_ free memory in the pre-allocated buffer.
36 *
37 * The reason for the selected implementation is simplicity.
38 * This allocator is designed for the usage in interrupt context when
39 * the caller may not wait for free memory.
40 */
41
42 /* pre-allocated buffer for memory allocations */
43 typedef struct nvbuf {
44 uintptr_t nvb_buf; /* address of pre-allocated buffer */
45 uintptr_t nvb_lim; /* limit address in the buffer */
46 uintptr_t nvb_cur; /* current address in the buffer */
47 } nvbuf_t;
48
49 /*
50 * Initialize the pre-allocated buffer allocator. The caller needs to supply
51 *
52 * buf address of pre-allocated buffer
53 * bufsz size of pre-allocated buffer
54 *
55 * nv_fixed_init() calculates the remaining members of nvbuf_t.
56 */
57 static int
nv_fixed_init(nv_alloc_t * nva,va_list valist)58 nv_fixed_init(nv_alloc_t *nva, va_list valist)
59 {
60 uintptr_t base = va_arg(valist, uintptr_t);
61 uintptr_t lim = base + va_arg(valist, size_t);
62 nvbuf_t *nvb = (nvbuf_t *)P2ROUNDUP(base, sizeof (uintptr_t));
63
64 if (base == 0 || (uintptr_t)&nvb[1] > lim)
65 return (EINVAL);
66
67 nvb->nvb_buf = (uintptr_t)&nvb[0];
68 nvb->nvb_cur = (uintptr_t)&nvb[1];
69 nvb->nvb_lim = lim;
70 nva->nva_arg = nvb;
71
72 return (0);
73 }
74
75 static void *
nv_fixed_alloc(nv_alloc_t * nva,size_t size)76 nv_fixed_alloc(nv_alloc_t *nva, size_t size)
77 {
78 nvbuf_t *nvb = nva->nva_arg;
79 uintptr_t new = nvb->nvb_cur;
80
81 if (size == 0 || new + size > nvb->nvb_lim)
82 return (NULL);
83
84 nvb->nvb_cur = P2ROUNDUP(new + size, sizeof (uintptr_t));
85
86 return ((void *)new);
87 }
88
89 static void
nv_fixed_free(nv_alloc_t * nva,void * buf,size_t size)90 nv_fixed_free(nv_alloc_t *nva, void *buf, size_t size)
91 {
92 /* don't free memory in the pre-allocated buffer */
93 (void) nva, (void) buf, (void) size;
94 }
95
96 static void
nv_fixed_reset(nv_alloc_t * nva)97 nv_fixed_reset(nv_alloc_t *nva)
98 {
99 nvbuf_t *nvb = nva->nva_arg;
100
101 nvb->nvb_cur = (uintptr_t)&nvb[1];
102 }
103
104 static const nv_alloc_ops_t nv_fixed_ops_def = {
105 .nv_ao_init = nv_fixed_init,
106 .nv_ao_fini = NULL,
107 .nv_ao_alloc = nv_fixed_alloc,
108 .nv_ao_free = nv_fixed_free,
109 .nv_ao_reset = nv_fixed_reset
110 };
111
112 const nv_alloc_ops_t *const nv_fixed_ops = &nv_fixed_ops_def;
113
114 #if defined(_KERNEL)
115 EXPORT_SYMBOL(nv_fixed_ops);
116 #endif
117