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      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/nvpair.h>
     30 #include <sys/sysmacros.h>
     31 #if defined(_KERNEL) && !defined(_BOOT)
     32 #include <sys/varargs.h>
     33 #else
     34 #include <stdarg.h>
     35 #include <strings.h>
     36 #endif
     37 
     38 /*
     39  * This allocator is very simple.
     40  *  - it uses a pre-allocated buffer for memory allocations.
     41  *  - it does _not_ free memory in the pre-allocated buffer.
     42  *
     43  * The reason for the selected implemention is simplicity.
     44  * This allocator is designed for the usage in interrupt context when
     45  * the caller may not wait for free memory.
     46  */
     47 
     48 /* pre-allocated buffer for memory allocations */
     49 typedef struct nvbuf {
     50 	uintptr_t	nvb_buf;	/* address of pre-allocated buffer */
     51 	uintptr_t 	nvb_lim;	/* limit address in the buffer */
     52 	uintptr_t	nvb_cur;	/* current address in the buffer */
     53 } nvbuf_t;
     54 
     55 /*
     56  * Initialize the pre-allocated buffer allocator. The caller needs to supply
     57  *
     58  *   buf	address of pre-allocated buffer
     59  *   bufsz	size of pre-allocated buffer
     60  *
     61  * nv_fixed_init() calculates the remaining members of nvbuf_t.
     62  */
     63 static int
     64 nv_fixed_init(nv_alloc_t *nva, va_list valist)
     65 {
     66 	uintptr_t base = va_arg(valist, uintptr_t);
     67 	uintptr_t lim = base + va_arg(valist, size_t);
     68 	nvbuf_t *nvb = (nvbuf_t *)P2ROUNDUP(base, sizeof (uintptr_t));
     69 
     70 	if (base == 0 || (uintptr_t)&nvb[1] > lim)
     71 		return (EINVAL);
     72 
     73 	nvb->nvb_buf = (uintptr_t)&nvb[0];
     74 	nvb->nvb_cur = (uintptr_t)&nvb[1];
     75 	nvb->nvb_lim = lim;
     76 	nva->nva_arg = nvb;
     77 
     78 	return (0);
     79 }
     80 
     81 static void *
     82 nv_fixed_alloc(nv_alloc_t *nva, size_t size)
     83 {
     84 	nvbuf_t *nvb = nva->nva_arg;
     85 	uintptr_t new = nvb->nvb_cur;
     86 
     87 	if (size == 0 || new + size > nvb->nvb_lim)
     88 		return (NULL);
     89 
     90 	nvb->nvb_cur = P2ROUNDUP(new + size, sizeof (uintptr_t));
     91 
     92 	return ((void *)new);
     93 }
     94 
     95 /*ARGSUSED*/
     96 static void
     97 nv_fixed_free(nv_alloc_t *nva, void *buf, size_t size)
     98 {
     99 	/* don't free memory in the pre-allocated buffer */
    100 }
    101 
    102 static void
    103 nv_fixed_reset(nv_alloc_t *nva)
    104 {
    105 	nvbuf_t *nvb = nva->nva_arg;
    106 
    107 	nvb->nvb_cur = (uintptr_t)&nvb[1];
    108 }
    109 
    110 const nv_alloc_ops_t nv_fixed_ops_def = {
    111 	nv_fixed_init,	/* nv_ao_init() */
    112 	NULL,		/* nv_ao_fini() */
    113 	nv_fixed_alloc,	/* nv_ao_alloc() */
    114 	nv_fixed_free,	/* nv_ao_free() */
    115 	nv_fixed_reset	/* nv_ao_reset() */
    116 };
    117 
    118 const nv_alloc_ops_t *nv_fixed_ops = &nv_fixed_ops_def;
    119