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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/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
     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 *
     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
     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
    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