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 2008 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 <unistd.h>
30#include <errno.h>
31#include <sys/mman.h>
32#include <sys/sysmacros.h>
33#include "vmem_base.h"
34
35#define	ALLOC_PROT	PROT_READ | PROT_WRITE | PROT_EXEC
36#define	FREE_PROT	PROT_NONE
37
38#define	ALLOC_FLAGS	MAP_PRIVATE | MAP_ANON
39#define	FREE_FLAGS	MAP_PRIVATE | MAP_ANON | MAP_NORESERVE
40
41#define	CHUNKSIZE	(64*1024)	/* 64 kilobytes */
42
43static vmem_t *mmap_heap;
44
45static void *
46vmem_mmap_alloc(vmem_t *src, size_t size, int vmflags)
47{
48	void *ret;
49	int old_errno = errno;
50
51	ret = vmem_alloc(src, size, vmflags);
52	if (ret != NULL &&
53	    mmap(ret, size, ALLOC_PROT, ALLOC_FLAGS | MAP_FIXED, -1, 0) ==
54	    MAP_FAILED) {
55		vmem_free(src, ret, size);
56		vmem_reap();
57
58		ASSERT((vmflags & VM_NOSLEEP) == VM_NOSLEEP);
59		errno = old_errno;
60		return (NULL);
61	}
62
63	errno = old_errno;
64	return (ret);
65}
66
67static void
68vmem_mmap_free(vmem_t *src, void *addr, size_t size)
69{
70	int old_errno = errno;
71	(void) mmap(addr, size, FREE_PROT, FREE_FLAGS | MAP_FIXED, -1, 0);
72	vmem_free(src, addr, size);
73	errno = old_errno;
74}
75
76static void *
77vmem_mmap_top_alloc(vmem_t *src, size_t size, int vmflags)
78{
79	void *ret;
80	void *buf;
81	int old_errno = errno;
82
83	ret = vmem_alloc(src, size, VM_NOSLEEP);
84
85	if (ret) {
86		errno = old_errno;
87		return (ret);
88	}
89	/*
90	 * Need to grow the heap
91	 */
92	buf = mmap((void *)CHUNKSIZE, size, FREE_PROT, FREE_FLAGS | MAP_ALIGN,
93	    -1, 0);
94
95	if (buf != MAP_FAILED) {
96		ret = _vmem_extend_alloc(src, buf, size, size, vmflags);
97		if (ret != NULL)
98			return (ret);
99		else {
100			(void) munmap(buf, size);
101			errno = old_errno;
102			return (NULL);
103		}
104	} else {
105		/*
106		 * Growing the heap failed.  The allocation above will
107		 * already have called umem_reap().
108		 */
109		ASSERT((vmflags & VM_NOSLEEP) == VM_NOSLEEP);
110
111		errno = old_errno;
112		return (NULL);
113	}
114}
115
116vmem_t *
117vmem_mmap_arena(vmem_alloc_t **a_out, vmem_free_t **f_out)
118{
119	size_t pagesize = sysconf(_SC_PAGESIZE);
120
121	if (mmap_heap == NULL) {
122		mmap_heap = vmem_init("mmap_top", CHUNKSIZE,
123		    vmem_mmap_top_alloc, vmem_free,
124		    "mmap_heap", NULL, 0, pagesize,
125		    vmem_mmap_alloc, vmem_mmap_free);
126	}
127
128	if (a_out != NULL)
129		*a_out = vmem_mmap_alloc;
130	if (f_out != NULL)
131		*f_out = vmem_mmap_free;
132
133	return (mmap_heap);
134}
135