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 "c_synonyms.h"
30 #include <unistd.h>
31 #include <errno.h>
32 #include <sys/mman.h>
33 #include <sys/sysmacros.h>
34 #include "vmem_base.h"
35 
36 #define	ALLOC_PROT	PROT_READ | PROT_WRITE | PROT_EXEC
37 #define	FREE_PROT	PROT_NONE
38 
39 #define	ALLOC_FLAGS	MAP_PRIVATE | MAP_ANON
40 #define	FREE_FLAGS	MAP_PRIVATE | MAP_ANON | MAP_NORESERVE
41 
42 #define	CHUNKSIZE	(64*1024)	/* 64 kilobytes */
43 
44 static vmem_t *mmap_heap;
45 
46 static void *
47 vmem_mmap_alloc(vmem_t *src, size_t size, int vmflags)
48 {
49 	void *ret;
50 	int old_errno = errno;
51 
52 	ret = vmem_alloc(src, size, vmflags);
53 	if (ret != NULL &&
54 	    mmap(ret, size, ALLOC_PROT, ALLOC_FLAGS | MAP_FIXED, -1, 0) ==
55 	    MAP_FAILED) {
56 		vmem_free(src, ret, size);
57 		vmem_reap();
58 
59 		ASSERT((vmflags & VM_NOSLEEP) == VM_NOSLEEP);
60 		errno = old_errno;
61 		return (NULL);
62 	}
63 
64 	errno = old_errno;
65 	return (ret);
66 }
67 
68 static void
69 vmem_mmap_free(vmem_t *src, void *addr, size_t size)
70 {
71 	int old_errno = errno;
72 	(void) mmap(addr, size, FREE_PROT, FREE_FLAGS | MAP_FIXED, -1, 0);
73 	vmem_free(src, addr, size);
74 	errno = old_errno;
75 }
76 
77 static void *
78 vmem_mmap_top_alloc(vmem_t *src, size_t size, int vmflags)
79 {
80 	void *ret;
81 	void *buf;
82 	int old_errno = errno;
83 
84 	ret = vmem_alloc(src, size, VM_NOSLEEP);
85 
86 	if (ret) {
87 		errno = old_errno;
88 		return (ret);
89 	}
90 	/*
91 	 * Need to grow the heap
92 	 */
93 	buf = mmap((void *)CHUNKSIZE, size, FREE_PROT, FREE_FLAGS | MAP_ALIGN,
94 	    -1, 0);
95 
96 	if (buf != MAP_FAILED) {
97 		ret = _vmem_extend_alloc(src, buf, size, size, vmflags);
98 		if (ret != NULL)
99 			return (ret);
100 		else {
101 			(void) munmap(buf, size);
102 			errno = old_errno;
103 			return (NULL);
104 		}
105 	} else {
106 		/*
107 		 * Growing the heap failed.  The allocation above will
108 		 * already have called umem_reap().
109 		 */
110 		ASSERT((vmflags & VM_NOSLEEP) == VM_NOSLEEP);
111 
112 		errno = old_errno;
113 		return (NULL);
114 	}
115 }
116 
117 vmem_t *
118 vmem_mmap_arena(vmem_alloc_t **a_out, vmem_free_t **f_out)
119 {
120 	size_t pagesize = sysconf(_SC_PAGESIZE);
121 
122 	if (mmap_heap == NULL) {
123 		mmap_heap = vmem_init("mmap_top", CHUNKSIZE,
124 		    vmem_mmap_top_alloc, vmem_free,
125 		    "mmap_heap", NULL, 0, pagesize,
126 		    vmem_mmap_alloc, vmem_mmap_free);
127 	}
128 
129 	if (a_out != NULL)
130 		*a_out = vmem_mmap_alloc;
131 	if (f_out != NULL)
132 		*f_out = vmem_mmap_free;
133 
134 	return (mmap_heap);
135 }
136