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 
43 static vmem_t *mmap_heap;
44 
45 static void *
vmem_mmap_alloc(vmem_t * src,size_t size,int vmflags)46 vmem_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 
67 static void
vmem_mmap_free(vmem_t * src,void * addr,size_t size)68 vmem_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 
76 static void *
vmem_mmap_top_alloc(vmem_t * src,size_t size,int vmflags)77 vmem_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 
116 vmem_t *
vmem_mmap_arena(vmem_alloc_t ** a_out,vmem_free_t ** f_out)117 vmem_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