xref: /illumos-gate/usr/src/lib/libumem/common/vmem_mmap.c (revision c6eba0f30b7d496dd9279554bb3d5f7da0a397fe)
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 #include <unistd.h>
28 #include <errno.h>
29 #include <sys/mman.h>
30 #include <sys/sysmacros.h>
31 #include "vmem_base.h"
32 
33 #define	ALLOC_PROT	PROT_READ | PROT_WRITE | PROT_EXEC
34 #define	FREE_PROT	PROT_NONE
35 
36 #define	ALLOC_FLAGS	MAP_PRIVATE | MAP_ANON
37 #define	FREE_FLAGS	MAP_PRIVATE | MAP_ANON | MAP_NORESERVE
38 
39 #define	CHUNKSIZE	(64*1024)	/* 64 kilobytes */
40 
41 static vmem_t *mmap_heap;
42 
43 static void *
44 vmem_mmap_alloc(vmem_t *src, size_t size, int vmflags)
45 {
46 	void *ret;
47 	int old_errno = errno;
48 
49 	ret = vmem_alloc(src, size, vmflags);
50 	if (ret != NULL &&
51 	    mmap(ret, size, ALLOC_PROT, ALLOC_FLAGS | MAP_FIXED, -1, 0) ==
52 	    MAP_FAILED) {
53 		vmem_free(src, ret, size);
54 		vmem_reap();
55 
56 		ASSERT((vmflags & VM_NOSLEEP) == VM_NOSLEEP);
57 		errno = old_errno;
58 		return (NULL);
59 	}
60 
61 	errno = old_errno;
62 	return (ret);
63 }
64 
65 static void
66 vmem_mmap_free(vmem_t *src, void *addr, size_t size)
67 {
68 	int old_errno = errno;
69 	(void) mmap(addr, size, FREE_PROT, FREE_FLAGS | MAP_FIXED, -1, 0);
70 	vmem_free(src, addr, size);
71 	errno = old_errno;
72 }
73 
74 static void *
75 vmem_mmap_top_alloc(vmem_t *src, size_t size, int vmflags)
76 {
77 	void *ret;
78 	void *buf;
79 	int old_errno = errno;
80 
81 	ret = vmem_alloc(src, size, VM_NOSLEEP);
82 
83 	if (ret) {
84 		errno = old_errno;
85 		return (ret);
86 	}
87 	/*
88 	 * Need to grow the heap
89 	 */
90 	buf = mmap((void *)CHUNKSIZE, size, FREE_PROT, FREE_FLAGS | MAP_ALIGN,
91 	    -1, 0);
92 
93 	if (buf != MAP_FAILED) {
94 		ret = _vmem_extend_alloc(src, buf, size, size, vmflags);
95 		if (ret != NULL)
96 			return (ret);
97 		else {
98 			(void) munmap(buf, size);
99 			errno = old_errno;
100 			return (NULL);
101 		}
102 	} else {
103 		/*
104 		 * Growing the heap failed.  The allocation above will
105 		 * already have called umem_reap().
106 		 */
107 		ASSERT((vmflags & VM_NOSLEEP) == VM_NOSLEEP);
108 
109 		errno = old_errno;
110 		return (NULL);
111 	}
112 }
113 
114 vmem_t *
115 vmem_mmap_arena(vmem_alloc_t **a_out, vmem_free_t **f_out)
116 {
117 	size_t pagesize = sysconf(_SC_PAGESIZE);
118 
119 	if (mmap_heap == NULL) {
120 		mmap_heap = vmem_init("mmap_top", CHUNKSIZE,
121 		    vmem_mmap_top_alloc, vmem_free,
122 		    "mmap_heap", NULL, 0, pagesize,
123 		    vmem_mmap_alloc, vmem_mmap_free);
124 	}
125 
126 	if (a_out != NULL)
127 		*a_out = vmem_mmap_alloc;
128 	if (f_out != NULL)
129 		*f_out = vmem_mmap_free;
130 
131 	return (mmap_heap);
132 }
133