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 #pragma weak _sbrk = sbrk
30 #pragma weak _brk = brk
31
32 #include "lint.h"
33 #include <synch.h>
34 #include <errno.h>
35 #include <sys/isa_defs.h>
36 #include <sys/types.h>
37 #include <sys/sysmacros.h>
38 #include <inttypes.h>
39 #include <unistd.h>
40 #include "mtlib.h"
41 #include "libc.h"
42
43 extern int _end;
44 void *_nd = &_end;
45 mutex_t __sbrk_lock = DEFAULTMUTEX;
46
47 extern int _brk_unlocked(void *);
48 extern void *_sbrk_unlocked(intptr_t);
49
50 /*
51 * The break must always be at least 8-byte aligned
52 */
53 #if (_MAX_ALIGNMENT < 8)
54 #define ALIGNSZ 8
55 #else
56 #define ALIGNSZ _MAX_ALIGNMENT
57 #endif
58
59 #define BRKALIGN(x) (caddr_t)P2ROUNDUP((uintptr_t)(x), ALIGNSZ)
60
61 void *
62 sbrk(intptr_t addend)
63 {
64 void *result;
65
66 if (!primary_link_map) {
67 errno = ENOTSUP;
68 return ((void *)-1);
69 }
70 lmutex_lock(&__sbrk_lock);
71 result = _sbrk_unlocked(addend);
72 lmutex_unlock(&__sbrk_lock);
73
74 return (result);
75 }
76
77 /*
78 * _sbrk_unlocked() aligns the old break, adds the addend, aligns
79 * the new break, and calls _brk_unlocked() to set the new break.
80 * We must align the old break because _nd may begin life misaligned.
81 * The addend can be either positive or negative, so there are two
82 * overflow/underflow edge conditions to reject:
83 *
84 * - the addend is negative and brk + addend < 0.
85 * - the addend is positive and brk + addend > ULONG_MAX
86 */
87 void *
88 _sbrk_unlocked(intptr_t addend)
89 {
90 char *old_brk = BRKALIGN(_nd);
91 char *new_brk = BRKALIGN(old_brk + addend);
92
93 if ((addend > 0 && new_brk < old_brk) ||
94 (addend < 0 && new_brk > old_brk)) {
95 errno = ENOMEM;
96 return ((void *)-1);
97 }
98 if (_brk_unlocked(new_brk) != 0)
99 return ((void *)-1);
100 _nd = new_brk;
101 return (old_brk);
102 }
103
104 /*
105 * _sbrk_grow_aligned() aligns the old break to a low_align boundry,
106 * adds min_size, aligns to a high_align boundry, and calls _brk_unlocked()
107 * to set the new break. The low_aligned-aligned value is returned, and
108 * the actual space allocated is returned through actual_size.
109 *
110 * Unlike sbrk(2), _sbrk_grow_aligned takes an unsigned size, and does
111 * not allow shrinking the heap.
112 */
113 void *
114 _sbrk_grow_aligned(size_t min_size, size_t low_align, size_t high_align,
115 size_t *actual_size)
116 {
117 uintptr_t old_brk;
118 uintptr_t ret_brk;
119 uintptr_t high_brk;
120 uintptr_t new_brk;
121 int brk_result;
122
123 if (!primary_link_map) {
124 errno = ENOTSUP;
125 return ((void *)-1);
126 }
127 if ((low_align & (low_align - 1)) != 0 ||
128 (high_align & (high_align - 1)) != 0) {
129 errno = EINVAL;
130 return ((void *)-1);
131 }
132 low_align = MAX(low_align, ALIGNSZ);
133 high_align = MAX(high_align, ALIGNSZ);
134
135 lmutex_lock(&__sbrk_lock);
136
137 old_brk = (uintptr_t)BRKALIGN(_nd);
138 ret_brk = P2ROUNDUP(old_brk, low_align);
139 high_brk = ret_brk + min_size;
140 new_brk = P2ROUNDUP(high_brk, high_align);
141
142 /*
143 * Check for overflow
144 */
145 if (ret_brk < old_brk || high_brk < ret_brk || new_brk < high_brk) {
146 lmutex_unlock(&__sbrk_lock);
147 errno = ENOMEM;
148 return ((void *)-1);
149 }
150
151 if ((brk_result = _brk_unlocked((void *)new_brk)) == 0)
152 _nd = (void *)new_brk;
153 lmutex_unlock(&__sbrk_lock);
154
155 if (brk_result != 0)
156 return ((void *)-1);
157
158 if (actual_size != NULL)
159 *actual_size = (new_brk - ret_brk);
160 return ((void *)ret_brk);
161 }
162
163 int
164 brk(void *new_brk)
165 {
166 int result;
167
168 if (!primary_link_map) {
169 errno = ENOTSUP;
170 return (-1);
171 }
172 /*
173 * Need to align this here; _brk_unlocked won't do it for us.
174 */
175 new_brk = BRKALIGN(new_brk);
176
177 lmutex_lock(&__sbrk_lock);
178 if ((result = _brk_unlocked(new_brk)) == 0)
179 _nd = new_brk;
180 lmutex_unlock(&__sbrk_lock);
181
182 return (result);
183 }