1 /**************************************************************************
2 *
3 * Copyright 2008-2010 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28
29 /*
30 * Memory alignment wrappers.
31 */
32
33
34 #ifndef _OS_MEMORY_H_
35 #error "Must not be included directly. Include os_memory.h instead"
36 #endif
37
38
39 #include "pipe/p_compiler.h"
40
41
42
43 /**
44 * Add two size_t values with integer overflow check.
45 * TODO: leverage __builtin_add_overflow where available
46 */
47 static inline bool
add_overflow_size_t(size_t a,size_t b,size_t * res)48 add_overflow_size_t(size_t a, size_t b, size_t *res)
49 {
50 *res = a + b;
51 return *res < a || *res < b;
52 }
53
54
55 /**
56 * Return memory on given byte alignment
57 */
58 static inline void *
os_malloc_aligned(size_t size,size_t alignment)59 os_malloc_aligned(size_t size, size_t alignment)
60 {
61 char *ptr, *buf;
62 size_t alloc_size;
63
64 /*
65 * Calculate
66 *
67 * alloc_size = size + alignment + sizeof(void *)
68 *
69 * while checking for overflow.
70 */
71 if (add_overflow_size_t(size, alignment, &alloc_size) ||
72 add_overflow_size_t(alloc_size, sizeof(void *), &alloc_size)) {
73 return NULL;
74 }
75
76 ptr = (char *) os_malloc(alloc_size);
77 if (!ptr)
78 return NULL;
79
80 buf = (char *)(((uintptr_t)ptr + sizeof(void *) + alignment - 1) & ~((uintptr_t)(alignment - 1)));
81 *(char **)(buf - sizeof(void *)) = ptr;
82
83 return buf;
84 }
85
86
87 /**
88 * Free memory returned by align_malloc().
89 */
90 static inline void
os_free_aligned(void * ptr)91 os_free_aligned(void *ptr)
92 {
93 if (ptr) {
94 void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
95 void *realAddr = *cubbyHole;
96 os_free(realAddr);
97 }
98 }
99