1 /*
2 * Mesa 3-D graphics library
3 *
4 * Copyright (C) 1999-2005 Brian Paul 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 "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice shall be included
14 * in all copies or substantial portions of the Software.
15 *
16 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
17 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
19 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
20 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
21 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
22 * OTHER DEALINGS IN THE SOFTWARE.
23 */
24
25
26 /**
27 * \file glapi_execmem.c
28 *
29 * Function for allocating executable memory for dispatch stubs.
30 *
31 * Copied from main/execmem.c and simplified for dispatch stubs.
32 */
33
34
35 #include "c99_compat.h"
36 #include "c11/threads.h"
37 #include "u_execmem.h"
38
39
40 #define EXEC_MAP_SIZE (4*1024)
41
42 static mtx_t exec_mutex = _MTX_INITIALIZER_NP;
43
44 static unsigned int head = 0;
45
46 static unsigned char *exec_mem = (unsigned char *)0;
47
48
49 #if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || defined(__sun) || defined(__HAIKU__)
50
51 #include <unistd.h>
52 #include <sys/mman.h>
53
54 #ifdef MESA_SELINUX
55 #include <selinux/selinux.h>
56 #endif
57
58
59 #ifndef MAP_ANONYMOUS
60 #define MAP_ANONYMOUS MAP_ANON
61 #endif
62
63
64 /*
65 * Dispatch stubs are of fixed size and never freed. Thus, we do not need to
66 * overlay a heap, we just mmap a page and manage through an index.
67 */
68
69 static int
init_map(void)70 init_map(void)
71 {
72 #ifdef MESA_SELINUX
73 if (is_selinux_enabled()) {
74 if (!security_get_boolean_active("allow_execmem") ||
75 !security_get_boolean_pending("allow_execmem"))
76 return 0;
77 }
78 #endif
79
80 if (!exec_mem)
81 exec_mem = mmap(NULL, EXEC_MAP_SIZE, PROT_EXEC | PROT_READ | PROT_WRITE,
82 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
83
84 return (exec_mem != MAP_FAILED);
85 }
86
87
88 #elif defined(_WIN32)
89
90 #include <windows.h>
91
92
93 /*
94 * Avoid Data Execution Prevention.
95 */
96
97 static int
init_map(void)98 init_map(void)
99 {
100 exec_mem = VirtualAlloc(NULL, EXEC_MAP_SIZE, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
101
102 return (exec_mem != NULL);
103 }
104
105
106 #else
107
108 #include <stdlib.h>
109
110 static int
init_map(void)111 init_map(void)
112 {
113 exec_mem = malloc(EXEC_MAP_SIZE);
114
115 return (exec_mem != NULL);
116 }
117
118
119 #endif
120
121 void *
u_execmem_alloc(unsigned int size)122 u_execmem_alloc(unsigned int size)
123 {
124 void *addr = NULL;
125
126 mtx_lock(&exec_mutex);
127
128 if (!init_map())
129 goto bail;
130
131 /* free space check, assumes no integer overflow */
132 if (head + size > EXEC_MAP_SIZE)
133 goto bail;
134
135 /* allocation, assumes proper addr and size alignement */
136 addr = exec_mem + head;
137 head += size;
138
139 bail:
140 mtx_unlock(&exec_mutex);
141
142 return addr;
143 }
144
145
146