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
42static mtx_t exec_mutex = _MTX_INITIALIZER_NP;
43
44static unsigned int head = 0;
45
46static 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
69static int
70init_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
97static int
98init_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
110static int
111init_map(void)
112{
113   exec_mem = malloc(EXEC_MAP_SIZE);
114
115   return (exec_mem != NULL);
116}
117
118
119#endif
120
121void *
122u_execmem_alloc(unsigned int size)
123{
124#ifndef MESA_EXECMEM
125   (void)size;
126   return NULL;
127#else
128   void *addr = NULL;
129
130   mtx_lock(&exec_mutex);
131
132   if (!init_map())
133      goto bail;
134
135   /* free space check, assumes no integer overflow */
136   if (head + size > EXEC_MAP_SIZE)
137      goto bail;
138
139   /* allocation, assumes proper addr and size alignement */
140   addr = exec_mem + head;
141   head += size;
142
143bail:
144   mtx_unlock(&exec_mutex);
145
146   return addr;
147#endif /* MESA_EXECMEM */
148}
149
150
151