1/*
2 * Mesa 3-D graphics library
3 * Version:  6.5
4 *
5 * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
20 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
21 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22 * CONNECTION WITH THE SOFTWARE OR THE USE OR 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 "u_compiler.h"
36#include "u_thread.h"
37#include "u_execmem.h"
38
39
40#define EXEC_MAP_SIZE (4*1024)
41
42u_mutex_declare_static(exec_mutex);
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)
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   void *addr = NULL;
125
126   u_mutex_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
139bail:
140   u_mutex_unlock(exec_mutex);
141
142   return addr;
143}
144
145
146