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 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 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 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 * 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