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 "c11/threads.h" 36#include "u_execmem.h" 37 38 39#define EXEC_MAP_SIZE (4*1024) 40 41static mtx_t exec_mutex = _MTX_INITIALIZER_NP; 42 43static unsigned int head = 0; 44 45static unsigned char *exec_mem = (unsigned char *)0; 46 47 48#if defined(__linux__) || defined(__OpenBSD__) || defined(__NetBSD__) || defined(__sun) || defined(__HAIKU__) 49 50#include <unistd.h> 51#include <sys/mman.h> 52 53#ifdef MESA_SELINUX 54#include <selinux/selinux.h> 55#endif 56 57 58#ifndef MAP_ANONYMOUS 59#define MAP_ANONYMOUS MAP_ANON 60#endif 61 62 63/* 64 * Dispatch stubs are of fixed size and never freed. Thus, we do not need to 65 * overlay a heap, we just mmap a page and manage through an index. 66 */ 67 68static int 69init_map(void) 70{ 71#ifdef MESA_SELINUX 72 if (is_selinux_enabled()) { 73 if (!security_get_boolean_active("allow_execmem") || 74 !security_get_boolean_pending("allow_execmem")) 75 return 0; 76 } 77#endif 78 79 if (!exec_mem) 80 exec_mem = mmap(NULL, EXEC_MAP_SIZE, PROT_EXEC | PROT_READ | PROT_WRITE, 81 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 82 83 return (exec_mem != MAP_FAILED); 84} 85 86 87#elif defined(_WIN32) 88 89#include <windows.h> 90 91 92/* 93 * Avoid Data Execution Prevention. 94 */ 95 96static int 97init_map(void) 98{ 99 exec_mem = VirtualAlloc(NULL, EXEC_MAP_SIZE, MEM_COMMIT, PAGE_EXECUTE_READWRITE); 100 101 return (exec_mem != NULL); 102} 103 104 105#else 106 107#include <stdlib.h> 108 109static int 110init_map(void) 111{ 112 exec_mem = malloc(EXEC_MAP_SIZE); 113 114 return (exec_mem != NULL); 115} 116 117 118#endif 119 120void * 121u_execmem_alloc(unsigned int size) 122{ 123#ifndef MESA_EXECMEM 124 (void)size; 125 return NULL; 126#else 127 void *addr = NULL; 128 129 mtx_lock(&exec_mutex); 130 131 if (!init_map()) 132 goto bail; 133 134 /* free space check, assumes no integer overflow */ 135 if (head + size > EXEC_MAP_SIZE) 136 goto bail; 137 138 /* allocation, assumes proper addr and size alignement */ 139 addr = exec_mem + head; 140 head += size; 141 142bail: 143 mtx_unlock(&exec_mutex); 144 145 return addr; 146#endif /* MESA_EXECMEM */ 147} 148 149 150