src/mapi/glapi/glapi_execmem.c

   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 #ifdef HAVE_DIX_CONFIG_H
  36 #include <dix-config.h>
  37 #include "glapi/mesa.h"
  38 #else
  39 #include "main/compiler.h"
  40 #endif
  41
  42 #include "glapi/glthread.h"
  43 #include "glapi/glapi_priv.h"
  44
  45
  46 #if defined(__linux__) || defined(__OpenBSD__) || defined(_NetBSD__) || defined(__sun)
  47
  48 #include <unistd.h>
  49 #include <sys/mman.h>
  50
  51 #ifdef MESA_SELINUX
  52 #include <selinux/selinux.h>
  53 #endif
  54
  55
  56 #ifndef MAP_ANONYMOUS
  57 #define MAP_ANONYMOUS MAP_ANON
  58 #endif
  59
  60
  61 #define EXEC_MAP_SIZE (4*1024)
  62
  63 _glthread_DECLARE_STATIC_MUTEX(exec_mutex);
  64
  65 static unsigned int head = 0;
  66
  67 static unsigned char *exec_mem = NULL;
  68
  69
  70 /*
  71  * Dispatch stubs are of fixed size and never freed. Thus, we do not need to
  72  * overlay a heap, we just mmap a page and manage through an index.
  73  */
  74
  75 static int
  76 init_map(void)
  77 {
  78 #ifdef MESA_SELINUX
  79    if (is_selinux_enabled()) {
  80       if (!security_get_boolean_active("allow_execmem") ||
  81           !security_get_boolean_pending("allow_execmem"))
  82          return 0;
  83    }
  84 #endif
  85
  86    if (!exec_mem)
  87       exec_mem = mmap(NULL, EXEC_MAP_SIZE, PROT_EXEC | PROT_READ | PROT_WRITE,
  88                       MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  89
  90    return (exec_mem != MAP_FAILED);
  91 }
  92
  93
  94 void *
  95 _glapi_exec_malloc(unsigned int size)
  96 {
  97    void *addr = NULL;
  98
  99    _glthread_LOCK_MUTEX(exec_mutex);
 100
 101    if (!init_map())
 102       goto bail;
 103
 104    /* free space check, assumes no integer overflow */
 105    if (head + size > EXEC_MAP_SIZE)
 106       goto bail;
 107
 108    /* allocation, assumes proper addr and size alignement */
 109    addr = exec_mem + head;
 110    head += size;
 111
 112 bail:
 113    _glthread_UNLOCK_MUTEX(exec_mutex);
 114
 115    return addr;
 116 }
 117
 118
 119 #else
 120
 121 void *
 122 _glapi_exec_malloc(unsigned int size)
 123 {
 124    return malloc(size);
 125 }
 126
 127
 128 #endif