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  1. /*
  2.  * Mesa 3-D graphics library
  3.  *
  4.  * Copyright (C) 2010 LunarG Inc.
  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 OR
  17.  * 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 OTHER
  20.  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21.  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  22.  * DEALINGS IN THE SOFTWARE.
  23.  *
  24.  * Authors:
  25.  *    Chia-I Wu <olv@lunarg.com>
  26.  */
  27.  
  28. #include <string.h>
  29.  
  30. __asm__(".text");
  31.  
  32. __asm__("x86_current_tls:\n\t"
  33.         "call 1f\n"
  34.         "1:\n\t"
  35.         "popl %eax\n\t"
  36.         "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %eax\n\t"
  37.         "movl " ENTRY_CURRENT_TABLE "@GOTNTPOFF(%eax), %eax\n\t"
  38.         "ret");
  39.  
  40. #ifndef GLX_X86_READONLY_TEXT
  41. __asm__(".section wtext, \"awx\", @progbits");
  42. #endif /* GLX_X86_READONLY_TEXT */
  43.  
  44. __asm__(".balign 16\n"
  45.         "x86_entry_start:");
  46.  
  47. #define STUB_ASM_ENTRY(func)     \
  48.    ".globl " func "\n"           \
  49.    ".type " func ", @function\n" \
  50.    ".balign 16\n"                \
  51.    func ":"
  52.  
  53. #define STUB_ASM_CODE(slot)      \
  54.    "call x86_current_tls\n\t"    \
  55.    "movl %gs:(%eax), %eax\n\t"   \
  56.    "jmp *(4 * " slot ")(%eax)"
  57.  
  58. #define MAPI_TMP_STUB_ASM_GCC
  59. #include "mapi_tmp.h"
  60.  
  61. #ifndef GLX_X86_READONLY_TEXT
  62. __asm__(".balign 16\n"
  63.         "x86_entry_end:");
  64. __asm__(".text");
  65. #endif /* GLX_X86_READONLY_TEXT */
  66.  
  67. #ifndef MAPI_MODE_BRIDGE
  68.  
  69. #include "u_execmem.h"
  70.  
  71. extern unsigned long
  72. x86_current_tls();
  73.  
  74. static char x86_entry_start[];
  75. static char x86_entry_end[];
  76.  
  77. void
  78. entry_patch_public(void)
  79. {
  80. #ifndef GLX_X86_READONLY_TEXT
  81.    char patch[8] = {
  82.       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
  83.       0x90, 0x90                          /* nop's */
  84.    };
  85.    char *entry;
  86.  
  87.    *((unsigned long *) (patch + 2)) = x86_current_tls();
  88.  
  89.    for (entry = x86_entry_start; entry < x86_entry_end; entry += 16)
  90.       memcpy(entry, patch, sizeof(patch));
  91. #endif
  92. }
  93.  
  94. mapi_func
  95. entry_get_public(int slot)
  96. {
  97.    return (mapi_func) (x86_entry_start + slot * 16);
  98. }
  99.  
  100. void
  101. entry_patch(mapi_func entry, int slot)
  102. {
  103.    char *code = (char *) entry;
  104.    *((unsigned long *) (code + 8)) = slot * sizeof(mapi_func);
  105. }
  106.  
  107. mapi_func
  108. entry_generate(int slot)
  109. {
  110.    const char code_templ[16] = {
  111.       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
  112.       0xff, 0xa0, 0x34, 0x12, 0x00, 0x00, /* jmp *0x1234(%eax) */
  113.       0x90, 0x90, 0x90, 0x90              /* nop's */
  114.    };
  115.    char *code;
  116.    mapi_func entry;
  117.  
  118.    code = u_execmem_alloc(sizeof(code_templ));
  119.    if (!code)
  120.       return NULL;
  121.  
  122.    memcpy(code, code_templ, sizeof(code_templ));
  123.  
  124.    *((unsigned long *) (code + 2)) = x86_current_tls();
  125.    entry = (mapi_func) code;
  126.    entry_patch(entry, slot);
  127.  
  128.    return entry;
  129. }
  130.  
  131. #endif /* MAPI_MODE_BRIDGE */
  132.