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  1. /*
  2.  * Mesa 3-D graphics library
  3.  * Version:  7.9
  4.  *
  5.  * Copyright (C) 2010 LunarG Inc.
  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 OR
  18.  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19.  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20.  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21.  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  22.  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  23.  * DEALINGS IN THE SOFTWARE.
  24.  *
  25.  * Authors:
  26.  *    Chia-I Wu <olv@lunarg.com>
  27.  */
  28.  
  29. #include <string.h>
  30. #include "u_execmem.h"
  31. #include "u_macros.h"
  32.  
  33. __asm__(".text");
  34.  
  35. __asm__("x86_current_tls:\n\t"
  36.         "call 1f\n"
  37.         "1:\n\t"
  38.         "popl %eax\n\t"
  39.         "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %eax\n\t"
  40.         "movl u_current_table_tls@GOTNTPOFF(%eax), %eax\n\t"
  41.         "ret");
  42.  
  43. #ifndef GLX_X86_READONLY_TEXT
  44. __asm__(".section wtext, \"awx\", @progbits\n"
  45.         ".balign 16\n"
  46.         "x86_entry_start:");
  47. #endif /* GLX_X86_READONLY_TEXT */
  48.  
  49. #define STUB_ASM_ENTRY(func)     \
  50.    ".globl " func "\n"           \
  51.    ".type " func ", @function\n" \
  52.    ".balign 16\n"                \
  53.    func ":"
  54.  
  55. #define STUB_ASM_CODE(slot)      \
  56.    "call x86_current_tls\n\t"    \
  57.    "movl %gs:(%eax), %eax\n\t"   \
  58.    "jmp *(4 * " slot ")(%eax)"
  59.  
  60. #define MAPI_TMP_STUB_ASM_GCC
  61. #include "mapi_tmp.h"
  62.  
  63. #ifndef GLX_X86_READONLY_TEXT
  64. __asm__(".balign 16\n"
  65.         "x86_entry_end:");
  66. __asm__(".text");
  67. #endif /* GLX_X86_READONLY_TEXT */
  68.  
  69. extern unsigned long
  70. x86_current_tls();
  71.  
  72. void
  73. entry_patch_public(void)
  74. {
  75. #ifndef GLX_X86_READONLY_TEXT
  76.    extern char x86_entry_start[];
  77.    extern char x86_entry_end[];
  78.    char patch[8] = {
  79.       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
  80.       0x90, 0x90                          /* nop's */
  81.    };
  82.    char *entry;
  83.  
  84.    *((unsigned long *) (patch + 2)) = x86_current_tls();
  85.  
  86.    for (entry = x86_entry_start; entry < x86_entry_end; entry += 16)
  87.       memcpy(entry, patch, sizeof(patch));
  88. #endif
  89. }
  90.  
  91. void
  92. entry_patch(mapi_func entry, int slot)
  93. {
  94.    char *code = (char *) entry;
  95.    *((unsigned long *) (code + 8)) = slot * sizeof(mapi_func);
  96. }
  97.  
  98. mapi_func
  99. entry_generate(int slot)
  100. {
  101.    const char code_templ[16] = {
  102.       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
  103.       0xff, 0xa0, 0x34, 0x12, 0x00, 0x00, /* jmp *0x1234(%eax) */
  104.       0x90, 0x90, 0x90, 0x90              /* nop's */
  105.    };
  106.    void *code;
  107.    mapi_func entry;
  108.  
  109.    code = u_execmem_alloc(sizeof(code_templ));
  110.    if (!code)
  111.       return NULL;
  112.  
  113.    memcpy(code, code_templ, sizeof(code_templ));
  114.  
  115.    *((unsigned long *) (code + 2)) = x86_current_tls();
  116.    entry = (mapi_func) code;
  117.    entry_patch(entry, slot);
  118.  
  119.    return entry;
  120. }
  121.