src/mapi/entry_x86_tls.h

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