src/mapi/mapi/entry_x86_tls.h

   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    void *code = (void *) 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 }