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 #ifdef __linux__
  34 __asm__(".section .note.ABI-tag, \"a\"\n\t"
  35         ".p2align 2\n\t"
  36         ".long 1f - 0f\n\t"      /* name length */
  37         ".long 3f - 2f\n\t"      /* data length */
  38         ".long 1\n\t"            /* note length */
  39         "0: .asciz \"GNU\"\n\t"  /* vendor name */
  40         "1: .p2align 2\n\t"
  41         "2: .long 0\n\t"         /* note data: the ABI tag */
  42         ".long 2,4,20\n\t"       /* Minimum kernel version w/TLS */
  43         "3: .p2align 2\n\t");    /* pad out section */
  44 #endif /* __linux__ */
  45
  46 __asm__(".text");
  47
  48 __asm__("x86_current_tls:\n\t"
  49         "call 1f\n"
  50         "1:\n\t"
  51         "popl %eax\n\t"
  52         "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %eax\n\t"
  53         "movl u_current_table@GOTNTPOFF(%eax), %eax\n\t"
  54         "ret");
  55
  56 #ifndef GLX_X86_READONLY_TEXT
  57 __asm__(".section wtext, \"awx\", @progbits\n"
  58         ".balign 16\n"
  59         "x86_entry_start:");
  60 #endif /* GLX_X86_READONLY_TEXT */
  61
  62 #define STUB_ASM_ENTRY(func)     \
  63    ".globl " func "\n"           \
  64    ".type " func ", @function\n" \
  65    ".balign 16\n"                \
  66    func ":"
  67
  68 #define STUB_ASM_CODE(slot)      \
  69    "call x86_current_tls\n\t"    \
  70    "movl %gs:(%eax), %eax\n\t"   \
  71    "jmp *(4 * " slot ")(%eax)"
  72
  73 #define MAPI_TMP_STUB_ASM_GCC
  74 #include "mapi_tmp.h"
  75
  76 #ifndef GLX_X86_READONLY_TEXT
  77 __asm__(".balign 16\n"
  78         "x86_entry_end:");
  79 __asm__(".text");
  80 #endif /* GLX_X86_READONLY_TEXT */
  81
  82 extern unsigned long
  83 x86_current_tls();
  84
  85 void
  86 entry_patch_public(void)
  87 {
  88 #ifndef GLX_X86_READONLY_TEXT
  89    extern char x86_entry_start[];
  90    extern char x86_entry_end[];
  91    char patch[8] = {
  92       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
  93       0x90, 0x90                          /* nop's */
  94    };
  95    char *entry;
  96
  97    *((unsigned long *) (patch + 2)) = x86_current_tls();
  98
  99    for (entry = x86_entry_start; entry < x86_entry_end; entry += 16)
 100       memcpy(entry, patch, sizeof(patch));
 101 #endif
 102 }
 103
 104 void
 105 entry_patch(mapi_func entry, int slot)
 106 {
 107    char *code = (char *) entry;
 108    *((unsigned long *) (code + 8)) = slot * sizeof(mapi_func);
 109 }
 110
 111 mapi_func
 112 entry_generate(int slot)
 113 {
 114    const char code_templ[16] = {
 115       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
 116       0xff, 0xa0, 0x34, 0x12, 0x00, 0x00, /* jmp *0x1234(%eax) */
 117       0x90, 0x90, 0x90, 0x90              /* nop's */
 118    };
 119    void *code;
 120    mapi_func entry;
 121
 122    code = u_execmem_alloc(sizeof(code_templ));
 123    if (!code)
 124       return NULL;
 125
 126    memcpy(code, code_templ, sizeof(code_templ));
 127
 128    *((unsigned long *) (code + 2)) = x86_current_tls();
 129    entry = (mapi_func) code;
 130    entry_patch(entry, slot);
 131
 132    return entry;
 133 }