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");
  58 #endif /* GLX_X86_READONLY_TEXT */
  59
  60 __asm__(".balign 16\n"
  61         "x86_entry_start:");
  62
  63 #define STUB_ASM_ENTRY(func)     \
  64    ".globl " func "\n"           \
  65    ".type " func ", @function\n" \
  66    ".balign 16\n"                \
  67    func ":"
  68
  69 #define STUB_ASM_CODE(slot)      \
  70    "call x86_current_tls\n\t"    \
  71    "movl %gs:(%eax), %eax\n\t"   \
  72    "jmp *(4 * " slot ")(%eax)"
  73
  74 #define MAPI_TMP_STUB_ASM_GCC
  75 #include "mapi_tmp.h"
  76
  77 #ifndef GLX_X86_READONLY_TEXT
  78 __asm__(".balign 16\n"
  79         "x86_entry_end:");
  80 __asm__(".text");
  81 #endif /* GLX_X86_READONLY_TEXT */
  82
  83 extern unsigned long
  84 x86_current_tls();
  85
  86 void
  87 entry_patch_public(void)
  88 {
  89 #ifndef GLX_X86_READONLY_TEXT
  90    extern char x86_entry_start[];
  91    extern char x86_entry_end[];
  92    char patch[8] = {
  93       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
  94       0x90, 0x90                          /* nop's */
  95    };
  96    char *entry;
  97
  98    *((unsigned long *) (patch + 2)) = x86_current_tls();
  99
 100    for (entry = x86_entry_start; entry < x86_entry_end; entry += 16)
 101       memcpy(entry, patch, sizeof(patch));
 102 #endif
 103 }
 104
 105 mapi_func
 106 entry_get_public(int slot)
 107 {
 108    extern char x86_entry_start[];
 109    return (mapi_func) (x86_entry_start + slot * 16);
 110 }
 111
 112 void
 113 entry_patch(mapi_func entry, int slot)
 114 {
 115    char *code = (char *) entry;
 116    *((unsigned long *) (code + 8)) = slot * sizeof(mapi_func);
 117 }
 118
 119 mapi_func
 120 entry_generate(int slot)
 121 {
 122    const char code_templ[16] = {
 123       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
 124       0xff, 0xa0, 0x34, 0x12, 0x00, 0x00, /* jmp *0x1234(%eax) */
 125       0x90, 0x90, 0x90, 0x90              /* nop's */
 126    };
 127    void *code;
 128    mapi_func entry;
 129
 130    code = u_execmem_alloc(sizeof(code_templ));
 131    if (!code)
 132       return NULL;
 133
 134    memcpy(code, code_templ, sizeof(code_templ));
 135
 136    *((unsigned long *) (code + 2)) = x86_current_tls();
 137    entry = (mapi_func) code;
 138    entry_patch(entry, slot);
 139
 140    return entry;
 141 }