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
  30 #ifdef HAVE_FUNC_ATTRIBUTE_VISIBILITY
  31 #define HIDDEN __attribute__((visibility("hidden")))
  32 #else
  33 #define HIDDEN
  34 #endif
  35
  36 #define X86_ENTRY_SIZE 16
  37
  38 __asm__(".text");
  39
  40 __asm__("x86_current_tls:\n\t"
  41         "call 1f\n"
  42         "1:\n\t"
  43         "popl %eax\n\t"
  44         "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %eax\n\t"
  45         "movl " ENTRY_CURRENT_TABLE "@GOTNTPOFF(%eax), %eax\n\t"
  46         "ret");
  47
  48 #ifndef GLX_X86_READONLY_TEXT
  49 __asm__(".section wtext, \"awx\", @progbits");
  50 #endif /* GLX_X86_READONLY_TEXT */
  51
  52 __asm__(".balign 16\n"
  53         "x86_entry_start:");
  54
  55 #define STUB_ASM_ENTRY(func)     \
  56    ".globl " func "\n"           \
  57    ".type " func ", @function\n" \
  58    ".balign 16\n"                \
  59    func ":"
  60
  61 #define STUB_ASM_CODE(slot)      \
  62    "call x86_current_tls\n\t"    \
  63    "movl %gs:(%eax), %eax\n\t"   \
  64    "jmp *(4 * " slot ")(%eax)"
  65
  66 #define MAPI_TMP_STUB_ASM_GCC
  67 #include "mapi_tmp.h"
  68
  69 #ifndef GLX_X86_READONLY_TEXT
  70 __asm__(".balign 16\n"
  71         "x86_entry_end:");
  72 __asm__(".text");
  73 #endif /* GLX_X86_READONLY_TEXT */
  74
  75 #ifndef MAPI_MODE_BRIDGE
  76
  77 #include "u_execmem.h"
  78
  79 extern unsigned long
  80 x86_current_tls();
  81
  82 extern char x86_entry_start[] HIDDEN;
  83 extern char x86_entry_end[] HIDDEN;
  84
  85 static inline mapi_func
  86 entry_generate_or_patch(int, char *, size_t);
  87
  88 void
  89 entry_patch_public(void)
  90 {
  91 #ifndef GLX_X86_READONLY_TEXT
  92    char *entry;
  93    int slot = 0;
  94    for (entry = x86_entry_start; entry < x86_entry_end;
  95         entry += X86_ENTRY_SIZE, ++slot)
  96       entry_generate_or_patch(slot, entry, X86_ENTRY_SIZE);
  97 #endif
  98 }
  99
 100 mapi_func
 101 entry_get_public(int slot)
 102 {
 103    return (mapi_func) (x86_entry_start + slot * X86_ENTRY_SIZE);
 104 }
 105
 106 void
 107 entry_patch(mapi_func entry, int slot)
 108 {
 109    char *code = (char *) entry;
 110    *((unsigned long *) (code + 8)) = slot * sizeof(mapi_func);
 111 }
 112
 113 static inline mapi_func
 114 entry_generate_or_patch(int slot, char *code, size_t size)
 115 {
 116    const char code_templ[16] = {
 117       0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
 118       0xff, 0xa0, 0x34, 0x12, 0x00, 0x00, /* jmp *0x1234(%eax) */
 119       0x90, 0x90, 0x90, 0x90              /* nop's */
 120    };
 121    mapi_func entry;
 122
 123    if (code == NULL) {
 124       size = sizeof(code_templ);
 125       code = u_execmem_alloc(size);
 126    }
 127    if (!code || size < sizeof(code_templ))
 128       return NULL;
 129
 130    memcpy(code, code_templ, sizeof(code_templ));
 131
 132    *((unsigned long *) (code + 2)) = x86_current_tls();
 133    entry = (mapi_func) code;
 134    entry_patch(entry, slot);
 135
 136    return entry;
 137 }
 138
 139 mapi_func
 140 entry_generate(int slot)
 141 {
 142    return entry_generate_or_patch(slot, NULL, 0);
 143 }
 144
 145 #endif /* MAPI_MODE_BRIDGE */