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#ifdef __CET__
29#define ENDBR "endbr32\n\t"
30#else
31#define ENDBR
32#endif
33
34#ifdef HAVE_FUNC_ATTRIBUTE_VISIBILITY
35#define HIDDEN __attribute__((visibility("hidden")))
36#else
37#define HIDDEN
38#endif
39
40#define X86_ENTRY_SIZE 64
41
42__asm__(".text\n");
43
44__asm__("x86_got:\n\t"
45        "call 1f\n"
46        "1:\n\t"
47        "popl %eax\n\t"
48        "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %eax\n\t"
49        "ret");
50
51__asm__(".balign 32\n"
52        "x86_entry_start:");
53
54#define STUB_ASM_ENTRY(func)        \
55   ".globl " func "\n"              \
56   ".type " func ", @function\n"    \
57   ".balign 32\n"                   \
58   func ":"
59
60#define LOC_BEGIN_SET_ECX
61#define LOC_END_SET_ECX
62#define LOC_END_JMP
63
64#define STUB_ASM_CODE(slot)         \
65   ENDBR                            \
66   LOC_BEGIN_SET_ECX	            \
67   "call 1f\n\t"                    \
68   "1:\n\t"                         \
69   "popl %ecx\n\t"                  \
70   "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %ecx\n\t" \
71   LOC_END_SET_ECX                                \
72   "movl " ENTRY_CURRENT_TABLE "@GOT(%ecx), %eax\n\t" \
73   "mov (%eax), %eax\n\t"           \
74   "testl %eax, %eax\n\t"           \
75   "jne 1f\n\t"                     \
76   "push %ebx\n\t"                  \
77   "movl %ecx, %ebx\n\t"            \
78   "call " ENTRY_CURRENT_TABLE_GET "@PLT\n\t" \
79   "popl %ebx\n\t"                  \
80   "1:\n\t"                         \
81   "jmp *(4 * " slot ")(%eax)\n\t" \
82   LOC_END_JMP
83
84#define MAPI_TMP_STUB_ASM_GCC
85#include "mapi_tmp.h"
86
87#ifndef MAPI_MODE_BRIDGE
88
89__asm__(".balign 32\n"
90        "x86_entry_end:");
91
92#undef LOC_BEGIN_SET_ECX
93#undef LOC_END_SET_ECX
94#undef LOC_END_JMP
95#define LOC_BEGIN_SET_ECX "jmp set_ecx\n\t"
96#define LOC_END_SET_ECX "set_ecx:movl $0x12345678, %ecx\n\tloc_end_set_ecx:\n\t"
97#define LOC_END_JMP "loc_end_jmp:"
98
99/* Any number big enough works. This is to make sure the final
100 * jmp is a long jmp */
101__asm__(STUB_ASM_CODE("10000"));
102
103extern const char loc_end_set_ecx[] HIDDEN;
104extern const char loc_end_jmp[] HIDDEN;
105
106#include <string.h>
107#include "u_execmem.h"
108
109extern unsigned long
110x86_got();
111
112extern const char x86_entry_start[] HIDDEN;
113extern const char x86_entry_end[] HIDDEN;
114
115void
116entry_patch_public(void)
117{
118}
119
120mapi_func
121entry_get_public(int slot)
122{
123   return (mapi_func) (x86_entry_start + slot * X86_ENTRY_SIZE);
124}
125
126void
127entry_patch(mapi_func entry, int slot)
128{
129   char *code = (char *) entry;
130   int offset = loc_end_jmp - x86_entry_end - sizeof(unsigned long);
131   *((unsigned long *) (code + offset)) = slot * sizeof(mapi_func);
132}
133
134mapi_func
135entry_generate(int slot)
136{
137   const char *code_templ = x86_entry_end;
138   char *code;
139   mapi_func entry;
140
141   code = u_execmem_alloc(X86_ENTRY_SIZE);
142   if (!code)
143      return NULL;
144
145   memcpy(code, code_templ, X86_ENTRY_SIZE);
146   entry = (mapi_func) code;
147   int ecx_value_off = loc_end_set_ecx - x86_entry_end - sizeof(unsigned long);
148   *((unsigned long *) (code + ecx_value_off)) = x86_got();
149
150   entry_patch(entry, slot);
151
152   return entry;
153}
154
155#endif /* MAPI_MODE_BRIDGE */
156