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
103 extern const char loc_end_set_ecx[] HIDDEN;
104 extern const char loc_end_jmp[] HIDDEN;
105
106 #include <string.h>
107 #include "u_execmem.h"
108
109 extern unsigned long
110 x86_got();
111
112 extern const char x86_entry_start[] HIDDEN;
113 extern const char x86_entry_end[] HIDDEN;
114
115 void
entry_patch_public(void)116 entry_patch_public(void)
117 {
118 }
119
120 mapi_func
entry_get_public(int slot)121 entry_get_public(int slot)
122 {
123 return (mapi_func) (x86_entry_start + slot * X86_ENTRY_SIZE);
124 }
125
126 void
entry_patch(mapi_func entry,int slot)127 entry_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
134 mapi_func
entry_generate(int slot)135 entry_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