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 <[email protected]>
26 */
27
28 #include <string.h>
29
30 #ifdef __CET__
31 #define ENDBR "endbr32\n\t"
32 #else
33 #define ENDBR
34 #endif
35
36 #ifdef HAVE_FUNC_ATTRIBUTE_VISIBILITY
37 #define HIDDEN __attribute__((visibility("hidden")))
38 #else
39 #define HIDDEN
40 #endif
41
42 #define X86_ENTRY_SIZE 32
43
44 __asm__(".text");
45
46 __asm__("x86_current_tls:\n\t"
47 "call 1f\n"
48 "1:\n\t"
49 "popl %eax\n\t"
50 "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %eax\n\t"
51 "movl _glapi_tls_Dispatch@GOTNTPOFF(%eax), %eax\n\t"
52 "ret");
53
54 #ifndef GLX_X86_READONLY_TEXT
55 __asm__(".section wtext, \"awx\", @progbits");
56 #endif /* GLX_X86_READONLY_TEXT */
57
58 __asm__(".balign 16\n"
59 "x86_entry_start:");
60
61 #define STUB_ASM_ENTRY(func) \
62 ".globl " func "\n" \
63 ".type " func ", @function\n" \
64 ".balign 16\n" \
65 func ":"
66
67 #define STUB_ASM_CODE(slot) \
68 ENDBR \
69 "call 1f\n" \
70 "1:\n\t" \
71 "popl %eax\n\t" \
72 "addl $_GLOBAL_OFFSET_TABLE_+[.-1b], %eax\n\t" \
73 "movl _glapi_tls_Dispatch@GOTNTPOFF(%eax), %eax\n\t" \
74 "movl %gs:(%eax), %eax\n\t" \
75 "jmp *(4 * " slot ")(%eax)"
76
77 #define MAPI_TMP_STUB_ASM_GCC
78 #include "mapi_tmp.h"
79
80 #ifndef GLX_X86_READONLY_TEXT
81 __asm__(".balign 16\n"
82 "x86_entry_end:");
83 __asm__(".text");
84 #endif /* GLX_X86_READONLY_TEXT */
85
86 #ifndef MAPI_MODE_BRIDGE
87
88 extern unsigned long
89 x86_current_tls();
90
91 extern char x86_entry_start[] HIDDEN;
92 extern char x86_entry_end[] HIDDEN;
93
94 static inline mapi_func
95 entry_generate_or_patch(int, char *, size_t);
96
97 void
entry_patch_public(void)98 entry_patch_public(void)
99 {
100 #ifndef GLX_X86_READONLY_TEXT
101 char *entry;
102 int slot = 0;
103 for (entry = x86_entry_start; entry < x86_entry_end;
104 entry += X86_ENTRY_SIZE, ++slot)
105 entry_generate_or_patch(slot, entry, X86_ENTRY_SIZE);
106 #endif
107 }
108
109 mapi_func
entry_get_public(int slot)110 entry_get_public(int slot)
111 {
112 return (mapi_func) (x86_entry_start + slot * X86_ENTRY_SIZE);
113 }
114
115 static void
entry_patch(mapi_func entry,int slot)116 entry_patch(mapi_func entry, int slot)
117 {
118 char *code = (char *) entry;
119 *((unsigned long *) (code + 8)) = slot * sizeof(mapi_func);
120 }
121
122 static inline mapi_func
entry_generate_or_patch(int slot,char * code,size_t size)123 entry_generate_or_patch(int slot, char *code, size_t size)
124 {
125 const char code_templ[16] = {
126 0x65, 0xa1, 0x00, 0x00, 0x00, 0x00, /* movl %gs:0x0, %eax */
127 0xff, 0xa0, 0x34, 0x12, 0x00, 0x00, /* jmp *0x1234(%eax) */
128 0x90, 0x90, 0x90, 0x90 /* nop's */
129 };
130 mapi_func entry;
131
132 if (size < sizeof(code_templ))
133 return NULL;
134
135 memcpy(code, code_templ, sizeof(code_templ));
136
137 *((unsigned long *) (code + 2)) = x86_current_tls();
138 entry = (mapi_func) code;
139 entry_patch(entry, slot);
140
141 return entry;
142 }
143
144 #endif /* MAPI_MODE_BRIDGE */
145