1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28 #include <pthread.h>
29
30
31 struct user_desc {
32 unsigned int entry_number;
33 unsigned long base_addr;
34 unsigned int limit;
35 unsigned int seg_32bit:1;
36 unsigned int contents:2;
37 unsigned int read_exec_only:1;
38 unsigned int limit_in_pages:1;
39 unsigned int seg_not_present:1;
40 unsigned int useable:1;
41 unsigned int empty:25;
42 };
43
44 extern int __set_thread_area(struct user_desc *u_info);
45
46 /* the following can't be const, since the first call will
47 * update the 'entry_number' field
48 */
49 static struct user_desc _tls_desc =
50 {
51 -1,
52 0,
53 0x1000,
54 1,
55 0,
56 0,
57 1,
58 0,
59 1,
60 0
61 };
62
63 static pthread_mutex_t _tls_desc_lock = PTHREAD_MUTEX_INITIALIZER;
64
65 struct _thread_area_head {
66 void *self;
67 };
68
69 /* we implement thread local storage through the gs: segment descriptor
70 * we create a segment descriptor for the tls
71 */
__set_tls(void * ptr)72 int __set_tls(void *ptr)
73 {
74 int rc, segment;
75
76 pthread_mutex_lock(&_tls_desc_lock);
77 _tls_desc.base_addr = (unsigned long)ptr;
78
79 /* We also need to write the location of the tls to ptr[0] */
80 ((struct _thread_area_head *)ptr)->self = ptr;
81
82 rc = __set_thread_area( &_tls_desc );
83 if (rc != 0)
84 {
85 /* could not set thread local area */
86 pthread_mutex_unlock(&_tls_desc_lock);
87 return -1;
88 }
89
90 /* this weird computation comes from GLibc */
91 segment = _tls_desc.entry_number*8 + 3;
92 asm __volatile__ (
93 " movw %w0, %%gs" :: "q"(segment)
94 );
95 pthread_mutex_unlock(&_tls_desc_lock);
96
97 return 0;
98 }
99
100
101
102