bionic_tls.h revision e5cc1f386b167b9f7bfdebc7219e89aa9b71e4b2 
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#ifndef _SYS_TLS_H
29#define _SYS_TLS_H
30
31#include <sys/cdefs.h>
32
33__BEGIN_DECLS
34
35/** WARNING WARNING WARNING
36 **
37 ** This header file is *NOT* part of the public Bionic ABI/API
38 ** and should not be used/included by user-serviceable parts of
39 ** the system (e.g. applications).
40 **
41 ** It is only provided here for the benefit of the system dynamic
42 ** linker and the OpenGL sub-system (which needs to access the
43 ** pre-allocated slot directly for performance reason).
44 **/
45
46/* maximum number of elements in the TLS array */
47#define BIONIC_TLS_SLOTS            64
48
49/* note that slot 0, called TLS_SLOT_SELF must point to itself.
50 * this is required to implement thread-local storage with the x86
51 * Linux kernel, that reads the TLS from fs:[0], where 'fs' is a
52 * thread-specific segment descriptor...
53 */
54
55/* Well known TLS slots */
56#define TLS_SLOT_SELF               0
57#define TLS_SLOT_THREAD_ID          1
58#define TLS_SLOT_ERRNO              2
59
60#define TLS_SLOT_OPENGL_API         3
61#define TLS_SLOT_OPENGL             4
62
63/* small technical note: it is not possible to call pthread_setspecific
64 * on keys that are <= TLS_SLOT_MAX_WELL_KNOWN, which is why it is set to
65 * TLS_SLOT_ERRNO.
66 *
67 * later slots like TLS_SLOT_OPENGL are pre-allocated through the use of
68 * TLS_DEFAULT_ALLOC_MAP. this means that there is no need to use
69 * pthread_key_create() to initialize them. on the other hand, there is
70 * no destructor associated to them (we might need to implement this later)
71 */
72#define TLS_SLOT_MAX_WELL_KNOWN     TLS_SLOT_ERRNO
73
74#define TLS_DEFAULT_ALLOC_MAP       0x0000001F
75
76/* set the Thread Local Storage, must contain at least BIONIC_TLS_SLOTS pointers */
77extern void __init_tls(void**  tls, void*  thread_info);
78
79/* syscall only, do not call directly */
80extern int __set_tls(void *ptr);
81
82/* get the TLS */
83#ifdef __arm__
84#  define __get_tls() ( *((volatile void **) 0xffff0ff0) )
85#else
86extern void*  __get_tls( void );
87#endif
88
89/* return the stack base and size, used by our malloc debugger */
90extern void*  __get_stack_base(int  *p_stack_size);
91
92__END_DECLS
93
94#endif /* _SYS_TLS_H */
95