008fd2ff72845afa4d0d0fd65c47395837208bde
[deb_libhybris.git] / hybris / common / gingerbread / bionic_tls.h
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 /* this slot is only used to pass information from the dynamic linker to
64 * libc.so when the C library is loaded in to memory. The C runtime init
65 * function will then clear it. Since its use is extremely temporary,
66 * we reuse an existing location.
67 */
68 #define TLS_SLOT_BIONIC_PREINIT (TLS_SLOT_ERRNO+1)
69
70 /* small technical note: it is not possible to call pthread_setspecific
71 * on keys that are <= TLS_SLOT_MAX_WELL_KNOWN, which is why it is set to
72 * TLS_SLOT_ERRNO.
73 *
74 * later slots like TLS_SLOT_OPENGL are pre-allocated through the use of
75 * TLS_DEFAULT_ALLOC_MAP. this means that there is no need to use
76 * pthread_key_create() to initialize them. on the other hand, there is
77 * no destructor associated to them (we might need to implement this later)
78 */
79 #define TLS_SLOT_MAX_WELL_KNOWN TLS_SLOT_ERRNO
80
81 #define TLS_DEFAULT_ALLOC_MAP 0x0000001F
82
83 /* set the Thread Local Storage, must contain at least BIONIC_TLS_SLOTS pointers */
84 extern void __init_tls(void** tls, void* thread_info);
85
86 /* syscall only, do not call directly */
87 extern int __set_tls(void *ptr);
88
89 /* get the TLS */
90 #ifdef __arm__
91 /* The standard way to get the TLS is to call a kernel helper
92 * function (i.e. a function provided at a fixed address in a
93 * "magic page" mapped in all user-space address spaces ), which
94 * contains the most appropriate code path for the target device.
95 *
96 * However, for performance reasons, we're going to use our own
97 * machine code for the system's C shared library.
98 *
99 * We cannot use this optimization in the static version of the
100 * C library, because we don't know where the corresponding code
101 * is going to run.
102 */
103 # ifdef LIBC_STATIC
104
105 /* Use the kernel helper in static C library. */
106 typedef volatile void* (__kernel_get_tls_t)(void);
107 # define __get_tls() (*(__kernel_get_tls_t *)0xffff0fe0)()
108
109 # else /* !LIBC_STATIC */
110 /* Use optimized code path.
111 * Note that HAVE_ARM_TLS_REGISTER is build-specific
112 * (it must match your kernel configuration)
113 */
114 # ifdef HAVE_ARM_TLS_REGISTER
115 /* We can read the address directly from a coprocessor
116 * register, which avoids touching the data cache
117 * completely.
118 */
119 # define __get_tls() \
120 ({ register unsigned int __val asm("r0"); \
121 asm ("mrc p15, 0, r0, c13, c0, 3" : "=r"(__val) ); \
122 (volatile void*)__val; })
123 # else /* !HAVE_ARM_TLS_REGISTER */
124 /* The kernel provides the address of the TLS at a fixed
125 * address of the magic page too.
126 */
127 # define __get_tls() ( *((volatile void **) 0xffff0ff0) )
128 # endif
129 # endif /* !LIBC_STATIC */
130 #else /* !ARM */
131 extern void* __get_tls( void );
132 #endif /* !ARM */
133
134 /* return the stack base and size, used by our malloc debugger */
135 extern void* __get_stack_base(int *p_stack_size);
136
137 __END_DECLS
138
139 #endif /* _SYS_TLS_H */