rtld_tls.h revision 281453 
1/*-
2 * Copyright (c) 2004 Doug Rabson
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 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 *	$FreeBSD: stable/10/libexec/rtld-elf/rtld_tls.h 281453 2015-04-12 06:45:40Z kib $
27 */
28
29/*
30 * Semi-public interface from thread libraries to rtld for managing
31 * TLS.
32 */
33
34#ifndef _RTLD_TLS_H_
35#define	_RTLD_TLS_H_
36
37/*
38 * Allocate a TLS block for a new thread. The memory allocated will
39 * include 'tcbsize' bytes aligned to a 'tcbalign' boundary (in bytes)
40 * for the thread library's private purposes. The location of the TCB
41 * block is returned by this function. For architectures using
42 * 'Variant I' TLS, the thread local storage follows the TCB, and for
43 * 'Variant II', the thread local storage precedes it. For
44 * architectures using the 'Variant II' model (e.g. i386, amd64,
45 * sparc64), the TCB must begin with two pointer fields which are used
46 * by rtld for its TLS implementation. For the 'Variant I' model, the
47 * TCB must begin with a single pointer field for rtld's
48 * implementation.
49 *
50 * If the value of 'oldtls' is non-NULL, the new TLS block will be
51 * initialised using the values contained in 'oldtls' and 'oldtls'
52 * will be freed. This is typically used when initialising a thread
53 * library to migrate from using the initial bootstrap TLS block
54 * created by rtld to one which contains suitable thread library
55 * private data.
56 *
57 * The value returned from this function is suitable for installing
58 * directly into the thread pointer register.
59 */
60void *_rtld_allocate_tls(void* oldtls, size_t tcbsize, size_t tcbalign)
61    __exported;
62
63/*
64 * Free a TLS block allocated using _rtld_allocate_tls(). The tcbsize
65 * and tcbalign parameters must be the same as those used to allocate
66 * the block.
67 */
68void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) __exported;
69
70#endif
71