1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2004 Doug Rabson
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 *	$FreeBSD$
29 */
30
31/*
32 * Semi-public interface from thread libraries to rtld for managing
33 * TLS.
34 */
35
36#ifndef _RTLD_TLS_H_
37#define	_RTLD_TLS_H_
38
39/*
40 * Allocate a TLS block for a new thread. The memory allocated will
41 * include 'tcbsize' bytes aligned to a 'tcbalign' boundary (in bytes)
42 * for the thread library's private purposes. The location of the TCB
43 * block is returned by this function. For architectures using
44 * 'Variant I' TLS, the thread local storage follows the TCB, and for
45 * 'Variant II', the thread local storage precedes it. For
46 * architectures using the 'Variant II' model (e.g. i386, amd64) the
47 * TCB must begin with two pointer fields which are used by rtld for
48 * its TLS implementation. For the 'Variant I' model, the TCB must
49 * begin with a single pointer field for rtld's implementation.
50 *
51 * If the value of 'oldtls' is non-NULL, the new TLS block will be
52 * initialised using the values contained in 'oldtls' and 'oldtls'
53 * will be freed. This is typically used when initialising a thread
54 * library to migrate from using the initial bootstrap TLS block
55 * created by rtld to one which contains suitable thread library
56 * private data.
57 *
58 * The value returned from this function is suitable for installing
59 * directly into the thread pointer register.
60 */
61void *_rtld_allocate_tls(void* oldtls, size_t tcbsize, size_t tcbalign)
62    __exported;
63
64/*
65 * Free a TLS block allocated using _rtld_allocate_tls(). The tcbsize
66 * and tcbalign parameters must be the same as those used to allocate
67 * the block.
68 */
69void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) __exported;
70
71#endif
72