1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
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
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) the
45 * TCB must begin with two pointer fields which are used by rtld for
46 * its TLS implementation. For the 'Variant I' model, the TCB must
47 * begin with a single pointer field for rtld's implementation.
48 *
49 * If the value of 'oldtls' is non-NULL, the new TLS block will be
50 * initialised using the values contained in 'oldtls' and 'oldtls'
51 * will be freed. This is typically used when initialising a thread
52 * library to migrate from using the initial bootstrap TLS block
53 * created by rtld to one which contains suitable thread library
54 * private data.
55 *
56 * The value returned from this function is suitable for installing
57 * directly into the thread pointer register.
58 */
59void *_rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)
60    __exported;
61
62/*
63 * Free a TLS block allocated using _rtld_allocate_tls(). The tcbsize
64 * and tcbalign parameters must be the same as those used to allocate
65 * the block.
66 */
67void _rtld_free_tls(void *tcb, size_t tcbsize, size_t tcbalign) __exported;
68
69#endif
70