1/* $OpenBSD: tcb.h,v 1.6 2017/10/13 05:14:02 guenther Exp $ */
2
3/*
4 * Copyright (c) 2011 Philip Guenther <guenther@openbsd.org>
5 *
6 * Permission to use, copy, modify, and distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17 */
18
19#ifndef _MACHINE_TCB_H_
20#define _MACHINE_TCB_H_
21
22#ifdef _KERNEL
23
24void *tcb_get(struct proc *_p);
25void tcb_set(struct proc *_p, void *_newtcb);
26
27#define TCB_GET(p) tcb_get(p)
28#define TCB_SET(p, addr) tcb_set(p, addr)
29
30/* address must be in canonical form; requiring lower-half is okay */
31#define TCB_INVALID(addr) ((u_long)(addr) > 0x00007fffffffffff)
32
33#else /* _KERNEL */
34
35/* ELF TLS ABI calls for big TCB, with static TLS data at negative offsets */
36#define TLS_VARIANT 2
37
38/* Read a slot from the TCB */
39static inline void *
40__amd64_read_tcb(long offset)
41{
42 void *val;
43 __asm__ ("movq %%fs:(%1),%0" : "=r" (val) : "r" (offset));
44 return val;
45}
46
47/* Get a pointer to the TCB itself */
48#define TCB_GET() __amd64_read_tcb(0)
49
50/* Setting the TCB pointer can only be done via syscall, so no TCB_SET() */
51
52#endif /* _KERNEL */
53#endif /* _MACHINE_TCB_H_ */