freebsd-dev/sys/arm64/include/tls.h
John Baldwin 1a62e9bc00 Add <machine/tls.h> header to hold MD constants and helpers for TLS.
The header exports the following:

- Definition of struct tcb.
- Helpers to get/set the tcb for the current thread.
- TLS_TCB_SIZE (size of TCB)
- TLS_TCB_ALIGN (alignment of TCB)
- TLS_VARIANT_I or TLS_VARIANT_II
- TLS_DTV_OFFSET (bias of pointers in dtv[])
- TLS_TP_OFFSET (bias of "thread pointer" relative to TCB)

Note that TLS_TP_OFFSET does not account for if the unbiased thread
pointer points to the start of the TCB (arm and x86) or the end of the
TCB (MIPS, PowerPC, and RISC-V).

Note also that for amd64, the struct tcb does not include the unused
tcb_spare field included in the current structure in libthr.  libthr
does not use this field, and the existing calls in libc and rtld that
allocate a TCB for amd64 assume it is the size of 3 Elf_Addr's (and
thus do not allocate room for tcb_spare).

A <sys/_tls_variant_i.h> header is used by architectures using
Variant I TLS which uses a common struct tcb.

Reviewed by:	kib (older version of x86/tls.h), jrtc27
Sponsored by:	The University of Cambridge, Google Inc.
Differential Revision:	https://reviews.freebsd.org/D33351
2021-12-09 13:17:13 -08:00

56 lines
1.9 KiB
C

/*-
* Copyright (c) 2005 David Xu <davidxu@freebsd.org>.
* Copyright (c) 2014 the FreeBSD Foundation
* All rights reserved.
*
* Portions of this software were developed by Andrew Turner
* under sponsorship from the FreeBSD Foundation
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef _MACHINE_TLS_H_
#define _MACHINE_TLS_H_
#include <sys/_tls_variant_i.h>
#define TLS_DTV_OFFSET 0
#define TLS_TCB_ALIGN 16
#define TLS_TP_OFFSET 0
static __inline void
_tcb_set(struct tcb *tcb)
{
__asm __volatile("msr tpidr_el0, %x0" :: "r" (tcb));
}
static __inline struct tcb *
_tcb_get(void)
{
struct tcb *tcb;
__asm __volatile("mrs %x0, tpidr_el0" : "=r" (tcb));
return (tcb);
}
#endif /* !_MACHINE_TLS_H_ */