It is up to the code that organizes the runtime to properly set the
signal handler, and to set %fsbase if libthr signal handler is to be
called. The change should leave the CPU state on the signal handler
entry identical to what it was before introduction of TLSBASE, for code
that provides its own startup and thread pointer, but still calls into
libthr as a hack.

Sponsored by:	The FreeBSD Foundation
MFC after:	1 week

_libc_get_static_tls_base() is just _tcb_get() followed by adding (for
Variant I) or subtracting (for Variant II) the offset, so just inline
that as the implementation (like we do in rtld-elf) rather than having
another copy (or equivalent) of _tcb_get()'s assembly.

_get_static_tls_base() doesn't even have any MD assembly as it's
reading thr->tcb, the only difference is whether to add or subtract, so
again just inline that.

Whilst here add some missing blank lines to comply with style(9) for
elf_utils.c's includes, and use a pointer type rather than uintptr_t to
reduce the need to cast, as is done in rtld-elf.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D50592

Add the ability to pre-resolve architecture-specific EABI symbols and
use it on arm for selected EABI functions. These functions can be called
with rtld bind lock write-locked, so they should be resolved in forward.

Reported by:	Mark Millard <marklmi@yahoo.com>, John F Carr <jfc@mit.edu>
Reviewed by:	kib, imp
MFC after:	1 week
Differential Revision:  https://reviews.freebsd.org/D46104

Declare in sys/umtx.h and implement in libsys.  Explicitly link libthr
with libsys.

When building libthr static include _umtx_op_err so we don't break static
linkage with -lpthread.

Reviewed by:	kib, emaste, imp
Pull Request:	https://github.com/freebsd/freebsd-src/pull/908

Remove /^\s*\*\n \*\s+\$FreeBSD\$$\n/

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix

In libthr we use PAGE_SIZE when allocating memory with mmap and to check
various structs will fit into a single page so we can use this allocator
for them.

Ask the kernel for the page size on init for use by the page allcator
and add a new machine dependent macro to hold the smallest page size
the architecture supports to check the structure is small enough.

This allows us to use the same libthr on arm64 with either 4k or 16k
pages.

Reviewed by:	kib, markj, imp
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34984

Note that on amd64 this effectively removes the unused tcb_spare field
from the end of struct tcb since the definition of struct tcb in
<x86/tls.h> does not include that field.

Reviewed by:	kib, jrtc27
Sponsored by:	The University of Cambridge, Google Inc.
Differential Revision:	https://reviews.freebsd.org/D33352

This macro is confusing as it is not related to the similarly named
TLS_DTV_OFFSET.  Instead, replace its one use with the desired
expression which is the same on all platforms.

Reviewed by:	kib, emaste, jrtc27
Sponsored by:	The University of Cambridge, Google Inc.
Differential Revision:	https://reviews.freebsd.org/D33345

As per r177853, we need to avoid using errno inside user mutex code, since
 signal handlers can interfere with it and mess up libthr internal state.

So, implement _umtx_op_err() instead, which makes a raw syscall and
returns the error value directly instead of using errno.

Approved by: jhibbits (mentor)
Differential Revision: https://reviews.freebsd.org/D20946