sys: Remove $FreeBSD$: one-line .h pattern

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

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

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

arm: Fix initialization of VFP context

Make sure that pcb_vfpsaved is always initialized.
Create a vfp_new_thread helper that is heavily based on the arm64 logic.
While here remove un unnecessary assigment and add an assertion
to make sure that it's been properly initialized before we return
from a VFP exception.

Reported by: Mark Millard <marklmi@yahoo.com>
Tested by: Mark Millard <marklmi@yahoo.com>
Differential Revision: https://reviews.freebsd.org/D38698

arm: Add support for using VFP in kernel

Add missing logic to allow in-kernel VFP usage for ARMv7 NEON.
The implementation is strongly based on arm64 code.
It introduces a family of fpu_kern_* functions to enable the usage
of VFP instructions in kernel.
Apart from that the existing armv7 VFP logic was modified,
taking into account that the state of the VFP registers can now
be modified in the kernel.

Co-developed by: Wojciech Macek <wma@FreeBSD.org>
Sponsored by: Stormshield
Obtained from: Semihalf
Reviewed by: andrew
Differential Revision: https://reviews.freebsd.org/D37419

arm: clean up empty lines in .c and .h files

sys/arm: further adoption of SPDX licensing ID tags.

Mainly focus on files that use BSD 2-Clause license, however the tool I
was using misidentified many licenses so this was mostly a manual - error
prone - task.

The Software Package Data Exchange (SPDX) group provides a specification
to make it easier for automated tools to detect and summarize well known
opensource licenses. We are gradually adopting the specification, noting
that the tags are considered only advisory and do not, in any way,
superceed or replace the license texts.

Fullify implementation of AT_HWCAP and AT_HWCAP2 for ARMv6,7.
This makes elf_aux_info(3) useable for ARM ports.

MFC after: 1 month

Export get/set_vfpcontext from machdep.c.

Should have been part of the previous commit to add ptrace operations
for VFP registers.

MFC after: 1 month

Cleanup structures related to VFP and/or mcontext_t.
- in mcontext_t, rename newer used 'union __vfp' to equaly sized 'mc_spare'.
Space allocated by 'union __vfp' is too small and cannot hold full
VFP context.
- move structures defined in fp.h to more appropriate headers.
- remove all unused VFP structures.

MFC after: 2 weeks

Treat synchronous VFP exception just like aynchronous: as an FP exception,
not as illegal instruction

Add more flags for the fpexc register from the ARM1176JZF-S Manual

Always call vfp_discard() on thread death, not just when the VFP is
enabled. In vfp_discard(), if the state in the VFP hardware belongs to
the thread which is dying, NULL out pcpu fpcurthread to indicate the
state currently in the hardware belongs to nobody.

Submitted by: Juergen Weiss
Pointy hat to: me

Rework the VFP code that handles demand-based save and restore of state.

The old code was full of complexity that would only matter if the
kernel itself used the VFP hardware. Now that's reduced to either killing
the userland process or panicking the kernel on an illegal VFP instruction.

This removes most of the complexity from the assembler code, reducing it
to just calling the save code if the outgoing thread used the VFP.

The routine that stores the VFP state now takes a flag that indicates
whether the hardware should be disabled after saving state. Right now it
always is, but this makes the code ready to be used by get/set_mcontext()
(doing so will be addressed in a future commit).

Remove the arm-specific pc_vfpcthread from struct pcpu and use the MI
field pc_fpcurthread instead.

Reviewed by: cognet

Fix the vfp code to work with the 16 register variants of the VFP unit. We
check which variant we are on, and if it is a VFPv3 or v4, and has 32
double registers we save these. This fixes VFP support on Raspberry Pi.

While here clean fmrx and fmxr up to use the register names from vfp.h
as opposed to the raw register names.

Export vfp_init() prototype, for use in the MP code.

Merging projects/armv6, part 1

Cummulative patch of changes that are not vendor-specific:
- ARMv6 and ARMv7 architecture support
- ARM SMP support
- VFP/Neon support
- ARM Generic Interrupt Controller driver
- Simplification of startup code for all platforms