Revert r330897:

This was intended to be a non-functional change. It wasn't. The commit
message was thus wrong. In addition it broke arm, and merged crypto
related code.

Revert with prejudice.

This revert skips files touched in r316370 since that commit was since
MFCed. This revert also skips files that require $FreeBSD$ property
changes.

Thank you to those who helped me get out of this mess including but not
limited to gonzo, kevans, rgrimes.

Requested by: gjb (re)

Partial merge of the SPDX changes

These changes are incomplete but are making it difficult
to determine what other changes can/should be merged.

No objections from: pfg

MFC r315900,r315973,r315974:

r315900:
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.
r315973:
Save VFP state on fork(). Update the copy of VFP state in PCB before it is
cloned for new process.
r315974:
Preserve VFP state across signal delivery.

MFC r306162:

Make it possible to safely use TPIDRURW from userspace.

On amd64, arm64 and i386, we have the possibility to switch between TLS
areas in userspace. The nice thing about this is that it makes it easier
to do light-weight threading, if we ever feel like doing that. On armv6,
let's go into the same direction by making it possible to safely use the
TPIDRURW register, which is intended for this purpose.

Clean up the ARMv6 code to remove md_tp entirely. Simply add a dedicated
field to the PCB to hold the value of TPIDRURW across context switches,
like we do for any other register. As userspace currently uses the
read-only TPIDRURO register, simply ensure that we keep both values in
sync where possible. The system calls for modifying the read-only
register will simply write the intended value into both registers, so
that it lazily ends up in the PCB during the next context switch.

Approved by: andrew
Reviewed by: imp
Differential Revision: https://reviews.freebsd.org/D7951

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Cleanup up ARM *frame structures...

- Eliminate unused irqframe
- Eliminate unused saframe
- Instead of splitting r4-sp storage between the stack and switchframe,
just put all the registers in switchframe and eliminate the un_32 struct.

Submitted by: Svatopluk Kraus <onwahe@gmail.com>,
Michal Meloun <meloun@miracle.cz>

Remove the last dregs of trapframe_t. It turns out only arm was using
this type, so remove it to make arm code more consistant with other
platforms. Thanks to bde@ for pointing out only arm used trapframe_t.

When entering exception handlers we may not have an aligned stack. This is
because an exception may happen at any time. The stack alignment rules on
ARM EABI state the only place the stack must be 8-byte aligned is on a
function boundary.

If an exception happens while a function is setting up or tearing down it's
stack frame it may not be correctly aligned. There is also no requirement
for it to be when the function is a leaf node.

The fix is to align the stack after we have stored a backup of the old stack
pointer, but before we have stored anything in the trapframe. Along with
this we need to adjust the size of the trapframe by 4 bytes to ensure the
stack below it is also correctly aligned.

Fix stack alignment in the kernel to be on an 8 byte boundary as required
by AAPCS.

trim trailing whitespace

Tweak how the MD code calls the fooclock() methods some. Instead of
passing a pointer to an opaque clockframe structure and requiring the
MD code to supply CLKF_FOO() macros to extract needed values out of the
opaque structure, just pass the needed values directly. In practice this
means passing the pair (usermode, pc) to hardclock() and profclock() and
passing the boolean (usermode) to hardclock_cpu() and hardclock_process().
Other details:
- Axe clockframe and CLKF_FOO() macros on all architectures. Basically,
all the archs were taking a trapframe and converting it into a clockframe
one way or another. Now they can just extract the PC and usermode values
directly out of the trapframe and pass it to fooclock().
- Renamed hardclock_process() to hardclock_cpu() as the latter is more
accurate.
- On Alpha, we now run profclock() at hz (profhz == hz) rather than at
the slower stathz.
- On Alpha, for the TurboLaser machines that don't have an 8254
timecounter, call hardclock() directly. This removes an extra
conditional check from every clock interrupt on Alpha on the BSP.
There is probably room for even further pruning here by changing Alpha
to use the simplified timecounter we use on x86 with the lapic timer
since we don't get interrupts from the 8254 on Alpha anyway.
- On x86, clkintr() shouldn't ever be called now unless using_lapic_timer
is false, so add a KASSERT() to that affect and remove a condition
to slightly optimize the non-lapic case.
- Change prototypeof arm_handler_execute() so that it's first arg is a
trapframe pointer rather than a void pointer for clarity.
- Use KCOUNT macro in profclock() to lookup the kernel profiling bucket.

Tested on: alpha, amd64, arm, i386, ia64, sparc64
Reviewed by: bde (mostly)

Start all license statements with /*-

Remove the kbd_trap() declaration.

Import FreeBSD/arm kernel bits.
It only supports sa1110 (on simics) right now, but xscale support should come
soon.
Some of the initial work has been provided by :
Stephane Potvin <sepotvin at videotron.ca>
Most of this comes from NetBSD.