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

Oops, fix a paste-o commited in r300533.

Use the new(-ish) CP15_SCTLR macro to generate system control reg accesses
where possible. In the places that doesn't work (multi-line inline asm,
and places where the old armv4 cpufuncs mechanism is used), annotate the
accesses with a comment that includes SCTLR. Now a grep -i sctlr can find
all the system control register manipulations.

No functional changes.

Replace broken implementation of fuswintr() and suswintr() by functions
which return -1 as well as on tier 1 archs. Remove block_userspace_access
used only in these implementations.

(1) These functions may be called in interrupt context and pcb_onfault
can be already set in this time. Thus, prior pcb_onfault must be saved
and restored afterwards.

(2) The check that an abort came either from nested interrupt or while
in critical section or holding not sleepable lock must be avoided for
this case.

These functions are called only for profiling reason, so there will be
only small gain by making the code more complex.

Unify interrupts bit definition and usage. While here remove PSR_C_bit.

Submitted by: Svatopluk Kraus <onwahe at gmail.com>,
Michal Meloun <meloun at miracle.cz>
Differential Revision: https://reviews.freebsd.org/D754

Fix unwind-info errors in our hand-written arm assembler code.

We have functions nested within functions, and places where we start a
function then never end it, we just jump to the middle of something else.
We tried to express this with nested ENTRY()/END() macros (which result
in .fnstart and .fnend directives), but it turns out there's no way to
express that nesting in ARM EHABI unwind info, and newer tools treat
multiple .fnstart directives without an intervening .fnend as an error.

These changes introduce two new macros, EENTRY() and EEND(). EENTRY()
creates a global label you can call/jump to just like ENTRY(), but it
doesn't emit a .fnstart. EEND() is a no-op that just documents the
conceptual endpoint that matches up with the same-named EENTRY().

This is based on patches submitted by Stepan Dyatkovskiy, but I made some
changes and added the EEND() stuff, so blame any problems on me.

Submitted by: Stepan Dyatkovskiy <stpworld@narod.ru>

Update all arm code that manipulates the PSR registers to use modern syntax.

It turns out the version of gas we're using interprets the old '_all' mask
as 'fc' instead of 'fsxc'. That is, "all" doesn't really mean "all".

This was the cause of the "wrong-endian register restore" bug that's
been causing problems with some cortex-a9 chips. The 'endian' bit in the
spsr register would never get changed (it falls into the 'x' mask group)
and the first return-from-exception would fail if the chip had powered on
with garbage in the spsr register that included the big-endian bit. It's
unknown why this affected only certain cortex-a9 chips.

Add an END macro to ARM. This is mostly used to tell gas where the bounds
of the functions are when creating the EABI unwind tables.

Final whitespace trim.

Don't assume pmap_update() will cpwait for us, pmap_update will disappear soon.

Start all license statements with /*-

Use the RET macro.

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.