Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

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

MFC r230426:
Add support for the extended FPU states on amd64, both for native
64bit and 32bit ABIs. As a side-effect, it enables AVX on capable
CPUs.

MFC r230765:
Synchronize the struct sigcontext definitions on x86 with mcontext_t.

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

MFaesni r215427:
Only save FPU context when not executing in the context of the crypto
thread.

Tested by: Mike Tancsa
MFC after: 1 week

Use the fpu_kern_enter() interface to properly separate usermode FPU
context from in-kernel execution of padlock instructions and to handle
spurious FPUDNA exceptions that sometime are raised when doing padlock
calculations.

Globally mark crypto(9) kthread as using FPU.

Reviewed by: pjd
Hardware provided by: Sentex Communications
Tested by: pho
PR: amd64/135014
MFC after: 1 month

Less magic.

MFC after: 3 days

Remove redundant check committed by accident.

Avoid memory allocations when the given address is already 16 bytes aligned.
Such an address can be used directly in padlock's AES.
This improves speed of geli(8) significantly:

# sysctl kern.geom.zero.clear=0
# geli onetime -s 4096 gzero
# dd if=/dev/gzero.eli of=/dev/null bs=1m count=1000

Before: 113MB/s
After: 203MB/s

BTW. If sector size is set to 128kB, I can read at 276MB/s :)

Style fixes.

Implement support for HMAC/SHA1 and HMAC/SHA256 acceleration found in
new VIA CPUs.
For older CPUs HMAC/SHA1 and HMAC/SHA256 (and others) will still be done
in software.

Move symmetric cryptography (currently only AES-CBC 128/192/256) to
padlock_cipher.c file. Move HMAC cryptography to padlock_hash.c file.

Hardware from: Centaur Technologies