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 323580,323933,323934,324814,324817: Enable AT_HWCAP on arm.

I reused the SV_HWCAP stub to cover the sv_hwcap2 field as well.

323580:
Add AT_HWCAP flags for VFP settings for FreeBSD/arm.

These flags match the meaning and value of flags in Linux, though
Linux has many more flags.

323933:
Correct HWCAP_VFP3* values to match Linux.

323934:
Detect NEON and set HWCAP_NEON if present.

324814:
Add AT_HWCAP2 ELF auxiliary vector.
- allocate value for new AT_HWCAP2 auxiliary vector on all platforms.
- expand 'struct sysentvec' by new 'u_long *sv_hwcap2', in exactly
same way as for AT_HWCAP.

324817:
Fullify implementation of AT_HWCAP and AT_HWCAP2 for ARMv6,7.
This makes elf_aux_info(3) useable for ARM ports.

Tested by: mmel

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.

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

Revert r290243, it's vaid "illegal instruction" case

DEX bit is set to 1 and exception raised whenever vectorized operation is
attempted on the VFP implementation that does not support it (i.e. on Cortex A7)

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

A follow-up to r288492. In fact, revert the mentioned commit for
pre-VFPv3 processors, since they do require software support code to
handle denormals. For VFPv3 and later, enable flush-to-zero if
hardware does not claim full denormals arithmetic support by VMVFR1_FZ
field in mvfr1 register.

The end result is that we do use correct fpu environment on Cortexes
with VFPv3, while ARM11 (e.g. rpi) is in non-compliant flush-to-zero
mode. At least CPUs without complete hardware implementation of
IEEE 754 do not cause unhandled floating point exception on underflow,
as it was before r288492.

Noted by: ian
Tested by: gjb
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

Remove pc_cpu, it was duplicating pc_cpuid so was unneeded.

Remove trailing whitespace from sys/arm/arm

Rework the vpf support code so that it compiles with clang 3.4, 3.5, and gcc.
Michal Meloun did most of the hard work in figuring out what would work with
which compiler, I just reformated things a bit before committing.

VFP fixes/cleanups for ARM11:
* Save the required VFP registers on context switch. If the exception bit
is set we need to save and restore the FPINST register, and if the fp2v
bit is also set we need to save and restore FPINST2.
* Move saving and restoring the floating point control registers to C.
* Clear the fpexc exception and fp2v flags on a floating-point exception.
* Signal a SIGFPE if the fpexc exception flag is set on an undefined
instruction. This is how the ARM core signals to software there is a
floating-point exception.

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

Make functions only used in this file static, and remove vfp_enable as it
is unused.

Change the way pcpu and curthread are stored per-core:
the old way was to store pcpu in a register, and get curthread from pcpu,
which is not very atomic, and led to issues if the thread was migrated
to another core between the time we got the pcpu address and the time we
got curthread.
Instead, we now store curthread where pcpu used to be store, and we
calculate the pcpu address based on the cpu id.

Remove #include <machine/frame.h> from all the arm code that doesn't
really need it. That would be almost everywhere it was included. Add
it in a couple files that really do need it and were previously getting
it by accident via another header.

Rename device vfp to option VFP and retire the ARM_VFP_SUPPORT option. This
simplifies enabling as previously both options were required to be enabled,
now we only need a single option.

While here enable VFP on the PandaBoard.

Fix vfp:
- We should check is_d32 to see howmany registers we have
- In vfp_restore mark vfpscr as an output register

Without the second part it appears we can return the incorrect value from
vfp_bounce if the VFP condition flags are set as it may override the
register holding the return value.

Fix the build with gcc.

Gcc outputs pre-UAL asm and expects the ldcl instruction with a condition
in the form ldc<c>l, where the code produces the instruction in the UAL
form ldcl<c>. Work around this by checking if we are using clang or gcc and
adjusting the instruction.

While here correct the cmp instruction's value to include the # before the
immediate value.

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.

Add the hw.floatingpoint sysctl to ARM to tell us if we have vfp support
in the kernel and the hardware includes a vfp unit.

Fix SMP build.

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