Make kernel log buffer derived from cmake config

This removes the explicit CMake configuration for the kernel log buffer
and replaces it with a #define that is enabled for the required
configurations.

Signed-off-by: Curtis Millar <curtis@curtism.me>

Convert license tags to SPDX identifiers

This commit also converts our own copyright headers to directly use
SPDX, but leaves all other copyright header intact, only adding the
SPDX ident. As far as possible this commit also merges multiple
Data61 copyright statements/headers into one for consistency.

Replace IPC_BUF_GLOBALS_FRAME with KERNEL_GLOBALS_FRAME

The globals frame no longer serves its original purpose of informing a
thread of its IPC buffer address, and instead as a virtual
implementation of thread ID registers.

arm: Make Arm VCPU states per-node.

arm/hyp: add support for running multiple ARM VMs

This commit saves/restores various control registers that can be
modified by guest VM kernels, so seL4 can execute multiple ARM
32-bit VMs multiplexing a single physical core.

When the CONFIG_HAVE_FPU option is selected, the commit allows
the VMs to use FPU registers and enables lazily saving/restoring
FPU registers for the VMs.

Share linker.h between architectures

SELFOUR-836: arm-hyp: Config option for saving/loading vs trapping debug state

Provides a configuration option for enabling HDCR.TD* traps, or saving and loading debug
state on VCPU switches. Currently verification only plans to support the trap setting.

As this option complicates all of the #ifdef's related to debug registers even further,
abstractions for enabling/disabling each individual piece of the debug code for different
configuration options are also implemented.

Part of these refactored #ifdef guards was to remove the guards completely from libsel4
around the definitions of the number of breakpoints and watchpoints.

SELFOUR-836: Debug-API: setup initial debug context in BOOT_CODE

A more efficient way of setting up threads' initial context is implemented
by this patch: essentially instead of reading the debug coprocessor everytime
we create a thread, we read the coprocessor once at boot and then assign
those pre-read values when initializing threads.

arm_hyp: Use an explicitly invalid PD when there is no user one

When the user has no PD in order to schedule them we must still set something as
the active PD, just so that they can then fault. Previously when hypervisor was
enabled `0` was at as the PD. This worked as platforms typically do not have
anything valid, and certainly nothing resembling a page directory, at physical
address 0. This assumption is not very clean and unknown physical addresses
should not be accessed, so this change adds an explicit PD that is empty that
can be switched to.

SELFOUR-553: Support alternate IPC buffer locations without globals frame

This commit adds support for using the ThreadID registers of the ARM MPCore
platforms for storing the address of the IPC buffer instead of the globals
frame. The choice of using the user readable/writeable ThreadID register
is chosen, even though it means the user cannot use it for its own
purposes, as it leaves room in the future for doing TLS support in the
user read only register, where compilers expect it.

arm_hyp: Add lazy vcpu switching

SELFOUR-556: Rationalize BITS vs INDEX_BITS

s/PGD_BITS/PGD_INDEX_BITS
Current convention is to say that X_BITS is the log base 2
size of an object, not the log base 2 number of indices

SELFOUR-556: Rationalize BITS vs INDEX_BITS

s/PD_BITS/PD_INDEX_BITS
Current convention is to say that X_BITS is the log base 2
size of an object, not the log base 2 number of indices

SELFOUR-556: Rationalize BITS vs INDEX_BITS

s/PT_BITS/PT_INDEX_BITS
Current convention is to say that X_BITS is the log base 2
size of an object, not the log base 2 number of indices

SELFOUR-518: User-level log buffer

Remove global ksLog and use KS_LOG_PPTR instead

Benchmark - Log buffer: use global page table

SELFOUR-555: Rename ksCurCPU->armHSCurVCPU

arm-hyp: Minor cleanups

Cleanup some small licensing, whitespace and configuration details

Correct previous merge

SELFOUR-399: object sizes and globals frame addr should come from the same source

Rearranging sources for aarch32 to 32/*