replacing all ifndef with pargma once

All the kernel header files now use pargma once rather than the ifndef,
as the pre-processed C files do not change while header files
are protected with pargma once. This will also solve any naming issues
caused by ifndef.

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.

Remove symlinked libsel4 files from include dir

These files can be included normally using libsel4 include paths. This
removes situations where the same file is available under different
include paths due to symlinking into different directory structures.

style: consistently attach return type

Add attach-return-type to astyle

style: consistently align pointer with name

Run astyle with align-pointer=name

style: correct parenthesis padding

Use astyle's unpad-paren to unpad all parentheses that are not included
by pad-header, pad-oper, and pad-comma.

trivial: s/framSizeConstants/frameSizeConstants

x86: Implement IBRS based Spectre mitigations

Provides the ability to enable the IBRS hardware Spectre mitigation strategies, as well
as completes the software mitigation by disabling jump tables in compilation. The
hardware mitigations are largely provided "for completeness" in the hopes that they
eventually become less expensive. For the moment there is no reason to turn on any
beyond STIBP if running in multicore

x86: Export PMC to user

Provides an option that, on kernel init, enables user reading of the performance
monitoring counters. This is a step towards removing the dependence on
seL4_DebugRun for user level benchmarking/profiling

x86: Explict enum for fault types

This creates a similar structure as ARM, where an `enum` is created with the `#define` values
from libsel4. Having these values as enum types provides a 'real' C symbol for verification.

SELFOUR-1062: Hide all VT-x related code behind #ifdef guards

The VT-x implementation is not going to be verified at the moment, and so the code for
it needs to be hidden from verification, which we do by #ifdef'ing it out if the VT-x
is not enabled. As a result the VT-x configuration depends on a non verification target

SELFOUR-1062: Hide all IOMMU related code behind #ifdef guards

The IOMMU implementation is not going to be verified at the moment, and so the code for
it needs to be hidden from verification, which we do by #ifdef'ing it out if the IOMMU
is not enabled. As a result the IOMMU configuration depends on a non verification target

Share linker.h between architectures

SELFOUR-881: add ghost state updates for x86-64

x64: implement seL4_BenchmarkFlushCaches

by moving the ia32 implementation up a level to x86
and implementing the syscall stub.

x86: define L1_CACHE_LINE_SIZE_BITS as with ARM

SELFOUR-287: 32-bit vt-x implementation

This is an implementation of vt-x for x86 kernels running in
ia32 mode.

x86: Remove circular include

x86/arch/machine/hardware.h gets include via types.h (through the
compound_types.h header). As this header is defining compound types
it really only needs access to the basic types (i.e. stdint.h)

x86: Define large frame types

x86: Fixup IOMMU implementation

Adds a mapping type to frame caps that tracks
what kind of hierarchy the cap is mapped into;
an MMU, IOMMU and in the future an EPT structure.

Additionally the IOMMU code is updated to
have correct functionality and be verification
friendly.

SELFOUR-617: one source of memory object sizes

Adds the following constants to libsel4
and uses them in the kernel.

seL4_SectionSize (arm)
seL4_SuperSectionSize (arm)
seL4_HugePageSize (x86 - pae)
seL4_LargePageSize (arm)
seL4_DataFault
seL4_InstructionFault

x86: Fix clflush invocation in flushCacheLine

This fixes flushCacheLine to flush the line pointer to be vaddr,
not the cache line of the stack location holding the vaddr pointer

x86: Rename ia32->x86

This is a stylistic commit to make names of variables/constants and
functions in the kernel more consistent. That is, things that are
not IA32 specific, but are generic x86, get renamed to having an
x86 name

x86: Extract 32-bit specific vspace functions in mode/vspace.c

x86: Rename constants and functions to have X86 prefix instead of IA32 prefix

unsigned int -> word_t

Rename uint32_t -> word_t in any relevant places

x86: Make x86 the name of the architecture instead of IA32

IA32 is 32bit version of the x86 architecture. Whilst only IA32
is supported, much of the code is generic x86. Using a generic
x86 architecture will aid in future 64bit support