Add support for pointer authentication ...

The previous commit added the infrastructure to load and save
ARMv8.3-PAuth registers during Non-secure <-> Secure world switches, but
didn't actually enable pointer authentication in the firmware.

This patch adds the functionality needed for platforms to provide
authentication keys for the firmware, and a new option (ENABLE_PAUTH) to
enable pointer authentication in the firmware itself. This option is
disabled by default, and it requires CTX_INCLUDE_PAUTH_REGS to be
enabled.

Change-Id: I35127ec271e1198d43209044de39fa712ef202a5
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Add ARMv8.3-PAuth registers to CPU context ...

ARMv8.3-PAuth adds functionality that supports address authentication of
the contents of a register before that register is used as the target of
an indirect branch, or as a load.

This feature is supported only in AArch64 state.

This feature is mandatory in ARMv8.3 implementations.

This feature adds several registers to EL1. A new option called
CTX_INCLUDE_PAUTH_REGS has been added to select if the TF needs to save
them during Non-secure <-> Secure world switches. This option must be
enabled if the hardware has the registers or the values will be leaked
during world switches.

To prevent leaks, this patch also disables pointer authentication in the
Secure world if CTX_INCLUDE_PAUTH_REGS is 0. Any attempt to use it will
be trapped in EL3.

Change-Id: I27beba9907b9a86c6df1d0c5bf6180c972830855
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

Sanitise includes across codebase ...

Enforce full include path for includes. Deprecate old paths.

The following folders inside include/lib have been left unchanged:

- include/lib/cpus/${ARCH}
- include/lib/el3_runtime/${ARCH}

The reason for this change is that having a global namespace for
includes isn't a good idea. It defeats one of the advantages of having
folders and it introduces problems that are sometimes subtle (because
you may not know the header you are actually including if there are two
of them).

For example, this patch had to be created because two headers were
called the same way: e0ea0928d5b7 ("Fix gpio includes of mt8173 platform
to avoid collision."). More recently, this patch has had similar
problems: 46f9b2c3a282 ("drivers: add tzc380 support").

This problem was introduced in commit 4ecca33988b9 ("Move include and
source files to logical locations"). At that time, there weren't too
many headers so it wasn't a real issue. However, time has shown that
this creates problems.

Platforms that want to preserve the way they include headers may add the
removed paths to PLAT_INCLUDES, but this is discouraged.

Change-Id: I39dc53ed98f9e297a5966e723d1936d6ccf2fc8f
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

RAS: Introduce handler for Double Faults ...

Double fault is when the PE receives another error whilst one is being
handled. To detect double fault condition, a per-CPU flag is introduced
to track the status of error handling. The flag is checked/modified
while temporarily masking external aborts on the PE.

This patch routes double faults to a separate platform-defined handler.

Change-Id: I70e9b7ba4c817273c55a0af978d9755ff32cc702
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

RAS: Introduce handler for Uncontainable errors ...

Uncontainable errors are the most severe form of errors, which typically
mean that the system state can't be trusted any more. This further means
that normal error recovery process can't be followed, and an orderly
shutdown of the system is often desirable.

This patch allows for the platform to define a handler for Uncontainable
errors received. Due to the nature of Uncontainable error, the handler
is expected to initiate an orderly shutdown of the system, and therefore
is not expected to return. A default implementation is added which falls
back to platform unhandled exception.

Also fix ras_arch.h header guards.

Change-Id: I072e336a391a0b382e77e627eb9e40729d488b55
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

RAS: Validate stack pointer after error handling ...

RAS handling flows might involve using setjmp/longjump calls introduced
in earlier patches; therefore, it'd be good to make sure the stack has
been unwound completely after the handling.

This patch inserts ASM assertions on the RAS handling path to validate
stack.

Change-Id: I59d40d3122010c977cdeab3cce3160f3909e7e69
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

RAS: Move EA handling to a separate file ...

A new file ea_delegate.S is introduced, and all EA-related functions are
moved into it. This makes runtime_exceptions.S less crowded and reads
better.

No functional changes.

Change-Id: I64b653b3931984cffd420563f8e8d1ba263f329f
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>