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>

Fix MISRA defects in BL31 common code ...

Change-Id: I5993b425445ee794e6d2a792c244c0af53640655
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

libc: Fix all includes in codebase ...

The codebase was using non-standard headers. It is needed to replace
them by the correct ones so that we can use the new libc headers.

Change-Id: I530f71d9510cb036e69fe79823c8230afe890b9d
Acked-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>

EHF: MISRA fixes ...

These changes address most of the required MISRA rules. In the process,
some from generic code are also fixed.

No functional changes.

Change-Id: I19786070af7bc5e1f6d15bdba93e22a4451d8fe9
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

EHF: Introduce preempted return code parameter to ehf_allow_ns_preemption() ...

When a Yielding SMC is preempted, it's possible that Non-secure world is
resumed afterwards. In this case, Non-secure execution would find itself
in a state where the SMC has returned. However, the dispatcher might not
get an opportunity to populate the corrected return code for having
been preempted, and therefore the caller of the Yielding SMC cannot
reliably determine whether the SMC had successfully completed or had
been preempted.

To solve this, this patch introduces a new parameter to the
ehf_allow_ns_preemption() API. An SPD, through this parameter, would
provide the expected error code when a Yielding SMC is preempted. EHF
can then populate the specified value in x0 of the Non-secure context so
that the caller of the Yielding SMC correctly identifies the SMC return
as a preemption.

Documentation updates to follow.

Change-Id: Ia9c3f8f03f9d72d81aa235eaae2ee0374b972e1e
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

BL31: Program Priority Mask for SMC handling ...

On GICv3 systems, as a side effect of adding provision to handle EL3
interrupts (unconditionally routing FIQs to EL3), pending Non-secure
interrupts (signalled as FIQs) may preempt execution in lower Secure ELs
[1]. This will inadvertently disrupt the semantics of Fast SMC
(previously called Atomic SMC) calls.

To retain semantics of Fast SMCs, the GIC PMR must be programmed to
prevent Non-secure interrupts from preempting Secure execution. To that
effect, two new functions in the Exception Handling Framework subscribe
to events introduced in an earlier commit:

  - Upon 'cm_exited_normal_world', the Non-secure PMR is stashed, and
    the PMR is programmed to the highest Non-secure interrupt priority.

  - Upon 'cm_entering_normal_world', the previously stashed Non-secure
    PMR is restored.

The above sequence however prevents Yielding SMCs from being preempted
by Non-secure interrupts as intended. To facilitate this, the public API
exc_allow_ns_preemption() is introduced that programs the PMR to the
original Non-secure PMR value. Another API
exc_is_ns_preemption_allowed() is also introduced to check if
exc_allow_ns_preemption() had been called previously.

API documentation to follow.

[1] On GICv2 systems, this isn't a problem as, unlike GICv3, pending NS
    IRQs during Secure execution are signalled as IRQs, which aren't
    routed to EL3.

Change-Id: Ief96b162b0067179b1012332cd991ee1b3051dd0
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

BL31: Introduce Exception Handling Framework ...

EHF is a framework that allows dispatching of EL3 interrupts to their
respective handlers in EL3.

This framework facilitates the firmware-first error handling policy in
which asynchronous exceptions may be routed to EL3. Such exceptions may
be handed over to respective exception handlers. Individual handlers
might further delegate exception handling to lower ELs.

The framework associates the delegated execution to lower ELs with a
priority value. For interrupts, this corresponds to the priorities
programmed in GIC; for other types of exceptions, viz. SErrors or
Synchronous External Aborts, individual dispatchers shall explicitly
associate delegation to a secure priority. In order to prevent lower
priority interrupts from preempting higher priority execution, the
framework provides helpers to control preemption by virtue of
programming Priority Mask register in the interrupt controller.

This commit allows for handling interrupts targeted at EL3. Exception
handlers own interrupts by assigning them a range of secure priorities,
and registering handlers for each priority range it owns.

Support for exception handling in BL31 image is enabled by setting the
build option EL3_EXCEPTION_HANDLING=1.

Documentation to follow.

NOTE: The framework assumes the priority scheme supported by platform
interrupt controller is compliant with that of ARM GIC architecture (v2
or later).

Change-Id: I7224337e4cea47c6ca7d7a4ca22a3716939f7e42
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>