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EHF currently allows for registering interrupt handlers for a defined
priority ranges. This is primarily targeted at various EL3 dispatchers
to own ranges of secure interrupt priorities in order to delegate
execution to lower ELs.

The RAS support added by earlier patches necessitates registering
handlers based on interrupt number so that error handling agents shall
receive and handle specific Error Recovery or Fault Handling interrupts
at EL3.

This patch introduces a macro, RAS_INTERRUPTS() to declare an array of
interrupt numbers and handlers. Error handling agents can use this macro
to register handlers for individual RAS interrupts. The array is
expected to be sorted in the increasing order of interrupt numbers.

As part of RAS initialisation, the list of all RAS interrupts are sorted
based on their ID so that, given an interrupt, its handler can be looked
up with a simple binary search.

For an error handling agent that wants to handle a RAS interrupt,
platform must:

  - Define PLAT_RAS_PRI to be the priority of all RAS exceptions.

  - Enumerate interrupts to have the GIC driver program individual EL3
    interrupts to the required priority range. This is required by EHF
    even before this patch.

Documentation to follow.

Change-Id: I9471e4887ff541f8a7a63309e9cd8f771f76aeda
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

RAS extensions are mandatory for ARMv8.2 CPUs, but are also optional
extensions to base ARMv8.0 architecture.

This patch adds build system support to enable RAS features in ARM
Trusted Firmware. A boolean build option RAS_EXTENSION is introduced for
this.

With RAS_EXTENSION, an Exception Synchronization Barrier (ESB) is
inserted at all EL3 vector entry and exit. ESBs will synchronize pending
external aborts before entering EL3, and therefore will contain and
attribute errors to lower EL execution. Any errors thus synchronized are
detected via. DISR_EL1 register.

When RAS_EXTENSION is set to 1, HANDLE_EL3_EA_FIRST must also be set to 1.

Change-Id: I38a19d84014d4d8af688bd81d61ba582c039383a
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>

At present, any External Abort routed to EL3 is reported as an unhandled
exception and cause a panic. This patch enables ARM Trusted Firmware to
handle External Aborts routed to EL3.

With this patch, when an External Abort is received at EL3, its handling
is delegated to plat_ea_handler() function. Platforms can provide their
own implementation of this function. This patch adds a weak definition
of the said function that prints out a message and just panics.

In order to support handling External Aborts at EL3, the build option
HANDLE_EA_EL3_FIRST must be set to 1.

Before this patch, HANDLE_EA_EL3_FIRST wasn't passed down to
compilation; this patch fixes that too.

Change-Id: I4d07b7e65eb191ff72d63b909ae9512478cd01a1
Signed-off-by: Jeenu Viswambharan <jeenu.viswambharan@arm.com>