arch/x86: Add BERT region support functions

Add code for generating the region pointed to in an ACPI Boot Error
Record Table.

The BERT region must be reported as Reserved to the OSPM, so this
code calls out to a system-specific region locator.  cbmem is
reported as type 16 and is not usable for the BERT region.

Events reported via BERT are Generic Error Data, and are constructed
as follows (see ACPI and UEFI specs for reference):
 * Each event begins with a Generic Error Status Block, which may
   contain zero or more Generic Data Entries
 * Each Generic Data Entry is identifiable by its Section Type field,
   and the data structures associated are also in the UEFI spec.
     * The GUIDs are listed in the Section Type field of the CPER
       Section Descriptor structure.  BERT doesn't use this structure
       but simply uses its GUIDs.
     * Data structures used in the Generic Data Entry are named as
       Error Sections in the UEFI spec.
         * Some sections may optionally include a variable number of
           additional structures, e.g. an IA32/X64 processor error
           can report error information as well as machine contexts.

It is worth noting that the Linux kernel (as of v4.4) does not attempt
to parse IA32/X64 sections, and opts to hexdump them instead.

BUG=b:65446699
TEST=inspect BERT region, and dmesg, on full patch stack.  Use test
     data plus a failing Grunt system.

Change-Id: I54826981639b5647a8ca33b8b55ff097681402b9
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/28470
Reviewed-by: Martin Roth <martinroth@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
4 files changed