ACPI, APEI, Error Record Serialization Table (ERST) support

ERST is a way provided by APEI to save and retrieve hardware error
record to and from some simple persistent storage (such as flash).

The Linux kernel support implementation is quite simple and workable
in NMI context. So it can be used to save hardware error record into
flash in hardware error exception or NMI handler, where other more
complex persistent storage such as disk is not usable. After saving
hardware error records via ERST in hardware error exception or NMI
handler, the error records can be retrieved and logged into disk or
network after a clean reboot.

For more information about ERST, please refer to ACPI Specification
version 4.0, section 17.4.

This patch incorporate fixes from Jin Dongming.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
CC: Jin Dongming <jin.dongming@np.css.fujitsu.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Documentation/kernel-parameters.txt

@@ -750,6 +750,10 @@ and is between 256 and 4096 characters. It is defined in the file
 			Default value is 0.
 			Value can be changed at runtime via /selinux/enforce.
 
+	erst_disable	[ACPI]
+			Disable Error Record Serialization Table (ERST)
+			support.
+
 	ether=		[HW,NET] Ethernet cards parameters
 			This option is obsoleted by the "netdev=" option, which
 			has equivalent usage. See its documentation for details.

drivers/acpi/apei/Makefile

@@ -2,4 +2,4 @@ obj-$(CONFIG_ACPI_APEI)		+= apei.o
 obj-$(CONFIG_ACPI_APEI_GHES)	+= ghes.o
 obj-$(CONFIG_ACPI_APEI_EINJ)	+= einj.o
 
-apei-y := apei-base.o hest.o cper.o
+apei-y := apei-base.o hest.o cper.o erst.o