s390: add ELF note type for encrypted CPU state of a PV VCPU

The type NT_S390_PV_CPU_DATA note contains the encrypted CPU state of
a PV VCPU. It's only relevant in dumps of s390 PV VMs and can't be
decrypted without a second block of encrypted data which provides key
parts. Therefore we only reserve the note type here.

The zgetdump tool from the s390-tools package can, together with a
Customer Communication Key, be used to convert a PV VM dump into a
normal VM dump. zgetdump will decrypt the CPU data and overwrite the
other respective notes to make the data accessible for crash and other
debugging tools.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
[agordeev@linux.ibm.com changed desctiption]
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

include/uapi/linux/elf.h

@@ -420,6 +420,7 @@ typedef struct elf64_shdr {
 #define NT_S390_GS_CB	0x30b		/* s390 guarded storage registers */
 #define NT_S390_GS_BC	0x30c		/* s390 guarded storage broadcast control block */
 #define NT_S390_RI_CB	0x30d		/* s390 runtime instrumentation */
+#define NT_S390_PV_CPU_DATA	0x30e	/* s390 protvirt cpu dump data */
 #define NT_ARM_VFP	0x400		/* ARM VFP/NEON registers */
 #define NT_ARM_TLS	0x401		/* ARM TLS register */
 #define NT_ARM_HW_BREAK	0x402		/* ARM hardware breakpoint registers */