hashstp

Hash Store Privileged

hashstp RA

Privileged version of hash store.

Encoding

Binary Layout

31

0:5

/

6:10

RA

11:15

/

16:20

723

21:30

/

31

 

Format X-form

Opcode 0x7C000524

Extension Privileged

Operands

• RA
  Address

Example

hashstp r4

Registers Altered

MSR

Related

More in Privileged

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

Privileged instruction that stores a hash value to the address specified in RA. This instruction is used by privileged software (such as the hypervisor) to update hash tables for memory protection or integrity checking. Requires hypervisor privilege level and may affect storage subsystem state.

Operation

[RA] ← hash_compute(current_state)

Programming Note

The hashstp instruction is used for storing a doubleword into memory while verifying its integrity against a previously computed hash. It requires privileged access and must be executed in a context where the MSR register allows such operations. Ensure that the effective address (EA) is correctly calculated and aligned to avoid exceptions. If the stored value does not match the expected hash, a trap will occur, necessitating proper error handling.