RDPKRU - Read Protection Key Rights for User Pages

Opcode*

Instruction

Op/ En

64/32bit Mode Support

CPUID Feature Flag

Description

NP 0F 01 EE

RDPKRU

ZO

V/V

OSPKE

Reads PKRU into EAX.

Instruction Operand Encoding

Op/En

Operand 1

Operand 2

Operand 3

Operand 4

ZO

N/A

N/A

N/A

N/A

Description

Reads the value of PKRU into EAX and clears EDX. ECX must be 0 when RDPKRU is executed; otherwise, a general- protection exception (#GP) occurs.

RDPKRU can be executed only if CR4.PKE = 1; otherwise, an invalid-opcode exception (#UD) occurs. Software can discover the value of CR4.PKE by examining CPUID.(EAX=07H,ECX=0H):ECX.OSPKE [bit 4].

On processors that support the Intel 64 Architecture, the high-order 32-bits of RCX are ignored and the high-order 32-bits of RDX and RAX are cleared.

Operation 

IF (ECX = 0) 
   THEN
       EAX := PKRU;
       EDX := 0;
   ELSE #GP(0); 
FI;

Flags Affected

None.

C/C++ Compiler Intrinsic Equivalent 

RDPKRU uint32_t _rdpkru_u32(void);

Protected Mode Exceptions

#GP(0)

#UD

If ECX != 0. If the LOCK prefix is used. If CR4.PKE = 0.

Real-Address Mode Exceptions

Same exceptions as in protected mode.

Virtual-8086 Mode Exceptions

Same exceptions as in protected mode.

Compatibility Mode Exceptions

Same exceptions as in protected mode.

64-Bit Mode Exceptions

Same exceptions as in protected mode.