RDPKRU—Read Protection Key Rights for User Pages

Opcode*

Instruction

Op/

64/32bit

CPUID

Description

En Mode Support Feature Flag
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 NA NA NA NA

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) If ECX ≠ 0.
#UD

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.