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WRPKRU (Intel x86/64 assembly instruction)

작성일 : 2020-09-01 이 글은 918 번 읽혔습니다.

WRPKRU

Write Data to User Page Key Register

참고 사항

아래 표를 해석하는 방법은 x86-64 명령어 레퍼런스 읽는 법 글을 참조하시기 바랍니다.

Opcode*

Instruction

Op/
En

64/32bit
Mode
Support

CPUID
Feature
Flag

Description

0F 01 EF

WRPKRU

NP

V/V

OSPKE

Writes EAX into PKRU.

Instruction Operand Encoding

Op/En

Operand 1

Operand 2

Operand 3

Operand 4

NP

NA

NA

NA

NA

Description

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

WRPKRU 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, RDX and RAX are ignored.

Operation

IF (ECX = 0 AND EDX = 0) 
    THEN PKRU <- EAX;
    ELSE #GP(0); 
FI;

Flags Affected

None.

C/C++ Compiler Intrinsic Equivalent

WRPKRU: void _wrpkru(uint32_t);

Protected Mode Exceptions

#GP(0)

  • If ECX >=B 0.

  • If EDX >=B 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.

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