endbr64

End Branch 64-bit

ENDBR64

Marker instruction for Indirect Branch Tracking (IBT).

Pseudocode Operation

// Marker instruction for Indirect Branch Tracking (IBT)

Encoding

Binary Layout

F3

+0

0F

+1

1E

+2

FA

+3

 

Format Legacy

Opcode F3 0F 1E FA

Extension CET-IBT

Operands

Related

More in CET-IBT

Reference

View in Intel® 64 and IA-32 Architectures SDM ↗ Intel® SDM

Instruction Forms

Opcode	Instruction	Op/En	64/32-bit Mode	CPUID	Description
F3 0F 1E FA	ENDBR64	ZO	V/V	CET_IBT	Terminate indirect branch in 64-bit mode.

Description

Terminate an indirect branch in 64 bit mode. This opcode is a NOP when CET indirect branch tracking is not enabled and on processors that do not support CET.

Operation

IF EndbranchEnabled(CPL) & IA32_EFER.LMA = 1 & CS.L = 1
IF CPL = 3
THEN
IA32_U_CET.TRACKER = IDLE
IA32_U_CET.SUPPRESS = 0
ELSE
IA32_S_CET.TRACKER = IDLE
IA32_S_CET.SUPPRESS = 0
FI;
FI;

Flags Affected

None. Exceptions #UD If the LOCK prefix is used. ENDBR64-Terminate an Indirect Branch in 64-bit Mode Vol. 2A 3-288