ENDBR32

ENDBR32 — Terminate an Indirect Branch in 32-bit and Compatibility Mode

Opcode/ Instruction	Op / En	64/32 bit Mode Support	CPUID Feature Flag	Description
F3 0F 1E FB ENDBR32	ZO	V/V	CET_IBT	Terminate indirect branch in 32-bit and compatibility mode.

Instruction Operand Encoding

Op/En	Tuple Type	Operand 1	Operand 2	Operand 3	Operand 4
ZO	N/A	N/A	N/A	N/A	N/A

Description

Terminate an indirect branch in 32 bit and compatibility 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 = 0 | (IA32_EFER.LMA=1 & CS.L = 0)
    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.

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Source: Intel® 64 and IA-32 Architectures Software Developer's Manual, Combined Volumes (Order Number 325462-091US, March 2026)
Generated: 7-6-2026