csdb

Consumption of Speculative Data Barrier (A32)

CSDB

Prevents speculative data consumption (v8.0).

Pseudocode Operation

// Prevent consumption of speculatively-loaded data
ConsumptionBarrier()
// Subsequent instructions cannot use data obtained through speculative execution prior to this barrier

Encoding

Binary Layout

cond

31:28

00110

27:23

0

22

10

21:20

0000

19:16

1

15

1

14

1

13

1

12

000000010100

11:0

 

Format System Hint

Opcode 0x0320F014

Extension A32 (v8.0)

Operands

Related

Other forms of csdb

• csdb Consumption of Speculative Data Barrier

More in A32 (v8.0)

Reference

View in Arm A64 ISA Reference ↗ Arm AArch32 ISA

Instruction Forms

Encoding	Instruction		ISA		Bit pattern
0x0320F014	CSDB{<c>}{<q>}		A32		cond | 00110 | 0 | 10 | 0000 | 1 | 1 | 1 | 1 | 000000010100
0xF3AF8014	CSDB{<c>}{<q>}		T32		111100111010 | 1 | 1 | 1 | 1 | 10 | 0 | 0 | 0 | 000 | 0001 | 0100

Description

Consumption of Speculative Data Barrier is a memory barrier that controls speculative execution and data value prediction. No instruction other than branch instructions and instructions that write to the PC appearing in program order after the CSDB can be speculatively executed using the results of any:

Operation

if ConditionPassed() then
    EncodingSpecificOperations();

    ConsumptionOfSpeculativeDataBarrier();