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Data Synchronization Barrier is a memory barrier that ensures the completion of memory accesses, see Data Synchronization Barrier (DSB).
It has encodings from the following instruction sets: A32 ( A1 ) and T32 ( T1 ) .
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | (1) | (1) | (1) | (1) | (1) | (1) | (1) | (1) | (0) | (0) | (0) | (0) | 0 | 1 | 0 | 0 | != 0x00 | |||
option |
// No additional decoding required
15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
1 | 1 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 1 | 1 | (1) | (1) | (1) | (1) | 1 | 0 | (0) | 0 | (1) | (1) | (1) | (1) | 0 | 1 | 0 | 0 | != 0x00 | |||
option |
// No additional decoding required
For more information about the constrained unpredictable behavior, see Architectural Constraints on UNPREDICTABLE behaviors.
<c> | For encoding A1: see Standard assembler syntax fields. Must be AL or omitted. |
For encoding T1: see Standard assembler syntax fields. |
<q> |
<option> | Specifies an optional limitation on the barrier operation. Values are:
For more information on whether an access is before or after a barrier instruction, see Data Synchronization Barrier (DSB). All other encodings of option are reserved. All unsupported and reserved options must execute as a full system DSB operation, but software must not rely on this behavior.
The instruction supports the following alternative <option> values, but Arm recommends that software does not use these alternative values:
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if ConditionPassed() then
EncodingSpecificOperations();
case option of
when '0001' domain = MBReqDomain_OuterShareable; types = MBReqTypes_Reads;
when '0010' domain = MBReqDomain_OuterShareable; types = MBReqTypes_Writes;
when '0011' domain = MBReqDomain_OuterShareable; types = MBReqTypes_All;
when '0101' domain = MBReqDomain_Nonshareable; types = MBReqTypes_Reads;
when '0110' domain = MBReqDomain_Nonshareable; types = MBReqTypes_Writes;
when '0111' domain = MBReqDomain_Nonshareable; types = MBReqTypes_All;
when '1001' domain = MBReqDomain_InnerShareable; types = MBReqTypes_Reads;
when '1010' domain = MBReqDomain_InnerShareable; types = MBReqTypes_Writes;
when '1011' domain = MBReqDomain_InnerShareable; types = MBReqTypes_All;
when '1101' domain = MBReqDomain_FullSystem; types = MBReqTypes_Reads;
when '1110' domain = MBReqDomain_FullSystem; types = MBReqTypes_Writes;
otherwise
if option == '0000' then SEE "SSBB";
elsif option == '0100' then SEE "PSSBB";
else domain = MBReqDomain_FullSystem; types = MBReqTypes_All;
if PSTATE.EL IN { ifEL2Enabled() && PSTATE.EL IN {EL0, EL1} && EL2Enabled() then
} then
if HCR.BSU == '11' then
domain = MBReqDomain_FullSystem;
if HCR.BSU == '10' && domain != MBReqDomain_FullSystem then
domain = MBReqDomain_OuterShareable;
if HCR.BSU == '01' && domain == MBReqDomain_Nonshareable then
domain = MBReqDomain_InnerShareable;
DataSynchronizationBarrier(domain, types);
Internal version only: isa v00_96v00_88, pseudocode r8p5_00bet2_rc5v85-xml-00bet9_rc1_1
; Build timestamp: 2019-03-28T072018-12-12T12:5933
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This document is Non-Confidential.
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