Visible to Intel only — GUID: nzl1487887011951
Ixiasoft
3.1. 843819: Memory Locations May be Accessed Speculatively Due to Instruction Fetches When HCR.VM is Set
3.2. 845719: A Load May Read Incorrect Data
3.3. 855871: ETM Does Not Report IDLE State When Disabled Using OSLOCK
3.4. 855872: A Store-Exclusive Instruction May Pass When it Should Fail
3.5. 711668: Configuration Extension Register Has Wrong Value Status
3.6. 720107: Periodic Synchronization Can Be Delayed and Cause Overflow
3.7. 855873: An Eviction Might Overtake a Cache Clean Operation
3.8. 853172: ETM May Assert AFREADY Before All Data Has Been Output
3.9. 836870: Non-Allocating Reads May Prevent a Store Exclusive From Passing
3.10. 836919: Write of the JMCR in EL0 Does Not Generate an UNDEFINED Exception
3.11. 845819: Instruction Sequences Containing AES Instructions May Produce Incorrect Results
3.12. 851672: ETM May Trace an Incorrect Exception Address
3.13. 851871: ETM May Lose Counter Events While Entering WFx Mode
3.14. 852071: Direct Branch Instructions Executed Before a Trace Flush May be Output in an Atom Packet After Flush Acknowledgment
3.15. 852521: A64 Unconditional Branch May Jump to Incorrect Address
3.16. 855827: PMU Counter Values May Be Inaccurate When Monitoring Certain Events
3.17. 855829: Reads of PMEVCNTR<n> are not Masked by HDCR.HPMN
3.18. 855830: Loads of Mismatched Size May not be Single-Copy Atomic
Visible to Intel only — GUID: nzl1487887011951
Ixiasoft
3.14. 852071: Direct Branch Instructions Executed Before a Trace Flush May be Output in an Atom Packet After Flush Acknowledgment
Description
The Embedded Trace Macrocell (ETMv4) architecture requires that when a trace flush is requested on the AMBA* Trace Bus (ATB), a Cortex-A53 MPCore* processor must complete any packets that are in the process of being encoded and output them prior to acknowledging the flush request. When trace is enabled, the Cortex-A53 MPCore* processor attempts to combine multiple direct branch instructions into a single atom packet. If a direct branch instruction is executed, and an atom packet is in the process of being generated, the processor does not force completion of the packet prior to acknowledging the flush request. This erratum is a violation of the ETMv4 architecture.
The following conditions are required for this erratum to occur:
- ETM is enabled.
- Instruction tracing is active.
- The processor executes one or more direct branch instructions.
- An atom packet is in the process of being encoded but is not complete.
- A trace flush is requested on the AMBA* ATB.
Impact
When the above conditions occur, the ETM must complete encoding and output the atom packet prior to the trace flush request being acknowledged. Because of this erratum, the atom packet is output after the flush is acknowledged. Therefore, it appears to software monitoring the trace that the direct branch was executed after the requested flush.