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fix(data): add Smctr/Ssctr and update sctrclr (#1238)
Signed-off-by: Derek Hower <[email protected]> Signed-off-by: Paul A. Clarke <[email protected]> Co-authored-by: Derek Hower <[email protected]> Co-authored-by: David Brash <[email protected]> Co-authored-by: Derek Hower <[email protected]>
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‎backends/instructions_appendix/all_instructions.golden.adoc‎

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== sctrclr
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Synopsis::
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No synopsis available
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Supervisor Control Transfer Record (CTR) clear
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Assembly::
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sctrclr
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....
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Description::
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No description available.
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When xref:csrs:mstateen0.adoc#udb:doc:csr_field:mstateen0:CTR[mstateen0.CTR]=1, the SCTRCLR instruction performs the following operations:
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* Zeroes all CTR Entry Registers, for all DEPTH values
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* Reset to Zero the optional CTR cycle counter where implemented
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** `ctrdata.CC` and `ctrdata.CCV` bit fields.
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Any read of `ctrsource`, `ctrtarget`, or `ctrdata` that follows SCTRCLR, such that it precedes the next
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qualified control transfer, will return the value 0.
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Further, the first recorded transfer following SCTRCLR will have `ctrdata.CCV`=0.
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SCTRCLR execution causes an `IllegalInstruction` exception if:
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* xref:exts:Smctr.adoc#udb:doc:ext:Smctr[Smctr] is not implemented
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* The instruction is executed in S/VS/VU-mode and xref:exts:Ssctr.adoc#udb:doc:ext:Ssctr[Ssctr] is not implemented, or xref:csrs:mstateen0.adoc#udb:doc:csr_field:mstateen0:CTR[mstateen0.CTR]=0
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* The instruction is executed in U-mode
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SCTRCLR execution causes a `VirtualInstruciton` exception if xref:csrs:mstateen0.adoc#udb:doc:csr_field:mstateen0:CTR[mstateen0.CTR]=1 and:
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* The instruction is executed in VS-mode and xref:csrs:hstateen0.adoc#udb:doc:csr_field:hstateen0:CTR[hstateen0.CTR]=0
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* The instruction is executed in VU-mode
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Decode Variables::
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|===
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| Extension | Version
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| *Smdbltrp* | ~> 1.0.0
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| *Smctr* | ~> 1.0.0
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| *Ssctr* | ~> 1.0.0
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|===
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‎spec/std/isa/ext/Smctr.yaml‎

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# Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
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# SPDX-License-Identifier: BSD-3-Clause-Clear
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# yaml-language-server: $schema=../../schemas/ext_schema.json
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$schema: "ext_schema.json#"
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kind: extension
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name: Smctr
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long_name: Control Transfer Records
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description: |
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A method for recording control flow transfer history is valuable not only for performance
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profiling but also for debugging.
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Control flow transfers refer to jump instructions (including function calls and returns), taken
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branch instructions, traps, and trap returns.
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Profiling tools, such as Linux perf, collect control transfer history when sampling software
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execution, thereby enabling tools, like AutoFDO, to identify hot paths for optimization.
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Control flow trace capabilities offer very deep transfer history, but the volume of data produced
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can result in significant performance overheads due to memory bandwidth consumption, buffer
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management, and decoder overhead.
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The Control Transfer Records (CTR) extension provides a method to record a limited history in
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register-accessible internal chip storage, with the intent of dramatically reducing the
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performance overhead and complexity of collecting transfer history.
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CTR defines a circular (FIFO) buffer. Each buffer entry holds a record for a single recorded
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control flow transfer.
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The number of records that can be held in the buffer depends upon both the implementation (the
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maximum supported depth) and the CTR configuration (the software selected depth).
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Only qualified transfers are recorded.
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Qualified transfers are those that meet the filtering criteria, which include the privilege mode
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and the transfer type.
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Recorded transfers are inserted at the write pointer, which is then incremented, while older
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recorded transfers may be overwritten once the buffer is full.
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Or the user can enable RAS (Return Address Stack) emulation mode, where only function calls are
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recorded, and function returns pop the last call record.
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The source PC, target PC, and some optional metadata (transfer type, elapsed cycles) are stored
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for each recorded transfer.
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The CTR buffer is accessible through an indirect CSR interface, such that software can specify
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which logical entry in the buffer it wishes to read or write.
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Logical entry 0 always corresponds to the youngest recorded transfer, followed by entry 1 as the
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next youngest, and so on.
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type: privileged
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versions:
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- version: "1.0.0"
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state: ratified
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ratification_date: 2024-11
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implies:
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name: Ssctr
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version: "1.0.0"
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requires:
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allOf:
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- name: S
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version: ~> 1.13 # The latest ratified version of S when Sscntr was ratified
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- name: Smcsrind
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version: ~> 1.0

‎spec/std/isa/ext/Ssctr.yaml‎

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# Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
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# SPDX-License-Identifier: BSD-3-Clause-Clear
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# yaml-language-server: $schema=../../schemas/ext_schema.json
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$schema: "ext_schema.json#"
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kind: extension
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name: Ssctr
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long_name: Control Transfer Records
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description: |
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The supervisor view of `Smctr`.
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type: privileged
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versions:
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- version: "1.0.0"
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state: ratified
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ratification_date: 2024-11
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requires:
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allOf:
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- name: S
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version: ~> 1.13 # The latest ratified version of S when Sscntr was ratified
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- name: Sscsrind
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version: ~> 1.0

‎spec/std/isa/inst/Smdbltrp/sctrclr.yaml‎

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$schema: inst_schema.json#
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kind: instruction
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name: sctrclr
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long_name: No synopsis available
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long_name: Supervisor Control Transfer Record (CTR) clear
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description: |
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No description available.
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definedBy: Smdbltrp
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When `mstateen0.CTR`=1, the SCTRCLR instruction performs the following operations:
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* Zeroes all CTR Entry Registers, for all DEPTH values
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* Reset to Zero the optional CTR cycle counter where implemented
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** `ctrdata.CC` and `ctrdata.CCV` bit fields.
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Any read of `ctrsource`, `ctrtarget`, or `ctrdata` that follows SCTRCLR, such that it precedes the next
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qualified control transfer, will return the value 0.
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Further, the first recorded transfer following SCTRCLR will have `ctrdata.CCV`=0.
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SCTRCLR execution causes an `IllegalInstruction` exception if:
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* `Smctr` is not implemented
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* The instruction is executed in S/VS/VU-mode and `Ssctr` is not implemented, or `mstateen0.CTR`=0
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* The instruction is executed in U-mode
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SCTRCLR execution causes a `VirtualInstruciton` exception if `mstateen0.CTR`=1 and:
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* The instruction is executed in VS-mode and `hstateen0.CTR`=0
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* The instruction is executed in VU-mode
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definedBy:
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anyOf: [Smctr, Ssctr]
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assembly: ""
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encoding:
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match: "00010000010000000000000001110011"

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