Add Smctr/Ssctr YAML and properly attribute SCTRCLR to them

arch/ext/Smctr.yaml

@@ -0,0 +1,55 @@
+# yaml-language-server: $schema=../../schemas/ext_schema.json
+
+$schema: "ext_schema.json#"
+kind: extension
+name: Smctr
+long_name: Control Transfer Records
+description: |
+  A method for recording control flow transfer history is valuable not only for performance
+  profiling but also for debugging.
+  Control flow transfers refer to jump instructions (including function calls and returns), taken
+  branch instructions, traps, and trap returns.
+  Profiling tools, such as Linux perf, collect control transfer history when sampling software
+  execution, thereby enabling tools, like AutoFDO, to identify hot paths for optimization.
+
+  Control flow trace capabilities offer very deep transfer history, but the volume of data produced
+  can result in significant performance overheads due to memory bandwidth consumption, buffer
+  management, and decoder overhead.
+  The Control Transfer Records (CTR) extension provides a method to record a limited history in
+  register-accessible internal chip storage, with the intent of dramatically reducing the
+  performance overhead and complexity of collecting transfer history.
+
+  CTR defines a circular (FIFO) buffer. Each buffer entry holds a record for a single recorded
+  control flow transfer.
+  The number of records that can be held in the buffer depends upon both the implementation (the
+  maximum supported depth) and the CTR configuration (the software selected depth).
+
+  Only qualified transfers are recorded.
+  Qualified transfers are those that meet the filtering criteria, which include the privilege mode
+  and the transfer type.
+
+  Recorded transfers are inserted at the write pointer, which is then incremented, while older
+  recorded transfers may be overwritten once the buffer is full.
+  Or the user can enable RAS (Return Address Stack) emulation mode, where only function calls are
+  recorded, and function returns pop the last call record.
+  The source PC, target PC, and some optional metadata (transfer type, elapsed cycles) are stored
+  for each recorded transfer.
+
+  The CTR buffer is accessible through an indirect CSR interface, such that software can specify
+  which logical entry in the buffer it wishes to read or write.
+  Logical entry 0 always corresponds to the youngest recorded transfer, followed by entry 1 as the
+  next youngest, and so on.
+type: privileged
+versions:
+  - version: "1.0.0"
+    state: ratified
+    ratification_date: 2024-11
+    implies:
+      name: Ssctr
+      version: "1.0.0"
+    requires:
+      allOf:
+        - name: S
+          version: ~> 1.13 # The latest ratified version of S when Sscntr was ratified
+        - name: Smcsrind
+          version: ~> 1.0

arch/ext/Ssctr.yaml

@@ -0,0 +1,19 @@
+# yaml-language-server: $schema=../../schemas/ext_schema.json
+
+$schema: "ext_schema.json#"
+kind: extension
+name: Ssctr
+long_name: Control Transfer Records
+description: |
+  The supervisor view of `Smctr`.
+type: privileged
+versions:
+  - version: "1.0.0"
+    state: ratified
+    ratification_date: 2024-11
+    requires:
+      allOf:
+        - name: S
+          version: ~> 1.13 # The latest ratified version of S when Sscntr was ratified
+        - name: Sscsrind
+          version: ~> 1.0

arch/inst/Smdbltrp/sctrclr.yaml

@@ -3,10 +3,42 @@
 $schema: inst_schema.json#
 kind: instruction
 name: sctrclr
-long_name: No synopsis available.
-description: |
-  No description available.
-definedBy: Smdbltrp
+long_name: Supervisor Control Transfer Record (CTR) clear
+description:
+  - id: inst-sctrclr-operation
+    normative: false
+    text: |
+      When `mstateen0.CTR`=1, the SCTRCLR instruction performs the following operations:
+
+      * Zeroes all CTR Entry Registers, for all DEPTH values
+      * Reset to Zero the optional CTR cycle counter where implemented
+      ** `ctrdata.CC` and `ctrdata.CCV` bit fields.
+  - id: inst-sctrclr-csr-effect
+    normative: true
+    text: |
+      Any read of `ctrsource`, `ctrtarget`, or `ctrdata` that follows SCTRCLR, such that it precedes the next
+      qualified control transfer, will return the value 0.
+  - id: inst-sctrclr-after
+    normative: true
+    text: |
+      Further, the first recorded transfer following SCTRCLR will have `ctrdata.CCV`=0.
+  - id: inst-sctrclr-illegal
+    normative: false
+    text: |
+      SCTRCLR execution causes an `IllegalInstruction` exception if:
+
+      * `Smctr` is not implemented
+      * The instruction is executed in S/VS/VU-mode and `Ssctr` is not implemented, or `mstateen0.CTR`=0
+      * The instruction is executed in U-mode
+  - id: inst-sctrclr-virtual
+    normative: false
+    text: |
+      SCTRCLR execution  causes a `VirtualInstruciton` exception if `mstateen0.CTR`=1 and:
+
+      * The instruction is executed in VS-mode and `hstateen0.CTR`=0
+      * The instruction is executed in VU-mode
+definedBy:
+  anyOf: [Smctr, Ssctr]
 assembly: sctrclr
 encoding:
   match: "00010000010000000000000001110011"