Added XLEN as a length type for CSRs (#534)

* Added XLEN as a length type for CSRs

* More updates to Ruby CSR object + description for CSR schema

* More fixes for Ruby CSR object

* More fixes to Ruby CSR object

---------

Signed-off-by: Katherine Hsu <67767297+neverlandiz@users.noreply.github.com>

Author: neverlandiz

arch/csr/schema.adoc

@@ -59,8 +59,8 @@ Length::
 
 |===
 | *key*         | length
-| *value type*  | one of [32, 64, "MXLEN", "SXLEN", "VSXLEN"]
-| *description* | Length, in bits, of the CSR. Can either be a 32, 64 or MXLEN, SXLEN, VSXLEN to indicate that is is equal to the effective XLEN for a given mode
+| *value type*  | one of [32, 64, "MXLEN", "SXLEN", "VSXLEN", "XLEN"]
+| *description* | Length, in bits, of the CSR. Can either be a 32, 64 or MXLEN, SXLEN, VSXLEN, XLEN to indicate that is is equal to the effective XLEN for a given mode
 |===
 
 Indirect::

lib/arch_obj_models/csr.rb

@@ -112,6 +112,15 @@ def dynamic_length?
     when "VSXLEN"
       # dynamic if either we don't know VSXLEN or VSXLEN is explicitly mutable
       [nil, 3264].include?(cfg_arch.param_values["VSXLEN"])
+    when "XLEN"
+      # must always have M-mode
+      # SXLEN condition applies if S-mode is possible
+      # VSXLEN condition applies if VS-mode is possible
+      (cfg_arch.mxlen.nil?) || \
+      (cfg_arch.possible_extensions.map(&:name).include?("S") && \
+      [nil, 3264].include(cfg_arch.param_values["SXLEN"])) || \
+      (cfg_arch.possible_extensions.map(&:name).include?("H") && \
+      [nil, 3264].include?(cfg_arch.param_values["VSXLEN"]))
     else
       raise "Unexpected length"
     end
@@ -121,7 +130,7 @@ def dynamic_length?
   # @return [Integer] Smallest length of the CSR in any mode
   def min_length
     case @data["length"]
-    when "MXLEN", "SXLEN", "VSXLEN"
+    when "MXLEN", "SXLEN", "VSXLEN", "XLEN"
       @cfg_arch.possible_xlens.min
     when Integer
       @data["length"]
@@ -173,6 +182,8 @@ def length(effective_xlen = nil)
         # don't know VSXLEN
         effective_xlen
       end
+    when "XLEN"
+      effective_xlen
     when Integer
       @data["length"]
     else
@@ -207,6 +218,42 @@ def max_length
       else
         64
       end
+    when "XLEN"
+      if cfg_arch.possible_extensions.map(&:name).include?("M")
+        cfg_arch.mxlen || 64
+      elsif cfg_arch.possible_extensions.map(&:name).include?("S")
+        if cfg_arch.param_values.key?("SXLEN")
+          if cfg_arch.param_values["SXLEN"] == 3264
+            64
+          else
+            cfg_arch.param_values["SXLEN"]
+          end
+        else
+          # SXLEN can never be greater than MXLEN
+          cfg_arch.mxlen || 64
+        end
+      elsif cfg_arch.possible_extensions.map(&:name).include?("H")
+        if cfg_arch.param_values.key?("VSXLEN")
+          if cfg_arch.param_values["VSXLEN"] == 3264
+            64
+          else
+            cfg_arch.param_values["VSXLEN"]
+          end
+        else
+          # VSXLEN can never be greater than MXLEN or SXLEN
+          if cfg_arch.param_values.key?("SXLEN")
+            if cfg_arch.param_values["SXLEN"] == 3264
+              64
+            else
+              cfg_arch.param_values["SXLEN"]
+            end
+          else
+            cfg_arch.mxlen || 64
+          end
+        end
+      else
+        raise "Unexpected"
+      end
     when Integer
       @data["length"]
     else
@@ -223,6 +270,8 @@ def length_cond32
       "CSR[mstatus].SXL == 0"
     when "VSXLEN"
       "CSR[hstatus].VSXL == 0"
+    when "XLEN"
+      "(priv_mode() == PrivilegeMode::M && CSR[misa].MXL == 0) || (priv_mode() == PrivilegeMode::S && CSR[mstatus].SXL == 0) || (priv_mode() == PrivilegeMode::VS && CSR[hstatus].VSXL == 0)"
     else
       raise "Unexpected length #{@data['length']} for #{name}"
     end
@@ -237,6 +286,8 @@ def length_cond64
       "CSR[mstatus].SXL == 1"
     when "VSXLEN"
       "CSR[hstatus].VSXL == 1"
+    when "XLEN"
+      "(priv_mode() == PrivilegeMode::M && CSR[misa].MXL == 1) || (priv_mode() == PrivilegeMode::S && CSR[mstatus].SXL == 1) || (priv_mode() == PrivilegeMode::VS && CSR[hstatus].VSXL == 1)"
     else
       raise "Unexpected length"
     end
@@ -254,6 +305,8 @@ def length_pretty(effective_xlen=nil)
           "CSR[mstatus].SXL == %%"
         when "VSXLEN"
           "CSR[hstatus].VSXL == %%"
+        when "XLEN"
+          "(priv_mode() == PrivilegeMode::M && CSR[misa].MXL == %%) || (priv_mode() == PrivilegeMode::S && CSR[mstatus].SXL == %%) || (priv_mode() == PrivilegeMode::VS && CSR[hstatus].VSXL == %%)"
         else
           raise "Unexpected length '#{@data['length']}'"
         end

schemas/csr_schema.json

@@ -245,8 +245,8 @@
           "enum": ["M", "S", "U", "VS"]
         },
         "length": {
-          "description": "Length, in bits, of the CSR. Can either be a 32, 64 or MXLEN, SXLEN, VSXLEN to indicate that is is dependent on the effective XLEN for a given mode",
-          "enum": [32, 64, "MXLEN", "SXLEN", "VSXLEN"]
+          "description": "Length, in bits, of the CSR. Can either be a 32, 64 or MXLEN, SXLEN, VSXLEN to indicate that it is dependent on the effective XLEN for a given mode. XLEN here refers to the effective XLEN in the current execution mode.",
+          "enum": [32, 64, "MXLEN", "SXLEN", "VSXLEN", "XLEN"]
         },
         "requires": {
           "type": "string",