Implement exception/fault encoder module

Makefile

@@ -15,6 +15,7 @@ obj_dir/apb0_memory.hex: obj_dir/firmware.bin tool/makebin.py
 	./tool/makebin.py obj_dir/firmware.bin $@
 
 obj_dir/firmware.bin: firmware/target/riscv32i-unknown-none-elf/release/firmware
+	mkdir -p obj_dir
 	llvm-objcopy -O binary $< $@
 
 firmware/target/riscv32i-unknown-none-elf/release/firmware: $(FIRMWARE_SRC)
@@ -22,7 +23,7 @@ firmware/target/riscv32i-unknown-none-elf/release/firmware: $(FIRMWARE_SRC)
 
 obj_dir/rvx0: $(SRC_MODULE) $(DEF_MODULE) $(MAIN_TOP) obj_dir/apb0_memory.hex
 	mkdir -p obj_dir
-	verilator --assert --binary -Isrc -o rvx0 $(MAIN_TOP) $(SRC_MODULE)
+	verilator -Wno-fatal --assert --binary -Isrc -o rvx0 $(MAIN_TOP) $(SRC_MODULE)
 #
 # obj_dir/firmware.elf: $(FIRMWARE_OBJ) src/firmware.ld
 #

src/core/rvx0_core.sv

@@ -1,4 +1,3 @@
-/* verilator lint_off PINMISSING */
 /* verilator lint_off MULTIDRIVEN */
 
 `include "rvx0_defs.svh"
@@ -205,14 +204,28 @@ module rvx0_core #(
         .mtvec_o                    (csr_mtvec)
     );
 
-    assign fault = fault_instruction_align ||
+    rvx0_fault_encoder fault_encoder (
-                   fault_instruction_fetch ||
+        .fault_instruction_decode_i (fault_instruction),
-                   fault_instruction ||
+        .fault_instruction_align_i  (fault_instruction_align),
-                   fault_memory_align ||
+        .fault_instruction_fetch_i  (fault_instruction_fetch),
-                   fault_memory_access ||
+        .fault_memory_align_i       (fault_memory_align),
-                   raise_ecall ||
+        .fault_memory_access_i      (fault_memory_access),
-                   raise_ebreak ||
+
-                   intr_ext_i;
+        .raise_ecall_i              (raise_ecall),
+        .raise_ebreak_i             (raise_ebreak),
+
+        .intr_ext_i                 (intr_ext_i),
+
+        .pc_value_i                 (pc_value),
+        .memory_address_i           (alu_output),
+        .instruction_i              (instruction),
+        .need_memory_write_i        (need_memory_write),
+
+        .fault_o                    (fault),
+        .mcause_write_value_o       (mcause_write_value),
+        .mtval_write_value_o        (mtval_write_value),
+        .mepc_write_value_o         (mepc_write_value)
+    );
 
     assign fault_instruction = fault_instruction_decode || (fault_unsupported_size && (need_memory_read || need_memory_write));
     assign fault_memory_align = fault_address_align && (need_memory_write || need_memory_read);
@@ -251,43 +264,6 @@ module rvx0_core #(
         end
     end
 
-    // Exception parameter encoding
-    always_comb begin
-        mcause_write_value = 0;
-        mtval_write_value = 0;
-        mepc_write_value = pc_value;
-
-        if (fault_instruction_align) begin
-            mcause_write_value = MCAUSE_INSTRUCTION_ADDRESS_MISALIGN;
-        end else if (fault_instruction_fetch) begin
-            mcause_write_value = MCAUSE_INSTRUCTION_ACCESS_FAULT;
-            mtval_write_value = pc_value;
-        end else if (fault_instruction) begin
-            mcause_write_value = MCAUSE_ILLEGAL_INSTRUCTION;
-            mtval_write_value = instruction;
-        end else if (raise_ebreak) begin
-            mcause_write_value = MCAUSE_BREAKPOINT;
-        end else if (~need_memory_write && fault_memory_align) begin
-            mcause_write_value = MCAUSE_LOAD_ADDRESS_MISALIGNED;
-            mtval_write_value = alu_output;
-        end else if (~need_memory_write && fault_memory_access) begin
-            mcause_write_value = MCAUSE_LOAD_ACCESS_FAULT;
-        end else if (fault_memory_align) begin
-            mcause_write_value = MCAUSE_STORE_ADDRESS_MISALIGNED;
-            mtval_write_value = alu_output;
-        end else if (fault_memory_access) begin
-            mcause_write_value = MCAUSE_STORE_ACCESS_FAULT;
-            // Because this happens at write pipeline stage and PC has already
-            // been incremented
-            mepc_write_value = pc_value - 4;
-            mtval_write_value = alu_output;
-        end else if (raise_ecall) begin
-            mcause_write_value = MCAUSE_ECALL_MMODE;
-        end else if (intr_ext_i) begin
-            mcause_write_value = MCAUSE_INTR_EXT_MMODE | MCAUSE_INTERRUPT;
-        end
-    end
-
     always @(posedge clk_i) begin
         case (control_state)
         CSTATE_EXEC: begin

src/core/rvx0_fault_encoder.sv

@@ -0,0 +1,71 @@
+module rvx0_fault_encoder (
+    // Instruction
+    input wire          fault_instruction_align_i,
+    input wire          fault_instruction_fetch_i,
+    input wire          fault_instruction_decode_i,
+    // Memory
+    input wire          fault_memory_align_i,
+    input wire          fault_memory_access_i,
+    // External
+    input wire          intr_ext_i,
+    // Internal
+    input wire          raise_ecall_i,
+    input wire          raise_ebreak_i,
+
+    input wire [31:0]   pc_value_i,
+    input wire [31:0]   instruction_i,
+    input wire [31:0]   memory_address_i,
+    input wire          need_memory_write_i,
+
+    output logic [31:0] mcause_write_value_o,
+    output logic [31:0] mtval_write_value_o,
+    output logic [31:0] mepc_write_value_o,
+    output logic        fault_o
+);
+    assign fault_o = fault_instruction_align_i ||
+                     fault_instruction_fetch_i ||
+                     fault_instruction_decode_i ||
+                     fault_memory_align_i ||
+                     fault_memory_access_i ||
+                     raise_ecall_i ||
+                     raise_ebreak_i ||
+                     intr_ext_i;
+
+    // Exception parameter encoding
+    always_comb begin
+        mcause_write_value_o = 0;
+        mtval_write_value_o = 0;
+        mepc_write_value_o = pc_value_i;
+
+        if (fault_instruction_align_i) begin
+            mcause_write_value_o = MCAUSE_INSTRUCTION_ADDRESS_MISALIGN;
+        end else if (fault_instruction_fetch_i) begin
+            mcause_write_value_o = MCAUSE_INSTRUCTION_ACCESS_FAULT;
+            mtval_write_value_o = pc_value_i;
+        end else if (fault_instruction_decode_i) begin
+            mcause_write_value_o = MCAUSE_ILLEGAL_INSTRUCTION;
+            mtval_write_value_o = instruction_i;
+        end else if (raise_ebreak_i) begin
+            mcause_write_value_o = MCAUSE_BREAKPOINT;
+        end else if (~need_memory_write_i && fault_memory_align_i) begin
+            mcause_write_value_o = MCAUSE_LOAD_ADDRESS_MISALIGNED;
+            mtval_write_value_o = memory_address_i;
+        end else if (~need_memory_write_i && fault_memory_access_i) begin
+            mcause_write_value_o = MCAUSE_LOAD_ACCESS_FAULT;
+        end else if (fault_memory_align_i) begin
+            mcause_write_value_o = MCAUSE_STORE_ADDRESS_MISALIGNED;
+            mtval_write_value_o = memory_address_i;
+        end else if (fault_memory_access_i) begin
+            mcause_write_value_o = MCAUSE_STORE_ACCESS_FAULT;
+            // Because this happens at write pipeline stage and PC has already
+            // been incremented
+            mepc_write_value_o = pc_value_i - 4;
+            mtval_write_value_o = memory_address_i;
+        end else if (raise_ecall_i) begin
+            mcause_write_value_o = MCAUSE_ECALL_MMODE;
+        end else if (intr_ext_i) begin
+            mcause_write_value_o = MCAUSE_INTR_EXT_MMODE | MCAUSE_INTERRUPT;
+        end
+    end
+
+endmodule