added a whole lot of debugging info for privileged emulation

riscemu/priv/PrivCPU.py

@@ -36,7 +36,7 @@ class PrivCPU(CPU):
     Reference to the control and status registers
     """
 
-    TIME_RESOLUTION_NS: int = 1000000
+    TIME_RESOLUTION_NS: int = 10000000
     """
     controls the resolution of the time csr register (in nanoseconds)
     """
@@ -162,6 +162,8 @@ class PrivCPU(CPU):
     def _handle_trap(self, trap: CpuTrap):
         # implement trap handling!
         self.pending_traps.append(trap)
+        print(FMT_CPU + "Trap {} encountered at {} (0x{:x})".format(trap, self.mmu.translate_address(self.pc), self.pc) + FMT_NONE)
+
 
     def step(self, verbose=True):
         try:
@@ -204,7 +206,7 @@ class PrivCPU(CPU):
         self.csr.set_mstatus('mpp', self.mode.value)
         self.csr.set_mstatus('mie', 0)
         self.csr.set('mcause', trap.mcause)
-        self.csr.set('mepc', self.pc-self.INS_XLEN)
+        self.csr.set('mepc', self.pc)
         self.csr.set('mtval', trap.mtval)
         self.mode = trap.priv
         mtvec = self.csr.get('mtvec')
@@ -242,3 +244,4 @@ class PrivCPU(CPU):
 
     def record_perf_profile(self):
         self._perf_counters.append((time.perf_counter_ns(), self.cycle))
+

riscemu/priv/PrivRV32I.py

@@ -77,15 +77,17 @@ class PrivRV32I(RV32I):
         self.cpu.mode = PrivModes(mpp)
         # restore pc
         mepc = self.cpu.csr.get('mepc')
-        self.cpu.pc = mepc
+        self.cpu.pc = mepc - self.cpu.INS_XLEN
 
         sec = self.mmu.get_sec_containing(mepc)
         if sec is not None:
-            print(FMT_CPU + "[CPU] [{}] returning to mode {} in {}".format(
+            print(FMT_CPU + "[CPU] [{}] returning to mode {} in {} (0x{:x})".format(
                 self.cpu.cycle,
                 PrivModes(mpp).name,
-                self.mmu.translate_address(mepc)
+                self.mmu.translate_address(mepc),
+                mepc
             ) + FMT_NONE)
+            self.regs.dump_reg_a()
 
     def instruction_uret(self, ins: 'LoadedInstruction'):
         raise IllegalInstructionTrap(ins)
@@ -137,6 +139,11 @@ class PrivRV32I(RV32I):
         ASSERT_LEN(ins.args, 2)
         reg = ins.get_reg(0)
         addr = ins.get_imm(1)
+        if reg == 'ra' and self.cpu.mode == PrivModes.USER:
+            print(FMT_CPU + 'Jumping to {} (0x{:x})'.format(
+                self.mmu.translate_address(self.pc + addr),
+                self.pc + addr
+            ) + FMT_NONE)
         self.regs.set(reg, self.pc)
         self.pc += addr - 4