[Priv] overhauled instruction architecture

riscemu/priv/CSR.py

@@ -1,7 +1,7 @@
 from typing import Dict, Union, Callable, Optional
 from collections import defaultdict
 from .privmodes import PrivModes
-from .Exceptions import IllegalInstructionTrap
+from .Exceptions import InstructionAccessFault
 from ..helpers import to_unsigned
 
 MSTATUS_OFFSETS = {

riscemu/priv/Exceptions.py

@@ -1,5 +1,16 @@
-from typing import Optional
+from typing import Optional, NewType
+from enum import Enum
+from .privmodes import PrivModes
 
+import typing
+if typing.TYPE_CHECKING:
+    from .ElfLoader import ElfInstruction
+
+class CpuTrapType(Enum):
+    TIMER = 1
+    SOFTWARE = 2
+    EXTERNAL = 3
+    EXCEPTION = 4
 
 class CpuTrap(BaseException):
     code: int
@@ -10,17 +21,28 @@ class CpuTrap(BaseException):
     """
     The isInterrupt bit in the mstatus register
     """
+
     mtval: int
     """
     contents of the mtval register
     """
 
-    def __init__(self, interrupt: int, code: int, mtval=0):
-        assert 0 <= interrupt <= 1
+    type: CpuTrapType
+    """
+    The type (timer, external, software) of the trap
+    """
 
-        self.interrupt = interrupt
+    priv: PrivModes
+    """
+    The privilege level this trap targets 
+    """
+
+    def __init__(self, code: int, mtval, type: CpuTrapType, priv: PrivModes = PrivModes.MACHINE):
+        self.interrupt = 0 if type == CpuTrapType.EXCEPTION else 1
         self.code = code
         self.mtval = mtval
+        self.priv = priv
+        self.type = type
 
     @property
     def mcause(self):
@@ -28,17 +50,20 @@ class CpuTrap(BaseException):
 
 
 class IllegalInstructionTrap(CpuTrap):
-    def __init__(self):
-        super().__init__(0, 2, 0)
+    def __init__(self, ins: 'ElfInstruction'):
+        super().__init__(2, ins.encoded, CpuTrapType.EXCEPTION)
 
 
 class InstructionAddressMisalignedTrap(CpuTrap):
     def __init__(self, addr: int):
-        super().__init__(0, 0, addr)
+        super().__init__(0, addr, CpuTrapType.EXCEPTION)
 
 
 class InstructionAccessFault(CpuTrap):
     def __init__(self, addr: int):
-        super().__init__(0, 1, addr)
+        super().__init__(1, addr, CpuTrapType.EXCEPTION)
 
 
+class TimerInterrupt(CpuTrap):
+    def __init(self):
+        super().__init__(7, 0, CpuTrapType.TIMER)

riscemu/priv/PrivCPU.py

@@ -169,7 +169,7 @@ class PrivCPU(CPU):
         if not self._time_interrupt_enabled:
             return
         if self._time_timecmp < (time.perf_counter_ns() // self.TIME_RESOLUTION_NS) - self._time_start:
-            self.pending_traps.append(CpuTrap(1, 7, 0))
+            self.pending_traps.append(TimerInterrupt())
             self._time_interrupt_enabled = False
 
     def _check_interrupt(self):

riscemu/priv/PrivRV32I.py

@@ -49,7 +49,7 @@ class PrivRV32I(RV32I):
     def instruction_mret(self, ins: 'LoadedInstruction'):
         if self.cpu.mode != PrivModes.MACHINE:
             print("MRET not inside machine level code!")
-            raise IllegalInstructionTrap()
+            raise IllegalInstructionTrap(ins)
         # retore mie
         mpie = self.cpu.csr.get_mstatus('mpie')
         self.cpu.csr.set_mstatus('mie', mpie)
@@ -61,21 +61,21 @@ class PrivRV32I(RV32I):
         self.cpu.pc = mepc
 
     def instruction_uret(self, ins: 'LoadedInstruction'):
-        raise IllegalInstructionTrap()
+        raise IllegalInstructionTrap(ins)
 
     def instruction_sret(self, ins: 'LoadedInstruction'):
-        raise IllegalInstructionTrap()
+        raise IllegalInstructionTrap(ins)
 
     def instruction_scall(self, ins: 'LoadedInstruction'):
         """
         Overwrite the scall from userspace RV32I
         """
         if self.cpu.mode == PrivModes.USER:
-            raise CpuTrap(0, 8)  # ecall from U mode
+            raise CpuTrap(8, 0, CpuTrapType.SOFTWARE, self.cpu.mode)  # ecall from U mode
         elif self.cpu.mode == PrivModes.SUPER:
-            raise CpuTrap(0, 9)  # ecall from S mode - should not happen
+            raise CpuTrap(9, 0, CpuTrapType.SOFTWARE, self.cpu.mode)  # ecall from S mode - should not happen
         elif self.cpu.mode == PrivModes.MACHINE:
-            raise CpuTrap(0, 11)  # ecall from M mode
+            raise CpuTrap(11, 0, CpuTrapType.SOFTWARE, self.cpu.mode)  # ecall from M mode
 
     def instruction_beq(self, ins: 'LoadedInstruction'):
         rs1, rs2, dst = self.parse_rs_rs_imm(ins)