mtvec made WARL

coreblocks/arch/isa_consts.py

@@ -165,6 +165,12 @@ class PrivilegeLevel(IntEnum, shape=2):
     MACHINE = 0b11
 
 
+@unique
+class TrapVectorMode(IntEnum, shape=2):
+    DIRECT = 0b00
+    VECTORED = 0b01
+
+
 @unique
 class InterruptCauseNumber(IntEnum):
     SSI = 1  # supervisor software interrupt

coreblocks/backend/retirement.py

@@ -214,12 +214,12 @@ def flush_instr(rob_entry):
 
                     handler_pc = Signal(self.gen_params.isa.xlen)
                     mtvec_offset = Signal(self.gen_params.isa.xlen)
-                    mtvec = m_csr.mtvec.read(m).data
+                    mtvec = m_csr.mtvec._fu_read(m).data
                     mcause = m_csr.mcause.read(m).data
 
                     # mtvec without mode is [mxlen-1:2], mode is two last bits.
                     # When mode=1 (Vectored), interrupts set pc to base + 4 * cause_number
-                    with m.If(mcause & (mtvec << (self.gen_params.isa.xlen - 1))):
+                    with m.If(mcause[-1] & (mtvec[0:1] == 1)):
                         m.d.av_comb += mtvec_offset.eq(mcause << 2)
 
                     m.d.av_comb += handler_pc.eq((mtvec & ~(0b11)) + mtvec_offset)

coreblocks/priv/csr/csr_instances.py

@@ -4,7 +4,7 @@
 from coreblocks.arch import CSRAddress
 from coreblocks.arch.csr_address import MstatusFieldOffsets
 from coreblocks.arch.isa import Extension
-from coreblocks.arch.isa_consts import PrivilegeLevel, XlenEncoding
+from coreblocks.arch.isa_consts import PrivilegeLevel, XlenEncoding, TrapVectorMode
 from coreblocks.params.genparams import GenParams
 from coreblocks.priv.csr.csr_register import CSRRegister
 from coreblocks.priv.csr.aliased import AliasedCSR
@@ -75,7 +75,7 @@ def __init__(self, gen_params: GenParams):
 
         self.mcause = CSRRegister(CSRAddress.MCAUSE, gen_params)
 
-        self.mtvec = CSRRegister(CSRAddress.MTVEC, gen_params)
+        self.mtvec = AliasedCSR(CSRAddress.MTVEC, gen_params)
 
         mepc_ro_bits = 0b1 if Extension.C in gen_params.isa.extensions else 0b11  # pc alignment (SPEC)
         self.mepc = CSRRegister(CSRAddress.MEPC, gen_params, ro_bits=mepc_ro_bits)
@@ -93,6 +93,7 @@ def __init__(self, gen_params: GenParams):
             self.priv_mode_public.add_field(0, self.priv_mode)
 
         self.mstatus_fields_implementation(gen_params, self.mstatus, self.mstatush)
+        self.mtvec_fields_implementation(gen_params, self.mtvec)
 
     def elaborate(self, platform):
         m = Module()
@@ -103,6 +104,19 @@ def elaborate(self, platform):
 
         return m
 
+    def mtvec_fields_implementation(self, gen_params: GenParams, mtvec: AliasedCSR):
+        def filter_legal_mode(m: TModule, v: Value):
+            legal = Signal(1)
+            m.d.av_comb += legal.eq((v == TrapVectorMode.DIRECT) | (v == TrapVectorMode.VECTORED))
+            return (legal, v)
+
+        self.mtvec_base = CSRRegister(None, gen_params, width=gen_params.isa.xlen - 2)
+        mtvec.add_field(TrapVectorMode.as_shape().width, self.mtvec_base)
+        self.mtvec_mode = CSRRegister(
+            None, gen_params, width=TrapVectorMode.as_shape().width, fu_write_filtermap=filter_legal_mode
+        )
+        mtvec.add_field(0, self.mtvec_mode)
+
     def mstatus_fields_implementation(self, gen_params: GenParams, mstatus: AliasedCSR, mstatush: AliasedCSR):
         def filter_legal_priv_mode(m: TModule, v: Value):
             legal = Signal(1)

test/asm/interrupt_vectored.asm

@@ -116,7 +116,6 @@ fail:
     csrwi 0x7ff, 2
     j fail
 
-
 .org 0x200
     nop
     nop
@@ -133,7 +132,7 @@ fail:
     nop
     nop
     nop
-    nop
+    j fail
     j int0_handler
     j int1_handler
     li x31, 0xae  # should never happen

test/test_core.py

@@ -186,16 +186,6 @@ def test_asm_source(self):
         ("interrupt.asm", 600, {4: 89, 8: 843}, {2: 89, 7: 843, 31: 0xDE}, 30, 50, False),
         # interrupts are only inserted on branches, we always have some forward progression. 15 for trigger variantion.
         ("interrupt.asm", 80, {4: 21, 8: 9349}, {2: 21, 7: 9349, 31: 0xDE}, 0, 15, False),
-        ("interrupt_vectored.asm", 900, {4: 89, 8: 843, 15: 322}, {2: 89, 7: 843, 14: 322, 31: 0xDE}, 30, 50, False),
-        (
-            "interrupt_vectored.asm",
-            1600,
-            {4: 24157817, 8: 199, 15: 521},
-            {2: 24157817, 7: 199, 14: 521, 31: 0xDE},
-            100,
-            200,
-            False,
-        ),
         (
             "interrupt_vectored.asm",
             300,