handle address errors (#1337)

src/device/cop0.rs

@@ -49,7 +49,7 @@ pub const COP0_STATUS_CU2: u64 = 1 << 30;
 pub const COP0_CAUSE_EXCCODE_MOD: u64 = 1 << 2;
 pub const COP0_CAUSE_EXCCODE_TLBL: u64 = 2 << 2;
 pub const COP0_CAUSE_EXCCODE_TLBS: u64 = 3 << 2;
-//const COP0_CAUSE_EXCCODE_ADEL: u64 = 4 << 2;
+pub const COP0_CAUSE_EXCCODE_ADEL: u64 = 4 << 2;
 //const COP0_CAUSE_EXCCODE_ADES: u64 = 5 << 2;
 pub const COP0_CAUSE_EXCCODE_SYS: u64 = 8 << 2;
 pub const COP0_CAUSE_EXCCODE_BP: u64 = 9 << 2;
@@ -169,6 +169,10 @@ fn eret(device: &mut device::Device, _opcode: u32) {
     }
     device.cpu.branch_state.state = device::cpu::State::Exception;
     device.cpu.llbit = false;
+    if device.cpu.pc & 3 != 0 {
+        device::exceptions::address_error_exception(device, device.cpu.pc);
+        return;
+    }
     device::exceptions::check_pending_interrupts(device)
 }
 

src/device/cpu.rs

@@ -9,6 +9,9 @@ pub enum State {
     DelaySlotNotTaken,
     Discard,
     Exception,
+    // jr/jalr to a misaligned target: the address error is raised after the delay slot
+    TakeAddressError,
+    DelaySlotAddressError,
 }
 
 #[derive(Clone, serde::Serialize, serde::Deserialize)]
@@ -242,12 +245,17 @@ pub fn init(device: &mut device::Device) {
 }
 
 pub fn in_delay_slot(device: &device::Device) -> bool {
-    device.cpu.branch_state.state == State::DelaySlotTaken
-        || device.cpu.branch_state.state == State::DelaySlotNotTaken
+    matches!(
+        device.cpu.branch_state.state,
+        State::DelaySlotTaken | State::DelaySlotNotTaken | State::DelaySlotAddressError
+    )
 }
 
 pub fn in_delay_slot_taken(device: &device::Device) -> bool {
-    device.cpu.branch_state.state == State::DelaySlotTaken
+    matches!(
+        device.cpu.branch_state.state,
+        State::DelaySlotTaken | State::DelaySlotAddressError
+    )
 }
 
 pub fn run(device: &mut device::Device) {
@@ -298,6 +306,15 @@ pub fn run(device: &mut device::Device) {
                 device.cpu.branch_state.state = State::Step
             }
             State::Exception => device.cpu.branch_state.state = State::Step,
+            State::TakeAddressError => {
+                device.cpu.pc += 4;
+                device.cpu.branch_state.state = State::DelaySlotAddressError
+            }
+            State::DelaySlotAddressError => {
+                device.cpu.pc = device.cpu.branch_state.pc;
+                device.cpu.branch_state.state = State::Step;
+                device::exceptions::address_error_exception(device, device.cpu.pc)
+            }
         }
         device::cop0::add_cycles(device, 1);
         if device.cpu.cop0.regs[device::cop0::COP0_COUNT_REG] > device.cpu.next_event_count {

src/device/cpu_instructions.rs

@@ -964,8 +964,13 @@ pub fn srav(device: &mut device::Device, opcode: u32) {
 
 pub fn jr(device: &mut device::Device, opcode: u32) {
     if !device::cpu::in_delay_slot_taken(device) {
-        device.cpu.branch_state.state = device::cpu::State::Take;
-        device.cpu.branch_state.pc = device.cpu.gpr[rs(opcode) as usize];
+        let target = device.cpu.gpr[rs(opcode) as usize];
+        device.cpu.branch_state.state = if target & 3 == 0 {
+            device::cpu::State::Take
+        } else {
+            device::cpu::State::TakeAddressError
+        };
+        device.cpu.branch_state.pc = target;
     } else if !device::cpu::in_delay_slot(device) {
         device.cpu.branch_state.state = device::cpu::State::NotTaken;
     }
@@ -975,8 +980,13 @@ pub fn jalr(device: &mut device::Device, opcode: u32) {
     let in_delay_slot_taken = device::cpu::in_delay_slot_taken(device);
 
     if !in_delay_slot_taken {
-        device.cpu.branch_state.state = device::cpu::State::Take;
-        device.cpu.branch_state.pc = device.cpu.gpr[rs(opcode) as usize];
+        let target = device.cpu.gpr[rs(opcode) as usize];
+        device.cpu.branch_state.state = if target & 3 == 0 {
+            device::cpu::State::Take
+        } else {
+            device::cpu::State::TakeAddressError
+        };
+        device.cpu.branch_state.pc = target;
     } else if !device::cpu::in_delay_slot(device) {
         device.cpu.branch_state.state = device::cpu::State::NotTaken;
     }

src/device/exceptions.rs

@@ -79,6 +79,13 @@ pub fn cop_unusable_exception(device: &mut device::Device, cop: u64) {
     exception_general(device, 0x180)
 }
 
+pub fn address_error_exception(device: &mut device::Device, address: u64) {
+    set_exception_cause(device, device::cop0::COP0_CAUSE_EXCCODE_ADEL);
+    device.cpu.cop0.regs[device::cop0::COP0_BADVADDR_REG] = address;
+
+    exception_general(device, 0x180)
+}
+
 pub fn tlb_miss_exception(
     device: &mut device::Device,
     address: u64,

src/device/rsp_cpu.rs

@@ -170,6 +170,9 @@ pub fn run(device: &mut device::Device) -> u64 {
             device::cpu::State::Exception => {
                 device.rsp.cpu.branch_state.state = device::cpu::State::Step
             }
+            device::cpu::State::TakeAddressError | device::cpu::State::DelaySlotAddressError => {
+                unreachable!() // VR4300-only states
+            }
         }
         device.rsp.regs2[device::rsp_interface::SP_PC_REG] &= 0xFFC;