Zicfilp: Handle software check exception -- landing pad fault

machine/mentry.S

@@ -29,6 +29,9 @@ trap_table:
   /* 13 */ .dc.a __trap_from_machine_mode
   /* 14 */ .dc.a bad_trap
   /* 15 */ .dc.a bad_trap
+  /* 16 */ .dc.a bad_trap
+  /* 17 */ .dc.a bad_trap
+  /* 18 */ .dc.a bad_trap
 
   .option norvc
   .section .text.init,"ax",@progbits

machine/minit.c

@@ -78,7 +78,8 @@ static void delegate_traps()
     (1U << CAUSE_BREAKPOINT) |
     (1U << CAUSE_LOAD_PAGE_FAULT) |
     (1U << CAUSE_STORE_PAGE_FAULT) |
-    (1U << CAUSE_USER_ECALL);
+    (1U << CAUSE_USER_ECALL) |
+    (1U << CAUSE_SOFTWARE_CHECK_FAULT);
 
   write_csr(mideleg, interrupts);
   write_csr(medeleg, exceptions);

pk/handlers.c

@@ -90,6 +90,21 @@ static void handle_interrupt(trapframe_t* tf)
   clear_csr(sip, SIP_SSIP);
 }
 
+static void handle_software_check_fault(trapframe_t* tf)
+{
+  dump_tf(tf);
+
+  const uint64_t stval = read_csr(stval);
+  switch (stval) {
+    case LANDING_PAD_FAULT:
+      panic("Invalid landing pad!");
+      break;
+    default:
+      panic("Software check fault: unhandled stval: %d", stval);
+      break;
+  }
+}
+
 void handle_trap(trapframe_t* tf)
 {
   if ((intptr_t)tf->cause < 0)
@@ -110,6 +125,7 @@ void handle_trap(trapframe_t* tf)
     [CAUSE_MISALIGNED_STORE] = handle_misaligned_store,
     [CAUSE_LOAD_PAGE_FAULT] = handle_fault_load,
     [CAUSE_STORE_PAGE_FAULT] = handle_fault_store,
+    [CAUSE_SOFTWARE_CHECK_FAULT] = handle_software_check_fault,
   };
 
   kassert(tf->cause < ARRAY_SIZE(trap_handlers) && trap_handlers[tf->cause]);