Fix a bug in privilege transition, add better transition logging.

2 files changed, 36 insertions, 5 deletions

diff --git a/riscv/riscv_sys.sail b/riscv/riscv_sys.sail
index 43ca915d..ce5ef321 100644
--- a/riscv/riscv_sys.sail
+++ b/riscv/riscv_sys.sail
@@ -619,7 +619,7 @@ union ctl_result = {
 
 function handle_trap(del_priv : Privilege, intr : bool, c : exc_code, pc : xlenbits, info : option(xlenbits))
                     -> xlenbits = {
-  cur_privilege = del_priv;
+  print("handling " ^ (if intr then "int#" else "exc#") ^ BitStr(c) ^ " at priv " ^ del_priv);
   match (del_priv) {
     Machine => {
        mcause->IsInterrupt() = intr;
@@ -627,10 +627,12 @@ function handle_trap(del_priv : Privilege, intr : bool, c : exc_code, pc : xlenb
 
        mstatus->MPIE() = mstatus.MIE();
        mstatus->MIE()  = false;
-       mstatus->MPP()  = privLevel_to_bits(del_priv);
+       mstatus->MPP()  = privLevel_to_bits(cur_privilege);
        mtval           = tval(info);
        mepc            = pc;
 
+       cur_privilege   = del_priv;
+
        match tvec_addr(mtvec, mcause) {
          Some(epc) => epc,
          None()    => internal_error("Invalid mtvec mode")
@@ -642,7 +644,7 @@ function handle_trap(del_priv : Privilege, intr : bool, c : exc_code, pc : xlenb
 
        mstatus->SPIE() = mstatus.SIE();
        mstatus->SIE()  = false;
-       mstatus->SPP()  = match (del_priv) {
+       mstatus->SPP()  = match (cur_privilege) {
                            User => false,
                            Supervisor => true,
                            Machine => internal_error("invalid privilege for s-mode trap")
@@ -650,6 +652,8 @@ function handle_trap(del_priv : Privilege, intr : bool, c : exc_code, pc : xlenb
        stval           = tval(info);
        sepc            = pc;
 
+       cur_privilege   = del_priv;
+
        match tvec_addr(stvec, scause) {
          Some(epc) => epc,
          None()    => internal_error("Invalid stvec mode")
@@ -657,29 +661,34 @@ function handle_trap(del_priv : Privilege, intr : bool, c : exc_code, pc : xlenb
 
     },
     User => internal_error("the N extension is currently unsupported")
-  }
+  };
 }
 
 function handle_exception(cur_priv : Privilege, ctl : ctl_result,
                           pc: xlenbits) -> xlenbits = {
-  print("handling exception ...");
   match (cur_priv, ctl) {
     (_, CTL_TRAP(e)) => {
       let del_priv = exception_delegatee(e.trap, cur_priv);
+      print("trapping from " ^ cur_priv ^ " to " ^ del_priv
+            ^ " to handle " ^ e.trap);
       handle_trap(del_priv, false, e.trap, pc, e.excinfo)
     },
     (_, CTL_MRET())  => {
+      let prev_priv = cur_privilege;
       mstatus->MIE()  = mstatus.MPIE();
       mstatus->MPIE() = true;
       cur_privilege   = privLevel_of_bits(mstatus.MPP());
       mstatus->MPP()  = privLevel_to_bits(User);
+      print("ret-ing from " ^ prev_priv ^ " to " ^ cur_privilege);
       mepc
     },
     (_, CTL_SRET())  => {
+      let prev_priv = cur_privilege;
       mstatus->SIE()  = mstatus.SPIE();
       mstatus->SPIE() = true;
       cur_privilege   = if mstatus.SPP() == true then Supervisor else User;
       mstatus->SPP()  = false;
+      print("ret-ing from " ^ prev_priv ^ " to " ^ cur_privilege);
       sepc
     }
   }
diff --git a/riscv/riscv_types.sail b/riscv/riscv_types.sail
index 5d602d61..2a5a03ec 100644
--- a/riscv/riscv_types.sail
+++ b/riscv/riscv_types.sail
@@ -194,6 +194,28 @@ function exceptionType_to_bits(e) = {
   }
 }
 
+val cast exceptionType_to_str : ExceptionType -> string
+function exceptionType_to_str(e) = {
+  match (e) {
+    E_Fetch_Addr_Align => "fisaligned-fetch",
+    E_Fetch_Access_Fault => "fetch-access-fault",
+    E_Illegal_Instr => "illegal-instruction",
+    E_Breakpoint => "breakpoint",
+    E_Load_Addr_Align => "misaligned-load",
+    E_Load_Access_Fault => "load-access-fault",
+    E_SAMO_Addr_Align => "misaliged-store/amo",
+    E_SAMO_Access_Fault => "store/amo-access-fault",
+    E_U_EnvCall => "u-call",
+    E_S_EnvCall => "s-call",
+    E_Reserved_10 => "reserved-0",
+    E_M_EnvCall => "m-call",
+    E_Fetch_Page_Fault => "fetch-page-fault",
+    E_Load_Page_Fault => "load-page-fault",
+    E_Reserved_14 => "reserved-1",
+    E_SAMO_Page_Fault => "store/amo-page-fault"
+  }
+}
+
 enum InterruptType = {
   I_U_Software,
   I_S_Software,