Zero mstatus.UPIE/UIE bits in legalize_mstatus

This was missed when we removed the N extension. I'm not really a fan of this code style - in other places we explicitly copy the bits that *are* implemented using their field names, which is also not ideal but definitely better and less error prone. We should change this code to do that at some point. I added a TODO.
riscv · Nov 6, 2024 · 0b9c639 · 0b9c639
1 parent ded340f
commit 0b9c639
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/model/riscv_sys_regs.sail b/model/riscv_sys_regs.sail
@@ -244,7 +244,9 @@ function legalize_mstatus(o : Mstatus, v : xlenbits) -> Mstatus = {
    * that does not have a matching bitfield entry. All bits above 32 are handled
    * explicitly later.
    */
-  let m : Mstatus = Mk_Mstatus(zero_extend(v[22 .. 7] @ 0b0 @ v[5 .. 3] @ 0b0 @ v[1 .. 0]));
+  // TODO: This method is error prone. We should instead explicitly copy the
+  // fields that are implemented. See legalize_mie() for an example.
+  let m : Mstatus = Mk_Mstatus(zero_extend(v[22 .. 7] @ 0b0 @ v[5 .. 5] @ 0b0 @ v[3 .. 3] @ 0b0 @ v[1 .. 1] @ 0b0));
 
   /* FS is WARL, and making FS writable can support the M-mode emulation of an FPU
    * to support code running in S/U-modes.  Spike does this, and for now, we match it,