switcher: ensure IRQs deferred on exit path
The thread exit path zeros out MTDC as part of transitioning to the
scheduler compartment. It's bad if we can get there with IRQs enabled,
so ensure that we cannot from switcher_skip_compartment_call.
diff --git a/sdk/core/switcher/entry.S b/sdk/core/switcher/entry.S
index c113d26..387a2d1 100644
--- a/sdk/core/switcher/entry.S
+++ b/sdk/core/switcher/entry.S
@@ -366,7 +366,7 @@
// loading is the csp on entry, which does not have a spilled area. In
// this case, we would fault when loading, so would exit the thread, but we
// should instead gracefully exit the thread.
- bgeu tp, t2, .Lset_mcause_and_exit_thread
+ bgeu tp, t2, .Lcommon_defer_irqs_and_thread_exit
cspecialr ctp, mtdc
cincoffset ct1, ctp, t2
// Restore the stack pointer. All other spilled values are spilled there.
@@ -868,6 +868,9 @@
#endif
j .Lhandle_error
+.Lcommon_defer_irqs_and_thread_exit:
+ csrci mstatus, 0x8
+ // Fall-through, now that IRQs are off
// Value 24 is reserved for custom use.
.Lset_mcause_and_exit_thread:
