git: efb0c54c7694 - main - amd64 FRED: handle in-kernel faults same as IDT

The branch main has been updated by kib:

URL: https://cgit.FreeBSD.org/src/commit/?id=efb0c54c7694798214a2c130ec8461a34444e1c4

commit efb0c54c7694798214a2c130ec8461a34444e1c4
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2026-10-28 13:58:49 +0000
Commit:     Konstantin Belousov <kib@FreeBSD.org>
CommitDate: 2026-10-29 01:33:47 +0000

    amd64 FRED: handle in-kernel faults same as IDT
    
    Pass #MC and #DF directly to corresponding handlers, avoiding EFI
    pcb_onfault case.
    
    If a fault occurs while kdb/ddb is active, handler must call
    kdb_reenter() and not do the normal processing, which typically ends up
    in panic() for kernel-mode faults.  But #MC and #DF should be excluded
    there as well.
    
    NMI is not an exception, it is delivered as specific event.
    
    Sponsored by:   The FreeBSD Foundation
    MFC after:      1 week
---
 sys/amd64/amd64/trap.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/sys/amd64/amd64/trap.c b/sys/amd64/amd64/trap.c
index 08485c852cac..f6b595d85af7 100644
--- a/sys/amd64/amd64/trap.c
+++ b/sys/amd64/amd64/trap.c
@@ -1766,8 +1766,17 @@ trap_fred_handle_k_exc(struct thread *td, struct trapframe_fred *frame,
 	 * there is no sense to enable interrupts.
 	 */
 
-	if (exc != IDT_PF && trap_check_pcb_onfault(td, &frame->tf_idt))
-		return;
+	if (exc != IDT_DF && exc != IDT_MC) {
+#ifdef KDB
+		if (kdb_active) {
+			kdb_reenter();
+			return;
+		}
+#endif
+		if (exc != IDT_PF && trap_check_pcb_onfault(td,
+		    &frame->tf_idt))
+			return;
+	}
 
 	switch (exc) {
 	case IDT_DE: