sparc64: Don't set %pil in rtrap_nmi too early

Commit 28a1f53 delays setting %pil to avoid potential
hardirq stack overflow in the common rtrap_irq path.
Setting %pil also needs to be delayed in the rtrap_nmi
path for the same reason.

Signed-off-by: Rob Gardner <rob.gardner@oracle.com>
Signed-off-by: Dave Aldridge <david.j.aldridge@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S
index 39f0c66..d08bdaf 100644 (file)
--- a/arch/sparc/kernel/rtrap_64.S
+++ b/arch/sparc/kernel/rtrap_64.S
@@ -73,7 +73,13 @@ rtrap_nmi:   ldx                     [%sp + PTREGS_OFF + PT_V9_TSTATE], %l1
                andn                    %l1, %l4, %l1
                srl                     %l4, 20, %l4
                ba,pt                   %xcc, rtrap_no_irq_enable
-                wrpr                   %l4, %pil
+               nop
+               /* Do not actually set the %pil here.  We will do that
+                * below after we clear PSTATE_IE in the %pstate register.
+                * If we re-enable interrupts here, we can recurse down
+                * the hardirq stack potentially endlessly, causing a
+                * stack overflow.
+                */
 
                .align                  64
                .globl                  rtrap_irq, rtrap, irqsz_patchme, rtrap_xcall