1 files changed, 11 insertions, 1 deletions

diff --git a/arch/sparc/kernel/rtrap_64.S b/arch/sparc/kernel/rtrap_64.S
index fd3cee4d117c..c720f0ccea1b 100644
--- a/arch/sparc/kernel/rtrap_64.S
+++ b/arch/sparc/kernel/rtrap_64.S
@@ -172,7 +172,17 @@ rtrap_xcall:
                  nop
                 call                    trace_hardirqs_on
                  nop
-                wrpr                    %l4, %pil
+                /* 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.
+                 *
+                 * It is tempting to put this test and trace_hardirqs_on
+                 * call at the 'rt_continue' label, but that will not work
+                 * as that path hits unconditionally and we do not want to
+                 * execute this in NMI return paths, for example.
+                 */
 #endif
 rtrap_no_irq_enable:
                 andcc                   %l1, TSTATE_PRIV, %l3