Merge tag 'powerpc-5.9-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc...

[uclinux-h8/linux.git] / arch / powerpc / kernel / exceptions-64s.S

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index eda5cee..f7d748b 100644 (file)
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -3208,10 +3208,18 @@ do_hash_page:
        ori     r0,r0,DSISR_BAD_FAULT_64S@l
        and.    r0,r5,r0                /* weird error? */
        bne-    handle_page_fault       /* if not, try to insert a HPTE */
+
+       /*
+        * If we are in an "NMI" (e.g., an interrupt when soft-disabled), then
+        * don't call hash_page, just fail the fault. This is required to
+        * prevent re-entrancy problems in the hash code, namely perf
+        * interrupts hitting while something holds H_PAGE_BUSY, and taking a
+        * hash fault. See the comment in hash_preload().
+        */
        ld      r11, PACA_THREAD_INFO(r13)
-       lwz     r0,TI_PREEMPT(r11)      /* If we're in an "NMI" */
-       andis.  r0,r0,NMI_MASK@h        /* (i.e. an irq when soft-disabled) */
-       bne     77f                     /* then don't call hash_page now */
+       lwz     r0,TI_PREEMPT(r11)
+       andis.  r0,r0,NMI_MASK@h
+       bne     77f
 
        /*
         * r3 contains the trap number