powerpc/64s/interrupt: masked handler debug check for previous hard disable

Prior changes eliminated cases of masked PACA_IRQ_MUST_HARD_MASK
interrupts that re-fire due to MSR[EE] being enabled while they are
pending. Add a debug check in the masked interrupt handler to catch
if this occurs.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926054305.2671436-6-npiggin@gmail.com

diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index a3b51441b039f237e89cd110945ee0ca5db0f42f..43e538502f523c9cd129ec066b4d632f757cc91b 100644 (file)
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -2794,6 +2794,16 @@ masked_Hinterrupt:
 masked_interrupt:
        .endif
        stw     r9,PACA_EXGEN+EX_CCR(r13)
+#ifdef CONFIG_PPC_IRQ_SOFT_MASK_DEBUG
+       /*
+        * Ensure there was no previous MUST_HARD_MASK interrupt or
+        * HARD_DIS setting.
+        */
+       lbz     r9,PACAIRQHAPPENED(r13)
+       andi.   r9,r9,(PACA_IRQ_MUST_HARD_MASK|PACA_IRQ_HARD_DIS)
+0:     tdnei   r9,0
+       EMIT_BUG_ENTRY 0b,__FILE__,__LINE__,0
+#endif
        lbz     r9,PACAIRQHAPPENED(r13)
        or      r9,r9,r10
        stb     r9,PACAIRQHAPPENED(r13)