[PATCH 4.15 113/128] powerpc/64: Dont trace irqs-off at interrupt return to soft-disabled context

Greg Kroah-Hartman
2018-03-16T15:44:25Z

From: Nicholas Piggin <npiggin@gmail.com>

[ Upstream commit acb1feab320e38588fccc568e3767761f494976f ]

When an interrupt is returning to a soft-disabled context (which can
happen for non-maskable interrupts or synchronous interrupts), it goes
through the motions of soft-disabling again, including calling
TRACE_DISABLE_INTS (i.e., trace_hardirqs_off()).

This is not necessary, because we must already be soft-disabled in the
interrupt context, it also may be causing crashes in the irq tracing
code to re-enter as an nmi. Replace it with a warning to ensure that
soft-interrupts are still disabled.

Fixes: 7c0482e3d055 ("powerpc/irq: Fix another case of lazy IRQ state getting out of sync")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/powerpc/kernel/entry_64.S | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -939,9 +939,13 @@ END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
beq 1f
rlwinm r7,r7,0,~PACA_IRQ_HARD_DIS
stb r7,PACAIRQHAPPENED(r13)
-1: li r0,0
- stb r0,PACASOFTIRQEN(r13);
- TRACE_DISABLE_INTS
+1:
+#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_BUG)
+ /* The interrupt should not have soft enabled. */
+ lbz r7,PACASOFTIRQEN(r13)
+1: tdnei r7,0
+ EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
+#endif
b .Ldo_restore

/*