From 71c3b05a8083d8774ca66c89672d29d7bf33813e Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@gmail.com>
Date: Wed, 26 Feb 2020 03:35:31 +1000
Subject: [PATCH] powerpc/64s/exception: Soft NMI interrupt should not use
ret_from_except
References: jsc#SLE-9246
Patch-mainline: v5.7-rc1
Git-commit: 71c3b05a8083d8774ca66c89672d29d7bf33813e
The soft NMI handler does not reconcile interrupt state, so it should
not return via the normal ret_from_except path. Return like other NMIs,
using the EXCEPTION_RESTORE_REGS macro.
This becomes important when the scv interrupt is implemented, which
must handle soft-masked interrupts that have r13 set to something
other than the PACA -- returning to kernel in this case must restore
r13.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200225173541.1549955-23-npiggin@gmail.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/kernel/exceptions-64s.S | 30 +++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 3ddabac6ede6..d75df223da7c 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -2731,6 +2731,7 @@ EXC_VIRT_NONE(0x5800, 0x100)
INT_DEFINE_BEGIN(soft_nmi)
IVEC=0x900
ISTACK=0
+ IRECONCILE=0 /* Soft-NMI may fire under local_irq_disable */
INT_DEFINE_END(soft_nmi)
/*
@@ -2749,9 +2750,36 @@ EXC_COMMON_BEGIN(soft_nmi_common)
subi r1,r1,INT_FRAME_SIZE
__GEN_COMMON_BODY soft_nmi
bl save_nvgprs
+
+ /*
+ * Set IRQS_ALL_DISABLED and save PACAIRQHAPPENED (see
+ * system_reset_common)
+ */
+ li r10,IRQS_ALL_DISABLED
+ stb r10,PACAIRQSOFTMASK(r13)
+ lbz r10,PACAIRQHAPPENED(r13)
+ std r10,_DAR(r1)
+ ori r10,r10,PACA_IRQ_HARD_DIS
+ stb r10,PACAIRQHAPPENED(r13)
+
addi r3,r1,STACK_FRAME_OVERHEAD
bl soft_nmi_interrupt
- b ret_from_except
+
+ /* Clear MSR_RI before setting SRR0 and SRR1. */
+ li r9,0
+ mtmsrd r9,1
+
+ /*
+ * Restore soft mask settings.
+ */
+ ld r10,_DAR(r1)
+ stb r10,PACAIRQHAPPENED(r13)
+ ld r10,SOFTE(r1)
+ stb r10,PACAIRQSOFTMASK(r13)
+
+ kuap_restore_amr r10
+ EXCEPTION_RESTORE_REGS hsrr=0
+ RFI_TO_KERNEL
#endif /* CONFIG_PPC_WATCHDOG */
--
2.28.0