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Diffstat (limited to 'arch/powerpc/kernel/exceptions-64s.S')
-rw-r--r--arch/powerpc/kernel/exceptions-64s.S10
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 9029afd1fa2a..f14f3c04ec7e 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -1325,10 +1325,18 @@ EXC_VIRT_NONE(0x5800, 0x100)
std r10,PACA_EXGEN+EX_R13(r13); \
EXCEPTION_PROLOG_PSERIES_1(soft_nmi_common, _H)
+/*
+ * Branch to soft_nmi_interrupt using the emergency stack. The emergency
+ * stack is one that is usable by maskable interrupts so long as MSR_EE
+ * remains off. It is used for recovery when something has corrupted the
+ * normal kernel stack, for example. The "soft NMI" must not use the process
+ * stack because we want irq disabled sections to avoid touching the stack
+ * at all (other than PMU interrupts), so use the emergency stack for this,
+ * and run it entirely with interrupts hard disabled.
+ */
EXC_COMMON_BEGIN(soft_nmi_common)
mr r10,r1
ld r1,PACAEMERGSP(r13)
- ld r1,PACA_NMI_EMERG_SP(r13)
subi r1,r1,INT_FRAME_SIZE
EXCEPTION_COMMON_NORET_STACK(PACA_EXGEN, 0x900,
system_reset, soft_nmi_interrupt,