powerpc/64s: Use emergency stack for 0x100 system reset interrupt

index 84d49b1..335b8f1 100644
@@ -191,11 +191,32 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 #define EXCEPTION_PROLOG_PSERIES_1(label, h)				\
 	__EXCEPTION_PROLOG_PSERIES_1(label, h)
 
+/* _NORI variant keeps MSR_RI clear */
+#define __EXCEPTION_PROLOG_PSERIES_1_NORI(label, h)			\
+	ld	r12,PACAKBASE(r13);	/* get high part of &label */	\
+	ld	r10,PACAKMSR(r13);	/* get MSR value for kernel */	\
+	xori	r10,r10,MSR_RI;		/* Clear MSR_RI */		\
+	mfspr	r11,SPRN_##h##SRR0;	/* save SRR0 */			\
+	LOAD_HANDLER(r12,label)						\
+	mtspr	SPRN_##h##SRR0,r12;					\
+	mfspr	r12,SPRN_##h##SRR1;	/* and SRR1 */			\
+	mtspr	SPRN_##h##SRR1,r10;					\
+	h##rfid;							\
+	b	.	/* prevent speculative execution */
+
+#define EXCEPTION_PROLOG_PSERIES_1_NORI(label, h)			\
+	__EXCEPTION_PROLOG_PSERIES_1_NORI(label, h)
+
 #define EXCEPTION_PROLOG_PSERIES(area, label, h, extra, vec)		\
 	EXCEPTION_PROLOG_0(area);					\
 	EXCEPTION_PROLOG_1(area, extra, vec);				\
 	EXCEPTION_PROLOG_PSERIES_1(label, h);
 
+#define EXCEPTION_PROLOG_PSERIES_NORI(area, label, h, extra, vec)	\
+	EXCEPTION_PROLOG_0(area);					\
+	EXCEPTION_PROLOG_1(area, extra, vec);				\
+	EXCEPTION_PROLOG_PSERIES_1_NORI(label, h);
+
 #define __KVMTEST(h, n)							\
 	lbz	r10,HSTATE_IN_GUEST(r13);				\
 	cmpwi	r10,0;							\

@@ -273,6 +294,19 @@ END_FTR_SECTION_NESTED(ftr,ftr,943)
 
 #define NOTEST(n)
 
+#define EXCEPTION_PROLOG_COMMON_EMSTACK(n, area)			   \
+	mr	r10,r1;			/* Save r1			*/ \
+	ld	r1,PACAEMERGSP(r13);	/* Use emergency kernel stack	*/ \
+	subi	r1,r1,INT_FRAME_SIZE;	/* alloc stack frame		*/ \
+	std	r9,_CCR(r1);		/* save CR in stackframe	*/ \
+	std	r11,_NIP(r1);		/* save SRR0 in stackframe	*/ \
+	std	r12,_MSR(r1);		/* save SRR1 in stackframe	*/ \
+	std	r10,0(r1);		/* make stack chain pointer	*/ \
+	std	r0,GPR0(r1);		/* save r0 in stackframe	*/ \
+	std	r10,GPR1(r1);		/* save r1 in stackframe	*/ \
+	EXCEPTION_PROLOG_COMMON_2(area)					   \
+	EXCEPTION_PROLOG_COMMON_3(n)
+
 /*
  * The common exception prolog is used for all except a few exceptions
  * such as a segment miss on a kernel address.  We have to be prepared

@@ -495,8 +529,16 @@ BEGIN_FTR_SECTION				\
 	beql	ppc64_runlatch_on_trampoline;	\
 END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
 
-#define EXCEPTION_COMMON(trap, label, hdlr, ret, additions)	\
-	EXCEPTION_PROLOG_COMMON(trap, PACA_EXGEN);		\
+#define EXCEPTION_COMMON(area, trap, label, hdlr, ret, additions) \
+	EXCEPTION_PROLOG_COMMON(trap, area);			\
+	/* Volatile regs are potentially clobbered here */	\
+	additions;						\
+	addi	r3,r1,STACK_FRAME_OVERHEAD;			\
+	bl	hdlr;						\
+	b	ret
+
+#define EXCEPTION_COMMON_EMSTACK(area, trap, label, hdlr, ret, additions) \
+	EXCEPTION_PROLOG_COMMON_EMSTACK(trap, area);		\
 	/* Volatile regs are potentially clobbered here */	\
 	additions;						\
 	addi	r3,r1,STACK_FRAME_OVERHEAD;			\

@@ -504,7 +546,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
 	b	ret
 
 #define STD_EXCEPTION_COMMON(trap, label, hdlr)			\
-	EXCEPTION_COMMON(trap, label, hdlr, ret_from_except,	\
+	EXCEPTION_COMMON(PACA_EXGEN, trap, label, hdlr, ret_from_except, \
 			 ADD_NVGPRS;ADD_RECONCILE)
 
 /*

@@ -512,9 +554,16 @@ END_FTR_SECTION_IFSET(CPU_FTR_CTRL)
  * in the idle task and therefore need the special idle handling
  * (finish nap and runlatch)
  */
-#define STD_EXCEPTION_COMMON_ASYNC(trap, label, hdlr)		  \
-	EXCEPTION_COMMON(trap, label, hdlr, ret_from_except_lite, \
-			 FINISH_NAP;ADD_RECONCILE;RUNLATCH_ON)
+#define STD_EXCEPTION_COMMON_ASYNC(trap, label, hdlr)			\
+	EXCEPTION_COMMON(PACA_EXGEN, trap, label, hdlr,			\
+		ret_from_except_lite, FINISH_NAP;ADD_RECONCILE;RUNLATCH_ON)
+
+/*
+ * Like STD_EXCEPTION_COMMON, but for "NMI" exceptions.
+ */
+#define NMI_EXCEPTION_COMMON_ASYNC(trap, label, hdlr)			\
+	EXCEPTION_COMMON_EMSTACK(PACA_EXNMI, trap, label, hdlr,		\
+		ret_from_except_lite, FINISH_NAP;ADD_RECONCILE;RUNLATCH_ON)
 
 /*
  * When the idle code in power4_idle puts the CPU into NAP mode,

index 6a6792b..06e9664 100644
@@ -99,7 +99,6 @@ struct paca_struct {
 	 */
 	/* used for most interrupts/exceptions */
 	u64 exgen[13] __attribute__((aligned(0x80)));
-	u64 exmc[13];		/* used for machine checks */
 	u64 exslb[13];		/* used for SLB/segment table misses
  				 * on the linear mapping */
 	/* SLB related definitions */

@@ -174,6 +173,11 @@ struct paca_struct {
 	u8 subcore_sibling_mask;
 #endif
 
+#ifdef CONFIG_PPC_STD_MMU_64
+	/* Non-maskable exceptions that are not performance critical */
+	u64 exnmi[13];		/* used for system reset (nmi) */
+	u64 exmc[13];		/* used for machine checks */
+#endif
 #ifdef CONFIG_PPC_BOOK3S_64
 	/* Exclusive emergency stack pointer for machine check exception. */
 	void *mc_emergency_sp;

index caec7bf..0e8fde5c 100644
@@ -222,8 +222,9 @@ int main(void)
 	DEFINE(PACACONTEXTSLLP, offsetof(struct paca_struct, mm_ctx_sllp));
 #endif /* CONFIG_PPC_MM_SLICES */
 	DEFINE(PACA_EXGEN, offsetof(struct paca_struct, exgen));
-	DEFINE(PACA_EXMC, offsetof(struct paca_struct, exmc));
 	DEFINE(PACA_EXSLB, offsetof(struct paca_struct, exslb));
+	DEFINE(PACA_EXNMI, offsetof(struct paca_struct, exnmi));
+	DEFINE(PACA_EXMC, offsetof(struct paca_struct, exmc));
 	DEFINE(PACALPPACAPTR, offsetof(struct paca_struct, lppaca_ptr));
 	DEFINE(PACA_SLBSHADOWPTR, offsetof(struct paca_struct, slb_shadow_ptr));
 	DEFINE(SLBSHADOW_STACKVSID,