tile: Enable NMIs on return from handle_nmi() without errors

NMI interrupts mask ALL interrupts before calling the handler,
so we need to unmask NMIs according to the value handle_nmi() returns.
If it returns zero, the NMIs should be re-enabled; if it returns
a non-zero error, the NMIs should be disabled.
Signed-off-by: Zhigang Lu <zlu@tilera.com>
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>

arch/tile/kernel/intvec_32.S

@@ -946,6 +946,13 @@ STD_ENTRY(interrupt_return)
 	bzt     r30, .Lrestore_regs
 3:
 
+	/* We are relying on INT_PERF_COUNT at 33, and AUX_PERF_COUNT at 48 */
+	{
+	 moveli r0, lo16(1 << (INT_PERF_COUNT - 32))
+	 bz     r31, .Lrestore_regs
+	}
+	auli    r0, r0, ha16(1 << (INT_AUX_PERF_COUNT - 32))
+	mtspr   SPR_INTERRUPT_MASK_RESET_K_1, r0
 
 	/*
 	 * We now commit to returning from this interrupt, since we will be
@@ -1171,6 +1178,10 @@ handle_nmi:
 	 PTREGS_PTR(r0, PTREGS_OFFSET_BASE)
 	}
 	FEEDBACK_REENTER(handle_nmi)
+	{
+	 movei  r30, 1
+	 seq    r31, r0, zero
+	}
 	j       interrupt_return
 	STD_ENDPROC(handle_nmi)
 

arch/tile/kernel/intvec_64.S

@@ -971,6 +971,15 @@ STD_ENTRY(interrupt_return)
 	beqzt   r30, .Lrestore_regs
 3:
 
+#if INT_PERF_COUNT + 1 != INT_AUX_PERF_COUNT
+# error Bad interrupt assumption
+#endif
+	{
+	 movei  r0, 3   /* two adjacent bits for the PERF_COUNT mask */
+	 beqz   r31, .Lrestore_regs
+	}
+	shli    r0, r0, INT_PERF_COUNT
+	mtspr   SPR_INTERRUPT_MASK_RESET_K, r0
 
 	/*
 	 * We now commit to returning from this interrupt, since we will be
@@ -1187,7 +1196,7 @@ handle_nmi:
 	FEEDBACK_REENTER(handle_nmi)
 	{
 	 movei  r30, 1
-	 move   r31, r0
+	 cmpeq  r31, r0, zero
 	}
 	j       interrupt_return
 	STD_ENDPROC(handle_nmi)