[SPARC64]: Refine register window trap handling.

When saving and restoing trap state, do the window spill/fill
handling inline so that we never trap deeper than 2 trap levels.
This is important for chips like Niagara.

The window fixup code is massively simplified, and many more
improvements are now possible.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/arch/sparc64/kernel/ttable.S b/arch/sparc64/kernel/ttable.S
index 9953142..2679b6e 100644
--- a/arch/sparc64/kernel/ttable.S
+++ b/arch/sparc64/kernel/ttable.S
@@ -92,11 +92,11 @@
 tl0_s0n:	SPILL_0_NORMAL
 tl0_s1n:	SPILL_1_NORMAL
 tl0_s2n:	SPILL_2_NORMAL
-tl0_s3n:	SPILL_3_NORMAL
-tl0_s4n:	SPILL_4_NORMAL
-tl0_s5n:	SPILL_5_NORMAL
-tl0_s6n:	SPILL_6_NORMAL
-tl0_s7n:	SPILL_7_NORMAL
+tl0_s3n:	SPILL_0_NORMAL_ETRAP
+tl0_s4n:	SPILL_1_GENERIC_ETRAP
+tl0_s5n:	SPILL_1_GENERIC_ETRAP_FIXUP
+tl0_s6n:	SPILL_2_GENERIC_ETRAP
+tl0_s7n:	SPILL_2_GENERIC_ETRAP_FIXUP
 tl0_s0o:	SPILL_0_OTHER
 tl0_s1o:	SPILL_1_OTHER
 tl0_s2o:	SPILL_2_OTHER
@@ -110,9 +110,9 @@
 tl0_f2n:	FILL_2_NORMAL
 tl0_f3n:	FILL_3_NORMAL
 tl0_f4n:	FILL_4_NORMAL
-tl0_f5n:	FILL_5_NORMAL
-tl0_f6n:	FILL_6_NORMAL
-tl0_f7n:	FILL_7_NORMAL
+tl0_f5n:	FILL_0_NORMAL_RTRAP
+tl0_f6n:	FILL_1_GENERIC_RTRAP
+tl0_f7n:	FILL_2_GENERIC_RTRAP
 tl0_f0o:	FILL_0_OTHER
 tl0_f1o:	FILL_1_OTHER
 tl0_f2o:	FILL_2_OTHER