[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/rtrap.S b/arch/sparc64/kernel/rtrap.S
index 61bd45e..ecfbbdc 100644
--- a/arch/sparc64/kernel/rtrap.S
+++ b/arch/sparc64/kernel/rtrap.S
@@ -267,15 +267,69 @@
wrpr %l2, %g0, %canrestore
wrpr %l1, %g0, %wstate
- wrpr %g0, %g0, %otherwin
+ brnz,pt %l2, user_rtt_restore
+ wrpr %g0, %g0, %otherwin
+
+ ldx [%g6 + TI_FLAGS], %g3
+ wr %g0, ASI_AIUP, %asi
+ rdpr %cwp, %g1
+ andcc %g3, _TIF_32BIT, %g0
+ sub %g1, 1, %g1
+ bne,pt %xcc, user_rtt_fill_32bit
+ wrpr %g1, %cwp
+ ba,a,pt %xcc, user_rtt_fill_64bit
+
+user_rtt_fill_fixup:
+ rdpr %cwp, %g1
+ add %g1, 1, %g1
+ wrpr %g1, 0x0, %cwp
+
+ rdpr %wstate, %g2
+ sll %g2, 3, %g2
+ wrpr %g2, 0x0, %wstate
+
+ /* We know %canrestore and %otherwin are both zero. */
+
+ sethi %hi(sparc64_kern_pri_context), %g2
+ ldx [%g2 + %lo(sparc64_kern_pri_context)], %g2
+ mov PRIMARY_CONTEXT, %g1
+ stxa %g2, [%g1] ASI_DMMU
+ sethi %hi(KERNBASE), %g1
+ flush %g1
+
+ or %g4, FAULT_CODE_WINFIXUP, %g4
+ stb %g4, [%g6 + TI_FAULT_CODE]
+ stx %g5, [%g6 + TI_FAULT_ADDR]
+
+ mov %g6, %l1
+ wrpr %g0, 0x0, %tl
+ wrpr %g0, RTRAP_PSTATE, %pstate
+ mov %l1, %g6
+ ldx [%g6 + TI_TASK], %g4
+ LOAD_PER_CPU_BASE(%g5, %g6, %g1, %g2, %g3)
+ call do_sparc64_fault
+ add %sp, PTREGS_OFF, %o0
+ ba,pt %xcc, rtrap
+ nop
+
+user_rtt_pre_restore:
+ add %g1, 1, %g1
+ wrpr %g1, 0x0, %cwp
+
+user_rtt_restore:
restore
rdpr %canrestore, %g1
wrpr %g1, 0x0, %cleanwin
retry
nop
-kern_rtt: restore
+kern_rtt: rdpr %canrestore, %g1
+ brz,pn %g1, kern_rtt_fill
+ nop
+kern_rtt_restore:
+ restore
retry
+
to_kernel:
#ifdef CONFIG_PREEMPT
ldsw [%g6 + TI_PRE_COUNT], %l5
