[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>

1 files changed, 56 insertions, 2 deletions

diff --git a/arch/sparc64/kernel/rtrap.S b/arch/sparc64/kernel/rtrap.S
index 61bd45e7697e..ecfbbdc56125 100644
--- a/arch/sparc64/kernel/rtrap.S
+++ b/arch/sparc64/kernel/rtrap.S
@@ -267,15 +267,69 @@ rt_continue:	ldx			[%sp + PTREGS_OFF + PT_V9_G1], %g1
 
                 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