[src/trunk]: src/sys/arch/sparc64/sparc64 sun4v: rft_user needs special handl...

[palle <palle%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/e70a354c5ef6
branches:  trunk
changeset: 351598:e70a354c5ef6
user:      palle <palle%NetBSD.org@localhost>
date:      Sun Feb 19 18:25:45 2017 +0000

description:
sun4v: rft_user needs special handling (a manual fill) since the restore instruction may cause the number of trap levels to exceed the maximum for sun4v - inspired by code from the the openbsd 
rft_user code path - verified using qemu for both sun4u and sun4v

diffstat:

 sys/arch/sparc64/sparc64/locore.s |  34 ++++++++++++++++++++++++++++++++--
 1 files changed, 32 insertions(+), 2 deletions(-)

diffs (55 lines):

diff -r b37c62284e33 -r e70a354c5ef6 sys/arch/sparc64/sparc64/locore.s
--- a/sys/arch/sparc64/sparc64/locore.s Sun Feb 19 18:07:12 2017 +0000
+++ b/sys/arch/sparc64/sparc64/locore.s Sun Feb 19 18:25:45 2017 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: locore.s,v 1.408 2017/02/10 23:26:23 palle Exp $       */
+/*     $NetBSD: locore.s,v 1.409 2017/02/19 18:25:45 palle Exp $       */
 
 /*
  * Copyright (c) 2006-2010 Matthew R. Green
@@ -3145,7 +3145,7 @@
        ba,a,pt %icc, return_from_trap
         nop
        NOTREACHED
-       
+
 /*
  * End of traps for sun4v.
  */
@@ -4747,6 +4747,36 @@
        wrpr    %g2, 0, %tpc
        wrpr    %g3, 0, %tnpc
        wrpr    %g1, %g0, %tstate
+
+       /*
+        * The restore instruction further down may cause the trap level
+        * to exceede the maximum trap level on sun4v, so a manual fill
+        * may be necessary.
+       */
+       
+#ifdef SUN4V
+       sethi   %hi(cputyp), %g5
+       ld      [%g5 + %lo(cputyp)], %g5
+       cmp     %g5, CPU_SUN4V
+       bne,pt  %icc, 1f
+        nop
+
+       ! Only manual fill if the restore instruction will cause a fill trap
+       rdpr    %canrestore, %g5
+       brnz    %g5, 1f
+        nop
+
+       ! Do a manual fill
+       wr      %g0, ASI_AIUS, %asi
+       rdpr    %cwp, %g4
+       dec     %g4
+       wrpr    %g4, 0, %cwp
+       FILL    ldxa, %sp+BIAS, 8, %asi
+       restored
+       inc     %g4
+       wrpr    %g4, 0, %cwp
+1:     
+#endif
        restore
 6:
        rdpr    %canrestore, %g5