- The firmware of Sun Fire V1280 has a misfeature of setting %wstate to

  7 which corresponds to WSTATE_KMIX in OpenSolaris whenever calling into
  it which totally screws us even when restoring %wstate afterwards as
  spill/fill traps can happen while in OFW. The rather hackish OpenBSD
  approach of just setting the equivalent of WSTATE_KERNEL to 7 also is
  no option as we treat %wstate as a bit field. So in order to deal with
  this problem actually implement spill/fill handlers for %wstate 7 which
  just act as the WSTATE_KERNEL ones except of theoretically also handling
  32-bit, turn off interrupts completely so we don't even take IPIs while
  in OFW which should ensure we only take spill/fill traps at most and
  restore %wstate after calling into OFW once we have taken over the trap
  table. While at it, actually set WSTATE_{,PROM}_KMIX before calling into
  OFW just like OpenSolaris does, which should at least help testing this
  change on non-V1280.
- Remove comments referring to the %wstate usage in BSD/OS.
- Remove the no longer used RSF_ALIGN_RETRY macro.
- Correct some trap table addresses in comments.
- Ensure %wstate is set to WSTATE_KERNEL when taking over the trap table.
- Ensure PSTATE_AM is off when entering or exiting to OFW as well as that
  interrupts are also completely off when exiting to OFW as the firmware
  trap table shouldn't be used to handle our interrupts.

1 files changed, 5 insertions, 30 deletions

diff --git a/sys/sparc64/include/wstate.h b/sys/sparc64/include/wstate.h
index 7ce0a49..aae2fda 100644
--- a/sys/sparc64/include/wstate.h
+++ b/sys/sparc64/include/wstate.h
@@ -33,7 +33,7 @@
 #define	_MACHINE_WSTATE_H_
 
 /*
- * Window state register bits.
+ * Window state register bits
  *
  * There really are no bits per se, just the two fields WSTATE.NORMAL
  * and WSTATE.OTHER.  The rest is up to software.
@@ -42,37 +42,8 @@
  * (whichever is currently in effect) and WSTATE_OTHER to represent
  * user mode saves (only).
  *
- * We use the low bit to suggest 32-bit mode, with the next bit set
- * once we succeed in saving in some mode.  That is, if the WSTATE_ASSUME
- * bit is set, the spill or fill handler we use will be one that makes
- * an assumption about the proper window-save mode.  If the spill or
- * fill fails with an alignment fault, the spill or fill op should
- * take the `assume' bit away retry the instruction that caused the
- * spill or fill.  This will use the new %wstate, which will test for
- * which mode to use.  The alignment fault code helps us out here by
- * resuming the spill vector at offset +70, where we are allowed to
- * execute two instructions (i.e., write to %wstate and RETRY).
- *
- * If the ASSUME bit is not set when the alignment fault occurs, the
- * given stack pointer is hopelessly wrong (and the spill, if it is a
- * spill, should be done as a sort of "panic spill") -- so those two
- * instructions will be a branch sequence.
- *
  * Note that locore.s assumes this same bit layout (since the translation
  * from "bits" to "{spill,fill}_N_{normal,other}" is done in hardware).
- *
- * The value 0 is preferred for unknown to make it easy to start in
- * unknown state and continue in whichever state unknown succeeds in --
- * a successful "other" save, for instance, can just set %wstate to
- * ASSUMExx << USERSHIFT and thus leave the kernel state "unknown".
- *
- * We also need values for managing the somewhat tricky transition from
- * user to kernel and back, so we use the one remaining free bit to mean
- * "although this looks like kernel mode, the window(s) involved are
- * user windows and should be saved ASI_AIUP".  Everything else is
- * otherwise the same, but we need not bother with assumptions in this
- * mode (we expect it to apply to at most one window spill or fill),
- * i.e., WSTATE_TRANSITION can ignore WSTATE_ASSUME if it likes.
  */
 
 #define	WSTATE_NORMAL_MASK	1	/* wstate normal minus transition */
@@ -88,4 +59,8 @@
 #define	WSTATE_NESTED			/* if set, spill must not fault */ \
 	(WSTATE_TRANSITION << WSTATE_OTHER_SHIFT)
 
+/* Values used by the PROM and (Open)Solaris */
+#define	WSTATE_PROM_KMIX	7
+#define	WSTATE_PROM_MASK	7
+
 #endif /* !_MACHINE_WSTATE_H_ */