svn commit: r192655 - projects/mips/sys/mips/mips

[Oleksandr Tymoshenko]

Author: gonzo
Date: Sat May 23 18:00:20 2009
New Revision: 192655
URL: http://svn.freebsd.org/changeset/base/192655

Log:
  - Remove stale comments
  - Replace a1 with k1 to while restoring context. a1 was there by mistake,
      interrupts are disabled at this point and it's safe to use k0, k1.
      This code never was reached beacasue current Status register handling
      prevented interrupta from user mode.

Modified:
  projects/mips/sys/mips/mips/exception.S

Modified: projects/mips/sys/mips/mips/exception.S
==============================================================================
--- projects/mips/sys/mips/mips/exception.S	Sat May 23 17:17:54 2009	(r192654)
+++ projects/mips/sys/mips/mips/exception.S	Sat May 23 18:00:20 2009	(r192655)
@@ -689,36 +689,27 @@ NNON_LEAF(MipsUserIntr, STAND_FRAME_SIZE
 /*
  * Call the interrupt handler.
  */
+	break
 	la	k0, _C_LABEL(cpu_intr)
 	jalr	k0
 	sw	a3, STAND_RA_OFFSET(sp)	# for debugging
+
 /*
- * Since interrupts are enabled at this point, we use a1 instead of
- * k0 or k1 to store the PCB pointer.  This is because k0 and k1
- * are not preserved across interrupts. ** RRS - And how did the
- * get enabled? cpu_intr clears the cause register but it does
- * not touch the sr as far as I can see thus intr are still
- * disabled.
+ * DO_AST enabled interrupts
  */
 	DO_AST
 	
 /*
- * Restore user registers and return. NOTE: interrupts are enabled.
- */
-
-/*
- * Since interrupts are enabled at this point, we use a1 instead of
- * k0 or k1 to store the PCB pointer.  This is because k0 and k1
- * are not preserved across interrupts.
+ * Restore user registers and return. 
  */
-	mtc0	zero, COP_0_STATUS_REG
+	mtc0	zero, COP_0_STATUS_REG	# re-disable interrupts
 	ITLBNOPFIX
 	li	v0, SR_EXL
 	mtc0	v0, COP_0_STATUS_REG	# set exeption level bit.
 	ITLBNOPFIX
 
 	GET_CPU_PCPU(k1)
-	lw	a1, PC_CURPCB(k1)
+	lw	k1, PC_CURPCB(k1)
 	RESTORE_U_PCB_REG(s0, S0, k1)
 	RESTORE_U_PCB_REG(s1, S1, k1)
 	RESTORE_U_PCB_REG(s2, S2, k1)