PERFORCE change 134779 for review

[Oleksandr Tymoshenko]

http://perforce.freebsd.org/chv.cgi?CH=134779

Change 134779 by gonzo at gonzo_jeeves on 2008/02/04 14:12:06

	o Fix MCHECK exception caused by tlbwi instruction in octeon emulation. 
	    The solution is to use bogus EntryHi value based on TLB entry 
	    index instead of fixed value.
	Tested by:	cognet

Affected files ...

.. //depot/projects/mips2-jnpr/src/sys/mips/mips/tlb.S#6 edit

Differences ...

==== //depot/projects/mips2-jnpr/src/sys/mips/mips/tlb.S#6 (text+ko) ====

@@ -81,12 +81,14 @@
 #define	_MFC0	dmfc0
 #define	_MTC0	dmtc0
 #define WIRED_SHIFT 34
+#define PAGE_SHIFT 34
 #else
 #define _SLL	sll
 #define	_SRL	srl
 #define	_MFC0	mfc0
 #define	_MTC0	mtc0
 #define WIRED_SHIFT 2
+#define PAGE_SHIFT 2
 #endif
 	.set	noreorder			# Noreorder is default style!
 #if defined(ISA_MIPS32)
@@ -287,9 +289,15 @@
 	tlbp					# Probe for the entry.
 	MIPS_CPU_NOP_DELAY
 	mfc0	v0, COP_0_TLB_INDEX		# See what we got
-	li	t1, MIPS_KSEG0_START		# Load invalid entry.
+	li	t1, MIPS_KSEG0_START + 0x0fff0000
 	bltz	v0, 1f				# index < 0 => !found
 	nop
+	# Load invalid entry, each TLB entry should have it's own bogus 
+	# address calculated by following expression:
+	# MIPS_KSEG0_START + 0x0fff0000 + 2 * i * PAGE_SIZE;
+	# One bogus value for every TLB entry might cause MCHECK exception
+	sll	v0, PAGE_SHIFT + 1
+	addu	t1, v0
 	_MTC0	t1, COP_0_TLB_HI		# Mark entry high as invalid
 
 	_MTC0	zero, COP_0_TLB_LO0		# Zero out low entry.