PERFORCE change 207154 for review

[Robert Watson]

http://p4web.freebsd.org/@@207154?ac=10

Change 207154 by rwatson at rwatson_svr_ctsrd_mipsbuild on 2012/03/01 08:35:07

	Adapt the FreeBSD/MIPS exception handler trampoline to work with a
	kernel running out of xkphys.  Previously, this code assumed that
	MipsDoTLBMiss, the kernel's actual exception handler, was within
	range for 'j', which jumps to a 26-bit immediate.  Instead, jump
	via a register to allow greater address differences (e.g.,
	0xffffffff80000080 to 0x98000000001efc80).
	
	Discussed with:		Juli Mallett

Affected files ...

.. //depot/projects/ctsrd/beribsd/src/sys/mips/mips/exception.S#4 edit

Differences ...

==== //depot/projects/ctsrd/beribsd/src/sys/mips/mips/exception.S#4 (text+ko) ====

@@ -90,7 +90,8 @@
 VECTOR(MipsTLBMiss, unknown)
 	.set push
 	.set noat
-	j	MipsDoTLBMiss
+	dla	k0, MipsDoTLBMiss
+	jr	k0
 	MFC0	k0, MIPS_COP_0_BAD_VADDR	# get the fault address
 	.set pop
 VECTOR_END(MipsTLBMiss)