[PATCH 2/3] MIPS: mm: Suppress TLB uniquification on EHINV hardware

[Maciej W. Rozycki]

Hardware that supports the EHINV feature, mandatory for R6 ISA and FTLB
implementation, lets software mark TLB entries invalid, which eliminates 
the need to ensure no duplicate matching entries are ever created.  This 
feature is already used by local_flush_tlb_all(), via the UNIQUE_ENTRYHI 
macro, making the preceding call to r4k_tlb_uniquify() superfluous.

The next change will also modify uniquification code such that it'll 
become incompatible with the FTLB and MMID features, as well as MIPSr6 
CPUs that do not implement 4KiB pages.

Therefore prevent r4k_tlb_uniquify() from being used on EHINV hardware, 
as denoted by `cpu_has_tlbinv'.

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxx>
---
 arch/mips/mm/tlb-r4k.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

linux-mips-tlb-r4k-uniquify-ehinv.diff
Index: linux-macro/arch/mips/mm/tlb-r4k.c
===================================================================
--- linux-macro.orig/arch/mips/mm/tlb-r4k.c
+++ linux-macro/arch/mips/mm/tlb-r4k.c
@@ -640,7 +640,8 @@ static void r4k_tlb_configure(void)
 	temp_tlb_entry = current_cpu_data.tlbsize - 1;
 
 	/* From this point on the ARC firmware is dead.	 */
-	r4k_tlb_uniquify();
+	if (!cpu_has_tlbinv)
+		r4k_tlb_uniquify();
 	local_flush_tlb_all();
 
 	/* Did I tell you that ARC SUCKS?  */