MIPS: tlb-r4k: If there are wired entries, don't use TLBINVF

When adding a wired entry to the TLB via add_wired_entry, the tlb is
flushed with local_flush_tlb_all, which on CPUs with TLBINV results in
the new wired entry being flushed again.

Behavior of the TLBINV instruction applies to all applicable TLB entries
and is unaffected by the setting of the Wired register. Therefore if
the TLB has any wired entries, fall back to iterating over the entries
rather than blasting them all using TLBINVF.

Signed-off-by: Matt Redfearn <[email protected]>
Cc: Bjorn Andersson <[email protected]>
Cc: Ohad Ben-Cohen <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: Hugh Dickins <[email protected]>
Cc: Huacai Chen <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Patchwork: https://patchwork.linux-mips.org/patch/14283/
Signed-off-by: Ralf Baechle <[email protected]>

Author: mpredfearn

arch/mips/mm/tlb-r4k.c

@@ -67,8 +67,11 @@ void local_flush_tlb_all(void)
 
 	entry = read_c0_wired();
 
-	/* Blast 'em all away. */
-	if (cpu_has_tlbinv) {
+	/*
+	 * Blast 'em all away.
+	 * If there are any wired entries, fall back to iterating
+	 */
+	if (cpu_has_tlbinv && !entry) {
 		if (current_cpu_data.tlbsizevtlb) {
 			write_c0_index(0);
 			mtc0_tlbw_hazard();