MIPS: Fix TLBR-use hazards for R2 cores in the TLB reload handlers

MIPS R2 documents state that an execution hazard barrier is needed
after a TLBR before reading EntryLo.

Original patch by Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>.
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/5526/

arch/mips/mm/tlbex.c

@@ -1935,6 +1935,19 @@ static void __cpuinit build_r4000_tlb_load_handler(void)
 		uasm_i_nop(&p);
 
 		uasm_i_tlbr(&p);
+
+		switch (current_cpu_type()) {
+		default:
+			if (cpu_has_mips_r2) {
+				uasm_i_ehb(&p);
+
+		case CPU_CAVIUM_OCTEON:
+		case CPU_CAVIUM_OCTEON_PLUS:
+		case CPU_CAVIUM_OCTEON2:
+				break;
+			}
+		}
+
 		/* Examine  entrylo 0 or 1 based on ptr. */
 		if (use_bbit_insns()) {
 			uasm_i_bbit0(&p, wr.r2, ilog2(sizeof(pte_t)), 8);
@@ -1989,6 +2002,19 @@ static void __cpuinit build_r4000_tlb_load_handler(void)
 		uasm_i_nop(&p);
 
 		uasm_i_tlbr(&p);
+
+		switch (current_cpu_type()) {
+		default:
+			if (cpu_has_mips_r2) {
+				uasm_i_ehb(&p);
+
+		case CPU_CAVIUM_OCTEON:
+		case CPU_CAVIUM_OCTEON_PLUS:
+		case CPU_CAVIUM_OCTEON2:
+				break;
+			}
+		}
+
 		/* Examine  entrylo 0 or 1 based on ptr. */
 		if (use_bbit_insns()) {
 			uasm_i_bbit0(&p, wr.r2, ilog2(sizeof(pte_t)), 8);