MIPS: R5000: Fix TLB hazard handling.

R5000 and the Nevada CPUs (RM5230, RM5231, RM5260, RM5261, RM5270 and
RM5271) are basically the same CPU core and all are documented to require
two instructions separating a write to c0_pagemask, c0_entryhi, c0_entrylo0,
c0_entrylo1 or c0_index.

So far we were only providing on cycle before / after a TLBR/TLBWI
for R5000 but 3 cycles before and 1 cycles after for the Nevadas.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 6ea152552e5164ef4d25d6554072cdc9e6ae0b85..2833dcb67b5adeaf838536580728176bbc715a77 100644 (file)
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -511,13 +511,19 @@ static void __cpuinit build_tlb_write_entry(u32 **p, struct uasm_label **l,
 
        case CPU_R4600:
        case CPU_R4700:
-       case CPU_R5000:
-       case CPU_R5000A:
                uasm_i_nop(p);
                tlbw(p);
                uasm_i_nop(p);
                break;
 
+       case CPU_R5000:
+       case CPU_R5000A:
+       case CPU_NEVADA:
+               uasm_i_nop(p); /* QED specifies 2 nops hazard */
+               uasm_i_nop(p); /* QED specifies 2 nops hazard */
+               tlbw(p);
+               break;
+
        case CPU_R4300:
        case CPU_5KC:
        case CPU_TX49XX:
@@ -551,19 +557,6 @@ static void __cpuinit build_tlb_write_entry(u32 **p, struct uasm_label **l,
                tlbw(p);
                break;
 
-       case CPU_NEVADA:
-               uasm_i_nop(p); /* QED specifies 2 nops hazard */
-               uasm_i_nop(p); /* QED specifies 2 nops hazard */
-               /*
-                * This branch uses up a mtc0 hazard nop slot and saves
-                * a nop after the tlbw instruction.
-                */
-               uasm_bgezl_hazard(p, r, hazard_instance);
-               tlbw(p);
-               uasm_bgezl_label(l, p, hazard_instance);
-               hazard_instance++;
-               break;
-
        case CPU_RM7000:
                uasm_i_nop(p);
                uasm_i_nop(p);