[MIPS] Provide empty irq_enable_hazard definition for legacy and R1 cores.

Following a strict interpretation the empty definition of irq_enable_hazard
has always been a bug - but an intentional one because it didn't bite.
This has now changed, for uniprocessor kernels mm/slab.c:do_drain()

[...]
        on_each_cpu(do_drain, cachep, 1, 1);
        check_irq_on();
[...]

may be compiled into a mtc0 c0_status; mfc0 c0_status sequence resulting
in a back-to-back hazard.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/include/asm-mips/hazards.h b/include/asm-mips/hazards.h
index 918a4894b587..6a5fa32f615b 100644
--- a/include/asm-mips/hazards.h
+++ b/include/asm-mips/hazards.h
@@ -172,6 +172,7 @@ ASMMACRO(tlb_probe_hazard,
          nop; nop; nop
         )
 ASMMACRO(irq_enable_hazard,
+         _ssnop; _ssnop; _ssnop;
         )
 ASMMACRO(irq_disable_hazard,
         nop; nop; nop