MIPS: Avoid potential hazard on Context register
set_saved_sp reads Context register. Avoid reading stale value from
earlier incomplete write.
Issue found and fixed for head.S by Chris Dearman <chris@mips.com>.
Signed-off-by: Chris Dearman <chris@mips.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/mmu_context.h b/arch/mips/include/asm/mmu_context.h
index ed331c2..6083db5 100644
--- a/arch/mips/include/asm/mmu_context.h
+++ b/arch/mips/include/asm/mmu_context.h
@@ -16,6 +16,7 @@
#include <linux/smp.h>
#include <linux/slab.h>
#include <asm/cacheflush.h>
+#include <asm/hazards.h>
#include <asm/tlbflush.h>
#ifdef CONFIG_MIPS_MT_SMTC
#include <asm/mipsmtregs.h>
@@ -36,11 +37,13 @@
#ifdef CONFIG_32BIT
#define TLBMISS_HANDLER_SETUP() \
write_c0_context((unsigned long) smp_processor_id() << 25); \
+ back_to_back_c0_hazard(); \
TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
#endif
#ifdef CONFIG_64BIT
#define TLBMISS_HANDLER_SETUP() \
write_c0_context((unsigned long) smp_processor_id() << 26); \
+ back_to_back_c0_hazard(); \
TLBMISS_HANDLER_SETUP_PGD(swapper_pg_dir)
#endif
diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index 531ce7b..ea695d9 100644
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -191,6 +191,7 @@
/* Set the SP after an empty pt_regs. */
PTR_LI sp, _THREAD_SIZE - 32 - PT_SIZE
PTR_ADDU sp, $28
+ back_to_back_c0_hazard
set_saved_sp sp, t0, t1
PTR_SUBU sp, 4 * SZREG # init stack pointer