[MIPS] R1: Fix hazard barriers to make kernels work on R2 also.

Tested with Malta; inflates malta_defconfig by 3932 bytes.  Ideally there
should be additional configuration to allow getting rid of this overhead
but that would be too much complexity at this stage of the release cycle.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

include/asm-mips/hazards.h

@@ -10,11 +10,12 @@
 #ifndef _ASM_HAZARDS_H
 #define _ASM_HAZARDS_H
 
-
 #ifdef __ASSEMBLY__
 #define ASMMACRO(name, code...) .macro name; code; .endm
 #else
 
+#include <asm/cpu-features.h>
+
 #define ASMMACRO(name, code...)						\
 __asm__(".macro " #name "; " #code "; .endm");				\
 									\
@@ -86,6 +87,57 @@ do {									\
 	: "=r" (tmp));							\
 } while (0)
 
+#elif defined(CONFIG_CPU_MIPSR1)
+
+/*
+ * These are slightly complicated by the fact that we guarantee R1 kernels to
+ * run fine on R2 processors.
+ */
+ASMMACRO(mtc0_tlbw_hazard,
+	_ssnop; _ssnop; _ehb
+	)
+ASMMACRO(tlbw_use_hazard,
+	_ssnop; _ssnop; _ssnop; _ehb
+	)
+ASMMACRO(tlb_probe_hazard,
+	 _ssnop; _ssnop; _ssnop; _ehb
+	)
+ASMMACRO(irq_enable_hazard,
+	 _ssnop; _ssnop; _ssnop; _ehb
+	)
+ASMMACRO(irq_disable_hazard,
+	_ssnop; _ssnop; _ssnop; _ehb
+	)
+ASMMACRO(back_to_back_c0_hazard,
+	 _ssnop; _ssnop; _ssnop; _ehb
+	)
+/*
+ * gcc has a tradition of misscompiling the previous construct using the
+ * address of a label as argument to inline assembler.  Gas otoh has the
+ * annoying difference between la and dla which are only usable for 32-bit
+ * rsp. 64-bit code, so can't be used without conditional compilation.
+ * The alterantive is switching the assembler to 64-bit code which happens
+ * to work right even for 32-bit code ...
+ */
+#define __instruction_hazard()						\
+do {									\
+	unsigned long tmp;						\
+									\
+	__asm__ __volatile__(						\
+	"	.set	mips64r2				\n"	\
+	"	dla	%0, 1f					\n"	\
+	"	jr.hb	%0					\n"	\
+	"	.set	mips0					\n"	\
+	"1:							\n"	\
+	: "=r" (tmp));							\
+} while (0)
+
+#define instruction_hazard()						\
+do {									\
+	if (cpu_has_mips_r2)						\
+		__instruction_hazard();					\
+} while (0)
+
 #elif defined(CONFIG_CPU_R10000)
 
 /*