powerpc/mm/radix: Update PID switch sequence

Update the PID switch as per ISA doc. slbia is needed in radix to
invalidate any implementation specific lookaside information.
We use the .long format due to build errors with the below compiler
version.

gcc (Ubuntu 5.3.1-14ubuntu2.1) 5.3.1 20160413
GNU assembler (GNU Binutils for Ubuntu) 2.26

CC arch/powerpc/mm//mmu_context_book3s64.o
{standard input}: Assembler messages:
{standard input}:506: Error: junk at end of line: `0x7'
scripts/Makefile.build:291: recipe for target 'arch/powerpc/mm//mmu_context_book3s64.o' failed
make[1]: *** [arch/powerpc/mm//mmu_context_book3s64.o] Error 1
Signed-off-by: Aneesh Kumar K.V <[e-mail]>
Signed-off-by: Michael Ellerman <[e-mail]>

arch/powerpc/include/asm/ppc-opcode.h

···
 #define PPC_INST_MTSPR_DSCR_USER	0x7c0303a6
 #define PPC_INST_MTSPR_DSCR_USER_MASK	0xfc1fffff
 #define PPC_INST_SLBFEE			0x7c0007a7
+#define PPC_INST_SLBIA			0x7c0003e4
 
 #define PPC_INST_STRING			0x7c00042a
 #define PPC_INST_STRING_MASK		0xfc0007fe
···
 					       ___PPC_RA(a) |		\
 					       ___PPC_RB(b))
 
+#define PPC_SLBIA(IH)	stringify_in_c(.long PPC_INST_SLBIA | \
+				       ((IH & 0x7) << 21))
 
 #endif /* _ASM_POWERPC_PPC_OPCODE_H */

arch/powerpc/mm/mmu_context_book3s64.c

···
 #ifdef CONFIG_PPC_RADIX_MMU
 void radix__switch_mmu_context(struct mm_struct *prev, struct mm_struct *next)
 {
-	mtspr(SPRN_PID, next->context.id);
 	asm volatile("isync": : :"memory");
+	mtspr(SPRN_PID, next->context.id);
+	asm volatile("isync \n"
+		     PPC_SLBIA(0x7)
+		     : : :"memory");
 }
 #endif