powerpc/32s: Slenderize _tlbia() for powerpc 603/603e

_tlbia() is a function used only on 603/603e core, ie on CPUs which
don't have a hash table.

_tlbia() uses the tlbia macro which implements a loop of 1024 tlbie.

On the 603/603e core, flushing the entire TLB requires no more than
32 tlbie.

Replace tlbia by a loop of 32 tlbie.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/12f4f4f0ff89aeab3b937fc96c84fb35e1b2517e.1580748445.git.christophe.leroy@c-s.fr

arch/powerpc/mm/book3s32/hash_low.S

@@ -696,18 +696,21 @@ _GLOBAL(_tlbia)
 	bne-	10b
 	stwcx.	r8,0,r9
 	bne-	10b
+#endif /* CONFIG_SMP */
+	li	r5, 32
+	lis	r4, KERNELBASE@h
+	mtctr	r5
 	sync
-	tlbia
+0:	tlbie	r4
+	addi	r4, r4, 0x1000
+	bdnz	0b
 	sync
+#ifdef CONFIG_SMP
 	TLBSYNC
 	li	r0,0
 	stw	r0,0(r9)		/* clear mmu_hash_lock */
 	mtmsr	r10
 	SYNC_601
 	isync
-#else /* CONFIG_SMP */
-	sync
-	tlbia
-	sync
 #endif /* CONFIG_SMP */
 	blr