powerpc/32s: Don't flush all TLBs when flushing one page

When flushing any memory range, the flushing function
flushes all TLBs.

When (start) and (end - 1) are in the same memory page,
flush that page instead.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b30b2eae6960502eaf0d9e36c60820b839693c33.1580542939.git.christophe.leroy@c-s.fr

arch/powerpc/mm/book3s32/tlb.c

@@ -79,11 +79,14 @@ static void flush_range(struct mm_struct *mm, unsigned long start,
 	int count;
 	unsigned int ctx = mm->context.id;
 
+	start &= PAGE_MASK;
 	if (!Hash) {
-		_tlbia();
+		if (end - start <= PAGE_SIZE)
+			_tlbie(start);
+		else
+			_tlbia();
 		return;
 	}
-	start &= PAGE_MASK;
 	if (start >= end)
 		return;
 	end = (end - 1) | ~PAGE_MASK;