powerpc/mm: sanity_check_fault() should work for all, not only BOOK3S

The verification and message introduced by commit 374f3f59
("powerpc/mm/hash: Handle user access of kernel address gracefully")
applies to all platforms, it should not be limited to BOOK3S.

Make the BOOK3S version of sanity_check_fault() the one for all,
and bail out earlier if not BOOK3S.

Fixes: 374f3f59 ("powerpc/mm/hash: Handle user access of kernel address gracefully")
Signed-off-by: NChristophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: NNicholas Piggin <npiggin@gmail.com>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/fe199d5af3578d3bf80035d203a94d742a7a28af.1607491748.git.christophe.leroy@csgroup.eu

arch/powerpc/mm/fault.c

@@ -303,7 +303,6 @@ static inline void cmo_account_page_fault(void)
 static inline void cmo_account_page_fault(void) { }
 #endif /* CONFIG_PPC_SMLPAR */
 
-#ifdef CONFIG_PPC_BOOK3S
 static void sanity_check_fault(bool is_write, bool is_user,
 			       unsigned long error_code, unsigned long address)
 {
@@ -320,6 +319,9 @@ static void sanity_check_fault(bool is_write, bool is_user,
 		return;
 	}
 
+	if (!IS_ENABLED(CONFIG_PPC_BOOK3S))
+		return;
+
 	/*
 	 * For hash translation mode, we should never get a
 	 * PROTFAULT. Any update to pte to reduce access will result in us
@@ -354,10 +356,6 @@ static void sanity_check_fault(bool is_write, bool is_user,
 
 	WARN_ON_ONCE(error_code & DSISR_PROTFAULT);
 }
-#else
-static void sanity_check_fault(bool is_write, bool is_user,
-			       unsigned long error_code, unsigned long address) { }
-#endif /* CONFIG_PPC_BOOK3S */
 
 /*
  * Define the correct "is_write" bit in error_code based