s390/compat: build error for large compat syscall args

Enforce 32 bit types for all compat syscall argument types.

This way we can make sure that all arguments get correct sign
or zero extension. Otherwise incorrect code would be generated.

E.g. for a 'long' type the COMPAT_SYSCALL_DEFINE macro wouldn't
generate code that would cause sign extension of the passed in 32
bit user space parameter.
This can cause quite subtle bugs like e.g. the one that was fixed
with dfd948e3 "fs/compat: fix parameter handling for compat
readv/writev syscalls".
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

arch/s390/include/asm/compat.h

@@ -8,7 +8,11 @@
 #include <linux/thread_info.h>
 
 #define __TYPE_IS_PTR(t) (!__builtin_types_compatible_p(typeof(0?(t)0:0ULL), u64))
-#define __SC_DELOUSE(t,v) (t)(__TYPE_IS_PTR(t) ? ((v) & 0x7fffffff) : (v))
+
+#define __SC_DELOUSE(t,v) ({ \
+	BUILD_BUG_ON(sizeof(t) > 4 && !__TYPE_IS_PTR(t)); \
+	(t)(__TYPE_IS_PTR(t) ? ((v) & 0x7fffffff) : (v)); \
+})
 
 #define PSW32_MASK_PER		0x40000000UL
 #define PSW32_MASK_DAT		0x04000000UL