s390: make use of CONFIG_FUNCTION_ALIGNMENT

Make use of CONFIG_FUNCTION_ALIGNMENT which was introduced with commit
d49a0626 ("arch: Introduce CONFIG_FUNCTION_ALIGNMENT").

Select FUNCTION_ALIGNMENT_8B for gcc in order to reflect gcc's default
function alignment. For all other compilers, which is only clang, select
a function alignment of 16 bytes which reflects the default function
alignment for clang.

Also change the __ALIGN define to follow whatever the value of
CONFIG_FUNCTION_ALIGNMENT is. This makes sure that the alignment of C and
assembler functions is the same.

In result everything still uses the default function alignment for both
compilers. However in addition this is now also true for all assembly
functions, so that all functions have a consistent alignment.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

arch/s390/Kconfig

@@ -131,6 +131,8 @@ config S390
 	select CLONE_BACKWARDS2
 	select DMA_OPS if PCI
 	select DYNAMIC_FTRACE if FUNCTION_TRACER
+	select FUNCTION_ALIGNMENT_8B if CC_IS_GCC
+	select FUNCTION_ALIGNMENT_16B if !CC_IS_GCC
 	select GCC12_NO_ARRAY_BOUNDS
 	select GENERIC_ALLOCATOR
 	select GENERIC_CPU_AUTOPROBE

arch/s390/include/asm/linkage.h

@@ -4,7 +4,7 @@
 
 #include <linux/stringify.h>
 
-#define __ALIGN .align 16, 0x07
+#define __ALIGN .balign CONFIG_FUNCTION_ALIGNMENT, 0x07
 #define __ALIGN_STR __stringify(__ALIGN)
 
 #endif