AT_VECTOR_SIZE_ARCH should be defined with the maximum number of
NEW_AUX_ENT entries that ARCH_DLINFO can contain, but it wasn't defined
for s390 at all even though ARCH_DLINFO can contain one NEW_AUX_ENT when
VDSO is enabled.
This shouldn't be a problem as AT_VECTOR_SIZE_BASE includes space for
AT_BASE_PLATFORM which s390 doesn't use, but lets define it now and add
the comment above ARCH_DLINFO as found in several other architectures to
remind future modifiers of ARCH_DLINFO to keep AT_VECTOR_SIZE_ARCH up to
date.
Fixes: b020632e40c3 ("[S390] introduce vdso on s390")
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
 #define MMAP_ALIGN_MASK        (is_compat_task() ? 0 : 0x7fUL)
 #define STACK_RND_MASK MMAP_RND_MASK
 
+/* update AT_VECTOR_SIZE_ARCH if the number of NEW_AUX_ENT entries changes */
 #define ARCH_DLINFO                                                        \
 do {                                                                       \
        if (vdso_enabled)                                                   \
 
 
 #define AT_SYSINFO_EHDR                33
 
+#define AT_VECTOR_SIZE_ARCH 1 /* entries in ARCH_DLINFO */
+
 #endif