arm64: Workaround circular dependency in pointer_auth.h

With the backport of f227e3e ("random32: update the net random
state on interrupt and activity") and its associated fixes, the
arm64 build explodes early:

In file included from ../include/linux/smp.h:67,
                  from ../include/linux/percpu.h:7,
                  from ../include/linux/prandom.h:12,
                  from ../include/linux/random.h:118,
                  from ../arch/arm64/include/asm/pointer_auth.h:6,
                  from ../arch/arm64/include/asm/processor.h:39,
                  from ../include/linux/mutex.h:19,
                  from ../include/linux/kernfs.h:12,
                  from ../include/linux/sysfs.h:16,
                  from ../include/linux/kobject.h:20,
                  from ../include/linux/of.h:17,
                  from ../include/linux/irqdomain.h:35,
                  from ../include/linux/acpi.h:13,
                  from ../include/acpi/apei.h:9,
                  from ../include/acpi/ghes.h:5,
                  from ../include/linux/arm_sdei.h:8,
                  from ../arch/arm64/kernel/asm-offsets.c:10:
../arch/arm64/include/asm/smp.h:100:29: error: field ‘ptrauth_key’ has
incomplete type

This is due to struct ptrauth_keys_kernel not being defined before
we transitively include asm/smp.h from linux/random.h.

Paper over it by moving the inclusion of linux/random.h *after* the
type has been defined.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/arm64/include/asm/pointer_auth.h

@@ -3,7 +3,6 @@
 #define __ASM_POINTER_AUTH_H
 
 #include <linux/bitops.h>
-#include <linux/random.h>
 
 #include <asm/cpufeature.h>
 #include <asm/memory.h>
@@ -30,6 +29,13 @@ struct ptrauth_keys {
 	struct ptrauth_key apga;
 };
 
+/*
+ * Only include random.h once ptrauth_keys_* structures are defined
+ * to avoid yet another circular include hell (random.h * ends up
+ * including asm/smp.h, which requires ptrauth_keys_kernel).
+ */
+#include <linux/random.h>
+
 static inline void ptrauth_keys_init(struct ptrauth_keys *keys)
 {
 	if (system_supports_address_auth()) {