ARM64 requires some tweaks; different header & kernel_neon_begin|end()

Reported-by: eibisidi

ch5/fp_in_lkm/Makefile

@@ -100,6 +100,8 @@ ifeq (${MYDEBUG}, y)
 else
   ccflags-y   += -UDEBUG
 endif
+ccflags-remove-y += -mgeneral-regs-only
+
 # We always keep the dynamic debug facility enabled; this allows us to turn
 # dynamically turn on/off debug printk's later... To disable it simply comment
 # out the following line

ch5/fp_in_lkm/fp_in_lkm.c

@@ -20,8 +20,15 @@
 
 #include <linux/init.h>
 #include <linux/module.h>
-//#include <linux/kernel.h>
+#ifdef CONFIG_X86
 #include <asm/fpu/api.h>
+#endif
+
+#ifdef CONFIG_ARM64
+#include <asm/neon.h>
+#define kernel_fpu_begin kernel_neon_begin
+#define kernel_fpu_end kernel_neon_end
+#endif
 
 MODULE_AUTHOR("<insert your name here>");
 MODULE_DESCRIPTION("LKP2E book:ch5/fp_in_lkm: no performing FP \