x86/kasan: Define KASAN_SHADOW_OFFSET per architecture

Current definition of KASAN_SHADOW_OFFSET in
include/linux/kasan.h will not work for upcomming arm64, so move
it to the arch header.

Signed-off-by: Andrey Ryabinin <[e-mail]>
Cc: Alexander Potapenko <[e-mail]>
Cc: Alexey Klimov <[e-mail]>
Cc: Andrew Morton <[e-mail]>
Cc: Aneesh Kumar K.V <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Catalin Marinas <[e-mail]>
Cc: David Keitel <[e-mail]>
Cc: Dmitry Vyukov <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Linus Walleij <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Rik van Riel <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Will Deacon <[e-mail]>
Cc: Yury <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

arch/x86/include/asm/kasan.h

···
 #ifndef _ASM_X86_KASAN_H
 #define _ASM_X86_KASAN_H
 
+#include <linux/const.h>
+#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
+
 /*
  * Compiler uses shadow offset assuming that addresses start
  * from 0. Kernel addresses don't start from 0, so shadow

include/linux/kasan.h

···
 #ifdef CONFIG_KASAN
 
 #define KASAN_SHADOW_SCALE_SHIFT 3
-#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
 
 #include <asm/kasan.h>
 #include <linux/sched.h>