arm64: add EXPORT_SYMBOL_NOKASAN()

So that we can export symbols directly from assembly files, let's make
use of the generic <asm/export.h>. We have a few symbols that we'll want
to conditionally export for !KASAN kernel builds, so we add a helper for
that in <asm/assembler.h>.
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/include/asm/assembler.h

@@ -23,6 +23,8 @@
 #ifndef __ASM_ASSEMBLER_H
 #define __ASM_ASSEMBLER_H
 
+#include <asm-generic/export.h>
+
 #include <asm/asm-offsets.h>
 #include <asm/cpufeature.h>
 #include <asm/debug-monitors.h>
@@ -490,6 +492,13 @@ USER(\label, ic	ivau, \tmp2)			// invalidate I line PoU
 #else
 #define NOKPROBE(x)
 #endif
+
+#ifdef CONFIG_KASAN
+#define EXPORT_SYMBOL_NOKASAN(name)
+#else
+#define EXPORT_SYMBOL_NOKASAN(name)	EXPORT_SYMBOL(name)
+#endif
+
 	/*
 	 * Emit a 64-bit absolute little endian symbol reference in a way that
 	 * ensures that it will be resolved at build time, even when building a