compiler.h: Make __ADDRESSABLE() symbol truly unique

The __ADDRESSABLE() macro uses the __LINE__ macro to create a temporary
symbol which has a unique name.  However, if the macro is used multiple
times from within another macro, the line number will always be the
same, resulting in duplicate symbols.

Make the temporary symbols truly unique by using __UNIQUE_ID instead of
__LINE__.
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Link: https://lore.kernel.org/r/20200818135804.564436253@infradead.org

include/linux/compiler.h

@@ -207,7 +207,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
  */
 #define __ADDRESSABLE(sym) \
 	static void * __section(.discard.addressable) __used \
-		__PASTE(__addressable_##sym, __LINE__) = (void *)&sym;
+		__UNIQUE_ID(__PASTE(__addressable_,sym)) = (void *)&sym;
 
 /**
  * offset_to_ptr - convert a relative memory offset to an absolute pointer