linux-kernel - [PATCH v2 1/4] compiler.h: Make __ADDRESSABLE() symbol truly unique

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Date:   Mon, 26 Nov 2018 07:54:57 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jason Baron <jbaron@...mai.com>, Jiri Kosina <jkosina@...e.cz>,
        David Laight <David.Laight@...LAB.COM>,
        Borislav Petkov <bp@...en8.de>,
        Julia Cartwright <julia@...com>, Jessica Yu <jeyu@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v2 1/4] 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@...hat.com>
---
 include/linux/compiler.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 06396c1cf127..4bb73fd918b5 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -282,7 +282,7 @@ unsigned long read_word_at_a_time(const void *addr)
  */
 #define __ADDRESSABLE(sym) \
 	static void * __section(".discard.addressable") __used \
-		__PASTE(__addressable_##sym, __LINE__) = (void *)&sym;
+		__UNIQUE_ID(__addressable_##sym) = (void *)&sym;
 
 /**
  * offset_to_ptr - convert a relative memory offset to an absolute pointer
-- 
2.17.2