linux-kernel - [PATCH 09/15] compiler.h: Make __ADDRESSABLE() symbol truly unique

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Date:   Wed, 05 Jun 2019 15:08:02 +0200
From:   Peter Zijlstra <peterz@...radead.org>
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>, Nadav Amit <namit@...are.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Edward Cree <ecree@...arflare.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>
Subject: [PATCH 09/15] compiler.h: Make __ADDRESSABLE() symbol truly unique

From: Josh Poimboeuf <jpoimboe@...hat.com>

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__.

Cc: Julia Cartwright <julia@...com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: x86@...nel.org
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Daniel Bristot de Oliveira <bristot@...hat.com>
Cc: Rasmus Villemoes <linux@...musvillemoes.dk>
Cc: Jason Baron <jbaron@...mai.com>
Cc: Edward Cree <ecree@...arflare.com>
Cc: Jiri Kosina <jkosina@...e.cz>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Jessica Yu <jeyu@...nel.org>
Cc: David Laight <David.Laight@...LAB.COM>
Cc: Nadav Amit <namit@...are.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Andy Lutomirski <luto@...nel.org>
Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Link: https://lkml.kernel.org/r/8bc857824f82462a296a8a3c4913a11a7f801e74.1547073843.git.jpoimboe@redhat.com
---
 include/linux/compiler.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -294,7 +294,7 @@ unsigned long read_word_at_a_time(const
  */
 #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