linux-kernel - [PATCH v3 1/6] compiler.h: Make __ADDRESSABLE() symbol truly unique

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Message-Id: <8bc857824f82462a296a8a3c4913a11a7f801e74.1547073843.git.jpoimboe@redhat.com>
Date:   Wed,  9 Jan 2019 16:59:36 -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>, Nadav Amit <namit@...are.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Edward Cree <ecree@...arflare.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>
Subject: [PATCH v3 1/6] 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__.

Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
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 fc5004a4b07d..5e45bc988b1e 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -291,7 +291,7 @@ 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