linux-kernel - [tip:core/objtool] objtool: Make unreachable annotation inline asms explicitly volatile

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Date:   Tue, 7 Nov 2017 01:52:21 -0800
From:   tip-bot for Josh Poimboeuf <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     jpoimboe@...hat.com, tglx@...utronix.de, peterz@...radead.org,
        torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
        mingo@...nel.org, hpa@...or.com
Subject: [tip:core/objtool] objtool: Make unreachable annotation inline asms
 explicitly volatile

Commit-ID:  10259821ac47dbefa6f83ae57f1fa9f1f2c54b3d
Gitweb:     https://git.kernel.org/tip/10259821ac47dbefa6f83ae57f1fa9f1f2c54b3d
Author:     Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Mon, 6 Nov 2017 07:17:38 -0600
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 7 Nov 2017 10:48:22 +0100

objtool: Make unreachable annotation inline asms explicitly volatile

Add 'volatile' to the unreachable annotation macro inline asm
statements.  They're already implicitly volatile because they don't have
output constraints, but it's clearer and more robust to make them
explicitly volatile.

Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: http://lkml.kernel.org/r/28659257b7a6adf4a7f65920dad70b2b0226e996.1509974104.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 include/linux/compiler.h | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index f8734fc..4fac29c 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -193,16 +193,16 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
  * unique, to convince GCC not to merge duplicate inline asm statements.
  */
 #define annotate_reachable() ({						\
-	asm("%c0:\n\t"							\
-	    ".pushsection .discard.reachable\n\t"			\
-	    ".long %c0b - .\n\t"					\
-	    ".popsection\n\t" : : "i" (__COUNTER__));			\
+	asm volatile("%c0:\n\t"						\
+		     ".pushsection .discard.reachable\n\t"		\
+		     ".long %c0b - .\n\t"				\
+		     ".popsection\n\t" : : "i" (__COUNTER__));		\
 })
 #define annotate_unreachable() ({					\
-	asm("%c0:\n\t"							\
-	    ".pushsection .discard.unreachable\n\t"			\
-	    ".long %c0b - .\n\t"					\
-	    ".popsection\n\t" : : "i" (__COUNTER__));			\
+	asm volatile("%c0:\n\t"						\
+		     ".pushsection .discard.unreachable\n\t"		\
+		     ".long %c0b - .\n\t"				\
+		     ".popsection\n\t" : : "i" (__COUNTER__));		\
 })
 #define ASM_UNREACHABLE							\
 	"999:\n\t"							\