linux-kernel - [PATCH 5.15 060/128] compiler.h: Fix annotation macro misplacement with Clang

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Message-Id: <20211227151333.508277236@linuxfoundation.org>
Date:   Mon, 27 Dec 2021 16:30:35 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, kernel test robot <lkp@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>, x86@...nel.org,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Miroslav Benes <mbenes@...e.cz>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 060/128] compiler.h: Fix annotation macro misplacement with Clang

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

[ Upstream commit dcce50e6cc4d86a63dc0a9a6ee7d4f948ccd53a1 ]

When building with Clang and CONFIG_TRACE_BRANCH_PROFILING, there are a
lot of unreachable warnings, like:

  arch/x86/kernel/traps.o: warning: objtool: handle_xfd_event()+0x134: unreachable instruction

Without an input to the inline asm, 'volatile' is ignored for some
reason and Clang feels free to move the reachable() annotation away from
its intended location.

Fix that by re-adding the counter value to the inputs.

Fixes: f1069a8756b9 ("compiler.h: Avoid using inline asm operand modifiers")
Fixes: c199f64ff93c ("instrumentation.h: Avoid using inline asm operand modifiers")
Reported-by: kernel test robot <lkp@...el.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Link: https://lore.kernel.org/r/0417e96909b97a406323409210de7bf13df0b170.1636410380.git.jpoimboe@redhat.com
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: x86@...nel.org
Cc: Vasily Gorbik <gor@...ux.ibm.com>
Cc: Miroslav Benes <mbenes@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/compiler.h        | 4 ++--
 include/linux/instrumentation.h | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 3d5af56337bdb..429dcebe2b992 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -121,7 +121,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	asm volatile(__stringify_label(c) ":\n\t"			\
 		     ".pushsection .discard.reachable\n\t"		\
 		     ".long " __stringify_label(c) "b - .\n\t"		\
-		     ".popsection\n\t");				\
+		     ".popsection\n\t" : : "i" (c));			\
 })
 #define annotate_reachable() __annotate_reachable(__COUNTER__)
 
@@ -129,7 +129,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	asm volatile(__stringify_label(c) ":\n\t"			\
 		     ".pushsection .discard.unreachable\n\t"		\
 		     ".long " __stringify_label(c) "b - .\n\t"		\
-		     ".popsection\n\t");				\
+		     ".popsection\n\t" : : "i" (c));			\
 })
 #define annotate_unreachable() __annotate_unreachable(__COUNTER__)
 
diff --git a/include/linux/instrumentation.h b/include/linux/instrumentation.h
index fa2cd8c63dcc9..24359b4a96053 100644
--- a/include/linux/instrumentation.h
+++ b/include/linux/instrumentation.h
@@ -11,7 +11,7 @@
 	asm volatile(__stringify(c) ": nop\n\t"				\
 		     ".pushsection .discard.instr_begin\n\t"		\
 		     ".long " __stringify(c) "b - .\n\t"		\
-		     ".popsection\n\t");				\
+		     ".popsection\n\t" : : "i" (c));			\
 })
 #define instrumentation_begin() __instrumentation_begin(__COUNTER__)
 
@@ -50,7 +50,7 @@
 	asm volatile(__stringify(c) ": nop\n\t"				\
 		     ".pushsection .discard.instr_end\n\t"		\
 		     ".long " __stringify(c) "b - .\n\t"		\
-		     ".popsection\n\t");				\
+		     ".popsection\n\t" : : "i" (c));			\
 })
 #define instrumentation_end() __instrumentation_end(__COUNTER__)
 #else
-- 
2.34.1