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Date:   Tue, 29 Sep 2020 12:43:18 -0700
Message-Id: <20200929194318.548707-1-ndesaulniers@google.com>
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Subject: [PATCH] compiler.h: avoid escaped section names
From:   Nick Desaulniers <ndesaulniers@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Nathan Chancellor <natechancellor@gmail.com>,
        linux-sparse@vger.kernel.org, linux-kernel@vger.kernel.org,
        clang-built-linux@googlegroups.com
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Precedence: bulk

The stringification operator, `#`, in the preprocessor escapes strings.
For example, `# "foo"` becomes `"\"foo\""`.  GCC and Clang differ in how
they treat section names that contain \".

The portable solution is to not use a string literal with the
preprocessor stringification operator.

In this case, since __section unconditionally uses the stringification
operator, we actually want the more verbose
__attribute__((__section__())).

Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Fixes: commit e04462fb82f8 ("Compiler Attributes: remove uses of __attribute__ from compiler.h")
Signed-off-by: Nick Desaulniers <ndesaulniers@google.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 92ef163a7479..ac45f6d40d39 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -155,7 +155,7 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val,
 	extern typeof(sym) sym;					\
 	static const unsigned long __kentry_##sym		\
 	__used							\
-	__section("___kentry" "+" #sym )			\
+	__attribute__((__section__("___kentry+" #sym)))		\
 	= (unsigned long)&sym;
 #endif
 
-- 
2.28.0.709.gb0816b6eb0-goog