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[008/181] compiler.h: avoid escaped section names

Message ID 20201013234758.d5YBasJCH%akpm@linux-foundation.org (mailing list archive)
State New, archived
Headers show
Series [001/181] compiler-clang: add build check for clang 10.0.1 | expand

Commit Message

Andrew Morton Oct. 13, 2020, 11:47 p.m. UTC 
From: Nick Desaulniers <ndesaulniers@google.com>
Subject: compiler.h: avoid escaped section names

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
Link: https://lkml.kernel.org/r/20200929194318.548707-1-ndesaulniers@google.com
Fixes: commit e04462fb82f8 ("Compiler Attributes: remove uses of __attribute__ from compiler.h")
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/compiler.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
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Patch

--- a/include/linux/compiler.h~compilerh-avoid-escaped-section-names
+++ a/include/linux/compiler.h
@@ -155,7 +155,7 @@  void ftrace_likely_update(struct ftrace_
 	extern typeof(sym) sym;					\
 	static const unsigned long __kentry_##sym		\
 	__used							\
-	__section("___kentry" "+" #sym )			\
+	__attribute__((__section__("___kentry+" #sym)))		\
 	= (unsigned long)&sym;
 #endif