export.h: fix section name for CONFIG_TRIM_UNUSED_KSYMS for Clang

When enabling CONFIG_TRIM_UNUSED_KSYMS, the linker will warn about the
orphan sections:

(".discard.ksym") is being placed in '".discard.ksym"'

repeatedly when linking vmlinux.  This is because the stringification
operator, `#`, in the preprocessor escapes strings.  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.

Fixes: commit bbda5ec671 ("kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS")
Reported-by: kbuild test robot <lkp@intel.com>
Suggested-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Cc: Nathan Chancellor <natechancellor@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Matthias Maennich <maennich@google.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Will Deacon <will@kernel.org>
Link: https://bugs.llvm.org/show_bug.cgi?id=42950
Link: https://github.com/ClangBuiltLinux/linux/issues/1166
Link: https://lkml.kernel.org/r/20200929190701.398762-1-ndesaulniers@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nick Desaulniers 2020-10-13 16:48:01 -07:00 committed by Linus Torvalds
parent a25c13b3aa
commit 4d6fb34acb

View File

@ -130,7 +130,7 @@ struct kernel_symbol {
* discarded in the final link stage.
*/
#define __ksym_marker(sym) \
static int __ksym_marker_##sym[0] __section(".discard.ksym") __used
static int __ksym_marker_##sym[0] __section(.discard.ksym) __used
#define __EXPORT_SYMBOL(sym, sec, ns) \
__ksym_marker(sym); \