objtool requires that all code must be contained in an ELF symbol. Symbol names that have a '.L' prefix do not emit symbol table entries, as they have special meaning for the assembler.
'.L' prefixed symbols can be used within a code region, but should be avoided for denoting a range of code via 'SYM_*_START/END' annotations. Add a new check to emit a warning on finding the usage of '.L' symbols for '.S' files in arch/x86/entry/* and arch/x86/lib/*, if it denotes range of code via SYM_*_START/END annotation pair. Suggested-by: Mark Brown <broo...@kernel.org> Link: https://groups.google.com/g/clang-built-linux/c/-drkmLgu-cU/m/4staOlf-CgAJ Signed-off-by: Aditya Srivastava <yashsri...@gmail.com> --- * Applies perfectly on next-20210122 Changes in v2: - Reduce the check to only SYM_*_START/END lines - Reduce the check for only .S files in arch/x86/entry/* and arch/x86/lib/* as suggested by Josh and Nick - Modify commit message scripts/checkpatch.pl | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl index 7030c4d6d126..e36cdf96dfe3 100755 --- a/scripts/checkpatch.pl +++ b/scripts/checkpatch.pl @@ -3590,6 +3590,13 @@ sub process { } } +# check for .L prefix local symbols in .S files + if ($realfile =~ m@^arch/x86/(?:entry|lib)/.*\.S$@ && + $line =~ /^\+\s*SYM_[A-Z]+_(?:START|END)(?:_[A-Z_]+)?\s*\(\s*\.L/) { + WARN("AVOID_L_PREFIX", + "Avoid using '.L' prefixed local symbol names for denoting a range of code via 'SYM_*_START/END' annotations; see Documentation/asm-annotations.rst\n" . $herecurr); + } + # check we are in a valid source file C or perl if not then ignore this hunk next if ($realfile !~ /\.(h|c|pl|dtsi|dts)$/); -- 2.17.1
