Messages in this thread | | | Subject | Re: [PATCH v2] checkpatch: add warning for avoiding .L prefix symbols in assembly files | From | Joe Perches <> | Date | Sat, 23 Jan 2021 09:21:02 -0800 |
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On Sat, 2021-01-23 at 20:44 +0530, Aditya Srivastava wrote: > 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 <broonie@kernel.org> > Link: https://groups.google.com/g/clang-built-linux/c/-drkmLgu-cU/m/4staOlf-CgAJ
Please do not use groups.google.com links, or if you must, please use links that are readable.
For instance, this is a better link as it shows the context without struggling with the poor interface:
https://groups.google.com/g/clang-built-linux/c/E-naBMt_1SM
> Signed-off-by: Aditya Srivastava <yashsri421@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
I think that's unnecessary.
> diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl [] > @@ -3590,6 +3590,13 @@ sub process { > } > } > > > +# check for .L prefix local symbols in .S files > + if ($realfile =~ m@^arch/x86/(?:entry|lib)/.*\.S$@ &&
Using /.S$/ should be enough
> + $line =~ /^\+\s*SYM_[A-Z]+_(?:START|END)(?:_[A-Z_]+)?\s*\(\s*\.L/) {
This might need to be
+ $line =~ /^\+\s*(?:[A-Z]+_)?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); > + } > +
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