Messages in this thread | | | From | Nick Desaulniers <> | Date | Wed, 20 Jan 2021 10:57:03 -0800 | Subject | Re: [PATCH] checkpatch: add warning for avoiding .L prefix symbols in assembly files |
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On Wed, Jan 20, 2021 at 10:43 AM Joe Perches <joe@perches.com> wrote: > > On Wed, 2021-01-20 at 18:23 +0530, Aditya wrote: > > On 20/1/21 2:51 pm, Joe Perches wrote: > > > On Wed, 2021-01-20 at 12:55 +0530, Aditya Srivastava wrote: > > > > Local symbols prefixed with '.L' 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 > > > > in '.S' files, if it lies within SYM_*_START/END annotation pair. > > > > > > I believe this needs a test for $file as it won't work well on > > > patches as the SYM_*_START/END may not be in the patch context. > > > > > Okay. > > > > > Also, is this supposed to work for local labels like '.L<foo>:'? > > > I don't think a warning should be generated for those. > > > > > Yes, currently it will generate warning for all symbols which start > > with .L and have non- white character symbol following it, if it is > > lying within SYM_*_START/END annotation pair. > > > > Should I reduce the check to \.L_\S+ instead? (please note "_" > > following ".L") > > Use grep first. That would still match several existing labels. > > > Pardon me, I'm not good with assembly :/ > > Spending time reading docs can help with that. > > Mark? Can you please comment about the below? > > I believe the test should be: > > if ($realfile =~ /\.S$/ && > $line =~ /^\+\s*SYM_[A-Z]+_(?:START|END)(?:_[A-Z_]+)?\s*\(\s*\.L/) { > WARN(...); > } > > so that only this code currently matches: > > $ git grep -P '^\s*SYM_[A-Z]+_(?:START|END)(?:_[A-Z_]+)?\s*\(\s*\.L' -- '*.S' > arch/x86/boot/compressed/head_32.S:SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) > arch/x86/boot/compressed/head_32.S:SYM_FUNC_END(.Lrelocated) > arch/x86/boot/compressed/head_64.S:SYM_FUNC_START_LOCAL_NOALIGN(.Lrelocated) > arch/x86/boot/compressed/head_64.S:SYM_FUNC_END(.Lrelocated) > arch/x86/boot/compressed/head_64.S:SYM_FUNC_START_LOCAL_NOALIGN(.Lpaging_enabled) > arch/x86/boot/compressed/head_64.S:SYM_FUNC_END(.Lpaging_enabled) > arch/x86/boot/compressed/head_64.S:SYM_FUNC_START_LOCAL_NOALIGN(.Lno_longmode) > arch/x86/boot/compressed/head_64.S:SYM_FUNC_END(.Lno_longmode) > arch/x86/boot/pmjump.S:SYM_FUNC_START_LOCAL_NOALIGN(.Lin_pm32) > arch/x86/boot/pmjump.S:SYM_FUNC_END(.Lin_pm32) > arch/x86/entry/entry_64.S:SYM_CODE_START_LOCAL_NOALIGN(.Lbad_gs) > arch/x86/entry/entry_64.S:SYM_CODE_END(.Lbad_gs) > arch/x86/lib/copy_user_64.S:SYM_CODE_START_LOCAL(.Lcopy_user_handle_tail) > arch/x86/lib/copy_user_64.S:SYM_CODE_END(.Lcopy_user_handle_tail) > arch/x86/lib/getuser.S:SYM_CODE_START_LOCAL(.Lbad_get_user_clac) > arch/x86/lib/getuser.S:SYM_CODE_END(.Lbad_get_user_clac) > arch/x86/lib/getuser.S:SYM_CODE_START_LOCAL(.Lbad_get_user_8_clac) > arch/x86/lib/getuser.S:SYM_CODE_END(.Lbad_get_user_8_clac) > arch/x86/lib/putuser.S:SYM_CODE_START_LOCAL(.Lbad_put_user_clac) > arch/x86/lib/putuser.S:SYM_CODE_END(.Lbad_put_user_clac) > arch/x86/realmode/rm/wakeup_asm.S:SYM_DATA_START_LOCAL(.Lwakeup_idt) > arch/x86/realmode/rm/wakeup_asm.S:SYM_DATA_END(.Lwakeup_idt)
Josh, I assume objtool does not annotate code under: arch/x86/boot/ arch/x86/entry/ arch/x86/realmode/ ?
The rest, ie arch/x86/lib/ seem potentially relevant? -- Thanks, ~Nick Desaulniers
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