On 23/1/21 10:51 pm, Joe Perches wrote:

On Sat, 2021-01-23 at 20:44 +0530, Aditya Srivastava wrote:

quoted

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

Okay, Got it.. I'll use lkml link for the best.

quoted

Signed-off-by: Aditya Srivastava <redacted>
---
* 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.

quoted

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl

[]

quoted

@@ -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

quoted

+		    $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/) {

Okay.. Thanks. I'll modify the patch accordingly.

Thanks
Aditya

quoted

+			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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