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Message-Id: <20210123151405.26267-1-yashsri421@gmail.com>
Date: Sat, 23 Jan 2021 20:44:05 +0530
From: Aditya Srivastava <yashsri421@...il.com>
To: linux-kernel@...r.kernel.org
Cc: yashsri421@...il.com, lukas.bulwahn@...il.com,
dwaipayanray1@...il.com, broonie@...nel.org, joe@...ches.com,
ndesaulniers@...gle.com, jpoimboe@...hat.com,
linux-kernel-mentees@...ts.linuxfoundation.org,
clang-built-linux@...glegroups.com
Subject: [PATCH v2] checkpatch: add warning for avoiding .L prefix symbols in assembly files
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@...nel.org>
Link: https://groups.google.com/g/clang-built-linux/c/-drkmLgu-cU/m/4staOlf-CgAJ
Signed-off-by: Aditya Srivastava <yashsri421@...il.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 ($realfile =~ m@...ch/x86/(?:entry|lib)/.*\.S$@ &&
+ $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
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