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From: Arnd Bergmann <arnd@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>,
	linux-kbuild@vger.kernel.org,
	Masahiro Yamada <masahiroy@kernel.org>,
	Michal Marek <michal.lkml@markovi.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
	stable@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>,
	Rikard Falkeborn <rikard.falkeborn@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] kbuild: avoid static_assert for genksyms
Date: Fri,  4 Dec 2020 00:09:44 +0100	[thread overview]
Message-ID: <20201203230955.1482058-1-arnd@kernel.org> (raw)

From: Arnd Bergmann <arnd@arndb.de>

genksyms does not know or care about the _Static_assert() built-in,
and sometimes falls back to ignoring the later symbols, which causes
undefined behavior such as

WARNING: modpost: EXPORT symbol "ethtool_set_ethtool_phy_ops" [vmlinux] version generation failed, symbol will not be versioned.
ld: net/ethtool/common.o: relocation R_AARCH64_ABS32 against `__crc_ethtool_set_ethtool_phy_ops' can not be used when making a shared object
net/ethtool/common.o:(_ftrace_annotated_branch+0x0): dangerous relocation: unsupported relocation

Redefine static_assert for genksyms to avoid that.

Cc: stable@vger.kernel.org
Suggested-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/build_bug.h | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/include/linux/build_bug.h b/include/linux/build_bug.h
index e3a0be2c90ad..7bb66e15b481 100644
--- a/include/linux/build_bug.h
+++ b/include/linux/build_bug.h
@@ -77,4 +77,9 @@
 #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
 #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
 
+#ifdef __GENKSYMS__
+/* genksyms gets confused by _Static_assert */
+#define _Static_assert(expr, ...)
+#endif
+
 #endif	/* _LINUX_BUILD_BUG_H */
-- 
2.27.0


             reply	other threads:[~2020-12-03 23:10 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-03 23:09 Arnd Bergmann [this message]
2020-12-06  2:48 ` [PATCH] kbuild: avoid static_assert for genksyms Masahiro Yamada
2020-12-07  8:53   ` Ard Biesheuvel
2020-12-10 16:12 ` Marco Elver

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