On Fri, Dec 4, 2020 at 8:10 AM Arnd Bergmann arnd@kernel.org wrote:

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.

Please tell the CONFIG options needed to reproduce this. I do not see it.

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

On Fri, Dec 04, 2020 at 12:09AM +0100, Arnd Bergmann wrote:

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

I had sent

https://lkml.kernel.org/r/20201201152017.3576951-1-elver@google.com

3 days before your patch. :-)

I guess what you propose is simpler, but might still have corner cases where we still get warnings. In particular, if some file (for whatever reason) does not include build_bug.h and uses a raw _Static_assert(), then we still get warnings. E.g. I see 1 user of raw _Static_assert() (drivers/gpu/drm/amd/amdgpu/amdgv_sriovmsg.h ).

In the end I don't mind either way, as long as those warnings are fixed in 5.11. :-)

Thanks, -- Marco