| Message ID | 20201203230955.1482058-1-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kbuild: avoid static_assert for genksyms | expand |
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 Sun, 6 Dec 2020 at 03:49, Masahiro Yamada <masahiroy@kernel.org> wrote: > > 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. > https://people.linaro.org/~ard.biesheuvel/randconfig-modversions-error
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
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 */