On Wed, Mar 20, 2019 at 10:55:06PM +0900, Masahiro Yamada wrote: > On Sat, Mar 16, 2019 at 4:55 AM Matthias Kaehlcke <m...@chromium.org> wrote: > > > > Building the 32-bit vDSO with a recent clang version fails due > > to undefined symbols: > > > > arch/x86/entry/vdso/vdso32.so.dbg: undefined symbols found > > > > The undefined symbol in this case is __lshrdi3, which is part of > > the compiler runtime library, however the vDSO isn't linked against > > this library. > > > > Include the kernel version of __lshrdi3 in the 32-bit vDSO build. > > > > Signed-off-by: Matthias Kaehlcke <m...@chromium.org> > > --- > > diff --git a/lib/lshrdi3.c b/lib/lshrdi3.c > > index 99cfa5721f2d..8a4fc6bcf3a4 100644 > > --- a/lib/lshrdi3.c > > +++ b/lib/lshrdi3.c > > @@ -16,7 +16,7 @@ > > * to the Free Software Foundation, Inc. > > */ > > > > -#include <linux/module.h> > > +#include <linux/export.h> > > #include <linux/libgcc.h> > > > > long long notrace __lshrdi3(long long u, word_type b) > > @@ -42,4 +42,6 @@ long long notrace __lshrdi3(long long u, word_type b) > > > > return w.ll; > > } > > +#ifndef BUILD_VDSO > > EXPORT_SYMBOL(__lshrdi3); > > +#endif > > > I picked up > https://patchwork.kernel.org/patch/10858565/
Great, thanks! > I do not know if this patch is still needed. no, with the change to -Os the patch isn't needed anymore. > FYI, just a tip to turn EXPORT_SYMBOL into no-op cleanly. > > You can use __DISABLE_EXPORTS > as drivers/firmware/efi/libstub/Makefile does. > > See commit f922c4abdf76. Good to know, thanks for the pointer!