[yyu168-linux_cet:cet 55/58] powerpc64le-linux-ld: warning: discarding dynamic section .rela___ksymtab+jiffies_to_timeval

[H.J. Lu]

On Wed, Feb 5, 2020 at 7:26 PM Michael Ellerman <mpe at ellerman.id.au> wrote:
>
> "H.J. Lu" <hjl.tools at gmail.com> writes:
> > On Tue, Feb 4, 2020 at 3:37 PM kbuild test robot <lkp at intel.com> wrote:
> >>
> >> tree:   https://github.com/yyu168/linux_cet.git cet
> >> head:   bba707cc4715c1036b6561ab38b16747f9c49cfa
> >> commit: 71bb971dd76eeacd351690f28864ad5c5bec3691 [55/58] Discard .note.gnu.property sections in generic NOTES
> >> config: powerpc-rhel-kconfig (attached as .config)
> >> compiler: powerpc64le-linux-gcc (GCC) 7.5.0
> >> reproduce:
> >>         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> >>         chmod +x ~/bin/make.cross
> >>         git checkout 71bb971dd76eeacd351690f28864ad5c5bec3691
> >>         # save the attached .config to linux build tree
> >>         GCC_VERSION=7.5.0 make.cross ARCH=powerpc
> >>
> >> If you fix the issue, kindly add following tag
> >> Reported-by: kbuild test robot <lkp at intel.com>
> >>
> >> All warnings (new ones prefixed by >>):
> >>
> >>    powerpc64le-linux-ld: warning: discarding dynamic section .rela___ksymtab_gpl+__wait_rcu_gp
> >
> > arch/powerpc/kernel/vmlinux.lds.S has
> >
> >  .rela.dyn : AT(ADDR(.rela.dyn) - (0xc000000000000000 -0x00000000))
> >  {
> >   __rela_dyn_start = .;
> >   *(.rela*) <<<<<<<< Keep .rela* sections
> >  }
>
> The above is inside #ifdef CONFIG_RELOCATABLE
>
> > ...
> >  /DISCARD/ : {
> >   *(*.EMB.apuinfo)
> >   *(.glink .iplt .plt .rela* .comment)
> >                            ^^^^ Discard  .rela* sections.  But it is ignored.
> >   *(.gnu.version*)
> >   *(.gnu.attributes)
> >   *(.eh_frame)
> >  }
>
> But that is not #ifdef'ed at all.
>
> > With my
> >
> > ommit 71bb971dd76eeacd351690f28864ad5c5bec3691
> > Author: H.J. Lu <hjl.tools at gmail.com>
> > Date:   Thu Jan 30 12:39:09 2020 -0800
> >
> >     Discard .note.gnu.property sections in generic NOTES
> >
> >     With the command-line option, -mx86-used-note=yes, the x86 assembler
> >     in binutils 2.32 and above generates a program property note in a note
> >     section, .note.gnu.property, to encode used x86 ISAs and features.  But
> >     kernel linker script only contains a single NOTE segment:
> >
> > /DISCARD/ : { *(.note.gnu.property) }
> >
> > is placed before
> >
> > .rela.dyn : AT(ADDR(.rela.dyn) - (0xc000000000000000 -0x00000000))
> >  {
> >   __rela_dyn_start = .;
> >   *(.rela*) <<<<<<<< Keep .rela* sections
> >  }
> >
> > Then .rela* in
> >
> >  /DISCARD/ : {
> >   *(*.EMB.apuinfo)
> >   *(.glink .iplt .plt .rela* .comment)
> >   *(.gnu.version*)
> >   *(.gnu.attributes)
> >   *(.eh_frame)
> >  }
> >
> > is honored.  Can someone from POWERPC comment on it?
>
> Hmm OK. I'm not really a toolchain person.
>
> The comment on DISCARDS says:
>
>    * Some archs want to discard exit text/data at runtime rather than
>    * link time due to cross-section references such as alt instructions,
>    * bug table, eh_frame, etc.  DISCARDS must be the last of output
>    * section definitions so that such archs put those in earlier section
>    * definitions.
>    */
>
> But I guess you're changing those semantics in your series.
>
> This seems to fix the warning for me?
>
> diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
> index b4c89a1acebb..076b3e8a849d 100644
> --- a/arch/powerpc/kernel/vmlinux.lds.S
> +++ b/arch/powerpc/kernel/vmlinux.lds.S
> @@ -365,9 +365,12 @@ SECTIONS
>         DISCARDS
>         /DISCARD/ : {
>                 *(*.EMB.apuinfo)
> -               *(.glink .iplt .plt .rela* .comment)
> +               *(.glink .iplt .plt .comment)
>                 *(.gnu.version*)
>                 *(.gnu.attributes)
>                 *(.eh_frame)
> +#ifndef CONFIG_RELOCATABLE
> +               *(.rela*)
> +#endif
>         }
>  }
>
>
> cheers

This looks correct me.

Reviewed-by: H.J. Lu <hjl.tools at gmail.com>

Thanks.

-- 
H.J.