Re: linux-next: build failure after merge of the tip tree

H.J. Lu
2020-03-30T03:54:21Z

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On Sun, Mar 29, 2020 at 8:35 PM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
> Hi all,
>
> After merging the tip tree, today's linux-next build (powerpc
> ppc64_defconfig) failed like this:
>
> ld: warning: discarding dynamic section .rela.data.rel.ro
>
> lots of similar warnings, followed by
>
> `.exit.text' referenced in section `__bug_table' of crypto/algboss.o: defined in discarded section `.exit.text' of crypto/algboss.o
> `.exit.text' referenced in section `__bug_table' of drivers/macintosh/windfarm_core.o: defined in discarded section `.exit.text' of drivers/macintosh/windfarm_core.o
> `.exit.text' referenced in section `__bug_table' of drivers/i2c/i2c-core-base.o: defined in discarded section `.exit.text' of drivers/i2c/i2c-core-base.o
>
> Caused by commit
>
> 72cb2113c1bb ("vmlinux.lds: Discard .note.gnu.property sections in generic NOTES")
>
> I don't see why, but reverting that commit fixes the build warnings
> and failure.

Please see my enclosing email. Is anyone from PPC community reading emails?

> I have reverted that commit for today.
> --
> Cheers,
> Stephen Rothwell

--
H.J.

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From: "H.J. Lu" <hjl.tools@gmail.com>
To: Yu-cheng Yu <yu-cheng.yu@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras <paulus@samba.org>, linuxppc-dev <linuxppc-dev@lists.ozlabs.org>, Kees Cook <keescook@chromium.org>
Subject: RFA [PPC kernel] Avoid upcoming PPC kernel build failure
Date: Fri, 27 Mar 2020 10:36:36 -0700
Message-ID: <CAMe9rOpKPYe55=9c1smGwBZBhRbk8PjpdJZ-xQ7RDXjN81gKug@mail.gmail.com>

On Fri, Mar 27, 2020 at 7:54 AM Yu-cheng Yu <yu-cheng.yu@intel.com> wrote:
>
> On Thu, 2020-02-06 at 04:55 -0800, H.J. Lu wrote:
> > On Wed, Feb 5, 2020 at 7:26 PM Michael Ellerman <mpe@ellerman.id.au> wrote:
> > > "H.J. Lu" <hjl.tools@gmail.com> writes:
> > > > On Tue, Feb 4, 2020 at 3:37 PM kbuild test robot <lkp@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@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@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@gmail.com>
> >
> > Thanks.
> >
>
> Has this been merged into any branch yet? I just checked the tip tree and did
> not see it.
>

FYI, my patches have been queued on x86/build branch. Could someone
from PPC community add this patch to PPC kernel to avoid upcoming PPC
kernel build failure?

Thanks.

--
H.J.