Re: [PATCH 6.1 fix build id for arm64 5/5] sh: define RUNTIME_DISCARD_EXIT

[Greg Kroah-Hartman]

On Mon, Feb 06, 2023 at 01:26:55PM -0600, Tom Saeger wrote:
> On Sat, Jan 28, 2023 at 07:52:39AM +0100, Greg Kroah-Hartman wrote:
> > On Fri, Jan 27, 2023 at 09:10:22PM -0700, Tom Saeger wrote:
> > > sh vmlinux fails to link with GNU ld < 2.40 (likely < 2.36) since
> > > commit 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv").
> > > 
> > > This is similar to fixes for powerpc and s390:
> > > commit 4b9880dbf3bd ("powerpc/vmlinux.lds: Define RUNTIME_DISCARD_EXIT").
> > > commit a494398bde27 ("s390: define RUNTIME_DISCARD_EXIT to fix link error
> > > with GNU ld < 2.36").
> > > 
> > >   $ sh4-linux-gnu-ld --version | head -n1
> > >   GNU ld (GNU Binutils for Debian) 2.35.2
> > > 
> > >   $ make ARCH=sh CROSS_COMPILE=sh4-linux-gnu- microdev_defconfig
> > >   $ make ARCH=sh CROSS_COMPILE=sh4-linux-gnu-
> > > 
> > >   `.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/char/hw_random/core.o: defined in discarded section
> > >   `.exit.text' of drivers/char/hw_random/core.o
> > >   make[2]: *** [scripts/Makefile.vmlinux:34: vmlinux] Error 1
> > >   make[1]: *** [Makefile:1252: vmlinux] Error 2
> > > 
> > > arch/sh/kernel/vmlinux.lds.S keeps EXIT_TEXT:
> > > 
> > > 	/*
> > > 	 * .exit.text is discarded at runtime, not link time, to deal with
> > > 	 * references from __bug_table
> > > 	 */
> > > 	.exit.text : AT(ADDR(.exit.text)) { EXIT_TEXT }
> > > 
> > > However, EXIT_TEXT is thrown away by
> > > DISCARD(include/asm-generic/vmlinux.lds.h) because
> > > sh does not define RUNTIME_DISCARD_EXIT.
> > > 
> > > GNU ld 2.40 does not have this issue and builds fine.
> > > This corresponds with Masahiro's comments in a494398bde27:
> > > "Nathan [Chancellor] also found that binutils
> > > commit 21401fc7bf67 ("Duplicate output sections in scripts") cured this
> > > issue, so we cannot reproduce it with binutils 2.36+, but it is better
> > > to not rely on it."
> > > 
> > > Fixes: 99cb0d917ffa ("arch: fix broken BuildID for arm64 and riscv")
> > > Link: https://lore.kernel.org/all/Y7Jal56f6UBh1abE@dev-arch.thelio-3990X/
> > > Link: https://lore.kernel.org/all/20230123194218.47ssfzhrpnv3xfez@xxxxxxxxxx/
> > > Signed-off-by: Tom Saeger <tom.saeger@xxxxxxxxxx>
> > > ---
> > >  arch/sh/kernel/vmlinux.lds.S | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/arch/sh/kernel/vmlinux.lds.S b/arch/sh/kernel/vmlinux.lds.S
> > > index 3161b9ccd2a5..791c06b9a54a 100644
> > > --- a/arch/sh/kernel/vmlinux.lds.S
> > > +++ b/arch/sh/kernel/vmlinux.lds.S
> > > @@ -4,6 +4,8 @@
> > >   * Written by Niibe Yutaka and Paul Mundt
> > >   */
> > >  OUTPUT_ARCH(sh)
> > > +#define RUNTIME_DISCARD_EXIT
> > > +
> > >  #include <asm/thread_info.h>
> > >  #include <asm/cache.h>
> > >  #include <asm/vmlinux.lds.h>
> > > -- 
> > > 2.39.1
> > > 
> > 
> > As my bot said last time you sent this:
> > 
> > <formletter>
> > 
> > This is not the correct way to submit patches for inclusion in the
> > stable kernel tree.  Please read:
> >     https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
> > for how to do this properly.
> > 
> > </formletter>
> > 
> > Sorry, we can not take ANY of this until it hits Linus's tree.  You know
> > this!
> Yep - sorry for the confusion, is it better to send as RFC in cases like
> this where folks on list have asked for the series to test?
> 
> > 
> > Please wait until then and then send the needed backports.  I'm dropping
> > all of these from you from my review queue.
> > 
> > greg k-h
> 
> This patch is now in Linus's tree. 
> 
> c1c551bebf92 ("sh: define RUNTIME_DISCARD_EXIT")
> 
> $ git describe --contains c1c551bebf92
> v6.2-rc7~18^2~5
> 
> commit c1c551bebf928889e7a8fef7415b44f9a64975f4 upstream.
> 
> Do you prefer I resend series for 6.1, 5.19, 5.15, and 5.4?
> 
> My questions for 6.1 still remain,
> 
>   https://lore.kernel.org/all/cover.1674876902.git.tom.saeger@xxxxxxxxxx/
>   This 6.1 series is not strictly necessary, as the problem
>   does not present itself in the current 6.1 stable kernels.
> 
>   However, 6.1 WOULD be broken with inclusion of either:
>   994b7ac1697b ("arm64: remove special treatment for the link order of head.o")
>   2348e6bf4421 ("riscv: remove special treatment for the link order of head.o")
>   Should we just include these as well?
> 
> My own preference is to included them, to track closer to upstream, and
> hopefully avoid 'ld' subtlties going forward.
> 
> Thoughts?

Stick to what is in Linus's tree as closely as possible whenever
possible please.

thanks,

greg k-h