linux-kernel - Re: [PATCH] arm64: Disable LLD linker ASSERT()s for the time being

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Message-ID: <CAMj1kXHypqdC9O+8WH7n1=aDOySMScZc2y526S3gc_-QNpqO=w@mail.gmail.com>
Date: Fri, 30 May 2025 16:23:16 +0200
From: Ard Biesheuvel <ardb@...nel.org>
To: Will Deacon <will@...nel.org>, Arnd Bergmann <arnd@...db.de>
Cc: Ard Biesheuvel <ardb+git@...gle.com>, linux-arm-kernel@...ts.infradead.org, 
	llvm@...ts.linux.dev, linux-kernel@...r.kernel.org, catalin.marinas@....com, 
	nathan@...nel.org
Subject: Re: [PATCH] arm64: Disable LLD linker ASSERT()s for the time being

On Fri, 30 May 2025 at 15:38, Will Deacon <will@...nel.org> wrote:
>
> On Thu, May 29, 2025 at 09:35:08AM +0200, Ard Biesheuvel wrote:
> > From: Ard Biesheuvel <ardb@...nel.org>
> >
> > It turns out that the way LLD handles ASSERT()s in the linker script can
> > result in spurious failures, so disable them for the newly introduced
> > BSS symbol export checks.
> >
> > Link: https://github.com/ClangBuiltLinux/linux/issues/2094
> > Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> > ---
> >  arch/arm64/kernel/image-vars.h | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h
> > index c5266430284b..86f088a16147 100644
> > --- a/arch/arm64/kernel/image-vars.h
> > +++ b/arch/arm64/kernel/image-vars.h
> > @@ -10,6 +10,10 @@
> >  #error This file should only be included in vmlinux.lds.S
> >  #endif
> >
> > +#if defined(CONFIG_LD_IS_LLD) && CONFIG_LLD_VERSION < 210000
> > +#define ASSERT(...)
> > +#endif
> > +
> >  #define PI_EXPORT_SYM(sym)           \
> >       __PI_EXPORT_SYM(sym, __pi_ ## sym, Cannot export BSS symbol sym to startup code)
> >  #define __PI_EXPORT_SYM(sym, pisym, msg)\
> > @@ -142,4 +146,6 @@ KVM_NVHE_ALIAS(kvm_protected_mode_initialized);
> >  _kernel_codesize = ABSOLUTE(__inittext_end - _text);
> >  #endif
> >
> > +#undef ASSERT
>
> What about the ASSERT()s at the end of vmlinux.lds.S? Are they not
> affected by the bug, for some reason?
>
> Also, even with this patch applied, I still see a link failure:
>
>   | ld.lld: error: assignment to symbol __init_end does not converge
>
> with the .config you sent me off-list.
>

That is a different error that has been lurking for a while now; Arnd
occasionally hits it but I haven't seen any other reports of it. AIUI,
the issue is that INIT_IDMAP_DIR_PAGES and INIT_DIR_SIZE are defined
in terms of (_end - KIMAGE_VADDR), resulting in a circular dependency.

The config in the kernel test robot's report [0] appears to build fine
with this patch applied.


[0] https://lore.kernel.org/all/202505261019.OUlitN6m-lkp@intel.com/T/#u