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

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Message-ID: <20250530023048.GA1491122@ax162>
Date: Thu, 29 May 2025 19:30:48 -0700
From: Nathan Chancellor <nathan@...nel.org>
To: Ard Biesheuvel <ardb+git@...gle.com>
Cc: linux-arm-kernel@...ts.infradead.org, llvm@...ts.linux.dev,
	linux-kernel@...r.kernel.org, will@...nel.org,
	catalin.marinas@....com, Ard Biesheuvel <ardb@...nel.org>
Subject: Re: [PATCH] arm64: Disable LLD linker ASSERT()s for the time being

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>

Reviewed-by: Nathan Chancellor <nathan@...nel.org>

You could add Fangrui's commit as a reference to why LLD 21 is needed
for this to work but it is probably not worth a v2 by itself.

https://github.com/llvm/llvm-project/commit/5859863bab7fb1cd98b6028293cba6ba25f7d514

> ---
>  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
> +
>  #endif /* __ARM64_KERNEL_IMAGE_VARS_H */
> -- 
> 2.49.0.1238.gf8c92423fb-goog
> 
>