linux-kernel - Re: [PATCH] x86: Fix build regression with CONFIG_KEXEC

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Message-ID: <1ad3aca1-9e53-4595-a01b-a5f6f2f65f02@kernel.org>
Date: Mon, 9 Dec 2024 19:34:54 +0900
From: Damien Le Moal <dlemoal@...nel.org>
To: Borislav Petkov <bp@...en8.de>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>,
 David Woodhouse <dwmw@...zon.co.uk>, Ingo Molnar <mingo@...nel.org>,
 Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Fix build regression with CONFIG_KEXEC_JUMP enabled

On 12/9/24 19:29, Borislav Petkov wrote:
> On Mon, Dec 09, 2024 at 08:53:32AM +0900, Damien Le Moal wrote:
>> Build 6.13-rc12 for x86_64 with gcc 14.2.1 fails with the error:
>>
>> ld: vmlinux.o: in function `virtual_mapped':
>> linux/arch/x86/kernel/relocate_kernel_64.S:249:(.text+0x5915b): undefined reference to `saved_context_gdt_desc'
>>
>> when CONFIG_KEXEC_JUMP is enabled.
> 
> Hmm, how do you trigger this? Care to share your .config?
> 
> Because I can't trigger it with my gcc13 and CONFIG_KEXEC_JUMP=y
> 
> It would be good to know how the 0day bot didn't catch it either...

The build bot uses gcc12 for x86_64 I think.
I have gcc 14.2.1 which is what comes with Fedora 41.

Nothing special about my config. It is attached. I checked that the compilation
error goes away if I disable CONFIG_KEXEC_JUMP or if I enable it and revert the
patch this fixes.

-- 
Damien Le Moal
Western Digital Research
View attachment "kernel-config" of type "text/plain" (183007 bytes)