linux-kernel - Re: [PATCH v3 3/7] x86/boot: Move the early GDT/IDT setup code into startup/

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Message-ID: <Z_ZG7pAZavKDgFDK@gmail.com>
Date: Wed, 9 Apr 2025 12:07:42 +0200
From: Ingo Molnar <mingo@...nel.org>
To: Ard Biesheuvel <ardb+git@...gle.com>
Cc: linux-efi@...r.kernel.org, x86@...nel.org, linux-kernel@...r.kernel.org,
	Ard Biesheuvel <ardb@...nel.org>,
	Tom Lendacky <thomas.lendacky@....com>,
	Dionna Amalie Glaze <dionnaglaze@...gle.com>,
	Kevin Loughlin <kevinloughlin@...gle.com>
Subject: Re: [PATCH v3 3/7] x86/boot: Move the early GDT/IDT setup code into
 startup/


* Ingo Molnar <mingo@...nel.org> wrote:

> 
> * Ard Biesheuvel <ardb+git@...gle.com> wrote:
> 
> > From: Ard Biesheuvel <ardb@...nel.org>
> > 
> > Move the early GDT/IDT setup code that runs long before the kernel
> > virtual mapping is up into arch/x86/boot/startup/, and build it in a way
> > that ensures that the code tolerates being called from the 1:1 mapping
> > of memory. The code itself is left unchanged by this patch.
> > 
> > Also tweak the sed symbol matching pattern in the decompressor to match
> > on lower case 't' or 'b', as these will be emitted by Clang for symbols
> > with hidden linkage.
> > 
> > Signed-off-by: Ard Biesheuvel <ardb@...nel.org>
> > ---
> >  arch/x86/boot/compressed/Makefile |  2 +-
> >  arch/x86/boot/startup/Makefile    | 15 ++++
> >  arch/x86/boot/startup/gdt_idt.c   | 83 ++++++++++++++++++++
> >  arch/x86/kernel/head64.c          | 73 -----------------
> >  4 files changed, 99 insertions(+), 74 deletions(-)
> 
> This causes the following build failure on x86-64-defconfig:
> 
>    arch/x86/boot/startup/gdt_idt.c:67:55: error: cast to generic address space pointer from disjoint ‘__seg_gs’ address space pointer [-Werror]

Caused by the previous patch:

  x86/asm: Make rip_rel_ptr() usable from fPIC code

Thanks,

	Ingo