linux-kernel - [PATCH v3 0/7] x86: Refactor and consolidate startup code

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Message-ID: <20250408085254.836788-9-ardb+git@google.com>
Date: Tue,  8 Apr 2025 10:52:55 +0200
From: Ard Biesheuvel <ardb+git@...gle.com>
To: linux-efi@...r.kernel.org
Cc: x86@...nel.org, mingo@...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: [PATCH v3 0/7] x86: Refactor and consolidate startup code

From: Ard Biesheuvel <ardb@...nel.org>

Reorganize C code that is used during early boot, either in the
decompressor/EFI stub or the kernel proper, but before the kernel
virtual mapping is up.

v3:
- keep rip_rel_ptr() around in PIC code - sadly, it is still needed in
  some cases
- remove RIP_REL_REF() uses in separate patches
- keep __head annotations for now, they will all be removed later
- disable objtool validation for library objects (i.e., pieces that are
  not linked into vmlinux)

I will follow up with a series that gets rid of .head.text altogether,
as it will no longer be needed at all once the startup code is checked
for absolute relocations.

The SEV startup code needs to be moved first, though, and this is a bit
more complicated, so I will decouple that effort from this series, also
because there is a known issue that needs to be fixed first related to
memory acceptance from the EFI stub.

Cc: Tom Lendacky <thomas.lendacky@....com>
Cc: Dionna Amalie Glaze <dionnaglaze@...gle.com>
Cc: Kevin Loughlin <kevinloughlin@...gle.com>

Ard Biesheuvel (7):
  x86/boot/startup: Disable objtool validation for library code
  x86/asm: Make rip_rel_ptr() usable from fPIC code
  x86/boot: Move the early GDT/IDT setup code into startup/
  x86/boot: Move early kernel mapping code into startup/
  x86/boot: Drop RIP_REL_REF() uses from early mapping code
  x86/boot: Move early SME init code into startup/
  x86/boot: Drop RIP_REL_REF() uses from SME startup code

 arch/x86/boot/compressed/Makefile                          |   2 +-
 arch/x86/boot/startup/Makefile                             |  22 ++
 arch/x86/boot/startup/gdt_idt.c                            |  83 ++++++
 arch/x86/boot/startup/map_kernel.c                         | 225 ++++++++++++++++
 arch/x86/{mm/mem_encrypt_identity.c => boot/startup/sme.c} |  19 +-
 arch/x86/coco/sev/core.c                                   |   2 +-
 arch/x86/coco/sev/shared.c                                 |   4 +-
 arch/x86/include/asm/asm.h                                 |   2 +-
 arch/x86/include/asm/coco.h                                |   2 +-
 arch/x86/include/asm/mem_encrypt.h                         |   2 +-
 arch/x86/kernel/head64.c                                   | 285 +-------------------
 arch/x86/mm/Makefile                                       |   6 -
 12 files changed, 346 insertions(+), 308 deletions(-)
 create mode 100644 arch/x86/boot/startup/gdt_idt.c
 create mode 100644 arch/x86/boot/startup/map_kernel.c
 rename arch/x86/{mm/mem_encrypt_identity.c => boot/startup/sme.c} (97%)


base-commit: 4f2d1bbc2c92a32fd612e6c3b51832d5c1c3678e
-- 
2.49.0.504.g3bcea36a83-goog