linux-kernel - [PATCH v5 0/4] arch/x86: Remove unnecessary dependencies on bootparam.h

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Message-ID: <20240112095000.8952-1-tzimmermann@suse.de>
Date: Fri, 12 Jan 2024 10:44:35 +0100
From: Thomas Zimmermann <tzimmermann@...e.de>
To: ardb@...nel.org,
	nathan@...nel.org,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com,
	bhelgaas@...gle.com,
	arnd@...db.de,
	zohar@...ux.ibm.com,
	dmitry.kasatkin@...il.com,
	paul@...l-moore.com,
	jmorris@...ei.org,
	serge@...lyn.com,
	javierm@...hat.com
Cc: linux-arch@...r.kernel.org,
	linux-efi@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	linux-integrity@...r.kernel.org,
	linux-security-module@...r.kernel.org,
	Thomas Zimmermann <tzimmermann@...e.de>
Subject: [PATCH v5 0/4] arch/x86: Remove unnecessary dependencies on bootparam.h

Reduce build time in some cases by removing unnecessary include statements
for <asm/bootparam.h>. Reorganize some header files accordingly.

While working on the kernel's boot-up graphics, I noticed that touching
include/linux/screen_info.h triggers a complete rebuild of the kernel
on x86. It turns out that the architecture's PCI and EFI headers include
<asm/bootparam.h>, which depends on <linux/screen_info.h>. But none of
the drivers have any business with boot parameters or the screen_info
state.

The patchset moves code from bootparam.h and efi.h into separate header
files and removes obsolete include statements on x86. I did

  make allmodconfig
  make -j28
  touch include/linux/screen_info.h
  time make -j28

to measure the time it takes to rebuild. Results without the patchset
are around 20 minutes.

  real    20m46,705s
  user    354m29,166s
  sys     28m27,359s

And with the patchset applied it goes down to less than one minute.

  real    0m56,643s
  user    4m0,661s
  sys     0m32,956s

The test system is an Intel i5-13500.

v5:
	* silence clang warnings for real-mode code (Nathan)
	* revert boot/compressed/misc.h (kernel test robot)
v4:
	* fix fwd declaration in compressed/misc.h (Ard)
v3:
	* keep setup_header in bootparam.h (Ard)
	* implement arch_ima_efi_boot_mode() in source file (Ard)
v2:
	* only keep struct boot_params in bootparam.h (Ard)
	* simplify arch_ima_efi_boot_mode define (Ard)
	* updated cover letter

Thomas Zimmermann (4):
  arch/x86: Move UAPI setup structures into setup_data.h
  arch/x86: Move internal setup_data structures into setup_data.h
  arch/x86: Implement arch_ima_efi_boot_mode() in source file
  arch/x86: Do not include <asm/bootparam.h> in several files

 arch/x86/Makefile                      |  3 +
 arch/x86/boot/compressed/acpi.c        |  2 +
 arch/x86/boot/compressed/cmdline.c     |  2 +
 arch/x86/boot/compressed/efi.c         |  2 +
 arch/x86/boot/compressed/efi.h         |  9 ---
 arch/x86/boot/compressed/pgtable_64.c  |  1 +
 arch/x86/boot/compressed/sev.c         |  1 +
 arch/x86/include/asm/efi.h             | 14 +----
 arch/x86/include/asm/kexec.h           |  1 -
 arch/x86/include/asm/mem_encrypt.h     |  2 +-
 arch/x86/include/asm/pci.h             | 13 ----
 arch/x86/include/asm/setup_data.h      | 32 ++++++++++
 arch/x86/include/asm/sev.h             |  3 +-
 arch/x86/include/asm/x86_init.h        |  2 -
 arch/x86/include/uapi/asm/bootparam.h  | 72 +---------------------
 arch/x86/include/uapi/asm/setup_data.h | 83 ++++++++++++++++++++++++++
 arch/x86/kernel/crash.c                |  1 +
 arch/x86/kernel/sev-shared.c           |  2 +
 arch/x86/platform/efi/efi.c            |  5 ++
 arch/x86/platform/pvh/enlighten.c      |  1 +
 arch/x86/xen/enlighten_pvh.c           |  1 +
 arch/x86/xen/vga.c                     |  1 -
 22 files changed, 143 insertions(+), 110 deletions(-)
 create mode 100644 arch/x86/include/asm/setup_data.h
 create mode 100644 arch/x86/include/uapi/asm/setup_data.h

-- 
2.43.0