kernel/arch/x86/boot/startup/map_kernel.c, branch linux-rolling-stable

x86/boot: Move startup code out of __head section

2025-09-03T16:06:04Z

Move startup code out of the __head section, now that this no longer has a special significance. Move everything into .text or .init.text as appropriate, so that startup code is not kept around unnecessarily. [ bp: Fold in hunk to fix 32-bit CPU hotplug: Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202509022207.56fd97f4-lkp@intel.com ] Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/20250828102202.1849035-45-ardb+git@google.com

x86/mm/64: Make 5-level paging support unconditional

2025-05-17T08:38:16Z

Both Intel and AMD CPUs support 5-level paging, which is expected to become more widely adopted in the future. All major x86 Linux distributions have the feature enabled. Remove CONFIG_X86_5LEVEL and related #ifdeffery for it to make it more readable. Suggested-by: Borislav Petkov Signed-off-by: Kirill A. Shutemov Signed-off-by: Ingo Molnar Reviewed-by: Ard Biesheuvel Reviewed-by: Borislav Petkov (AMD) Cc: Dave Hansen Cc: H. Peter Anvin Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250516123306.3812286-4-kirill.shutemov@linux.intel.com

x86/boot: Defer initialization of VM space related global variables

2025-05-14T08:06:35Z

The global pseudo-constants 'page_offset_base', 'vmalloc_base' and 'vmemmap_base' are not used extremely early during the boot, and cannot be used safely until after the KASLR memory randomization code in kernel_randomize_memory() executes, which may update their values. So there is no point in setting these variables extremely early, and it can wait until after the kernel itself is mapped and running from its permanent virtual mapping. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250513111157.717727-9-ardb+git@google.com

x86/boot: Disregard __supported_pte_mask in __startup_64()

2025-05-04T13:27:23Z

__supported_pte_mask is statically initialized to U64_MAX and never assigned until long after the startup code executes that creates the initial page tables. So applying the mask is unnecessary, and can be avoided. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: Arnd Bergmann Cc: David Woodhouse Cc: Dionna Amalie Glaze Cc: H. Peter Anvin Cc: Kees Cook Cc: Kevin Loughlin Cc: Len Brown Cc: Linus Torvalds Cc: Rafael J. Wysocki Cc: Tom Lendacky Cc: linux-efi@vger.kernel.org Link: https://lore.kernel.org/r/20250504095230.2932860-27-ardb+git@google.com

x86/boot: Drop RIP_REL_REF() uses from early mapping code

2025-04-12T09:13:05Z

Now that __startup_64() is built using -fPIC, RIP_REL_REF() has become a NOP and can be removed. Only some occurrences of rip_rel_ptr() will remain, to explicitly take the address of certain global structures in the 1:1 mapping of memory. While at it, update the code comment to describe why this is needed. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: Dionna Amalie Glaze Cc: H. Peter Anvin Cc: Kees Cook Cc: Kevin Loughlin Cc: Linus Torvalds Cc: Tom Lendacky Cc: linux-efi@vger.kernel.org Link: https://lore.kernel.org/r/20250410134117.3713574-17-ardb+git@google.com

x86/boot: Move early kernel mapping code into startup/

2025-04-12T09:13:05Z

The startup code that constructs the kernel virtual mapping runs from the 1:1 mapping of memory itself, and therefore, cannot use absolute symbol references. Before making changes in subsequent patches, move this code into a separate source file under arch/x86/boot/startup/ where all such code will be kept from now on. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: Dionna Amalie Glaze Cc: H. Peter Anvin Cc: Kees Cook Cc: Kevin Loughlin Cc: Linus Torvalds Cc: Tom Lendacky Cc: linux-efi@vger.kernel.org Link: https://lore.kernel.org/r/20250410134117.3713574-16-ardb+git@google.com