kernel/linux.git/arch/x86/include/asm/boot.h, branch v6.19.11

efistub/x86: Remap inittext read-execute when needed

2025-09-03T16:05:42+00:00

Recent EFI x86 systems are more strict when it comes to mapping boot images, and require that mappings are either read-write or read-execute. Now that the boot code is being cleaned up and refactored, most of it is being moved into .init.text [where it arguably belongs] but that implies that when booting on such strict EFI firmware, we need to take care to map .init.text (and the .altinstr_aux section that follows it) read-execute as well. Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/20250828102202.1849035-44-ardb+git@google.com

x86/boot/compressed: Merge the local pgtable.h include into

2025-04-06T18:15:14+00:00

Merge the local include "pgtable.h" -which declares the API of the 5-level paging trampoline- into so that its implementation in la57toggle.S as well as the calling code can be decoupled from the traditional decompressor. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: David Woodhouse Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250401133416.1436741-9-ardb+git@google.com

x86/headers: Replace ASSEMBLY with ASSEMBLER in non-UAPI headers

2025-03-19T10:47:30+00:00

While the GCC and Clang compilers already define __ASSEMBLER__ automatically when compiling assembly code, __ASSEMBLY__ is a macro that only gets defined by the Makefiles in the kernel. This can be very confusing when switching between userspace and kernelspace coding, or when dealing with UAPI headers that rather should use __ASSEMBLER__ instead. So let's standardize on the __ASSEMBLER__ macro that is provided by the compilers now. This is mostly a mechanical patch (done with a simple "sed -i" statement), with some manual tweaks in , and that mentioned this macro in comments with some missing underscores. Signed-off-by: Thomas Huth Signed-off-by: Ingo Molnar Cc: Brian Gerst Cc: Juergen Gross Cc: H. Peter Anvin Cc: Kees Cook Cc: Linus Torvalds Link: https://lore.kernel.org/r/20250314071013.1575167-38-thuth@redhat.com

Merge tag 'x86-build-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-05-14T01:05:08+00:00

Pull x86 build updates from Ingo Molnar: - Use -fpic to build the kexec 'purgatory' (the self-contained code that runs between two kernels) - Clean up vmlinux.lds.S generation - Simplify the X86_EXTENDED_PLATFORM section of the x86 Kconfig - Misc cleanups & fixes * tag 'x86-build-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/Kconfig: Merge the two CONFIG_X86_EXTENDED_PLATFORM entries x86/purgatory: Switch to the position-independent small code model x86/boot: Replace __PHYSICAL_START with LOAD_PHYSICAL_ADDR x86/vmlinux.lds.S: Take __START_KERNEL out conditional definition x86/vmlinux.lds.S: Remove conditional definition of LOAD_OFFSET vmlinux.lds.h: Fix a typo in comment

x86/boot: Replace __PHYSICAL_START with LOAD_PHYSICAL_ADDR

2024-03-22T10:36:45+00:00

Both __PHYSICAL_START and LOAD_PHYSICAL_ADDR are defined to get aligned CONFIG_PHYSICAL_START, so we can replace __PHYSICAL_START with LOAD_PHYSICAL_ADDR. And then remove the definition of __PHYSICAL_START, which is only used to define __START_KERNEL. Since includes , which includes , it is fine to move definition from to . Signed-off-by: Wei Yang Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20240313075839.8321-3-richard.weiyang@gmail.com

x86/efistub: Remap kernel text read-only before dropping NX attribute

2024-03-09T10:37:18+00:00

Currently, the EFI stub invokes the EFI memory attributes protocol to strip any NX restrictions from the entire loaded kernel, resulting in all code and data being mapped read-write-execute. The point of the EFI memory attributes protocol is to remove the need for all memory allocations to be mapped with both write and execute permissions by default, and make it the OS loader's responsibility to transition data mappings to code mappings where appropriate. Even though the UEFI specification does not appear to leave room for denying memory attribute changes based on security policy, let's be cautious and avoid relying on the ability to create read-write-execute mappings. This is trivially achievable, given that the amount of kernel code executing via the firmware's 1:1 mapping is rather small and limited to the .head.text region. So let's drop the NX restrictions only on that subregion, but not before remapping it as read-only first. Signed-off-by: Ard Biesheuvel

Merge tag 'x86-boot-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-10-31T00:11:57+00:00

Pull x86 boot updates from Ingo Molnar: - Rework PE header generation, primarily to generate a modern, 4k aligned kernel image view with narrower W^X permissions. - Further refine init-lifetime annotations - Misc cleanups & fixes * tag 'x86-boot-2023-10-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits) x86/boot: efistub: Assign global boot_params variable x86/boot: Rename conflicting 'boot_params' pointer to 'boot_params_ptr' x86/head/64: Move the __head definition to x86/head/64: Add missing __head annotation to startup_64_load_idt() x86/head/64: Mark 'startup_gdt[]' and 'startup_gdt_descr' as __initdata x86/boot: Harmonize the style of array-type parameter for fixup_pointer() calls x86/boot: Fix incorrect startup_gdt_descr.size x86/boot: Compile boot code with -std=gnu11 too x86/boot: Increase section and file alignment to 4k/512 x86/boot: Split off PE/COFF .data section x86/boot: Drop PE/COFF .reloc section x86/boot: Construct PE/COFF .text section from assembler x86/boot: Derive file size from _edata symbol x86/boot: Define setup size in linker script x86/boot: Set EFI handover offset directly in header asm x86/boot: Grab kernel_info offset from zoffset header directly x86/boot: Drop references to startup_64 x86/boot: Drop redundant code setting the root device x86/boot: Omit compression buffer from PE/COFF image memory footprint x86/boot: Remove the 'bugger off' message ...

x86/boot: Rename conflicting 'boot_params' pointer to 'boot_params_ptr'

2023-10-18T10:03:03+00:00

The x86 decompressor is built and linked as a separate executable, but it shares components with the kernel proper, which are either #include'd as C files, or linked into the decompresor as a static library (e.g, the EFI stub) Both the kernel itself and the decompressor define a global symbol 'boot_params' to refer to the boot_params struct, but in the former case, it refers to the struct directly, whereas in the decompressor, it refers to a global pointer variable referring to the struct boot_params passed by the bootloader or constructed from scratch. This ambiguity is unfortunate, and makes it impossible to assign this decompressor variable from the x86 EFI stub, given that declaring it as extern results in a clash. So rename the decompressor version (whose scope is limited) to boot_params_ptr. [ mingo: Renamed 'boot_params_p' to 'boot_params_ptr' for clarity ] Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Cc: linux-kernel@vger.kernel.org

x86/boot/compressed: Reserve more memory for page tables

2023-09-17T07:48:57+00:00

The decompressor has a hard limit on the number of page tables it can allocate. This limit is defined at compile-time and will cause boot failure if it is reached. The kernel is very strict and calculates the limit precisely for the worst-case scenario based on the current configuration. However, it is easy to forget to adjust the limit when a new use-case arises. The worst-case scenario is rarely encountered during sanity checks. In the case of enabling 5-level paging, a use-case was overlooked. The limit needs to be increased by one to accommodate the additional level. This oversight went unnoticed until Aaron attempted to run the kernel via kexec with 5-level paging and unaccepted memory enabled. Update wost-case calculations to include 5-level paging. To address this issue, let's allocate some extra space for page tables. 128K should be sufficient for any use-case. The logic can be simplified by using a single value for all kernel configurations. [ Also add a warning, should this memory run low - by Dave Hansen. ] Fixes: 34bbb0009f3b ("x86/boot/compressed: Enable 5-level paging during decompression stage") Reported-by: Aaron Lu Signed-off-by: Kirill A. Shutemov Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915070221.10266-1-kirill.shutemov@linux.intel.com

x86/decompressor: Factor out kernel decompression and relocation

2023-08-07T18:59:13+00:00

Factor out the decompressor sequence that invokes the decompressor, parses the ELF and applies the relocations so that it can be called directly from the EFI stub. Signed-off-by: Ard Biesheuvel Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230807162720.545787-21-ardb@kernel.org