kernel/linux.git/arch/x86/boot/tools, branch v6.12.80

x86/boot: Increase section and file alignment to 4k/512

2023-09-17T17:48:44+00:00

Align x86 with other EFI architectures, and increase the section alignment to the EFI page size (4k), so that firmware is able to honour the section permission attributes and map code read-only and data non-executable. There are a number of requirements that have to be taken into account: - the sign tools get cranky when there are gaps between sections in the file view of the image - the virtual offset of each section must be aligned to the image's section alignment - the file offset *and size* of each section must be aligned to the image's file alignment - the image size must be aligned to the section alignment - each section's virtual offset must be greater than or equal to the size of the headers. In order to meet all these requirements, while avoiding the need for lots of padding to accommodate the .compat section, the latter is placed at an arbitrary offset towards the end of the image, but aligned to the minimum file alignment (512 bytes). The space before the .text section is therefore distributed between the PE header, the .setup section and the .compat section, leaving no gaps in the file coverage, making the signing tools happy. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-18-ardb@google.com

x86/boot: Drop PE/COFF .reloc section

2023-09-17T17:48:43+00:00

Ancient buggy EFI loaders may have required a .reloc section to be present at some point in time, but this has not been true for a long time so the .reloc section can just be dropped. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-16-ardb@google.com

x86/boot: Construct PE/COFF .text section from assembler

2023-09-17T17:48:43+00:00

Now that the size of the setup block is visible to the assembler, it is possible to populate the PE/COFF header fields from the asm code directly, instead of poking the values into the binary using the build tool. This will make it easier to reorganize the section layout without having to tweak the build tool in lockstep. This change has no impact on the resulting bzImage binary. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-15-ardb@google.com

x86/boot: Derive file size from _edata symbol

2023-09-17T17:48:42+00:00

Tweak the linker script so that the value of _edata represents the decompressor binary's file size rounded up to the appropriate alignment. This removes the need to calculate it in the build tool, and will make it easier to refer to the file size from the header directly in subsequent changes to the PE header layout. While adding _edata to the sed regex that parses the compressed vmlinux's symbol list, tweak the regex a bit for conciseness. This change has no impact on the resulting bzImage binary when configured with CONFIG_EFI_STUB=y. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-14-ardb@google.com

x86/boot: Define setup size in linker script

2023-09-17T17:48:42+00:00

The setup block contains the real mode startup code that is used when booting from a legacy BIOS, along with the boot_params/setup_data that is used by legacy x86 bootloaders to pass the command line and initial ramdisk parameters, among other things. The setup block also contains the PE/COFF header of the entire combined image, which includes the compressed kernel image, the decompressor and the EFI stub. This PE header describes the layout of the executable image in memory, and currently, the fact that the setup block precedes it makes it rather fiddly to get the right values into the right place in the final image. Let's make things a bit easier by defining the setup_size in the linker script so it can be referenced from the asm code directly, rather than having to rely on the build tool to calculate it. For the time being, add 64 bytes of fixed padding for the .reloc and .compat sections - this will be removed in a subsequent patch after the PE/COFF header has been reorganized. This change has no impact on the resulting bzImage binary when configured with CONFIG_EFI_MIXED=y. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-13-ardb@google.com

x86/boot: Set EFI handover offset directly in header asm

2023-09-17T17:48:42+00:00

The offsets of the EFI handover entrypoints are available to the assembler when constructing the header, so there is no need to set them from the build tool afterwards. This change has no impact on the resulting bzImage binary. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-12-ardb@google.com

x86/boot: Grab kernel_info offset from zoffset header directly

2023-09-17T17:48:42+00:00

Instead of parsing zoffset.h and poking the kernel_info offset value into the header from the build tool, just grab the value directly in the asm file that describes this header. This change has no impact on the resulting bzImage binary. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230915171623.655440-11-ardb@google.com

x86/boot: Drop references to startup_64

2023-09-15T09:18:42+00:00

The x86 boot image generation tool assign a default value to startup_64 and subsequently parses the actual value from zoffset.h but it never actually uses the value anywhere. So remove this code. This change has no impact on the resulting bzImage binary. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230912090051.4014114-25-ardb@google.com

x86/boot: Drop redundant code setting the root device

2023-09-15T09:18:42+00:00

The root device defaults to 0,0 and is no longer configurable at build time [0], so there is no need for the build tool to ever write to this field. [0] 079f85e624189292 ("x86, build: Do not set the root_dev field in bzImage") This change has no impact on the resulting bzImage binary. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230912090051.4014114-23-ardb@google.com

x86/boot: Omit compression buffer from PE/COFF image memory footprint

2023-09-15T09:18:41+00:00

Now that the EFI stub decompresses the kernel and hands over to the decompressed image directly, there is no longer a need to provide a decompression buffer as part of the .BSS allocation of the PE/COFF image. It also means the PE/COFF image can be loaded anywhere in memory, and setting the preferred image base is unnecessary. So drop the handling of this from the header and from the build tool. Signed-off-by: Ard Biesheuvel Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230912090051.4014114-22-ardb@google.com