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* arm64: efi: split Image code and data into separate PE/COFF sectionsArd Biesheuvel2017-04-041-5/+18
| | | | | | | | | | | | | | | | | To prevent unintended modifications to the kernel text (malicious or otherwise) while running the EFI stub, describe the kernel image as two separate sections: a .text section with read-execute permissions, covering .text, .rodata and .init.text, and a .data section with read-write permissions, covering .init.data, .data and .bss. This relies on the firmware to actually take the section permission flags into account, but this is something that is currently being implemented in EDK2, which means we will likely start seeing it in the wild between one and two years from now. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: efi: replace open coded constants with symbolic onesArd Biesheuvel2017-04-041-17/+21
| | | | | | | | | Replace open coded constants with symbolic ones throughout the Image and the EFI headers. No binary level changes are intended. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: efi: remove pointless dummy .reloc sectionArd Biesheuvel2017-04-041-21/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | The kernel's EFI PE/COFF header contains a dummy .reloc section, and an explanatory comment that claims that this is required for the EFI application loader to accept the Image as a relocatable image (i.e., one that can be loaded at any offset and fixed up in place) This was inherited from the x86 implementation, which has elaborate host tooling to mangle the PE/COFF header post-link time, and which populates the .reloc section with a single dummy base relocation. On ARM, no such tooling exists, and the .reloc section remains empty, and is never even exposed via the BaseRelocationTable directory entry, which is where the PE/COFF loader looks for it. The PE/COFF spec is unclear about relocatable images that do not require any fixups, but the EDK2 implementation, which is the de facto reference for PE/COFF in the UEFI space, clearly does not care, and explicitly mentions (in a comment) that relocatable images with no base relocations are perfectly fine, as long as they don't have the RELOCS_STRIPPED attribute set (which is not the case for our PE/COFF image) So simply remove the .reloc section altogether. Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Peter Jones <pjones@redhat.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: efi: remove forbidden values from the PE/COFF headerArd Biesheuvel2017-04-041-3/+3
| | | | | | | | | Bring the PE/COFF header in line with the PE/COFF spec, by setting NumberOfSymbols to 0, and removing the section alignment flags. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
* arm64: efi: move EFI header and related data to a separate .S fileArd Biesheuvel2017-04-041-0/+158
In preparation of yet another round of modifications to the PE/COFF header, macroize it and move the definition into a separate source file. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>