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UEFI v2.6 introduces EFI_MEMORY_ATTRIBUTES_TABLE which describes memory protections that may be applied to the EFI Runtime code and data regions by the kernel. This enables the kernel to map these regions more strictly thereby increasing security. Presently, the only valid bits for the attribute field of a memory descriptor are EFI_MEMORY_RO and EFI_MEMORY_XP, hence use these bits to update the mappings in efi_pgd. The UEFI specification recommends to use this feature instead of EFI_PROPERTIES_TABLE and hence while updating EFI mappings we first check for EFI_MEMORY_ATTRIBUTES_TABLE and if it's present we update the mappings according to this table and hence disregarding EFI_PROPERTIES_TABLE even if it's published by the firmware. We consider EFI_PROPERTIES_TABLE only when EFI_MEMORY_ATTRIBUTES_TABLE is absent. Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com> Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Fenghua Yu <fenghua.yu@intel.com> Cc: Lee, Chun-Yi <jlee@suse.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ravi Shankar <ravi.v.shankar@intel.com> Cc: Ricardo Neri <ricardo.neri@intel.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/1485868902-20401-6-git-send-email-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.