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The way the arm64 kernel virtual address space is constructed guarantees that swapper PGD entries are never shared between the linear region on the one hand, and the vmalloc region on the other, which is where all kernel text, module text and BPF text mappings reside. This means that mappings in the linear region (which never require executable permissions) never share any table entries at any level with mappings that do require executable permissions, and so we can set the table-level PXN attributes for all table entries that are created while setting up mappings in the linear region. Since swapper's PGD level page table is mapped r/o itself, this adds another layer of robustness to the way the kernel manages its own page tables. While at it, set the UXN attribute as well for all kernel mappings created at boot. Acked-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Link: https://lore.kernel.org/r/20210310104942.174584-3-ardb@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> |
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| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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.