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A mirror of the official Linux kernel repository just in case
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This patch implements Kernel Userspace Access Protection for book3s/32. Due to limitations of the processor page protection capabilities, the protection is only against writing. read protection cannot be achieved using page protection. The previous patch modifies the page protection so that RW user pages are RW for Key 0 and RO for Key 1, and it sets Key 0 for both user and kernel. This patch changes userspace segment registers are set to Ku 0 and Ks 1. When kernel needs to write to RW pages, the associated segment register is then changed to Ks 0 in order to allow write access to the kernel. In order to avoid having the read all segment registers when locking/unlocking the access, some data is kept in the thread_struct and saved on stack on exceptions. The field identifies both the first unlocked segment and the first segment following the last unlocked one. When no segment is unlocked, it contains value 0. As the hash_page() function is not able to easily determine if a protfault is due to a bad kernel access to userspace, protfaults need to be handled by handle_page_fault when KUAP is set. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> [mpe: Drop allow_read/write_to/from_user() as they're now in kup.h, and adapt allow_user_access() to do nothing when to == NULL] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> |
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arch | ||
block | ||
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.