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bedb4dbe44
In preparation of implementing user_access_begin and friends on powerpc, the book3s/32 version of prevent_user_access() need to be prepared for user_access_end(). user_access_end() doesn't provide the address and size which were passed to user_access_begin(), required by prevent_user_access() to know which segment to modify. The list of segments which where unprotected by allow_user_access() are available in current->kuap. But we don't want prevent_user_access() to read this all the time, especially everytime it is 0 (for instance because the access was not a write access). Implement a special direction named KUAP_CURRENT. In this case only, the addr and end are retrieved from current->kuap. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/55bcc1f25d8200892a31f67a0b024ff3b816c3cc.1579866752.git.christophe.leroy@c-s.fr
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.