0fb2126db8
Add a wrapper for the EMODPR ENCLS leaf function used to restrict enclave page permissions as maintained in the SGX hardware's Enclave Page Cache Map (EPCM). EMODPR: 1) Updates the EPCM permissions of an enclave page by treating the new permissions as a mask. Supplying a value that attempts to relax EPCM permissions has no effect on EPCM permissions (PR bit, see below, is changed). 2) Sets the PR bit in the EPCM entry of the enclave page to indicate that permission restriction is in progress. The bit is reset by the enclave by invoking ENCLU leaf function EACCEPT or EACCEPTCOPY. The enclave may access the page throughout the entire process if conforming to the EPCM permissions for the enclave page. After performing the permission restriction by issuing EMODPR the kernel needs to collaborate with the hardware to ensure that all logical processors sees the new restricted permissions. This is required for the enclave's EACCEPT/EACCEPTCOPY to succeed and is accomplished with the ETRACK flow. Expand enum sgx_return_code with the possible EMODPR return values. Signed-off-by: Reinette Chatre <reinette.chatre@intel.com> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> Reviewed-by: Jarkko Sakkinen <jarkko@kernel.org> Link: https://lkml.kernel.org/r/d15e7a769e13e4ca671fa2d0a0d3e3aec5aedbd4.1652137848.git.reinette.chatre@intel.com
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.