Memory Protection Keys (MPK) Submitted For Linux 4.6
Written by Michael Larabel in Intel on 17 March 2016 at 09:01 AM EDT. 3 Comments
INTEL --
Support for Memory Protection Keys (PKeys/MPK) that will be found on future Intel CPUs is being proposed for inclusion into Linux 4.6.

Memory Protection Keys were previously described by the Intel developers as "a CPU feature which will be found in future Intel CPUs...Memory Protection Keys provides a mechanism for enforcing page-based protections, but without requiring modification of the page tables when an application changes protection domains. It works by dedicating 4 previously ignored bits in each page table entry to a 'protection key', giving 16 possible keys. There is also a new user-accessible register (PKRU) with two separate bits (Access Disable and Write Disable) for each key. Being a CPU register, PKRU is inherently thread-local, potentially giving each thread a different set of protections from every other thread. There are two new instructions (RDPKRU/WRPKRU) for reading and writing to the new register. The feature is only available in 64-bit mode, even though there is theoretically space in the PAE PTEs. These permissions are enforced on data access only and have no effect on instruction fetches."

The Intel Memory Protection Keys will be added to a future generation of Intel CPUs. There's already been work on the compiler changes for supporting PKU while the kernel-side work is being proposed for the Linux 4.6 kernel.

For those wanting to learn more about this kernel implementation and feature to be found in future Intel CPUs, see the pull request that was mailed in this morning by Ingo Molnar.
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Michael Larabel is the principal author of Phoronix.com and founded the site in 2004 with a focus on enriching the Linux hardware experience. Michael has written more than 10,000 articles covering the state of Linux hardware support, Linux performance, graphics drivers, and other topics. Michael is also the lead developer of the Phoronix Test Suite, Phoromatic, and OpenBenchmarking.org automated benchmarking software. He can be followed via Twitter or contacted via MichaelLarabel.com.

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