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Babu Moger authored
AMD Zen 2 introduces a new RDPRU instruction which is used to give
access to some processor registers that are typically only accessible
when the privilege level is zero.

ECX is used as the implicit register to specify which register to read.
RDPRU places the specified register’s value into EDX:EAX.

For example, the RDPRU instruction can be used to read MPERF and APERF
at CPL > 0.

Add the feature bit so it is visible in /proc/cpuinfo.

Details are available in the AMD64 Architecture Programmer’s Manual:
https://www.amd.com/system/files/TechDocs/24594.pdf



Signed-off-by: default avatarBabu Moger <babu.moger@amd.com>
Signed-off-by: default avatarBorislav Petkov <bp@suse.de>
Cc: Aaron Lewis <aaronlewis@google.com>
Cc: ak@linux.intel.com
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: robert.hu@linux.intel.com
Cc: Thomas Gleixne...
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Forked from BeagleBoard.org / Linux
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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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
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the problems which may result by upgrading your kernel.