Ard Biesheuvel d6f5bc5ff0 x86/sme: Move early SME kernel encryption handling into .head.text
[ Commit 48204aba801f1b512b3abed10b8e1a63e03f3dd1 upstream ]

The .head.text section is the initial primary entrypoint of the core
kernel, and is entered with the CPU executing from a 1:1 mapping of
memory. Such code must never access global variables using absolute
references, as these are based on the kernel virtual mapping which is
not active yet at this point.

Given that the SME startup code is also called from this early execution
context, move it into .head.text as well. This will allow more thorough
build time checks in the future to ensure that early startup code only
uses RIP-relative references to global variables.

Also replace some occurrences of __pa_symbol() [which relies on the
compiler generating an absolute reference, which is not guaranteed] and
an open coded RIP-relative access with RIP_REL_REF().

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20240227151907.387873-18-ardb+git@google.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-04-27 17:07:07 +02:00
2024-04-03 15:19:25 +02:00
2022-09-28 09:02:20 +02:00
2022-09-28 09:02:20 +02:00
2024-03-06 14:45:17 +00:00
2024-04-17 11:18:29 +02:00

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.
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