James Morse 0465045e68 arm64: entry: Free up another register on kpti's tramp_exit path
commit 03aff3a77a58b5b52a77e00537a42090ad57b80b upstream.

Kpti stashes x30 in far_el1 while it uses x30 for all its work.

Making the vectors a per cpu data structure will require a second
register.

Allow tramp_exit two registers before it unmaps the kernel by
leaving x30 on the stack and stashing x29 in far_el1.

Change-Id: I324402ec90a8401780ac88d6ed91eaa50fb1911a
Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Git-commit: 51acb81130
Git-repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Kishor Krishna Bhat <quic_kishkris@quicinc.com>
2022-10-17 04:00:43 -07:00

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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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