Dave Hansen c5129ecc12 x86/mm: Ease W^X enforcement back to just a warning
Currently, the "change_page_attr" (CPA) code refuses to create
W+X mappings on 64-bit kernels.  There have been reports both
from 32-bit[1] and from BPF[2] users where this change kept the
system from booting.

These reports are showing up even after about a month of soak
time in -next.

To avoid breaking anything, never enforce W^X.  Always warn
and return the requested permissions even if a problem is
detected.

1. https://lore.kernel.org/all/CAMj1kXHcF_iK_g0OZSkSv56Wmr=eQGQwNstcNjLEfS=mm7a06w@mail.gmail.com/
2. https://lore.kernel.org/bpf/c84cc27c1a5031a003039748c3c099732a718aec.camel@kernel.org/T/#u

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
2022-10-04 12:53:52 -07:00
2022-08-28 15:05:29 -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.

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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