Heiko Carstens b4d70a6134 s390/mm: use invalid asce for user space when switching to init_mm
Currently only idle_task_exit() explicitly switches (switch_mm) to
init_mm. This causes the kernel asce to be loaded into cr7 and
therefore it would be used for potential user space accesses.

This is currently no problem since idle_task_exit() is nearly the last
thing a CPU executes before it is taken down. However things might
change - and therefore make sure that always the invalid asce is used
for cr7 when active_mm is init_mm.

This makes sure that all potential user space accesses will fail,
instead of accessing kernel address space.

Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2020-12-09 21:02:08 +01:00
2020-10-28 19:12:03 +01:00
2020-11-08 16:10:16 -08:00

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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