717f08fb51
[ Upstream commit e6b2dab41888332bf83f592131e7ea07756770a4 ]
The KERNEL_FPR mask only contains a flag for the first eight vector
registers. However floating point registers overlay parts of the first
sixteen vector registers.
This could lead to vector register corruption if a kernel fpu context uses
any of the vector registers 8 to 15 and is interrupted or calls a
KERNEL_FPR context. If that context uses also vector registers 8 to 15,
their contents will be corrupted on return.
Luckily this is currently not a real bug, since the kernel has only one
KERNEL_FPR user with s390_adjust_jiffies() and it is only using floating
point registers 0 to 2.
Fix this by using the correct bits for KERNEL_FPR.
Fixes: 7f79695cc1 ("s390/fpu: improve kernel_fpu_[begin|end]")
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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.