702644249d
It is quite subtle to use test_fp_ctl() correctly. Therefore remove it - instead copy whatever new floating point control (fpc) register values are supposed to be used into its save area. Test the validity of the new value when loading it. If the new value is invalid, load the fpc register with zero. This seems to be a the best way to approach this problem. Even though this changes behavior: - sigreturn with an invalid fpc value on the stack will succeed, and continue with zero value, instead of returning with SIGSEGV - ptraced processes will also use a zero value instead of letting the request fail with -EINVAL However all of this seems to acceptable. After all testing of the value was only implemented to avoid that user space can crash the kernel. It is not there to test values for validity; and the assumption is that there is no existing user space which is doing this. Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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.