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4ca4f418b7
commit c4abe6234246c75cdc43326415d9cff88b7cf06c upstream.
Use "a" constraint for the shift operand of the __pcilg_mio_inuser() inline
assembly. The used "d" constraint allows the compiler to use any general
purpose register for the shift operand, including register zero.
If register zero is used this my result in incorrect code generation:
8f6: a7 0a ff f8 ahi %r0,-8
8fa: eb 32 00 00 00 0c srlg %r3,%r2,0 <----
If register zero is selected to contain the shift value, the srlg
instruction ignores the contents of the register and always shifts zero
bits. Therefore use the "a" constraint which does not permit to select
register zero.
Fixes: f058599e22 ("s390/pci: Fix s390_mmio_read/write with MIO")
Cc: stable@vger.kernel.org
Reported-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.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.