tree 1d3bfe8d68e86d17e945d91cc9ecb91040f3c376
parent 3794633dfdd86263627459b262ba6ce4c9719bd6
author Heiko Carstens <hca@linux.ibm.com> 1623674971 +0200
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1626789944 +0200

s390/ipl_parm: fix program check new psw handling

[ Upstream commit 88c2510cecb7e2b518e3c4fdf3cf0e13ebe9377c ]

The __diag308() inline asm temporarily changes the program check new
psw to redirect a potential program check on the diag instruction.
Restoring of the program check new psw is done in C code behind the
inline asm.

This can be problematic, especially if the function is inlined, since
the compiler can reorder instructions in such a way that a different
instruction, which may result in a program check, might be executed
before the program check new psw has been restored.

To avoid such a scenario move restoring into the inline asm. For
consistency reasons move also saving of the original program check new
psw into the inline asm.

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>