tree 637c842b6ec72e8a4f588a200e8b5f8394c21c9f
parent 5a5120b162798fdf07147dff03b23b69f147d311
author Heiko Carstens <hca@linux.ibm.com> 1597251388 +0200
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1598430663 +0200

s390/ptrace: fix storage key handling

[ Upstream commit fd78c59446b8d050ecf3e0897c5a486c7de7c595 ]

The key member of the runtime instrumentation control block contains
only the access key, not the complete storage key. Therefore the value
must be shifted by four bits. Since existing user space does not
necessarily query and set the access key correctly, just ignore the
user space provided key and use the correct one.
Note: this is only relevant for debugging purposes in case somebody
compiles a kernel with a default storage access key set to a value not
equal to zero.

Fixes: 262832bc5acd ("s390/ptrace: add runtime instrumention register get/set")
Reported-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>