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authorHeiko Carstens <heiko.carstens@de.ibm.com>2017-11-09 23:00:14 +0100
committerHeiko Carstens <heiko.carstens@de.ibm.com>2017-11-10 18:58:08 +0100
commitd0e810eeb3d326978f248b8f0233a2f30f58c72d (patch)
treee8ada4a3ddac2d0b5e0dfd57c345c0604ee50ac0 /arch/s390/include/asm/string.h
parenta1c5befc1c24eb9c1ee83f711e0f21ee79cbb556 (diff)
s390/noexec: execute kexec datamover without DAT
Rebooting into a new kernel with kexec fails (system dies) if tried on a machine that has no-execute support. Reason for this is that the so called datamover code gets executed with DAT on (MMU is active) and the page that contains the datamover is marked as non-executable. Therefore when branching into the datamover an unexpected program check happens and afterwards the machine is dead. This can be simply avoided by disabling DAT, which also disables any no-execute checks, just before the datamover gets executed. In fact the first thing done by the datamover is to disable DAT. The code in the datamover that disables DAT can be removed as well. Thanks to Michael Holzheu and Gerald Schaefer for tracking this down. Reviewed-by: Michael Holzheu <holzheu@linux.vnet.ibm.com> Reviewed-by: Philipp Rudo <prudo@linux.vnet.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Fixes: 57d7f939e7bd ("s390: add no-execute support") Cc: <stable@vger.kernel.org> # v4.11+ Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Diffstat (limited to 'arch/s390/include/asm/string.h')
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