s390/mcck: always enter C handler with DAT enabled

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The machine check handler must be entered with DAT disabled
in case control registers are corrupted or a storage error
happened and we can not tell if such error corresponds to a
page table.

Both of described conditions end up in stopping all CPUs and
entering the disabled wait in C half of the handler. However,
the storage errors are still checked after the DAT is enabled
and C code is entered. In case a page table is damaged such
flow is not expected to work.

This update paves the way for moving the storage error checks
from C to assembler half. All fatal errors that can only be
handled with DAT disabled are handled in assembler half also.
As result, the C half is only entered if the DAT is secured.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>

...

This commit is contained in:

Alexander Gordeev 2021-06-18 08:17:15 +02:00 • committed by Vasily Gorbik

parent e2c13d6420

commit 7f6dc8d4c8

2 changed files with 32 additions and 32 deletions

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35

arch/s390/kernel/entry.S

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29

arch/s390/kernel/nmi.c

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