s390/mem_detect: fix tprot() program check new psw handling

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The tprot() 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>

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Heiko Carstens 2021-06-14 22:09:20 +02:00 • committed by Vasily Gorbik

parent 1b2f281f45

commit da90575767

1 changed files with 17 additions and 11 deletions

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arch/s390/boot/mem_detect.c

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