s390: critical section cleanup vs. machine checks

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The current machine check code uses the registers stored by the machine
in the lowcore at __LC_GPREGS_SAVE_AREA as the registers of the interrupted
context. The registers 0-7 of a user process can get clobbered if a machine
checks interrupts the execution of a critical section in entry[64].S.

The reason is that the critical section cleanup code may need to modify
the PSW and the registers for the previous context to get to the end of a
critical section. If registers 0-7 have to be replaced the relevant copy
will be in the registers, which invalidates the copy in the lowcore. The
machine check handler needs to explicitly store registers 0-7 to the stack.

Cc: stable@vger.kernel.org
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

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Martin Schwidefsky 2013-02-28 16:28:41 +01:00

parent 6dbe51c251

commit 6551fbdfd8

2 changed files with 5 additions and 3 deletions

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3

arch/s390/kernel/entry.S

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5

arch/s390/kernel/entry64.S

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