• Martin Schwidefsky's avatar
    s390: critical section cleanup vs. machine checks · 6551fbdf
    Martin Schwidefsky authored
    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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
    6551fbdf
entry64.S 27.4 KB