• Sven Schnelle's avatar
    s390: fix fpu restore in entry.S · 1179f170
    Sven Schnelle authored
    We need to disable interrupts in load_fpu_regs(). Otherwise an
    interrupt might come in after the registers are loaded, but before
    CIF_FPU is cleared in load_fpu_regs(). When the interrupt returns,
    CIF_FPU will be cleared and the registers will never be restored.
    
    The entry.S code usually saves the interrupt state in __SF_EMPTY on the
    stack when disabling/restoring interrupts. sie64a however saves the pointer
    to the sie control block in __SF_SIE_CONTROL, which references the same
    location.  This is non-obvious to the reader. To avoid thrashing the sie
    control block pointer in load_fpu_regs(), move the __SIE_* offsets eight
    bytes after __SF_EMPTY on the stack.
    
    Cc: <stable@vger.kernel.org> # 5.8
    Fixes: 0b0ed657 ("s390: remove critical section cleanup from entry.S")
    Reported-by: default avatarPierre Morel <pmorel@linux.ibm.com>
    Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
    Acked-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
    Reviewed-by: default avatarHeiko Carstens <hca@linux.ibm.com>
    Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
    1179f170
asm-offsets.c 7.81 KB