• Michael Ellerman's avatar
    powerpc/64: Save stack pointer when we hard disable interrupts · 7b08729c
    Michael Ellerman authored
    A CPU that gets stuck with interrupts hard disable can be difficult to
    debug, as on some platforms we have no way to interrupt the CPU to
    find out what it's doing.
    
    A stop-gap is to have the CPU save it's stack pointer (r1) in its paca
    when it hard disables interrupts. That way if we can't interrupt it,
    we can at least trace the stack based on where it last disabled
    interrupts.
    
    In some cases that will be total junk, but the stack trace code should
    handle that. In the simple case of a CPU that disable interrupts and
    then gets stuck in a loop, the stack trace should be informative.
    
    We could clear the saved stack pointer when we enable interrupts, but
    that loses information which could be useful if we have nothing else
    to go on.
    Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
    Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
    7b08729c
paca.h 8.3 KB