scripts/gdb: add class to iterate over CPU masks

    return pointer.cast(var_ptr.type).dereference()

cpu_mask = {}

def cpu_mask_invalidate(event):

    global cpu_mask

    cpu_mask = {}

    gdb.events.stop.disconnect(cpu_mask_invalidate)

    if hasattr(gdb.events, 'new_objfile'):

        gdb.events.new_objfile.disconnect(cpu_mask_invalidate)

class CpuList():

    def __init__(self, mask_name):

        global cpu_mask

        self.mask = None

        if mask_name in cpu_mask:

            self.mask = cpu_mask[mask_name]

        if self.mask is None:

            self.mask = gdb.parse_and_eval(mask_name + ".bits")

            if hasattr(gdb, 'events'):

                cpu_mask[mask_name] = self.mask

                gdb.events.stop.connect(cpu_mask_invalidate)

                if hasattr(gdb.events, 'new_objfile'):

                    gdb.events.new_objfile.connect(cpu_mask_invalidate)

        self.bits_per_entry = self.mask[0].type.sizeof * 8

        self.num_entries = self.mask.type.sizeof * 8 / self.bits_per_entry

        self.entry = -1

        self.bits = 0

    def __iter__(self):

        return self

    def next(self):

        while self.bits == 0:

            self.entry += 1

            if self.entry == self.num_entries:

                raise StopIteration

            self.bits = self.mask[self.entry]

            if self.bits != 0:

                self.bit = 0

                break

        while self.bits & 1 == 0:

            self.bits >>= 1

            self.bit += 1

        cpu = self.entry * self.bits_per_entry + self.bit

        self.bits >>= 1

        self.bit += 1

        return cpu

class PerCpu(gdb.Function):

    """Return per-cpu variable.