void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p)
{
	unsigned long tifp, tifn;

	tifn = READ_ONCE(task_thread_info(next_p)->flags);
	tifp = READ_ONCE(task_thread_info(prev_p)->flags);

	switch_to_bitmap(tifp);

	propagate_user_return_notify(prev_p, next_p);

	if ((tifp & _TIF_BLOCKSTEP || tifn & _TIF_BLOCKSTEP) &&
	    arch_has_block_step()) {
		unsigned long debugctl, msk;

		rdmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
		debugctl &= ~DEBUGCTLMSR_BTF;
		msk = tifn & _TIF_BLOCKSTEP;
		debugctl |= (msk >> TIF_BLOCKSTEP) << DEBUGCTLMSR_BTF_SHIFT;
		wrmsrl(MSR_IA32_DEBUGCTLMSR, debugctl);
	}

	if ((tifp ^ tifn) & _TIF_NOTSC)
		cr4_toggle_bits_irqsoff(X86_CR4_TSD);

	if ((tifp ^ tifn) & _TIF_NOCPUID)
		set_cpuid_faulting(!!(tifn & _TIF_NOCPUID));

	if (likely(!((tifp | tifn) & _TIF_SPEC_FORCE_UPDATE))) {
		__speculation_ctrl_update(tifp, tifn);
	} else {
		speculation_ctrl_update_tif(prev_p);
		tifn = speculation_ctrl_update_tif(next_p);

		/* Enforce MSR update to ensure consistent state */
		__speculation_ctrl_update(~tifn, tifn);
	}

	if ((tifp ^ tifn) & _TIF_SLD)
		switch_to_sld(tifn);
}
Unknown