linux/arch/x86/kernel/process.h

/* SPDX-License-Identifier: GPL-2.0 */
//
// Code shared between 32 and 64 bit

#include <asm/spec-ctrl.h>

void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p);

/*
 * This needs to be inline to optimize for the common case where no extra
 * work needs to be done.
 */
static inline void switch_to_extra(struct task_struct *prev,
				   struct task_struct *next)
{ … }