1 /* SPDX-License-Identifier: GPL-2.0 */
2 //
3 // Code shared between 32 and 64 bit
4
5 #include <asm/spec-ctrl.h>
6
7 void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p);
8
9 /*
10 * This needs to be inline to optimize for the common case where no extra
11 * work needs to be done.
12 */
13 static inline void switch_to_extra(struct task_struct *prev,
14 struct task_struct *next)
15 {
16 unsigned long next_tif = task_thread_info(next)->flags;
17 unsigned long prev_tif = task_thread_info(prev)->flags;
18
19 if (IS_ENABLED(CONFIG_SMP)) {
20 /*
21 * Avoid __switch_to_xtra() invocation when conditional
22 * STIBP is disabled and the only different bit is
23 * TIF_SPEC_IB. For CONFIG_SMP=n TIF_SPEC_IB is not
24 * in the TIF_WORK_CTXSW masks.
25 */
26 if (!static_branch_likely(&switch_to_cond_stibp)) {
27 prev_tif &= ~_TIF_SPEC_IB;
28 next_tif &= ~_TIF_SPEC_IB;
29 }
30 }
31
32 /*
33 * __switch_to_xtra() handles debug registers, i/o bitmaps,
34 * speculation mitigations etc.
35 */
36 if (unlikely(next_tif & _TIF_WORK_CTXSW_NEXT ||
37 prev_tif & _TIF_WORK_CTXSW_PREV))
38 __switch_to_xtra(prev, next);
39 }