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 = read_task_thread_flags(next); |
17 | unsigned long prev_tif = read_task_thread_flags(prev); |
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_p: prev, next_p: next); |
39 | } |
40 |