1/* SPDX-License-Identifier: GPL-2.0 */
 2//
 3// Code shared between 32 and 64 bit
 4
 5#include <asm/spec-ctrl.h>
 6
 7void __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 */
13static 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}

 1/* SPDX-License-Identifier: GPL-2.0 */
 2//
 3// Code shared between 32 and 64 bit
 4
 5#include <asm/spec-ctrl.h>
 6
 7void __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 */
13static 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, next);
39}