1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_SWITCH_TO_H
3 #define _ASM_X86_SWITCH_TO_H
5 struct task_struct
; /* one of the stranger aspects of C forward declarations */
7 struct task_struct
*__switch_to_asm(struct task_struct
*prev
,
8 struct task_struct
*next
);
10 __visible
struct task_struct
*__switch_to(struct task_struct
*prev
,
11 struct task_struct
*next
);
13 void __switch_to_xtra(struct task_struct
*prev_p
, struct task_struct
*next_p
,
14 struct tss_struct
*tss
);
16 /* This runs runs on the previous thread's stack. */
17 static inline void prepare_switch_to(struct task_struct
*prev
,
18 struct task_struct
*next
)
20 #ifdef CONFIG_VMAP_STACK
22 * If we switch to a stack that has a top-level paging entry
23 * that is not present in the current mm, the resulting #PF will
24 * will be promoted to a double-fault and we'll panic. Probe
25 * the new stack now so that vmalloc_fault can fix up the page
26 * tables if needed. This can only happen if we use a stack
29 * We assume that the stack is aligned so that it never spans
30 * more than one top-level paging entry.
32 * To minimize cache pollution, just follow the stack pointer.
34 READ_ONCE(*(unsigned char *)next
->thread
.sp
);
38 asmlinkage
void ret_from_fork(void);
41 * This is the structure pointed to by thread.sp for an inactive task. The
42 * order of the fields must match the code in __switch_to_asm().
44 struct inactive_task_frame
{
57 * These two fields must be together. They form a stack frame header,
58 * needed by get_frame_pointer().
61 unsigned long ret_addr
;
65 struct inactive_task_frame frame
;
69 #define switch_to(prev, next, last) \
71 prepare_switch_to(prev, next); \
73 ((last) = __switch_to_asm((prev), (next))); \
76 #endif /* _ASM_X86_SWITCH_TO_H */