1 #ifndef _ASM_X86_SWITCH_TO_H
2 #define _ASM_X86_SWITCH_TO_H
4 #include <linux/sched/task_stack.h>
6 struct task_struct
; /* one of the stranger aspects of C forward declarations */
8 struct task_struct
*__switch_to_asm(struct task_struct
*prev
,
9 struct task_struct
*next
);
11 __visible
struct task_struct
*__switch_to(struct task_struct
*prev
,
12 struct task_struct
*next
);
14 void __switch_to_xtra(struct task_struct
*prev_p
, struct task_struct
*next_p
,
15 struct tss_struct
*tss
);
17 /* This runs runs on the previous thread's stack. */
18 static inline void prepare_switch_to(struct task_struct
*prev
,
19 struct task_struct
*next
)
21 #ifdef CONFIG_VMAP_STACK
23 * If we switch to a stack that has a top-level paging entry
24 * that is not present in the current mm, the resulting #PF will
25 * will be promoted to a double-fault and we'll panic. Probe
26 * the new stack now so that vmalloc_fault can fix up the page
27 * tables if needed. This can only happen if we use a stack
30 * We assume that the stack is aligned so that it never spans
31 * more than one top-level paging entry.
33 * To minimize cache pollution, just follow the stack pointer.
35 READ_ONCE(*(unsigned char *)next
->thread
.sp
);
39 asmlinkage
void ret_from_fork(void);
42 * This is the structure pointed to by thread.sp for an inactive task. The
43 * order of the fields must match the code in __switch_to_asm().
45 struct inactive_task_frame
{
58 * These two fields must be together. They form a stack frame header,
59 * needed by get_frame_pointer().
62 unsigned long ret_addr
;
66 struct inactive_task_frame frame
;
70 #define switch_to(prev, next, last) \
72 prepare_switch_to(prev, next); \
74 ((last) = __switch_to_asm((prev), (next))); \
78 static inline void refresh_sysenter_cs(struct thread_struct
*thread
)
80 /* Only happens when SEP is enabled, no need to test "SEP"arately: */
81 if (unlikely(this_cpu_read(cpu_tss_rw
.x86_tss
.ss1
) == thread
->sysenter_cs
))
84 this_cpu_write(cpu_tss_rw
.x86_tss
.ss1
, thread
->sysenter_cs
);
85 wrmsr(MSR_IA32_SYSENTER_CS
, thread
->sysenter_cs
, 0);
89 /* This is used when switching tasks or entering/exiting vm86 mode. */
90 static inline void update_sp0(struct task_struct
*task
)
92 /* On x86_64, sp0 always points to the entry trampoline stack, which is constant: */
94 load_sp0(task
->thread
.sp0
);
96 if (static_cpu_has(X86_FEATURE_XENPV
))
97 load_sp0(task_top_of_stack(task
));
101 #endif /* _ASM_X86_SWITCH_TO_H */