1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _ASM_X86_SWITCH_TO_H
3 #define _ASM_X86_SWITCH_TO_H
5 #include <linux/sched/task_stack.h>
7 struct task_struct; /* one of the stranger aspects of C forward declarations */
9 struct task_struct *__switch_to_asm(struct task_struct *prev,
10 struct task_struct *next);
12 __visible struct task_struct *__switch_to(struct task_struct *prev,
13 struct task_struct *next);
15 asmlinkage void ret_from_fork(void);
18 * This is the structure pointed to by thread.sp for an inactive task. The
19 * order of the fields must match the code in __switch_to_asm().
21 struct inactive_task_frame {
35 * These two fields must be together. They form a stack frame header,
36 * needed by get_frame_pointer().
39 unsigned long ret_addr;
43 struct inactive_task_frame frame;
47 #define switch_to(prev, next, last) \
49 ((last) = __switch_to_asm((prev), (next))); \
53 static inline void refresh_sysenter_cs(struct thread_struct *thread)
55 /* Only happens when SEP is enabled, no need to test "SEP"arately: */
56 if (unlikely(this_cpu_read(cpu_tss_rw.x86_tss.ss1) == thread->sysenter_cs))
59 this_cpu_write(cpu_tss_rw.x86_tss.ss1, thread->sysenter_cs);
60 wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0);
64 /* This is used when switching tasks or entering/exiting vm86 mode. */
65 static inline void update_task_stack(struct task_struct *task)
67 /* sp0 always points to the entry trampoline stack, which is constant: */
69 if (static_cpu_has(X86_FEATURE_XENPV))
70 load_sp0(task->thread.sp0);
72 this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0);
75 * x86-64 updates x86_tss.sp1 via cpu_current_top_of_stack. That
76 * doesn't work on x86-32 because sp1 and
77 * cpu_current_top_of_stack have different values (because of
78 * the non-zero stack-padding on 32bit).
80 if (static_cpu_has(X86_FEATURE_XENPV))
81 load_sp0(task_top_of_stack(task));
85 static inline void kthread_frame_init(struct inactive_task_frame *frame,
86 unsigned long fun, unsigned long arg)
96 #endif /* _ASM_X86_SWITCH_TO_H */