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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
f05e798a DH |
2 | #ifndef _ASM_X86_SWITCH_TO_H |
3 | #define _ASM_X86_SWITCH_TO_H | |
4 | ||
d375cf15 AL |
5 | #include <linux/sched/task_stack.h> |
6 | ||
f05e798a | 7 | struct task_struct; /* one of the stranger aspects of C forward declarations */ |
0100301b BG |
8 | |
9 | struct task_struct *__switch_to_asm(struct task_struct *prev, | |
10 | struct task_struct *next); | |
11 | ||
35ea7903 | 12 | __visible struct task_struct *__switch_to(struct task_struct *prev, |
0100301b | 13 | struct task_struct *next); |
f05e798a | 14 | |
e37e43a4 | 15 | /* This runs runs on the previous thread's stack. */ |
7ac139ea | 16 | static inline void prepare_switch_to(struct task_struct *next) |
e37e43a4 AL |
17 | { |
18 | #ifdef CONFIG_VMAP_STACK | |
19 | /* | |
20 | * If we switch to a stack that has a top-level paging entry | |
21 | * that is not present in the current mm, the resulting #PF will | |
22 | * will be promoted to a double-fault and we'll panic. Probe | |
23 | * the new stack now so that vmalloc_fault can fix up the page | |
24 | * tables if needed. This can only happen if we use a stack | |
25 | * in vmap space. | |
26 | * | |
27 | * We assume that the stack is aligned so that it never spans | |
28 | * more than one top-level paging entry. | |
29 | * | |
30 | * To minimize cache pollution, just follow the stack pointer. | |
31 | */ | |
32 | READ_ONCE(*(unsigned char *)next->thread.sp); | |
33 | #endif | |
34 | } | |
35 | ||
616d2483 BG |
36 | asmlinkage void ret_from_fork(void); |
37 | ||
2c96b2fe JP |
38 | /* |
39 | * This is the structure pointed to by thread.sp for an inactive task. The | |
40 | * order of the fields must match the code in __switch_to_asm(). | |
41 | */ | |
7b32aead | 42 | struct inactive_task_frame { |
0100301b BG |
43 | #ifdef CONFIG_X86_64 |
44 | unsigned long r15; | |
45 | unsigned long r14; | |
46 | unsigned long r13; | |
47 | unsigned long r12; | |
48 | #else | |
64604d54 | 49 | unsigned long flags; |
0100301b BG |
50 | unsigned long si; |
51 | unsigned long di; | |
52 | #endif | |
53 | unsigned long bx; | |
2c96b2fe JP |
54 | |
55 | /* | |
56 | * These two fields must be together. They form a stack frame header, | |
57 | * needed by get_frame_pointer(). | |
58 | */ | |
7b32aead | 59 | unsigned long bp; |
0100301b | 60 | unsigned long ret_addr; |
7b32aead BG |
61 | }; |
62 | ||
0100301b BG |
63 | struct fork_frame { |
64 | struct inactive_task_frame frame; | |
65 | struct pt_regs regs; | |
66 | }; | |
f05e798a | 67 | |
f05e798a DH |
68 | #define switch_to(prev, next, last) \ |
69 | do { \ | |
7ac139ea | 70 | prepare_switch_to(next); \ |
e37e43a4 | 71 | \ |
0100301b | 72 | ((last) = __switch_to_asm((prev), (next))); \ |
f05e798a DH |
73 | } while (0) |
74 | ||
bd7dc5a6 AL |
75 | #ifdef CONFIG_X86_32 |
76 | static inline void refresh_sysenter_cs(struct thread_struct *thread) | |
77 | { | |
78 | /* Only happens when SEP is enabled, no need to test "SEP"arately: */ | |
c482feef | 79 | if (unlikely(this_cpu_read(cpu_tss_rw.x86_tss.ss1) == thread->sysenter_cs)) |
bd7dc5a6 AL |
80 | return; |
81 | ||
c482feef | 82 | this_cpu_write(cpu_tss_rw.x86_tss.ss1, thread->sysenter_cs); |
bd7dc5a6 AL |
83 | wrmsr(MSR_IA32_SYSENTER_CS, thread->sysenter_cs, 0); |
84 | } | |
85 | #endif | |
86 | ||
46f5a10a | 87 | /* This is used when switching tasks or entering/exiting vm86 mode. */ |
252e1a05 | 88 | static inline void update_task_stack(struct task_struct *task) |
46f5a10a | 89 | { |
45d7b255 | 90 | /* sp0 always points to the entry trampoline stack, which is constant: */ |
d375cf15 | 91 | #ifdef CONFIG_X86_32 |
45d7b255 JR |
92 | if (static_cpu_has(X86_FEATURE_XENPV)) |
93 | load_sp0(task->thread.sp0); | |
94 | else | |
95 | this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0); | |
d375cf15 | 96 | #else |
45d7b255 JR |
97 | /* |
98 | * x86-64 updates x86_tss.sp1 via cpu_current_top_of_stack. That | |
99 | * doesn't work on x86-32 because sp1 and | |
100 | * cpu_current_top_of_stack have different values (because of | |
101 | * the non-zero stack-padding on 32bit). | |
102 | */ | |
7f2590a1 AL |
103 | if (static_cpu_has(X86_FEATURE_XENPV)) |
104 | load_sp0(task_top_of_stack(task)); | |
d375cf15 | 105 | #endif |
2fff071d | 106 | } |
45d7b255 | 107 | |
2fff071d TG |
108 | static inline void kthread_frame_init(struct inactive_task_frame *frame, |
109 | unsigned long fun, unsigned long arg) | |
110 | { | |
111 | frame->bx = fun; | |
112 | #ifdef CONFIG_X86_32 | |
113 | frame->di = arg; | |
114 | #else | |
115 | frame->r12 = arg; | |
116 | #endif | |
46f5a10a AL |
117 | } |
118 | ||
f05e798a | 119 | #endif /* _ASM_X86_SWITCH_TO_H */ |