| 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
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| 2 | #ifndef _ASM_X86_SWITCH_TO_H |
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| 3 | #define _ASM_X86_SWITCH_TO_H |
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| 4 | |
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| 5 | #include <linux/sched/task_stack.h> |
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| 6 | |
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| 7 | struct task_struct; /* one of the stranger aspects of C forward declarations */ |
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| 8 | |
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| 9 | struct task_struct *__switch_to_asm(struct task_struct *prev, |
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| 10 | struct task_struct *next); |
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| 11 | |
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| 12 | __visible struct task_struct *__switch_to(struct task_struct *prev, |
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| 13 | struct task_struct *next); |
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| 14 | |
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| 15 | asmlinkage void ret_from_fork_asm(void); |
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| 16 | __visible void ret_from_fork(struct task_struct *prev, struct pt_regs *regs, |
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| 17 | int (*fn)(void *), void *fn_arg); |
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| 18 | |
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| 19 | /* |
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| 20 | * This is the structure pointed to by thread.sp for an inactive task. The |
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| 21 | * order of the fields must match the code in __switch_to_asm(). |
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| 22 | */ |
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| 23 | struct inactive_task_frame { |
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| 24 | #ifdef CONFIG_X86_64 |
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| 25 | unsigned long r15; |
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| 26 | unsigned long r14; |
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| 27 | unsigned long r13; |
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| 28 | unsigned long r12; |
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| 29 | #else |
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| 30 | unsigned long flags; |
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| 31 | unsigned long si; |
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| 32 | unsigned long di; |
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| 33 | #endif |
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| 34 | unsigned long bx; |
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| 35 | |
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| 36 | /* |
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| 37 | * These two fields must be together. They form a stack frame header, |
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| 38 | * needed by get_frame_pointer(). |
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| 39 | */ |
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| 40 | unsigned long bp; |
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| 41 | unsigned long ret_addr; |
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| 42 | }; |
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| 43 | |
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| 44 | struct fork_frame { |
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| 45 | struct inactive_task_frame frame; |
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| 46 | struct pt_regs regs; |
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| 47 | }; |
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| 48 | |
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| 49 | #define switch_to(prev, next, last) \ |
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| 50 | do { \ |
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| 51 | ((last) = __switch_to_asm((prev), (next))); \ |
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| 52 | } while (0) |
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| 53 | |
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| 54 | #ifdef CONFIG_X86_32 |
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| 55 | #include <asm/msr.h> |
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| 56 | |
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| 57 | static inline void refresh_sysenter_cs(struct thread_struct *thread) |
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| 58 | { |
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| 59 | /* Only happens when SEP is enabled, no need to test "SEP"arately: */ |
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| 60 | if (unlikely(this_cpu_read(cpu_tss_rw.x86_tss.ss1) == thread->sysenter_cs)) |
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| 61 | return; |
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| 62 | |
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| 63 | this_cpu_write(cpu_tss_rw.x86_tss.ss1, thread->sysenter_cs); |
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| 64 | wrmsrq(MSR_IA32_SYSENTER_CS, thread->sysenter_cs); |
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| 65 | } |
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| 66 | #endif |
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| 67 | |
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| 68 | /* This is used when switching tasks or entering/exiting vm86 mode. */ |
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| 69 | static inline void update_task_stack(struct task_struct *task) |
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| 70 | { |
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| 71 | /* sp0 always points to the entry trampoline stack, which is constant: */ |
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| 72 | #ifdef CONFIG_X86_32 |
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| 73 | this_cpu_write(cpu_tss_rw.x86_tss.sp1, task->thread.sp0); |
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| 74 | #else |
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| 75 | if (!cpu_feature_enabled(X86_FEATURE_FRED) && cpu_feature_enabled(X86_FEATURE_XENPV)) |
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| 76 | /* Xen PV enters the kernel on the thread stack. */ |
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| 77 | load_sp0(task_top_of_stack(task)); |
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| 78 | #endif |
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| 79 | } |
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| 80 | |
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| 81 | static inline void kthread_frame_init(struct inactive_task_frame *frame, |
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| 82 | int (*fun)(void *), void *arg) |
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| 83 | { |
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| 84 | frame->bx = (unsigned long)fun; |
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| 85 | #ifdef CONFIG_X86_32 |
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| 86 | frame->di = (unsigned long)arg; |
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| 87 | #else |
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| 88 | frame->r12 = (unsigned long)arg; |
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| 89 | #endif |
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| 90 | } |
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| 91 | |
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| 92 | #endif /* _ASM_X86_SWITCH_TO_H */ |
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| 93 | |
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