1 #ifndef _ASM_X86_SWITCH_TO_H 2 #define _ASM_X86_SWITCH_TO_H 3 4 struct task_struct; /* one of the stranger aspects of C forward declarations */ 5 6 struct task_struct *__switch_to_asm(struct task_struct *prev, 7 struct task_struct *next); 8 9 __visible struct task_struct *__switch_to(struct task_struct *prev, 10 struct task_struct *next); 11 struct tss_struct; 12 void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p, 13 struct tss_struct *tss); 14 15 /* This runs runs on the previous thread's stack. */ 16 static inline void prepare_switch_to(struct task_struct *prev, 17 struct task_struct *next) 18 { 19 #ifdef CONFIG_VMAP_STACK 20 /* 21 * If we switch to a stack that has a top-level paging entry 22 * that is not present in the current mm, the resulting #PF will 23 * will be promoted to a double-fault and we'll panic. Probe 24 * the new stack now so that vmalloc_fault can fix up the page 25 * tables if needed. This can only happen if we use a stack 26 * in vmap space. 27 * 28 * We assume that the stack is aligned so that it never spans 29 * more than one top-level paging entry. 30 * 31 * To minimize cache pollution, just follow the stack pointer. 32 */ 33 READ_ONCE(*(unsigned char *)next->thread.sp); 34 #endif 35 } 36 37 asmlinkage void ret_from_fork(void); 38 39 /* data that is pointed to by thread.sp */ 40 struct inactive_task_frame { 41 #ifdef CONFIG_X86_64 42 unsigned long r15; 43 unsigned long r14; 44 unsigned long r13; 45 unsigned long r12; 46 #else 47 unsigned long si; 48 unsigned long di; 49 #endif 50 unsigned long bx; 51 unsigned long bp; 52 unsigned long ret_addr; 53 }; 54 55 struct fork_frame { 56 struct inactive_task_frame frame; 57 struct pt_regs regs; 58 }; 59 60 #define switch_to(prev, next, last) \ 61 do { \ 62 prepare_switch_to(prev, next); \ 63 \ 64 ((last) = __switch_to_asm((prev), (next))); \ 65 } while (0) 66 67 #endif /* _ASM_X86_SWITCH_TO_H */ 68