[mirror_ubuntu-focal-kernel.git] / arch / x86 / include / asm / switch_to.h

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_X86_SWITCH_TO_H
#define _ASM_X86_SWITCH_TO_H

struct task_struct; /* one of the stranger aspects of C forward declarations */

struct task_struct *__switch_to_asm(struct task_struct *prev,
				    struct task_struct *next);

__visible struct task_struct *__switch_to(struct task_struct *prev,
					  struct task_struct *next);
struct tss_struct;
void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
		      struct tss_struct *tss);

/* This runs runs on the previous thread's stack. */
static inline void prepare_switch_to(struct task_struct *prev,
				     struct task_struct *next)
{
#ifdef CONFIG_VMAP_STACK
	/*
	 * If we switch to a stack that has a top-level paging entry
	 * that is not present in the current mm, the resulting #PF will
	 * will be promoted to a double-fault and we'll panic.  Probe
	 * the new stack now so that vmalloc_fault can fix up the page
	 * tables if needed.  This can only happen if we use a stack
	 * in vmap space.
	 *
	 * We assume that the stack is aligned so that it never spans
	 * more than one top-level paging entry.
	 *
	 * To minimize cache pollution, just follow the stack pointer.
	 */
	READ_ONCE(*(unsigned char *)next->thread.sp);
#endif
}

asmlinkage void ret_from_fork(void);

/*
 * This is the structure pointed to by thread.sp for an inactive task.  The
 * order of the fields must match the code in __switch_to_asm().
 */
struct inactive_task_frame {
#ifdef CONFIG_X86_64
	unsigned long r15;
	unsigned long r14;
	unsigned long r13;
	unsigned long r12;
#else
	unsigned long si;
	unsigned long di;
#endif
	unsigned long bx;

	/*
	 * These two fields must be together.  They form a stack frame header,
	 * needed by get_frame_pointer().
	 */
	unsigned long bp;
	unsigned long ret_addr;
};

struct fork_frame {
	struct inactive_task_frame frame;
	struct pt_regs regs;
};

#define switch_to(prev, next, last)					\
do {									\
	prepare_switch_to(prev, next);					\
									\
	((last) = __switch_to_asm((prev), (next)));			\
} while (0)

#endif /* _ASM_X86_SWITCH_TO_H */
Commit	Line	Data
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
	5	struct task_struct; /* one of the stranger aspects of C forward declarations */
0100301b BG	6
	7	struct task_struct __switch_to_asm(struct task_struct prev,
	8	struct task_struct *next);
	9
35ea7903	10	__visible struct task_struct __switch_to(struct task_struct prev,
0100301b	11	struct task_struct *next);
f05e798a DH	12	struct tss_struct;
	13	void __switch_to_xtra(struct task_struct prev_p, struct task_struct next_p,
	14	struct tss_struct *tss);
	15
e37e43a4 AL	16	/* This runs runs on the previous thread's stack. */
	17	static inline void prepare_switch_to(struct task_struct *prev,
	18	struct task_struct *next)
	19	{
	20	#ifdef CONFIG_VMAP_STACK
	21	/*
	22	* If we switch to a stack that has a top-level paging entry
	23	* that is not present in the current mm, the resulting #PF will
	24	* will be promoted to a double-fault and we'll panic. Probe
	25	* the new stack now so that vmalloc_fault can fix up the page
	26	* tables if needed. This can only happen if we use a stack
	27	* in vmap space.
	28	*
	29	* We assume that the stack is aligned so that it never spans
	30	* more than one top-level paging entry.
	31	*
	32	* To minimize cache pollution, just follow the stack pointer.
	33	*/
	34	READ_ONCE((unsigned char )next->thread.sp);
	35	#endif
	36	}
	37
616d2483 BG	38	asmlinkage void ret_from_fork(void);
616d2483 BG	39
2c96b2fe JP	40	/*
	41	* This is the structure pointed to by thread.sp for an inactive task. The
	42	* order of the fields must match the code in __switch_to_asm().
	43	*/
7b32aead	44	struct inactive_task_frame {
0100301b BG	45	#ifdef CONFIG_X86_64
	46	unsigned long r15;
	47	unsigned long r14;
	48	unsigned long r13;
	49	unsigned long r12;
	50	#else
	51	unsigned long si;
	52	unsigned long di;
	53	#endif
	54	unsigned long bx;
2c96b2fe JP	55
	56	/*
	57	* These two fields must be together. They form a stack frame header,
	58	* needed by get_frame_pointer().
	59	*/
7b32aead	60	unsigned long bp;
0100301b	61	unsigned long ret_addr;
7b32aead BG	62	};
7b32aead BG	63
0100301b BG	64	struct fork_frame {
	65	struct inactive_task_frame frame;
	66	struct pt_regs regs;
	67	};
f05e798a	68
f05e798a DH	69	#define switch_to(prev, next, last) \
f05e798a DH	70	do { \
e37e43a4 AL	71	prepare_switch_to(prev, next); \
e37e43a4 AL	72	\
0100301b	73	((last) = __switch_to_asm((prev), (next))); \
f05e798a DH	74	} while (0)
f05e798a DH	75
f05e798a	76	#endif /* _ASM_X86_SWITCH_TO_H */