Release 4.14 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
}

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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 */
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Directory: arch/x86/include/asm

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