[mirror_ubuntu-jammy-kernel.git] / include / linux / secretmem.h

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _LINUX_SECRETMEM_H
#define _LINUX_SECRETMEM_H

#ifdef CONFIG_SECRETMEM

extern const struct address_space_operations secretmem_aops;

static inline bool page_is_secretmem(struct page *page)
{
	struct address_space *mapping;

	/*
	 * Using page_mapping() is quite slow because of the actual call
	 * instruction and repeated compound_head(page) inside the
	 * page_mapping() function.
	 * We know that secretmem pages are not compound and LRU so we can
	 * save a couple of cycles here.
	 */
	if (PageCompound(page) || !PageLRU(page))
		return false;

	mapping = (struct address_space *)
		((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);

	if (mapping != page->mapping)
		return false;

	return mapping->a_ops == &secretmem_aops;
}

bool vma_is_secretmem(struct vm_area_struct *vma);
bool secretmem_active(void);

#else

static inline bool vma_is_secretmem(struct vm_area_struct *vma)
{
	return false;
}

static inline bool page_is_secretmem(struct page *page)
{
	return false;
}

static inline bool secretmem_active(void)
{
	return false;
}

#endif /* CONFIG_SECRETMEM */

#endif /* _LINUX_SECRETMEM_H */
Commit	Line	Data
1507f512 MR	1	/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
	2	#ifndef _LINUX_SECRETMEM_H
	3	#define _LINUX_SECRETMEM_H
	4
	5	#ifdef CONFIG_SECRETMEM
	6
	7	extern const struct address_space_operations secretmem_aops;
	8
	9	static inline bool page_is_secretmem(struct page *page)
	10	{
	11	struct address_space *mapping;
	12
	13	/*
	14	* Using page_mapping() is quite slow because of the actual call
	15	* instruction and repeated compound_head(page) inside the
	16	* page_mapping() function.
	17	* We know that secretmem pages are not compound and LRU so we can
	18	* save a couple of cycles here.
	19	*/
	20	if (PageCompound(page) \|\| !PageLRU(page))
	21	return false;
	22
	23	mapping = (struct address_space *)
	24	((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
	25
	26	if (mapping != page->mapping)
	27	return false;
	28
	29	return mapping->a_ops == &secretmem_aops;
	30	}
	31
	32	bool vma_is_secretmem(struct vm_area_struct *vma);
9a436f8f	33	bool secretmem_active(void);
1507f512 MR	34
	35	#else
	36
	37	static inline bool vma_is_secretmem(struct vm_area_struct *vma)
	38	{
	39	return false;
	40	}
	41
	42	static inline bool page_is_secretmem(struct page *page)
	43	{
	44	return false;
	45	}
	46
9a436f8f MR	47	static inline bool secretmem_active(void)
	48	{
	49	return false;
	50	}
	51
1507f512 MR	52	#endif /* CONFIG_SECRETMEM */
	53
	54	#endif /* _LINUX_SECRETMEM_H */