LXR linux/include/linux/secretmem.h

   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
   7extern const struct address_space_operations secretmem_aops;
   8
   9static 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 || mapping != page->mapping)
  27                return false;
  28
  29        return mapping->a_ops == &secretmem_aops;
  30}
  31
  32bool vma_is_secretmem(struct vm_area_struct *vma);
  33bool secretmem_active(void);
  34
  35#else
  36
  37static inline bool vma_is_secretmem(struct vm_area_struct *vma)
  38{
  39        return false;
  40}
  41
  42static inline bool page_is_secretmem(struct page *page)
  43{
  44        return false;
  45}
  46
  47static inline bool secretmem_active(void)
  48{
  49        return false;
  50}
  51
  52#endif /* CONFIG_SECRETMEM */
  53
  54#endif /* _LINUX_SECRETMEM_H */
  55