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 || 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); 33 bool secretmem_active(void); 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 47 static inline bool secretmem_active(void) 48 { 49 return false; 50 } 51 52 #endif /* CONFIG_SECRETMEM */ 53 54 #endif /* _LINUX_SECRETMEM_H */ 55