xref: /linux/arch/arm64/include/asm/pgtable.h (revision 3932b9ca55b0be314a36d3e84faff3e823c081f5)
1 /*
2  * Copyright (C) 2012 ARM Ltd.
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * This program is distributed in the hope that it will be useful,
9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
11  * GNU General Public License for more details.
12  *
13  * You should have received a copy of the GNU General Public License
14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
15  */
16 #ifndef __ASM_PGTABLE_H
17 #define __ASM_PGTABLE_H
18 
19 #include <asm/proc-fns.h>
20 
21 #include <asm/memory.h>
22 #include <asm/pgtable-hwdef.h>
23 
24 /*
25  * Software defined PTE bits definition.
26  */
27 #define PTE_VALID		(_AT(pteval_t, 1) << 0)
28 #define PTE_FILE		(_AT(pteval_t, 1) << 2)	/* only when !pte_present() */
29 #define PTE_DIRTY		(_AT(pteval_t, 1) << 55)
30 #define PTE_SPECIAL		(_AT(pteval_t, 1) << 56)
31 #define PTE_WRITE		(_AT(pteval_t, 1) << 57)
32 #define PTE_PROT_NONE		(_AT(pteval_t, 1) << 58) /* only when !PTE_VALID */
33 
34 /*
35  * VMALLOC and SPARSEMEM_VMEMMAP ranges.
36  *
37  * VMEMAP_SIZE: allows the whole VA space to be covered by a struct page array
38  *	(rounded up to PUD_SIZE).
39  * VMALLOC_START: beginning of the kernel VA space
40  * VMALLOC_END: extends to the available space below vmmemmap, PCI I/O space,
41  *	fixed mappings and modules
42  */
43 #define VMEMMAP_SIZE		ALIGN((1UL << (VA_BITS - PAGE_SHIFT)) * sizeof(struct page), PUD_SIZE)
44 #define VMALLOC_START		(UL(0xffffffffffffffff) << VA_BITS)
45 #define VMALLOC_END		(PAGE_OFFSET - PUD_SIZE - VMEMMAP_SIZE - SZ_64K)
46 
47 #define vmemmap			((struct page *)(VMALLOC_END + SZ_64K))
48 
49 #define FIRST_USER_ADDRESS	0
50 
51 #ifndef __ASSEMBLY__
52 extern void __pte_error(const char *file, int line, unsigned long val);
53 extern void __pmd_error(const char *file, int line, unsigned long val);
54 extern void __pud_error(const char *file, int line, unsigned long val);
55 extern void __pgd_error(const char *file, int line, unsigned long val);
56 
57 #ifdef CONFIG_SMP
58 #define PROT_DEFAULT		(PTE_TYPE_PAGE | PTE_AF | PTE_SHARED)
59 #define PROT_SECT_DEFAULT	(PMD_TYPE_SECT | PMD_SECT_AF | PMD_SECT_S)
60 #else
61 #define PROT_DEFAULT		(PTE_TYPE_PAGE | PTE_AF)
62 #define PROT_SECT_DEFAULT	(PMD_TYPE_SECT | PMD_SECT_AF)
63 #endif
64 
65 #define PROT_DEVICE_nGnRE	(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_DEVICE_nGnRE))
66 #define PROT_NORMAL_NC		(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL_NC))
67 #define PROT_NORMAL		(PROT_DEFAULT | PTE_PXN | PTE_UXN | PTE_ATTRINDX(MT_NORMAL))
68 
69 #define PROT_SECT_DEVICE_nGnRE	(PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_DEVICE_nGnRE))
70 #define PROT_SECT_NORMAL	(PROT_SECT_DEFAULT | PMD_SECT_PXN | PMD_SECT_UXN | PMD_ATTRINDX(MT_NORMAL))
71 #define PROT_SECT_NORMAL_EXEC	(PROT_SECT_DEFAULT | PMD_SECT_UXN | PMD_ATTRINDX(MT_NORMAL))
72 
73 #define _PAGE_DEFAULT		(PROT_DEFAULT | PTE_ATTRINDX(MT_NORMAL))
74 
75 #define PAGE_KERNEL		__pgprot(_PAGE_DEFAULT | PTE_PXN | PTE_UXN | PTE_DIRTY | PTE_WRITE)
76 #define PAGE_KERNEL_EXEC	__pgprot(_PAGE_DEFAULT | PTE_UXN | PTE_DIRTY | PTE_WRITE)
77 
78 #define PAGE_HYP		__pgprot(_PAGE_DEFAULT | PTE_HYP)
79 #define PAGE_HYP_DEVICE		__pgprot(PROT_DEVICE_nGnRE | PTE_HYP)
80 
81 #define PAGE_S2			__pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_NORMAL) | PTE_S2_RDONLY)
82 #define PAGE_S2_DEVICE		__pgprot(PROT_DEFAULT | PTE_S2_MEMATTR(MT_S2_DEVICE_nGnRE) | PTE_S2_RDWR | PTE_UXN)
83 
84 #define PAGE_NONE		__pgprot(((_PAGE_DEFAULT) & ~PTE_TYPE_MASK) | PTE_PROT_NONE | PTE_PXN | PTE_UXN)
85 #define PAGE_SHARED		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN | PTE_WRITE)
86 #define PAGE_SHARED_EXEC	__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_WRITE)
87 #define PAGE_COPY		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
88 #define PAGE_COPY_EXEC		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
89 #define PAGE_READONLY		__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN | PTE_UXN)
90 #define PAGE_READONLY_EXEC	__pgprot(_PAGE_DEFAULT | PTE_USER | PTE_NG | PTE_PXN)
91 
92 #define __P000  PAGE_NONE
93 #define __P001  PAGE_READONLY
94 #define __P010  PAGE_COPY
95 #define __P011  PAGE_COPY
96 #define __P100  PAGE_READONLY_EXEC
97 #define __P101  PAGE_READONLY_EXEC
98 #define __P110  PAGE_COPY_EXEC
99 #define __P111  PAGE_COPY_EXEC
100 
101 #define __S000  PAGE_NONE
102 #define __S001  PAGE_READONLY
103 #define __S010  PAGE_SHARED
104 #define __S011  PAGE_SHARED
105 #define __S100  PAGE_READONLY_EXEC
106 #define __S101  PAGE_READONLY_EXEC
107 #define __S110  PAGE_SHARED_EXEC
108 #define __S111  PAGE_SHARED_EXEC
109 
110 /*
111  * ZERO_PAGE is a global shared page that is always zero: used
112  * for zero-mapped memory areas etc..
113  */
114 extern struct page *empty_zero_page;
115 #define ZERO_PAGE(vaddr)	(empty_zero_page)
116 
117 #define pte_ERROR(pte)		__pte_error(__FILE__, __LINE__, pte_val(pte))
118 
119 #define pte_pfn(pte)		((pte_val(pte) & PHYS_MASK) >> PAGE_SHIFT)
120 
121 #define pfn_pte(pfn,prot)	(__pte(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
122 
123 #define pte_none(pte)		(!pte_val(pte))
124 #define pte_clear(mm,addr,ptep)	set_pte(ptep, __pte(0))
125 #define pte_page(pte)		(pfn_to_page(pte_pfn(pte)))
126 
127 /* Find an entry in the third-level page table. */
128 #define pte_index(addr)		(((addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
129 
130 #define pte_offset_kernel(dir,addr)	(pmd_page_vaddr(*(dir)) + pte_index(addr))
131 
132 #define pte_offset_map(dir,addr)	pte_offset_kernel((dir), (addr))
133 #define pte_offset_map_nested(dir,addr)	pte_offset_kernel((dir), (addr))
134 #define pte_unmap(pte)			do { } while (0)
135 #define pte_unmap_nested(pte)		do { } while (0)
136 
137 /*
138  * The following only work if pte_present(). Undefined behaviour otherwise.
139  */
140 #define pte_present(pte)	(!!(pte_val(pte) & (PTE_VALID | PTE_PROT_NONE)))
141 #define pte_dirty(pte)		(!!(pte_val(pte) & PTE_DIRTY))
142 #define pte_young(pte)		(!!(pte_val(pte) & PTE_AF))
143 #define pte_special(pte)	(!!(pte_val(pte) & PTE_SPECIAL))
144 #define pte_write(pte)		(!!(pte_val(pte) & PTE_WRITE))
145 #define pte_exec(pte)		(!(pte_val(pte) & PTE_UXN))
146 
147 #define pte_valid_user(pte) \
148 	((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER))
149 #define pte_valid_not_user(pte) \
150 	((pte_val(pte) & (PTE_VALID | PTE_USER)) == PTE_VALID)
151 
152 static inline pte_t pte_wrprotect(pte_t pte)
153 {
154 	pte_val(pte) &= ~PTE_WRITE;
155 	return pte;
156 }
157 
158 static inline pte_t pte_mkwrite(pte_t pte)
159 {
160 	pte_val(pte) |= PTE_WRITE;
161 	return pte;
162 }
163 
164 static inline pte_t pte_mkclean(pte_t pte)
165 {
166 	pte_val(pte) &= ~PTE_DIRTY;
167 	return pte;
168 }
169 
170 static inline pte_t pte_mkdirty(pte_t pte)
171 {
172 	pte_val(pte) |= PTE_DIRTY;
173 	return pte;
174 }
175 
176 static inline pte_t pte_mkold(pte_t pte)
177 {
178 	pte_val(pte) &= ~PTE_AF;
179 	return pte;
180 }
181 
182 static inline pte_t pte_mkyoung(pte_t pte)
183 {
184 	pte_val(pte) |= PTE_AF;
185 	return pte;
186 }
187 
188 static inline pte_t pte_mkspecial(pte_t pte)
189 {
190 	pte_val(pte) |= PTE_SPECIAL;
191 	return pte;
192 }
193 
194 static inline void set_pte(pte_t *ptep, pte_t pte)
195 {
196 	*ptep = pte;
197 
198 	/*
199 	 * Only if the new pte is valid and kernel, otherwise TLB maintenance
200 	 * or update_mmu_cache() have the necessary barriers.
201 	 */
202 	if (pte_valid_not_user(pte)) {
203 		dsb(ishst);
204 		isb();
205 	}
206 }
207 
208 extern void __sync_icache_dcache(pte_t pteval, unsigned long addr);
209 
210 static inline void set_pte_at(struct mm_struct *mm, unsigned long addr,
211 			      pte_t *ptep, pte_t pte)
212 {
213 	if (pte_valid_user(pte)) {
214 		if (!pte_special(pte) && pte_exec(pte))
215 			__sync_icache_dcache(pte, addr);
216 		if (pte_dirty(pte) && pte_write(pte))
217 			pte_val(pte) &= ~PTE_RDONLY;
218 		else
219 			pte_val(pte) |= PTE_RDONLY;
220 	}
221 
222 	set_pte(ptep, pte);
223 }
224 
225 /*
226  * Huge pte definitions.
227  */
228 #define pte_huge(pte)		(!(pte_val(pte) & PTE_TABLE_BIT))
229 #define pte_mkhuge(pte)		(__pte(pte_val(pte) & ~PTE_TABLE_BIT))
230 
231 /*
232  * Hugetlb definitions.
233  */
234 #define HUGE_MAX_HSTATE		2
235 #define HPAGE_SHIFT		PMD_SHIFT
236 #define HPAGE_SIZE		(_AC(1, UL) << HPAGE_SHIFT)
237 #define HPAGE_MASK		(~(HPAGE_SIZE - 1))
238 #define HUGETLB_PAGE_ORDER	(HPAGE_SHIFT - PAGE_SHIFT)
239 
240 #define __HAVE_ARCH_PTE_SPECIAL
241 
242 static inline pte_t pmd_pte(pmd_t pmd)
243 {
244 	return __pte(pmd_val(pmd));
245 }
246 
247 static inline pmd_t pte_pmd(pte_t pte)
248 {
249 	return __pmd(pte_val(pte));
250 }
251 
252 /*
253  * THP definitions.
254  */
255 
256 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
257 #define pmd_trans_huge(pmd)	(pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT))
258 #define pmd_trans_splitting(pmd)	pte_special(pmd_pte(pmd))
259 #endif
260 
261 #define pmd_young(pmd)		pte_young(pmd_pte(pmd))
262 #define pmd_wrprotect(pmd)	pte_pmd(pte_wrprotect(pmd_pte(pmd)))
263 #define pmd_mksplitting(pmd)	pte_pmd(pte_mkspecial(pmd_pte(pmd)))
264 #define pmd_mkold(pmd)		pte_pmd(pte_mkold(pmd_pte(pmd)))
265 #define pmd_mkwrite(pmd)	pte_pmd(pte_mkwrite(pmd_pte(pmd)))
266 #define pmd_mkdirty(pmd)	pte_pmd(pte_mkdirty(pmd_pte(pmd)))
267 #define pmd_mkyoung(pmd)	pte_pmd(pte_mkyoung(pmd_pte(pmd)))
268 #define pmd_mknotpresent(pmd)	(__pmd(pmd_val(pmd) & ~PMD_TYPE_MASK))
269 
270 #define __HAVE_ARCH_PMD_WRITE
271 #define pmd_write(pmd)		pte_write(pmd_pte(pmd))
272 
273 #define pmd_mkhuge(pmd)		(__pmd(pmd_val(pmd) & ~PMD_TABLE_BIT))
274 
275 #define pmd_pfn(pmd)		(((pmd_val(pmd) & PMD_MASK) & PHYS_MASK) >> PAGE_SHIFT)
276 #define pfn_pmd(pfn,prot)	(__pmd(((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)))
277 #define mk_pmd(page,prot)	pfn_pmd(page_to_pfn(page),prot)
278 
279 #define pmd_page(pmd)           pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
280 #define pud_pfn(pud)		(((pud_val(pud) & PUD_MASK) & PHYS_MASK) >> PAGE_SHIFT)
281 
282 #define set_pmd_at(mm, addr, pmdp, pmd)	set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd))
283 
284 static inline int has_transparent_hugepage(void)
285 {
286 	return 1;
287 }
288 
289 #define __pgprot_modify(prot,mask,bits) \
290 	__pgprot((pgprot_val(prot) & ~(mask)) | (bits))
291 
292 /*
293  * Mark the prot value as uncacheable and unbufferable.
294  */
295 #define pgprot_noncached(prot) \
296 	__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRnE) | PTE_PXN | PTE_UXN)
297 #define pgprot_writecombine(prot) \
298 	__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN)
299 #define __HAVE_PHYS_MEM_ACCESS_PROT
300 struct file;
301 extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
302 				     unsigned long size, pgprot_t vma_prot);
303 
304 #define pmd_none(pmd)		(!pmd_val(pmd))
305 #define pmd_present(pmd)	(pmd_val(pmd))
306 
307 #define pmd_bad(pmd)		(!(pmd_val(pmd) & 2))
308 
309 #define pmd_table(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
310 				 PMD_TYPE_TABLE)
311 #define pmd_sect(pmd)		((pmd_val(pmd) & PMD_TYPE_MASK) == \
312 				 PMD_TYPE_SECT)
313 
314 #ifdef CONFIG_ARM64_64K_PAGES
315 #define pud_sect(pud)		(0)
316 #else
317 #define pud_sect(pud)		((pud_val(pud) & PUD_TYPE_MASK) == \
318 				 PUD_TYPE_SECT)
319 #endif
320 
321 static inline void set_pmd(pmd_t *pmdp, pmd_t pmd)
322 {
323 	*pmdp = pmd;
324 	dsb(ishst);
325 	isb();
326 }
327 
328 static inline void pmd_clear(pmd_t *pmdp)
329 {
330 	set_pmd(pmdp, __pmd(0));
331 }
332 
333 static inline pte_t *pmd_page_vaddr(pmd_t pmd)
334 {
335 	return __va(pmd_val(pmd) & PHYS_MASK & (s32)PAGE_MASK);
336 }
337 
338 #define pmd_page(pmd)		pfn_to_page(__phys_to_pfn(pmd_val(pmd) & PHYS_MASK))
339 
340 /*
341  * Conversion functions: convert a page and protection to a page entry,
342  * and a page entry and page directory to the page they refer to.
343  */
344 #define mk_pte(page,prot)	pfn_pte(page_to_pfn(page),prot)
345 
346 #if CONFIG_ARM64_PGTABLE_LEVELS > 2
347 
348 #define pmd_ERROR(pmd)		__pmd_error(__FILE__, __LINE__, pmd_val(pmd))
349 
350 #define pud_none(pud)		(!pud_val(pud))
351 #define pud_bad(pud)		(!(pud_val(pud) & 2))
352 #define pud_present(pud)	(pud_val(pud))
353 
354 static inline void set_pud(pud_t *pudp, pud_t pud)
355 {
356 	*pudp = pud;
357 	dsb(ishst);
358 	isb();
359 }
360 
361 static inline void pud_clear(pud_t *pudp)
362 {
363 	set_pud(pudp, __pud(0));
364 }
365 
366 static inline pmd_t *pud_page_vaddr(pud_t pud)
367 {
368 	return __va(pud_val(pud) & PHYS_MASK & (s32)PAGE_MASK);
369 }
370 
371 /* Find an entry in the second-level page table. */
372 #define pmd_index(addr)		(((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1))
373 
374 static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr)
375 {
376 	return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(addr);
377 }
378 
379 #endif	/* CONFIG_ARM64_PGTABLE_LEVELS > 2 */
380 
381 #if CONFIG_ARM64_PGTABLE_LEVELS > 3
382 
383 #define pud_ERROR(pud)		__pud_error(__FILE__, __LINE__, pud_val(pud))
384 
385 #define pgd_none(pgd)		(!pgd_val(pgd))
386 #define pgd_bad(pgd)		(!(pgd_val(pgd) & 2))
387 #define pgd_present(pgd)	(pgd_val(pgd))
388 
389 static inline void set_pgd(pgd_t *pgdp, pgd_t pgd)
390 {
391 	*pgdp = pgd;
392 	dsb(ishst);
393 }
394 
395 static inline void pgd_clear(pgd_t *pgdp)
396 {
397 	set_pgd(pgdp, __pgd(0));
398 }
399 
400 static inline pud_t *pgd_page_vaddr(pgd_t pgd)
401 {
402 	return __va(pgd_val(pgd) & PHYS_MASK & (s32)PAGE_MASK);
403 }
404 
405 /* Find an entry in the frst-level page table. */
406 #define pud_index(addr)		(((addr) >> PUD_SHIFT) & (PTRS_PER_PUD - 1))
407 
408 static inline pud_t *pud_offset(pgd_t *pgd, unsigned long addr)
409 {
410 	return (pud_t *)pgd_page_vaddr(*pgd) + pud_index(addr);
411 }
412 
413 #endif  /* CONFIG_ARM64_PGTABLE_LEVELS > 3 */
414 
415 #define pgd_ERROR(pgd)		__pgd_error(__FILE__, __LINE__, pgd_val(pgd))
416 
417 /* to find an entry in a page-table-directory */
418 #define pgd_index(addr)		(((addr) >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1))
419 
420 #define pgd_offset(mm, addr)	((mm)->pgd+pgd_index(addr))
421 
422 /* to find an entry in a kernel page-table-directory */
423 #define pgd_offset_k(addr)	pgd_offset(&init_mm, addr)
424 
425 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
426 {
427 	const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY |
428 			      PTE_PROT_NONE | PTE_VALID | PTE_WRITE;
429 	pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask);
430 	return pte;
431 }
432 
433 static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
434 {
435 	return pte_pmd(pte_modify(pmd_pte(pmd), newprot));
436 }
437 
438 extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
439 extern pgd_t idmap_pg_dir[PTRS_PER_PGD];
440 
441 /*
442  * Encode and decode a swap entry:
443  *	bits 0-1:	present (must be zero)
444  *	bit  2:		PTE_FILE
445  *	bits 3-8:	swap type
446  *	bits 9-57:	swap offset
447  */
448 #define __SWP_TYPE_SHIFT	3
449 #define __SWP_TYPE_BITS		6
450 #define __SWP_OFFSET_BITS	49
451 #define __SWP_TYPE_MASK		((1 << __SWP_TYPE_BITS) - 1)
452 #define __SWP_OFFSET_SHIFT	(__SWP_TYPE_BITS + __SWP_TYPE_SHIFT)
453 #define __SWP_OFFSET_MASK	((1UL << __SWP_OFFSET_BITS) - 1)
454 
455 #define __swp_type(x)		(((x).val >> __SWP_TYPE_SHIFT) & __SWP_TYPE_MASK)
456 #define __swp_offset(x)		(((x).val >> __SWP_OFFSET_SHIFT) & __SWP_OFFSET_MASK)
457 #define __swp_entry(type,offset) ((swp_entry_t) { ((type) << __SWP_TYPE_SHIFT) | ((offset) << __SWP_OFFSET_SHIFT) })
458 
459 #define __pte_to_swp_entry(pte)	((swp_entry_t) { pte_val(pte) })
460 #define __swp_entry_to_pte(swp)	((pte_t) { (swp).val })
461 
462 /*
463  * Ensure that there are not more swap files than can be encoded in the kernel
464  * PTEs.
465  */
466 #define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > __SWP_TYPE_BITS)
467 
468 /*
469  * Encode and decode a file entry:
470  *	bits 0-1:	present (must be zero)
471  *	bit  2:		PTE_FILE
472  *	bits 3-57:	file offset / PAGE_SIZE
473  */
474 #define pte_file(pte)		(pte_val(pte) & PTE_FILE)
475 #define pte_to_pgoff(x)		(pte_val(x) >> 3)
476 #define pgoff_to_pte(x)		__pte(((x) << 3) | PTE_FILE)
477 
478 #define PTE_FILE_MAX_BITS	55
479 
480 extern int kern_addr_valid(unsigned long addr);
481 
482 #include <asm-generic/pgtable.h>
483 
484 #define pgtable_cache_init() do { } while (0)
485 
486 #endif /* !__ASSEMBLY__ */
487 
488 #endif /* __ASM_PGTABLE_H */
489