xref: /linux/arch/mips/include/asm/pgtable.h (revision 04303f8ec14269b0ea2553863553bc7eaadca1f8)
1 /*
2  * This file is subject to the terms and conditions of the GNU General Public
3  * License.  See the file "COPYING" in the main directory of this archive
4  * for more details.
5  *
6  * Copyright (C) 2003 Ralf Baechle
7  */
8 #ifndef _ASM_PGTABLE_H
9 #define _ASM_PGTABLE_H
10 
11 #include <linux/mm_types.h>
12 #include <linux/mmzone.h>
13 #ifdef CONFIG_32BIT
14 #include <asm/pgtable-32.h>
15 #endif
16 #ifdef CONFIG_64BIT
17 #include <asm/pgtable-64.h>
18 #endif
19 
20 #include <asm/io.h>
21 #include <asm/pgtable-bits.h>
22 
23 struct mm_struct;
24 struct vm_area_struct;
25 
26 #define PAGE_NONE	__pgprot(_PAGE_PRESENT | _CACHE_CACHABLE_NONCOHERENT)
27 #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_WRITE | (cpu_has_rixi ? 0 : _PAGE_READ) | \
28 				 _page_cachable_default)
29 #define PAGE_COPY	__pgprot(_PAGE_PRESENT | (cpu_has_rixi ? 0 : _PAGE_READ) | \
30 				 (cpu_has_rixi ?  _PAGE_NO_EXEC : 0) | _page_cachable_default)
31 #define PAGE_READONLY	__pgprot(_PAGE_PRESENT | (cpu_has_rixi ? 0 : _PAGE_READ) | \
32 				 _page_cachable_default)
33 #define PAGE_KERNEL	__pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
34 				 _PAGE_GLOBAL | _page_cachable_default)
35 #define PAGE_KERNEL_NC	__pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
36 				 _PAGE_GLOBAL | _CACHE_CACHABLE_NONCOHERENT)
37 #define PAGE_USERIO	__pgprot(_PAGE_PRESENT | (cpu_has_rixi ? 0 : _PAGE_READ) | _PAGE_WRITE | \
38 				 _page_cachable_default)
39 #define PAGE_KERNEL_UNCACHED __pgprot(_PAGE_PRESENT | __READABLE | \
40 			__WRITEABLE | _PAGE_GLOBAL | _CACHE_UNCACHED)
41 
42 /*
43  * If _PAGE_NO_EXEC is not defined, we can't do page protection for
44  * execute, and consider it to be the same as read. Also, write
45  * permissions imply read permissions. This is the closest we can get
46  * by reasonable means..
47  */
48 
49 /*
50  * Dummy values to fill the table in mmap.c
51  * The real values will be generated at runtime
52  */
53 #define __P000 __pgprot(0)
54 #define __P001 __pgprot(0)
55 #define __P010 __pgprot(0)
56 #define __P011 __pgprot(0)
57 #define __P100 __pgprot(0)
58 #define __P101 __pgprot(0)
59 #define __P110 __pgprot(0)
60 #define __P111 __pgprot(0)
61 
62 #define __S000 __pgprot(0)
63 #define __S001 __pgprot(0)
64 #define __S010 __pgprot(0)
65 #define __S011 __pgprot(0)
66 #define __S100 __pgprot(0)
67 #define __S101 __pgprot(0)
68 #define __S110 __pgprot(0)
69 #define __S111 __pgprot(0)
70 
71 extern unsigned long _page_cachable_default;
72 
73 /*
74  * ZERO_PAGE is a global shared page that is always zero; used
75  * for zero-mapped memory areas etc..
76  */
77 
78 extern unsigned long empty_zero_page;
79 extern unsigned long zero_page_mask;
80 
81 #define ZERO_PAGE(vaddr) \
82 	(virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask))))
83 #define __HAVE_COLOR_ZERO_PAGE
84 
85 extern void paging_init(void);
86 
87 /*
88  * Conversion functions: convert a page and protection to a page entry,
89  * and a page entry and page directory to the page they refer to.
90  */
91 #define pmd_phys(pmd)		virt_to_phys((void *)pmd_val(pmd))
92 
93 #define __pmd_page(pmd)		(pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT))
94 #ifndef CONFIG_TRANSPARENT_HUGEPAGE
95 #define pmd_page(pmd)		__pmd_page(pmd)
96 #endif /* CONFIG_TRANSPARENT_HUGEPAGE  */
97 
98 #define pmd_page_vaddr(pmd)	pmd_val(pmd)
99 
100 #define htw_stop()							\
101 do {									\
102 	if (cpu_has_htw)						\
103 		write_c0_pwctl(read_c0_pwctl() &			\
104 			       ~(1 << MIPS_PWCTL_PWEN_SHIFT));		\
105 } while(0)
106 
107 #define htw_start()							\
108 do {									\
109 	if (cpu_has_htw)						\
110 		write_c0_pwctl(read_c0_pwctl() |			\
111 			       (1 << MIPS_PWCTL_PWEN_SHIFT));		\
112 } while(0)
113 
114 
115 #define htw_reset()							\
116 do {									\
117 	if (cpu_has_htw) {						\
118 		htw_stop();						\
119 		back_to_back_c0_hazard();				\
120 		htw_start();						\
121 		back_to_back_c0_hazard();				\
122 	}								\
123 } while(0)
124 
125 extern void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
126 	pte_t pteval);
127 
128 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
129 
130 #define pte_none(pte)		(!(((pte).pte_low | (pte).pte_high) & ~_PAGE_GLOBAL))
131 #define pte_present(pte)	((pte).pte_low & _PAGE_PRESENT)
132 
133 static inline void set_pte(pte_t *ptep, pte_t pte)
134 {
135 	ptep->pte_high = pte.pte_high;
136 	smp_wmb();
137 	ptep->pte_low = pte.pte_low;
138 
139 	if (pte.pte_low & _PAGE_GLOBAL) {
140 		pte_t *buddy = ptep_buddy(ptep);
141 		/*
142 		 * Make sure the buddy is global too (if it's !none,
143 		 * it better already be global)
144 		 */
145 		if (pte_none(*buddy)) {
146 			buddy->pte_low	|= _PAGE_GLOBAL;
147 			buddy->pte_high |= _PAGE_GLOBAL;
148 		}
149 	}
150 }
151 
152 static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
153 {
154 	pte_t null = __pte(0);
155 
156 	/* Preserve global status for the pair */
157 	if (ptep_buddy(ptep)->pte_low & _PAGE_GLOBAL)
158 		null.pte_low = null.pte_high = _PAGE_GLOBAL;
159 
160 	set_pte_at(mm, addr, ptep, null);
161 	htw_reset();
162 }
163 #else
164 
165 #define pte_none(pte)		(!(pte_val(pte) & ~_PAGE_GLOBAL))
166 #define pte_present(pte)	(pte_val(pte) & _PAGE_PRESENT)
167 
168 /*
169  * Certain architectures need to do special things when pte's
170  * within a page table are directly modified.  Thus, the following
171  * hook is made available.
172  */
173 static inline void set_pte(pte_t *ptep, pte_t pteval)
174 {
175 	*ptep = pteval;
176 #if !defined(CONFIG_CPU_R3000) && !defined(CONFIG_CPU_TX39XX)
177 	if (pte_val(pteval) & _PAGE_GLOBAL) {
178 		pte_t *buddy = ptep_buddy(ptep);
179 		/*
180 		 * Make sure the buddy is global too (if it's !none,
181 		 * it better already be global)
182 		 */
183 		if (pte_none(*buddy))
184 			pte_val(*buddy) = pte_val(*buddy) | _PAGE_GLOBAL;
185 	}
186 #endif
187 }
188 
189 static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
190 {
191 #if !defined(CONFIG_CPU_R3000) && !defined(CONFIG_CPU_TX39XX)
192 	/* Preserve global status for the pair */
193 	if (pte_val(*ptep_buddy(ptep)) & _PAGE_GLOBAL)
194 		set_pte_at(mm, addr, ptep, __pte(_PAGE_GLOBAL));
195 	else
196 #endif
197 		set_pte_at(mm, addr, ptep, __pte(0));
198 	htw_reset();
199 }
200 #endif
201 
202 /*
203  * (pmds are folded into puds so this doesn't get actually called,
204  * but the define is needed for a generic inline function.)
205  */
206 #define set_pmd(pmdptr, pmdval) do { *(pmdptr) = (pmdval); } while(0)
207 
208 #ifndef __PAGETABLE_PMD_FOLDED
209 /*
210  * (puds are folded into pgds so this doesn't get actually called,
211  * but the define is needed for a generic inline function.)
212  */
213 #define set_pud(pudptr, pudval) do { *(pudptr) = (pudval); } while(0)
214 #endif
215 
216 #define PGD_T_LOG2	(__builtin_ffs(sizeof(pgd_t)) - 1)
217 #define PMD_T_LOG2	(__builtin_ffs(sizeof(pmd_t)) - 1)
218 #define PTE_T_LOG2	(__builtin_ffs(sizeof(pte_t)) - 1)
219 
220 /*
221  * We used to declare this array with size but gcc 3.3 and older are not able
222  * to find that this expression is a constant, so the size is dropped.
223  */
224 extern pgd_t swapper_pg_dir[];
225 
226 /*
227  * The following only work if pte_present() is true.
228  * Undefined behaviour if not..
229  */
230 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
231 static inline int pte_write(pte_t pte)	{ return pte.pte_low & _PAGE_WRITE; }
232 static inline int pte_dirty(pte_t pte)	{ return pte.pte_low & _PAGE_MODIFIED; }
233 static inline int pte_young(pte_t pte)	{ return pte.pte_low & _PAGE_ACCESSED; }
234 
235 static inline pte_t pte_wrprotect(pte_t pte)
236 {
237 	pte.pte_low  &= ~(_PAGE_WRITE | _PAGE_SILENT_WRITE);
238 	pte.pte_high &= ~_PAGE_SILENT_WRITE;
239 	return pte;
240 }
241 
242 static inline pte_t pte_mkclean(pte_t pte)
243 {
244 	pte.pte_low  &= ~(_PAGE_MODIFIED | _PAGE_SILENT_WRITE);
245 	pte.pte_high &= ~_PAGE_SILENT_WRITE;
246 	return pte;
247 }
248 
249 static inline pte_t pte_mkold(pte_t pte)
250 {
251 	pte.pte_low  &= ~(_PAGE_ACCESSED | _PAGE_SILENT_READ);
252 	pte.pte_high &= ~_PAGE_SILENT_READ;
253 	return pte;
254 }
255 
256 static inline pte_t pte_mkwrite(pte_t pte)
257 {
258 	pte.pte_low |= _PAGE_WRITE;
259 	if (pte.pte_low & _PAGE_MODIFIED) {
260 		pte.pte_low  |= _PAGE_SILENT_WRITE;
261 		pte.pte_high |= _PAGE_SILENT_WRITE;
262 	}
263 	return pte;
264 }
265 
266 static inline pte_t pte_mkdirty(pte_t pte)
267 {
268 	pte.pte_low |= _PAGE_MODIFIED;
269 	if (pte.pte_low & _PAGE_WRITE) {
270 		pte.pte_low  |= _PAGE_SILENT_WRITE;
271 		pte.pte_high |= _PAGE_SILENT_WRITE;
272 	}
273 	return pte;
274 }
275 
276 static inline pte_t pte_mkyoung(pte_t pte)
277 {
278 	pte.pte_low |= _PAGE_ACCESSED;
279 	if (pte.pte_low & _PAGE_READ) {
280 		pte.pte_low  |= _PAGE_SILENT_READ;
281 		pte.pte_high |= _PAGE_SILENT_READ;
282 	}
283 	return pte;
284 }
285 #else
286 static inline int pte_write(pte_t pte)	{ return pte_val(pte) & _PAGE_WRITE; }
287 static inline int pte_dirty(pte_t pte)	{ return pte_val(pte) & _PAGE_MODIFIED; }
288 static inline int pte_young(pte_t pte)	{ return pte_val(pte) & _PAGE_ACCESSED; }
289 
290 static inline pte_t pte_wrprotect(pte_t pte)
291 {
292 	pte_val(pte) &= ~(_PAGE_WRITE | _PAGE_SILENT_WRITE);
293 	return pte;
294 }
295 
296 static inline pte_t pte_mkclean(pte_t pte)
297 {
298 	pte_val(pte) &= ~(_PAGE_MODIFIED | _PAGE_SILENT_WRITE);
299 	return pte;
300 }
301 
302 static inline pte_t pte_mkold(pte_t pte)
303 {
304 	pte_val(pte) &= ~(_PAGE_ACCESSED | _PAGE_SILENT_READ);
305 	return pte;
306 }
307 
308 static inline pte_t pte_mkwrite(pte_t pte)
309 {
310 	pte_val(pte) |= _PAGE_WRITE;
311 	if (pte_val(pte) & _PAGE_MODIFIED)
312 		pte_val(pte) |= _PAGE_SILENT_WRITE;
313 	return pte;
314 }
315 
316 static inline pte_t pte_mkdirty(pte_t pte)
317 {
318 	pte_val(pte) |= _PAGE_MODIFIED;
319 	if (pte_val(pte) & _PAGE_WRITE)
320 		pte_val(pte) |= _PAGE_SILENT_WRITE;
321 	return pte;
322 }
323 
324 static inline pte_t pte_mkyoung(pte_t pte)
325 {
326 	pte_val(pte) |= _PAGE_ACCESSED;
327 	if (cpu_has_rixi) {
328 		if (!(pte_val(pte) & _PAGE_NO_READ))
329 			pte_val(pte) |= _PAGE_SILENT_READ;
330 	} else {
331 		if (pte_val(pte) & _PAGE_READ)
332 			pte_val(pte) |= _PAGE_SILENT_READ;
333 	}
334 	return pte;
335 }
336 
337 #ifdef _PAGE_HUGE
338 static inline int pte_huge(pte_t pte)	{ return pte_val(pte) & _PAGE_HUGE; }
339 
340 static inline pte_t pte_mkhuge(pte_t pte)
341 {
342 	pte_val(pte) |= _PAGE_HUGE;
343 	return pte;
344 }
345 #endif /* _PAGE_HUGE */
346 #endif
347 static inline int pte_special(pte_t pte)	{ return 0; }
348 static inline pte_t pte_mkspecial(pte_t pte)	{ return pte; }
349 
350 /*
351  * Macro to make mark a page protection value as "uncacheable".	 Note
352  * that "protection" is really a misnomer here as the protection value
353  * contains the memory attribute bits, dirty bits, and various other
354  * bits as well.
355  */
356 #define pgprot_noncached pgprot_noncached
357 
358 static inline pgprot_t pgprot_noncached(pgprot_t _prot)
359 {
360 	unsigned long prot = pgprot_val(_prot);
361 
362 	prot = (prot & ~_CACHE_MASK) | _CACHE_UNCACHED;
363 
364 	return __pgprot(prot);
365 }
366 
367 static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
368 {
369 	unsigned long prot = pgprot_val(_prot);
370 
371 	/* cpu_data[0].writecombine is already shifted by _CACHE_SHIFT */
372 	prot = (prot & ~_CACHE_MASK) | cpu_data[0].writecombine;
373 
374 	return __pgprot(prot);
375 }
376 
377 /*
378  * Conversion functions: convert a page and protection to a page entry,
379  * and a page entry and page directory to the page they refer to.
380  */
381 #define mk_pte(page, pgprot)	pfn_pte(page_to_pfn(page), (pgprot))
382 
383 #if defined(CONFIG_PHYS_ADDR_T_64BIT) && defined(CONFIG_CPU_MIPS32)
384 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
385 {
386 	pte.pte_low  &= _PAGE_CHG_MASK;
387 	pte.pte_high &= (_PFN_MASK | _CACHE_MASK);
388 	pte.pte_low  |= pgprot_val(newprot);
389 	pte.pte_high |= pgprot_val(newprot) & ~(_PFN_MASK | _CACHE_MASK);
390 	return pte;
391 }
392 #else
393 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
394 {
395 	return __pte((pte_val(pte) & _PAGE_CHG_MASK) | pgprot_val(newprot));
396 }
397 #endif
398 
399 
400 extern void __update_tlb(struct vm_area_struct *vma, unsigned long address,
401 	pte_t pte);
402 
403 static inline void update_mmu_cache(struct vm_area_struct *vma,
404 	unsigned long address, pte_t *ptep)
405 {
406 	pte_t pte = *ptep;
407 	__update_tlb(vma, address, pte);
408 }
409 
410 static inline void update_mmu_cache_pmd(struct vm_area_struct *vma,
411 	unsigned long address, pmd_t *pmdp)
412 {
413 	pte_t pte = *(pte_t *)pmdp;
414 
415 	__update_tlb(vma, address, pte);
416 }
417 
418 #define kern_addr_valid(addr)	(1)
419 
420 #ifdef CONFIG_PHYS_ADDR_T_64BIT
421 extern int remap_pfn_range(struct vm_area_struct *vma, unsigned long from, unsigned long pfn, unsigned long size, pgprot_t prot);
422 
423 static inline int io_remap_pfn_range(struct vm_area_struct *vma,
424 		unsigned long vaddr,
425 		unsigned long pfn,
426 		unsigned long size,
427 		pgprot_t prot)
428 {
429 	phys_addr_t phys_addr_high = fixup_bigphys_addr(pfn << PAGE_SHIFT, size);
430 	return remap_pfn_range(vma, vaddr, phys_addr_high >> PAGE_SHIFT, size, prot);
431 }
432 #define io_remap_pfn_range io_remap_pfn_range
433 #endif
434 
435 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
436 
437 extern int has_transparent_hugepage(void);
438 
439 static inline int pmd_trans_huge(pmd_t pmd)
440 {
441 	return !!(pmd_val(pmd) & _PAGE_HUGE);
442 }
443 
444 static inline pmd_t pmd_mkhuge(pmd_t pmd)
445 {
446 	pmd_val(pmd) |= _PAGE_HUGE;
447 
448 	return pmd;
449 }
450 
451 static inline int pmd_trans_splitting(pmd_t pmd)
452 {
453 	return !!(pmd_val(pmd) & _PAGE_SPLITTING);
454 }
455 
456 static inline pmd_t pmd_mksplitting(pmd_t pmd)
457 {
458 	pmd_val(pmd) |= _PAGE_SPLITTING;
459 
460 	return pmd;
461 }
462 
463 extern void set_pmd_at(struct mm_struct *mm, unsigned long addr,
464 		       pmd_t *pmdp, pmd_t pmd);
465 
466 #define __HAVE_ARCH_PMDP_SPLITTING_FLUSH
467 /* Extern to avoid header file madness */
468 extern void pmdp_splitting_flush(struct vm_area_struct *vma,
469 					unsigned long address,
470 					pmd_t *pmdp);
471 
472 #define __HAVE_ARCH_PMD_WRITE
473 static inline int pmd_write(pmd_t pmd)
474 {
475 	return !!(pmd_val(pmd) & _PAGE_WRITE);
476 }
477 
478 static inline pmd_t pmd_wrprotect(pmd_t pmd)
479 {
480 	pmd_val(pmd) &= ~(_PAGE_WRITE | _PAGE_SILENT_WRITE);
481 	return pmd;
482 }
483 
484 static inline pmd_t pmd_mkwrite(pmd_t pmd)
485 {
486 	pmd_val(pmd) |= _PAGE_WRITE;
487 	if (pmd_val(pmd) & _PAGE_MODIFIED)
488 		pmd_val(pmd) |= _PAGE_SILENT_WRITE;
489 
490 	return pmd;
491 }
492 
493 static inline int pmd_dirty(pmd_t pmd)
494 {
495 	return !!(pmd_val(pmd) & _PAGE_MODIFIED);
496 }
497 
498 static inline pmd_t pmd_mkclean(pmd_t pmd)
499 {
500 	pmd_val(pmd) &= ~(_PAGE_MODIFIED | _PAGE_SILENT_WRITE);
501 	return pmd;
502 }
503 
504 static inline pmd_t pmd_mkdirty(pmd_t pmd)
505 {
506 	pmd_val(pmd) |= _PAGE_MODIFIED;
507 	if (pmd_val(pmd) & _PAGE_WRITE)
508 		pmd_val(pmd) |= _PAGE_SILENT_WRITE;
509 
510 	return pmd;
511 }
512 
513 static inline int pmd_young(pmd_t pmd)
514 {
515 	return !!(pmd_val(pmd) & _PAGE_ACCESSED);
516 }
517 
518 static inline pmd_t pmd_mkold(pmd_t pmd)
519 {
520 	pmd_val(pmd) &= ~(_PAGE_ACCESSED|_PAGE_SILENT_READ);
521 
522 	return pmd;
523 }
524 
525 static inline pmd_t pmd_mkyoung(pmd_t pmd)
526 {
527 	pmd_val(pmd) |= _PAGE_ACCESSED;
528 
529 	if (cpu_has_rixi) {
530 		if (!(pmd_val(pmd) & _PAGE_NO_READ))
531 			pmd_val(pmd) |= _PAGE_SILENT_READ;
532 	} else {
533 		if (pmd_val(pmd) & _PAGE_READ)
534 			pmd_val(pmd) |= _PAGE_SILENT_READ;
535 	}
536 
537 	return pmd;
538 }
539 
540 /* Extern to avoid header file madness */
541 extern pmd_t mk_pmd(struct page *page, pgprot_t prot);
542 
543 static inline unsigned long pmd_pfn(pmd_t pmd)
544 {
545 	return pmd_val(pmd) >> _PFN_SHIFT;
546 }
547 
548 static inline struct page *pmd_page(pmd_t pmd)
549 {
550 	if (pmd_trans_huge(pmd))
551 		return pfn_to_page(pmd_pfn(pmd));
552 
553 	return pfn_to_page(pmd_phys(pmd) >> PAGE_SHIFT);
554 }
555 
556 static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot)
557 {
558 	pmd_val(pmd) = (pmd_val(pmd) & _PAGE_CHG_MASK) | pgprot_val(newprot);
559 	return pmd;
560 }
561 
562 static inline pmd_t pmd_mknotpresent(pmd_t pmd)
563 {
564 	pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY);
565 
566 	return pmd;
567 }
568 
569 /*
570  * The generic version pmdp_get_and_clear uses a version of pmd_clear() with a
571  * different prototype.
572  */
573 #define __HAVE_ARCH_PMDP_GET_AND_CLEAR
574 static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm,
575 				       unsigned long address, pmd_t *pmdp)
576 {
577 	pmd_t old = *pmdp;
578 
579 	pmd_clear(pmdp);
580 
581 	return old;
582 }
583 
584 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
585 
586 #include <asm-generic/pgtable.h>
587 
588 /*
589  * uncached accelerated TLB map for video memory access
590  */
591 #ifdef CONFIG_CPU_SUPPORTS_UNCACHED_ACCELERATED
592 #define __HAVE_PHYS_MEM_ACCESS_PROT
593 
594 struct file;
595 pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
596 		unsigned long size, pgprot_t vma_prot);
597 int phys_mem_access_prot_allowed(struct file *file, unsigned long pfn,
598 		unsigned long size, pgprot_t *vma_prot);
599 #endif
600 
601 /*
602  * We provide our own get_unmapped area to cope with the virtual aliasing
603  * constraints placed on us by the cache architecture.
604  */
605 #define HAVE_ARCH_UNMAPPED_AREA
606 #define HAVE_ARCH_UNMAPPED_AREA_TOPDOWN
607 
608 /*
609  * No page table caches to initialise
610  */
611 #define pgtable_cache_init()	do { } while (0)
612 
613 #endif /* _ASM_PGTABLE_H */
614