blob: ff4947b7a9762b6ea414aa8b0159af8abb90e9dc [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001#ifndef _ASM_GENERIC_PGTABLE_H
2#define _ASM_GENERIC_PGTABLE_H
3
Rusty Russell673eae82006-09-25 23:32:29 -07004#ifndef __ASSEMBLY__
Greg Ungerer95352392007-08-10 13:01:20 -07005#ifdef CONFIG_MMU
Rusty Russell673eae82006-09-25 23:32:29 -07006
Ben Hutchingsfbd71842011-02-27 05:41:35 +00007#include <linux/mm_types.h>
Paul Gortmaker187f1882011-11-23 20:12:59 -05008#include <linux/bug.h>
Ben Hutchingsfbd71842011-02-27 05:41:35 +00009
Linus Torvalds1da177e2005-04-16 15:20:36 -070010#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
Andrea Arcangelie2cda322011-01-13 15:46:40 -080011extern int ptep_set_access_flags(struct vm_area_struct *vma,
12 unsigned long address, pte_t *ptep,
13 pte_t entry, int dirty);
14#endif
15
16#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
17extern int pmdp_set_access_flags(struct vm_area_struct *vma,
18 unsigned long address, pmd_t *pmdp,
19 pmd_t entry, int dirty);
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#endif
21
22#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
Andrea Arcangelie2cda322011-01-13 15:46:40 -080023static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
24 unsigned long address,
25 pte_t *ptep)
26{
27 pte_t pte = *ptep;
28 int r = 1;
29 if (!pte_young(pte))
30 r = 0;
31 else
32 set_pte_at(vma->vm_mm, address, ptep, pte_mkold(pte));
33 return r;
34}
35#endif
36
37#ifndef __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG
38#ifdef CONFIG_TRANSPARENT_HUGEPAGE
39static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
40 unsigned long address,
41 pmd_t *pmdp)
42{
43 pmd_t pmd = *pmdp;
44 int r = 1;
45 if (!pmd_young(pmd))
46 r = 0;
47 else
48 set_pmd_at(vma->vm_mm, address, pmdp, pmd_mkold(pmd));
49 return r;
50}
51#else /* CONFIG_TRANSPARENT_HUGEPAGE */
52static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma,
53 unsigned long address,
54 pmd_t *pmdp)
55{
56 BUG();
57 return 0;
58}
59#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
Linus Torvalds1da177e2005-04-16 15:20:36 -070060#endif
61
62#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
Andrea Arcangelie2cda322011-01-13 15:46:40 -080063int ptep_clear_flush_young(struct vm_area_struct *vma,
64 unsigned long address, pte_t *ptep);
65#endif
66
67#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
68int pmdp_clear_flush_young(struct vm_area_struct *vma,
69 unsigned long address, pmd_t *pmdp);
Linus Torvalds1da177e2005-04-16 15:20:36 -070070#endif
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
Andrea Arcangelie2cda322011-01-13 15:46:40 -080073static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
74 unsigned long address,
75 pte_t *ptep)
76{
77 pte_t pte = *ptep;
78 pte_clear(mm, address, ptep);
79 return pte;
80}
81#endif
82
83#ifndef __HAVE_ARCH_PMDP_GET_AND_CLEAR
84#ifdef CONFIG_TRANSPARENT_HUGEPAGE
85static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm,
86 unsigned long address,
87 pmd_t *pmdp)
88{
89 pmd_t pmd = *pmdp;
90 pmd_clear(mm, address, pmdp);
91 return pmd;
Nicolas Kaiser49b24d62011-06-15 15:08:34 -070092}
Andrea Arcangelie2cda322011-01-13 15:46:40 -080093#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
Linus Torvalds1da177e2005-04-16 15:20:36 -070094#endif
95
Zachary Amsdena6003882005-09-03 15:55:04 -070096#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL
Andrea Arcangelie2cda322011-01-13 15:46:40 -080097static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm,
98 unsigned long address, pte_t *ptep,
99 int full)
100{
101 pte_t pte;
102 pte = ptep_get_and_clear(mm, address, ptep);
103 return pte;
104}
Zachary Amsdena6003882005-09-03 15:55:04 -0700105#endif
106
Zachary Amsden9888a1c2006-09-30 23:29:31 -0700107/*
108 * Some architectures may be able to avoid expensive synchronization
109 * primitives when modifications are made to PTE's which are already
110 * not present, or in the process of an address space destruction.
111 */
112#ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL
Andrea Arcangelie2cda322011-01-13 15:46:40 -0800113static inline void pte_clear_not_present_full(struct mm_struct *mm,
114 unsigned long address,
115 pte_t *ptep,
116 int full)
117{
118 pte_clear(mm, address, ptep);
119}
Zachary Amsdena6003882005-09-03 15:55:04 -0700120#endif
121
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
Andrea Arcangelie2cda322011-01-13 15:46:40 -0800123extern pte_t ptep_clear_flush(struct vm_area_struct *vma,
124 unsigned long address,
125 pte_t *ptep);
126#endif
127
128#ifndef __HAVE_ARCH_PMDP_CLEAR_FLUSH
129extern pmd_t pmdp_clear_flush(struct vm_area_struct *vma,
130 unsigned long address,
131 pmd_t *pmdp);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700132#endif
133
134#ifndef __HAVE_ARCH_PTEP_SET_WRPROTECT
Tim Schmielau8c65b4a2005-11-07 00:59:43 -0800135struct mm_struct;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700136static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep)
137{
138 pte_t old_pte = *ptep;
139 set_pte_at(mm, address, ptep, pte_wrprotect(old_pte));
140}
141#endif
142
Andrea Arcangelie2cda322011-01-13 15:46:40 -0800143#ifndef __HAVE_ARCH_PMDP_SET_WRPROTECT
144#ifdef CONFIG_TRANSPARENT_HUGEPAGE
145static inline void pmdp_set_wrprotect(struct mm_struct *mm,
146 unsigned long address, pmd_t *pmdp)
147{
148 pmd_t old_pmd = *pmdp;
149 set_pmd_at(mm, address, pmdp, pmd_wrprotect(old_pmd));
150}
151#else /* CONFIG_TRANSPARENT_HUGEPAGE */
152static inline void pmdp_set_wrprotect(struct mm_struct *mm,
153 unsigned long address, pmd_t *pmdp)
154{
155 BUG();
156}
157#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
158#endif
159
160#ifndef __HAVE_ARCH_PMDP_SPLITTING_FLUSH
Chris Metcalf73636b12012-03-28 13:59:18 -0400161extern void pmdp_splitting_flush(struct vm_area_struct *vma,
162 unsigned long address, pmd_t *pmdp);
Andrea Arcangelie2cda322011-01-13 15:46:40 -0800163#endif
164
Linus Torvalds1da177e2005-04-16 15:20:36 -0700165#ifndef __HAVE_ARCH_PTE_SAME
Andrea Arcangelie2cda322011-01-13 15:46:40 -0800166static inline int pte_same(pte_t pte_a, pte_t pte_b)
167{
168 return pte_val(pte_a) == pte_val(pte_b);
169}
170#endif
171
172#ifndef __HAVE_ARCH_PMD_SAME
173#ifdef CONFIG_TRANSPARENT_HUGEPAGE
174static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
175{
176 return pmd_val(pmd_a) == pmd_val(pmd_b);
177}
178#else /* CONFIG_TRANSPARENT_HUGEPAGE */
179static inline int pmd_same(pmd_t pmd_a, pmd_t pmd_b)
180{
181 BUG();
182 return 0;
183}
184#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185#endif
186
Martin Schwidefsky2d425522011-05-23 10:24:39 +0200187#ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY
188#define page_test_and_clear_dirty(pfn, mapped) (0)
Martin Schwidefsky6c210482007-04-27 16:01:57 +0200189#endif
190
Martin Schwidefsky2d425522011-05-23 10:24:39 +0200191#ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_DIRTY
Abhijit Karmarkarb4955ce2005-06-21 17:15:13 -0700192#define pte_maybe_dirty(pte) pte_dirty(pte)
193#else
194#define pte_maybe_dirty(pte) (1)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700195#endif
196
197#ifndef __HAVE_ARCH_PAGE_TEST_AND_CLEAR_YOUNG
Martin Schwidefsky2d425522011-05-23 10:24:39 +0200198#define page_test_and_clear_young(pfn) (0)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700199#endif
200
201#ifndef __HAVE_ARCH_PGD_OFFSET_GATE
202#define pgd_offset_gate(mm, addr) pgd_offset(mm, addr)
203#endif
204
David S. Miller0b0968a2006-06-01 17:47:25 -0700205#ifndef __HAVE_ARCH_MOVE_PTE
Nick Piggin8b1f3122005-09-27 21:45:18 -0700206#define move_pte(pte, prot, old_addr, new_addr) (pte)
Nick Piggin8b1f3122005-09-27 21:45:18 -0700207#endif
208
Shaohua Li61c77322010-08-16 09:16:55 +0800209#ifndef flush_tlb_fix_spurious_fault
210#define flush_tlb_fix_spurious_fault(vma, address) flush_tlb_page(vma, address)
211#endif
212
Paul Mundt0634a632009-06-23 13:51:19 +0200213#ifndef pgprot_noncached
214#define pgprot_noncached(prot) (prot)
215#endif
216
venkatesh.pallipadi@intel.com2520bd32008-12-18 11:41:32 -0800217#ifndef pgprot_writecombine
218#define pgprot_writecombine pgprot_noncached
219#endif
220
Linus Torvalds1da177e2005-04-16 15:20:36 -0700221/*
Hugh Dickins8f6c99c2005-04-19 13:29:17 -0700222 * When walking page tables, get the address of the next boundary,
223 * or the end address of the range if that comes earlier. Although no
224 * vma end wraps to 0, rounded up __boundary may wrap to 0 throughout.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225 */
226
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227#define pgd_addr_end(addr, end) \
228({ unsigned long __boundary = ((addr) + PGDIR_SIZE) & PGDIR_MASK; \
229 (__boundary - 1 < (end) - 1)? __boundary: (end); \
230})
Linus Torvalds1da177e2005-04-16 15:20:36 -0700231
232#ifndef pud_addr_end
233#define pud_addr_end(addr, end) \
234({ unsigned long __boundary = ((addr) + PUD_SIZE) & PUD_MASK; \
235 (__boundary - 1 < (end) - 1)? __boundary: (end); \
236})
237#endif
238
239#ifndef pmd_addr_end
240#define pmd_addr_end(addr, end) \
241({ unsigned long __boundary = ((addr) + PMD_SIZE) & PMD_MASK; \
242 (__boundary - 1 < (end) - 1)? __boundary: (end); \
243})
244#endif
245
Linus Torvalds1da177e2005-04-16 15:20:36 -0700246/*
247 * When walking page tables, we usually want to skip any p?d_none entries;
248 * and any p?d_bad entries - reporting the error before resetting to none.
249 * Do the tests inline, but report and clear the bad entry in mm/memory.c.
250 */
251void pgd_clear_bad(pgd_t *);
252void pud_clear_bad(pud_t *);
253void pmd_clear_bad(pmd_t *);
254
255static inline int pgd_none_or_clear_bad(pgd_t *pgd)
256{
257 if (pgd_none(*pgd))
258 return 1;
259 if (unlikely(pgd_bad(*pgd))) {
260 pgd_clear_bad(pgd);
261 return 1;
262 }
263 return 0;
264}
265
266static inline int pud_none_or_clear_bad(pud_t *pud)
267{
268 if (pud_none(*pud))
269 return 1;
270 if (unlikely(pud_bad(*pud))) {
271 pud_clear_bad(pud);
272 return 1;
273 }
274 return 0;
275}
276
277static inline int pmd_none_or_clear_bad(pmd_t *pmd)
278{
279 if (pmd_none(*pmd))
280 return 1;
281 if (unlikely(pmd_bad(*pmd))) {
282 pmd_clear_bad(pmd);
283 return 1;
284 }
285 return 0;
286}
Greg Ungerer95352392007-08-10 13:01:20 -0700287
Jeremy Fitzhardinge1ea07042008-06-16 04:30:00 -0700288static inline pte_t __ptep_modify_prot_start(struct mm_struct *mm,
289 unsigned long addr,
290 pte_t *ptep)
291{
292 /*
293 * Get the current pte state, but zero it out to make it
294 * non-present, preventing the hardware from asynchronously
295 * updating it.
296 */
297 return ptep_get_and_clear(mm, addr, ptep);
298}
299
300static inline void __ptep_modify_prot_commit(struct mm_struct *mm,
301 unsigned long addr,
302 pte_t *ptep, pte_t pte)
303{
304 /*
305 * The pte is non-present, so there's no hardware state to
306 * preserve.
307 */
308 set_pte_at(mm, addr, ptep, pte);
309}
310
311#ifndef __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION
312/*
313 * Start a pte protection read-modify-write transaction, which
314 * protects against asynchronous hardware modifications to the pte.
315 * The intention is not to prevent the hardware from making pte
316 * updates, but to prevent any updates it may make from being lost.
317 *
318 * This does not protect against other software modifications of the
319 * pte; the appropriate pte lock must be held over the transation.
320 *
321 * Note that this interface is intended to be batchable, meaning that
322 * ptep_modify_prot_commit may not actually update the pte, but merely
323 * queue the update to be done at some later time. The update must be
324 * actually committed before the pte lock is released, however.
325 */
326static inline pte_t ptep_modify_prot_start(struct mm_struct *mm,
327 unsigned long addr,
328 pte_t *ptep)
329{
330 return __ptep_modify_prot_start(mm, addr, ptep);
331}
332
333/*
334 * Commit an update to a pte, leaving any hardware-controlled bits in
335 * the PTE unmodified.
336 */
337static inline void ptep_modify_prot_commit(struct mm_struct *mm,
338 unsigned long addr,
339 pte_t *ptep, pte_t pte)
340{
341 __ptep_modify_prot_commit(mm, addr, ptep, pte);
342}
343#endif /* __HAVE_ARCH_PTEP_MODIFY_PROT_TRANSACTION */
Sebastian Siewiorfe1a6872008-07-15 22:28:46 +0200344#endif /* CONFIG_MMU */
Jeremy Fitzhardinge1ea07042008-06-16 04:30:00 -0700345
Greg Ungerer95352392007-08-10 13:01:20 -0700346/*
347 * A facility to provide lazy MMU batching. This allows PTE updates and
348 * page invalidations to be delayed until a call to leave lazy MMU mode
349 * is issued. Some architectures may benefit from doing this, and it is
350 * beneficial for both shadow and direct mode hypervisors, which may batch
351 * the PTE updates which happen during this window. Note that using this
352 * interface requires that read hazards be removed from the code. A read
353 * hazard could result in the direct mode hypervisor case, since the actual
354 * write to the page tables may not yet have taken place, so reads though
355 * a raw PTE pointer after it has been modified are not guaranteed to be
356 * up to date. This mode can only be entered and left under the protection of
357 * the page table locks for all page tables which may be modified. In the UP
358 * case, this is required so that preemption is disabled, and in the SMP case,
359 * it must synchronize the delayed page table writes properly on other CPUs.
360 */
361#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
362#define arch_enter_lazy_mmu_mode() do {} while (0)
363#define arch_leave_lazy_mmu_mode() do {} while (0)
364#define arch_flush_lazy_mmu_mode() do {} while (0)
365#endif
366
367/*
Jeremy Fitzhardinge7fd7d832009-02-17 23:24:03 -0800368 * A facility to provide batching of the reload of page tables and
369 * other process state with the actual context switch code for
370 * paravirtualized guests. By convention, only one of the batched
371 * update (lazy) modes (CPU, MMU) should be active at any given time,
372 * entry should never be nested, and entry and exits should always be
373 * paired. This is for sanity of maintaining and reasoning about the
374 * kernel code. In this case, the exit (end of the context switch) is
375 * in architecture-specific code, and so doesn't need a generic
376 * definition.
Greg Ungerer95352392007-08-10 13:01:20 -0700377 */
Jeremy Fitzhardinge7fd7d832009-02-17 23:24:03 -0800378#ifndef __HAVE_ARCH_START_CONTEXT_SWITCH
Jeremy Fitzhardinge224101e2009-02-18 11:18:57 -0800379#define arch_start_context_switch(prev) do {} while (0)
Greg Ungerer95352392007-08-10 13:01:20 -0700380#endif
381
venkatesh.pallipadi@intel.com34801ba2008-12-19 13:47:29 -0800382#ifndef __HAVE_PFNMAP_TRACKING
383/*
384 * Interface that can be used by architecture code to keep track of
385 * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
386 *
387 * track_pfn_vma_new is called when a _new_ pfn mapping is being established
388 * for physical range indicated by pfn and size.
389 */
venkatesh.pallipadi@intel.come4b866e2009-01-09 16:13:11 -0800390static inline int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
venkatesh.pallipadi@intel.com34801ba2008-12-19 13:47:29 -0800391 unsigned long pfn, unsigned long size)
392{
393 return 0;
394}
395
396/*
397 * Interface that can be used by architecture code to keep track of
398 * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
399 *
400 * track_pfn_vma_copy is called when vma that is covering the pfnmap gets
401 * copied through copy_page_range().
402 */
403static inline int track_pfn_vma_copy(struct vm_area_struct *vma)
404{
405 return 0;
406}
407
408/*
409 * Interface that can be used by architecture code to keep track of
410 * memory type of pfn mappings (remap_pfn_range, vm_insert_pfn)
411 *
412 * untrack_pfn_vma is called while unmapping a pfnmap for a region.
413 * untrack can be called for a specific region indicated by pfn and size or
414 * can be for the entire vma (in which case size can be zero).
415 */
416static inline void untrack_pfn_vma(struct vm_area_struct *vma,
417 unsigned long pfn, unsigned long size)
418{
419}
420#else
venkatesh.pallipadi@intel.come4b866e2009-01-09 16:13:11 -0800421extern int track_pfn_vma_new(struct vm_area_struct *vma, pgprot_t *prot,
venkatesh.pallipadi@intel.com34801ba2008-12-19 13:47:29 -0800422 unsigned long pfn, unsigned long size);
423extern int track_pfn_vma_copy(struct vm_area_struct *vma);
424extern void untrack_pfn_vma(struct vm_area_struct *vma, unsigned long pfn,
425 unsigned long size);
426#endif
427
Andrea Arcangeli1a5a9902012-03-21 16:33:42 -0700428#ifdef CONFIG_MMU
429
Andrea Arcangeli5f6e8da2011-01-13 15:46:40 -0800430#ifndef CONFIG_TRANSPARENT_HUGEPAGE
431static inline int pmd_trans_huge(pmd_t pmd)
432{
433 return 0;
434}
435static inline int pmd_trans_splitting(pmd_t pmd)
436{
437 return 0;
438}
Andrea Arcangelie2cda322011-01-13 15:46:40 -0800439#ifndef __HAVE_ARCH_PMD_WRITE
440static inline int pmd_write(pmd_t pmd)
441{
442 BUG();
443 return 0;
444}
445#endif /* __HAVE_ARCH_PMD_WRITE */
Andrea Arcangeli1a5a9902012-03-21 16:33:42 -0700446#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
447
Andrea Arcangeli26c19172012-05-29 15:06:49 -0700448#ifndef pmd_read_atomic
449static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
450{
451 /*
452 * Depend on compiler for an atomic pmd read. NOTE: this is
453 * only going to work, if the pmdval_t isn't larger than
454 * an unsigned long.
455 */
456 return *pmdp;
457}
458#endif
459
Andrea Arcangeli1a5a9902012-03-21 16:33:42 -0700460/*
461 * This function is meant to be used by sites walking pagetables with
462 * the mmap_sem hold in read mode to protect against MADV_DONTNEED and
463 * transhuge page faults. MADV_DONTNEED can convert a transhuge pmd
464 * into a null pmd and the transhuge page fault can convert a null pmd
465 * into an hugepmd or into a regular pmd (if the hugepage allocation
466 * fails). While holding the mmap_sem in read mode the pmd becomes
467 * stable and stops changing under us only if it's not null and not a
468 * transhuge pmd. When those races occurs and this function makes a
469 * difference vs the standard pmd_none_or_clear_bad, the result is
470 * undefined so behaving like if the pmd was none is safe (because it
471 * can return none anyway). The compiler level barrier() is critically
472 * important to compute the two checks atomically on the same pmdval.
Andrea Arcangeli26c19172012-05-29 15:06:49 -0700473 *
474 * For 32bit kernels with a 64bit large pmd_t this automatically takes
475 * care of reading the pmd atomically to avoid SMP race conditions
476 * against pmd_populate() when the mmap_sem is hold for reading by the
477 * caller (a special atomic read not done by "gcc" as in the generic
478 * version above, is also needed when THP is disabled because the page
479 * fault can populate the pmd from under us).
Andrea Arcangeli1a5a9902012-03-21 16:33:42 -0700480 */
481static inline int pmd_none_or_trans_huge_or_clear_bad(pmd_t *pmd)
482{
Andrea Arcangeli26c19172012-05-29 15:06:49 -0700483 pmd_t pmdval = pmd_read_atomic(pmd);
Andrea Arcangeli1a5a9902012-03-21 16:33:42 -0700484 /*
485 * The barrier will stabilize the pmdval in a register or on
486 * the stack so that it will stop changing under the code.
Andrea Arcangelie4eed032012-06-20 12:52:57 -0700487 *
488 * When CONFIG_TRANSPARENT_HUGEPAGE=y on x86 32bit PAE,
489 * pmd_read_atomic is allowed to return a not atomic pmdval
490 * (for example pointing to an hugepage that has never been
491 * mapped in the pmd). The below checks will only care about
492 * the low part of the pmd with 32bit PAE x86 anyway, with the
493 * exception of pmd_none(). So the important thing is that if
494 * the low part of the pmd is found null, the high part will
495 * be also null or the pmd_none() check below would be
496 * confused.
Andrea Arcangeli1a5a9902012-03-21 16:33:42 -0700497 */
498#ifdef CONFIG_TRANSPARENT_HUGEPAGE
499 barrier();
Andrea Arcangeli5f6e8da2011-01-13 15:46:40 -0800500#endif
Andrea Arcangeli1a5a9902012-03-21 16:33:42 -0700501 if (pmd_none(pmdval))
502 return 1;
503 if (unlikely(pmd_bad(pmdval))) {
504 if (!pmd_trans_huge(pmdval))
505 pmd_clear_bad(pmd);
506 return 1;
507 }
508 return 0;
509}
510
511/*
512 * This is a noop if Transparent Hugepage Support is not built into
513 * the kernel. Otherwise it is equivalent to
514 * pmd_none_or_trans_huge_or_clear_bad(), and shall only be called in
515 * places that already verified the pmd is not none and they want to
516 * walk ptes while holding the mmap sem in read mode (write mode don't
517 * need this). If THP is not enabled, the pmd can't go away under the
518 * code even if MADV_DONTNEED runs, but if THP is enabled we need to
519 * run a pmd_trans_unstable before walking the ptes after
520 * split_huge_page_pmd returns (because it may have run when the pmd
521 * become null, but then a page fault can map in a THP and not a
522 * regular page).
523 */
524static inline int pmd_trans_unstable(pmd_t *pmd)
525{
526#ifdef CONFIG_TRANSPARENT_HUGEPAGE
527 return pmd_none_or_trans_huge_or_clear_bad(pmd);
528#else
529 return 0;
530#endif
531}
532
533#endif /* CONFIG_MMU */
Andrea Arcangeli5f6e8da2011-01-13 15:46:40 -0800534
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535#endif /* !__ASSEMBLY__ */
536
537#endif /* _ASM_GENERIC_PGTABLE_H */