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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * mm/pgtable-generic.c
4 *
5 * Generic pgtable methods declared in asm-generic/pgtable.h
6 *
7 * Copyright (C) 2010 Linus Torvalds
8 */
9
10#include <linux/pagemap.h>
11#include <linux/hugetlb.h>
12#include <asm/tlb.h>
13#include <asm-generic/pgtable.h>
14
15/*
16 * If a p?d_bad entry is found while walking page tables, report
17 * the error, before resetting entry to p?d_none. Usually (but
18 * very seldom) called out from the p?d_none_or_clear_bad macros.
19 */
20
21void pgd_clear_bad(pgd_t *pgd)
22{
23 pgd_ERROR(*pgd);
24 pgd_clear(pgd);
25}
26
27void p4d_clear_bad(p4d_t *p4d)
28{
29 p4d_ERROR(*p4d);
30 p4d_clear(p4d);
31}
32
33void pud_clear_bad(pud_t *pud)
34{
35 pud_ERROR(*pud);
36 pud_clear(pud);
37}
38
39void pmd_clear_bad(pmd_t *pmd)
40{
41 pmd_ERROR(*pmd);
42 pmd_clear(pmd);
43}
44
45#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
46/*
47 * Only sets the access flags (dirty, accessed), as well as write
48 * permission. Furthermore, we know it always gets set to a "more
49 * permissive" setting, which allows most architectures to optimize
50 * this. We return whether the PTE actually changed, which in turn
51 * instructs the caller to do things like update__mmu_cache. This
52 * used to be done in the caller, but sparc needs minor faults to
53 * force that call on sun4c so we changed this macro slightly
54 */
55int ptep_set_access_flags(struct vm_area_struct *vma,
56 unsigned long address, pte_t *ptep,
57 pte_t entry, int dirty)
58{
59 int changed = !pte_same(*ptep, entry);
60 if (changed) {
61 set_pte_at(vma->vm_mm, address, ptep, entry);
62 flush_tlb_fix_spurious_fault(vma, address);
63 }
64 return changed;
65}
66#endif
67
68#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
69int ptep_clear_flush_young(struct vm_area_struct *vma,
70 unsigned long address, pte_t *ptep)
71{
72 int young;
73 young = ptep_test_and_clear_young(vma, address, ptep);
74 if (young)
75 flush_tlb_page(vma, address);
76 return young;
77}
78#endif
79
80#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
81pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
82 pte_t *ptep)
83{
84 struct mm_struct *mm = (vma)->vm_mm;
85 pte_t pte;
86 pte = ptep_get_and_clear(mm, address, ptep);
87 if (pte_accessible(mm, pte))
88 flush_tlb_page(vma, address);
89 return pte;
90}
91#endif
92
93#ifdef CONFIG_TRANSPARENT_HUGEPAGE
94
95#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
96int pmdp_set_access_flags(struct vm_area_struct *vma,
97 unsigned long address, pmd_t *pmdp,
98 pmd_t entry, int dirty)
99{
100 int changed = !pmd_same(*pmdp, entry);
101 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
102 if (changed) {
103 set_pmd_at(vma->vm_mm, address, pmdp, entry);
104 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
105 }
106 return changed;
107}
108#endif
109
110#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
111int pmdp_clear_flush_young(struct vm_area_struct *vma,
112 unsigned long address, pmd_t *pmdp)
113{
114 int young;
115 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
116 young = pmdp_test_and_clear_young(vma, address, pmdp);
117 if (young)
118 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
119 return young;
120}
121#endif
122
123#ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
124pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
125 pmd_t *pmdp)
126{
127 pmd_t pmd;
128 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
129 VM_BUG_ON((pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) &&
130 !pmd_devmap(*pmdp)) || !pmd_present(*pmdp));
131 pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
132 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
133 return pmd;
134}
135
136#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
137pud_t pudp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
138 pud_t *pudp)
139{
140 pud_t pud;
141
142 VM_BUG_ON(address & ~HPAGE_PUD_MASK);
143 VM_BUG_ON(!pud_trans_huge(*pudp) && !pud_devmap(*pudp));
144 pud = pudp_huge_get_and_clear(vma->vm_mm, address, pudp);
145 flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
146 return pud;
147}
148#endif
149#endif
150
151#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
152void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
153 pgtable_t pgtable)
154{
155 assert_spin_locked(pmd_lockptr(mm, pmdp));
156
157 /* FIFO */
158 if (!pmd_huge_pte(mm, pmdp))
159 INIT_LIST_HEAD(&pgtable->lru);
160 else
161 list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
162 pmd_huge_pte(mm, pmdp) = pgtable;
163}
164#endif
165
166#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
167/* no "address" argument so destroys page coloring of some arch */
168pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
169{
170 pgtable_t pgtable;
171
172 assert_spin_locked(pmd_lockptr(mm, pmdp));
173
174 /* FIFO */
175 pgtable = pmd_huge_pte(mm, pmdp);
176 pmd_huge_pte(mm, pmdp) = list_first_entry_or_null(&pgtable->lru,
177 struct page, lru);
178 if (pmd_huge_pte(mm, pmdp))
179 list_del(&pgtable->lru);
180 return pgtable;
181}
182#endif
183
184#ifndef __HAVE_ARCH_PMDP_INVALIDATE
185pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
186 pmd_t *pmdp)
187{
188 pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mknotpresent(*pmdp));
189 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
190 return old;
191}
192#endif
193
194#ifndef pmdp_collapse_flush
195pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
196 pmd_t *pmdp)
197{
198 /*
199 * pmd and hugepage pte format are same. So we could
200 * use the same function.
201 */
202 pmd_t pmd;
203
204 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
205 VM_BUG_ON(pmd_trans_huge(*pmdp));
206 pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
207
208 /* collapse entails shooting down ptes not pmd */
209 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
210 return pmd;
211}
212#endif
213#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * mm/pgtable-generic.c
4 *
5 * Generic pgtable methods declared in linux/pgtable.h
6 *
7 * Copyright (C) 2010 Linus Torvalds
8 */
9
10#include <linux/pagemap.h>
11#include <linux/hugetlb.h>
12#include <linux/pgtable.h>
13#include <linux/swap.h>
14#include <linux/swapops.h>
15#include <linux/mm_inline.h>
16#include <asm/pgalloc.h>
17#include <asm/tlb.h>
18
19/*
20 * If a p?d_bad entry is found while walking page tables, report
21 * the error, before resetting entry to p?d_none. Usually (but
22 * very seldom) called out from the p?d_none_or_clear_bad macros.
23 */
24
25void pgd_clear_bad(pgd_t *pgd)
26{
27 pgd_ERROR(*pgd);
28 pgd_clear(pgd);
29}
30
31#ifndef __PAGETABLE_P4D_FOLDED
32void p4d_clear_bad(p4d_t *p4d)
33{
34 p4d_ERROR(*p4d);
35 p4d_clear(p4d);
36}
37#endif
38
39#ifndef __PAGETABLE_PUD_FOLDED
40void pud_clear_bad(pud_t *pud)
41{
42 pud_ERROR(*pud);
43 pud_clear(pud);
44}
45#endif
46
47/*
48 * Note that the pmd variant below can't be stub'ed out just as for p4d/pud
49 * above. pmd folding is special and typically pmd_* macros refer to upper
50 * level even when folded
51 */
52void pmd_clear_bad(pmd_t *pmd)
53{
54 pmd_ERROR(*pmd);
55 pmd_clear(pmd);
56}
57
58#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
59/*
60 * Only sets the access flags (dirty, accessed), as well as write
61 * permission. Furthermore, we know it always gets set to a "more
62 * permissive" setting, which allows most architectures to optimize
63 * this. We return whether the PTE actually changed, which in turn
64 * instructs the caller to do things like update__mmu_cache. This
65 * used to be done in the caller, but sparc needs minor faults to
66 * force that call on sun4c so we changed this macro slightly
67 */
68int ptep_set_access_flags(struct vm_area_struct *vma,
69 unsigned long address, pte_t *ptep,
70 pte_t entry, int dirty)
71{
72 int changed = !pte_same(ptep_get(ptep), entry);
73 if (changed) {
74 set_pte_at(vma->vm_mm, address, ptep, entry);
75 flush_tlb_fix_spurious_fault(vma, address, ptep);
76 }
77 return changed;
78}
79#endif
80
81#ifndef __HAVE_ARCH_PTEP_CLEAR_YOUNG_FLUSH
82int ptep_clear_flush_young(struct vm_area_struct *vma,
83 unsigned long address, pte_t *ptep)
84{
85 int young;
86 young = ptep_test_and_clear_young(vma, address, ptep);
87 if (young)
88 flush_tlb_page(vma, address);
89 return young;
90}
91#endif
92
93#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH
94pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address,
95 pte_t *ptep)
96{
97 struct mm_struct *mm = (vma)->vm_mm;
98 pte_t pte;
99 pte = ptep_get_and_clear(mm, address, ptep);
100 if (pte_accessible(mm, pte))
101 flush_tlb_page(vma, address);
102 return pte;
103}
104#endif
105
106#ifdef CONFIG_TRANSPARENT_HUGEPAGE
107
108#ifndef __HAVE_ARCH_PMDP_SET_ACCESS_FLAGS
109int pmdp_set_access_flags(struct vm_area_struct *vma,
110 unsigned long address, pmd_t *pmdp,
111 pmd_t entry, int dirty)
112{
113 int changed = !pmd_same(*pmdp, entry);
114 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
115 if (changed) {
116 set_pmd_at(vma->vm_mm, address, pmdp, entry);
117 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
118 }
119 return changed;
120}
121#endif
122
123#ifndef __HAVE_ARCH_PMDP_CLEAR_YOUNG_FLUSH
124int pmdp_clear_flush_young(struct vm_area_struct *vma,
125 unsigned long address, pmd_t *pmdp)
126{
127 int young;
128 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
129 young = pmdp_test_and_clear_young(vma, address, pmdp);
130 if (young)
131 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
132 return young;
133}
134#endif
135
136#ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH
137pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
138 pmd_t *pmdp)
139{
140 pmd_t pmd;
141 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
142 VM_BUG_ON(pmd_present(*pmdp) && !pmd_trans_huge(*pmdp) &&
143 !pmd_devmap(*pmdp));
144 pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
145 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
146 return pmd;
147}
148
149#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
150pud_t pudp_huge_clear_flush(struct vm_area_struct *vma, unsigned long address,
151 pud_t *pudp)
152{
153 pud_t pud;
154
155 VM_BUG_ON(address & ~HPAGE_PUD_MASK);
156 VM_BUG_ON(!pud_trans_huge(*pudp) && !pud_devmap(*pudp));
157 pud = pudp_huge_get_and_clear(vma->vm_mm, address, pudp);
158 flush_pud_tlb_range(vma, address, address + HPAGE_PUD_SIZE);
159 return pud;
160}
161#endif
162#endif
163
164#ifndef __HAVE_ARCH_PGTABLE_DEPOSIT
165void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
166 pgtable_t pgtable)
167{
168 assert_spin_locked(pmd_lockptr(mm, pmdp));
169
170 /* FIFO */
171 if (!pmd_huge_pte(mm, pmdp))
172 INIT_LIST_HEAD(&pgtable->lru);
173 else
174 list_add(&pgtable->lru, &pmd_huge_pte(mm, pmdp)->lru);
175 pmd_huge_pte(mm, pmdp) = pgtable;
176}
177#endif
178
179#ifndef __HAVE_ARCH_PGTABLE_WITHDRAW
180/* no "address" argument so destroys page coloring of some arch */
181pgtable_t pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
182{
183 pgtable_t pgtable;
184
185 assert_spin_locked(pmd_lockptr(mm, pmdp));
186
187 /* FIFO */
188 pgtable = pmd_huge_pte(mm, pmdp);
189 pmd_huge_pte(mm, pmdp) = list_first_entry_or_null(&pgtable->lru,
190 struct page, lru);
191 if (pmd_huge_pte(mm, pmdp))
192 list_del(&pgtable->lru);
193 return pgtable;
194}
195#endif
196
197#ifndef __HAVE_ARCH_PMDP_INVALIDATE
198pmd_t pmdp_invalidate(struct vm_area_struct *vma, unsigned long address,
199 pmd_t *pmdp)
200{
201 pmd_t old = pmdp_establish(vma, address, pmdp, pmd_mkinvalid(*pmdp));
202 flush_pmd_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
203 return old;
204}
205#endif
206
207#ifndef __HAVE_ARCH_PMDP_INVALIDATE_AD
208pmd_t pmdp_invalidate_ad(struct vm_area_struct *vma, unsigned long address,
209 pmd_t *pmdp)
210{
211 return pmdp_invalidate(vma, address, pmdp);
212}
213#endif
214
215#ifndef pmdp_collapse_flush
216pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
217 pmd_t *pmdp)
218{
219 /*
220 * pmd and hugepage pte format are same. So we could
221 * use the same function.
222 */
223 pmd_t pmd;
224
225 VM_BUG_ON(address & ~HPAGE_PMD_MASK);
226 VM_BUG_ON(pmd_trans_huge(*pmdp));
227 pmd = pmdp_huge_get_and_clear(vma->vm_mm, address, pmdp);
228
229 /* collapse entails shooting down ptes not pmd */
230 flush_tlb_range(vma, address, address + HPAGE_PMD_SIZE);
231 return pmd;
232}
233#endif
234
235/* arch define pte_free_defer in asm/pgalloc.h for its own implementation */
236#ifndef pte_free_defer
237static void pte_free_now(struct rcu_head *head)
238{
239 struct page *page;
240
241 page = container_of(head, struct page, rcu_head);
242 pte_free(NULL /* mm not passed and not used */, (pgtable_t)page);
243}
244
245void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable)
246{
247 struct page *page;
248
249 page = pgtable;
250 call_rcu(&page->rcu_head, pte_free_now);
251}
252#endif /* pte_free_defer */
253#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
254
255#if defined(CONFIG_GUP_GET_PXX_LOW_HIGH) && \
256 (defined(CONFIG_SMP) || defined(CONFIG_PREEMPT_RCU))
257/*
258 * See the comment above ptep_get_lockless() in include/linux/pgtable.h:
259 * the barriers in pmdp_get_lockless() cannot guarantee that the value in
260 * pmd_high actually belongs with the value in pmd_low; but holding interrupts
261 * off blocks the TLB flush between present updates, which guarantees that a
262 * successful __pte_offset_map() points to a page from matched halves.
263 */
264static unsigned long pmdp_get_lockless_start(void)
265{
266 unsigned long irqflags;
267
268 local_irq_save(irqflags);
269 return irqflags;
270}
271static void pmdp_get_lockless_end(unsigned long irqflags)
272{
273 local_irq_restore(irqflags);
274}
275#else
276static unsigned long pmdp_get_lockless_start(void) { return 0; }
277static void pmdp_get_lockless_end(unsigned long irqflags) { }
278#endif
279
280pte_t *__pte_offset_map(pmd_t *pmd, unsigned long addr, pmd_t *pmdvalp)
281{
282 unsigned long irqflags;
283 pmd_t pmdval;
284
285 rcu_read_lock();
286 irqflags = pmdp_get_lockless_start();
287 pmdval = pmdp_get_lockless(pmd);
288 pmdp_get_lockless_end(irqflags);
289
290 if (pmdvalp)
291 *pmdvalp = pmdval;
292 if (unlikely(pmd_none(pmdval) || is_pmd_migration_entry(pmdval)))
293 goto nomap;
294 if (unlikely(pmd_trans_huge(pmdval) || pmd_devmap(pmdval)))
295 goto nomap;
296 if (unlikely(pmd_bad(pmdval))) {
297 pmd_clear_bad(pmd);
298 goto nomap;
299 }
300 return __pte_map(&pmdval, addr);
301nomap:
302 rcu_read_unlock();
303 return NULL;
304}
305
306pte_t *pte_offset_map_nolock(struct mm_struct *mm, pmd_t *pmd,
307 unsigned long addr, spinlock_t **ptlp)
308{
309 pmd_t pmdval;
310 pte_t *pte;
311
312 pte = __pte_offset_map(pmd, addr, &pmdval);
313 if (likely(pte))
314 *ptlp = pte_lockptr(mm, &pmdval);
315 return pte;
316}
317
318/*
319 * pte_offset_map_lock(mm, pmd, addr, ptlp), and its internal implementation
320 * __pte_offset_map_lock() below, is usually called with the pmd pointer for
321 * addr, reached by walking down the mm's pgd, p4d, pud for addr: either while
322 * holding mmap_lock or vma lock for read or for write; or in truncate or rmap
323 * context, while holding file's i_mmap_lock or anon_vma lock for read (or for
324 * write). In a few cases, it may be used with pmd pointing to a pmd_t already
325 * copied to or constructed on the stack.
326 *
327 * When successful, it returns the pte pointer for addr, with its page table
328 * kmapped if necessary (when CONFIG_HIGHPTE), and locked against concurrent
329 * modification by software, with a pointer to that spinlock in ptlp (in some
330 * configs mm->page_table_lock, in SPLIT_PTLOCK configs a spinlock in table's
331 * struct page). pte_unmap_unlock(pte, ptl) to unlock and unmap afterwards.
332 *
333 * But it is unsuccessful, returning NULL with *ptlp unchanged, if there is no
334 * page table at *pmd: if, for example, the page table has just been removed,
335 * or replaced by the huge pmd of a THP. (When successful, *pmd is rechecked
336 * after acquiring the ptlock, and retried internally if it changed: so that a
337 * page table can be safely removed or replaced by THP while holding its lock.)
338 *
339 * pte_offset_map(pmd, addr), and its internal helper __pte_offset_map() above,
340 * just returns the pte pointer for addr, its page table kmapped if necessary;
341 * or NULL if there is no page table at *pmd. It does not attempt to lock the
342 * page table, so cannot normally be used when the page table is to be updated,
343 * or when entries read must be stable. But it does take rcu_read_lock(): so
344 * that even when page table is racily removed, it remains a valid though empty
345 * and disconnected table. Until pte_unmap(pte) unmaps and rcu_read_unlock()s
346 * afterwards.
347 *
348 * pte_offset_map_nolock(mm, pmd, addr, ptlp), above, is like pte_offset_map();
349 * but when successful, it also outputs a pointer to the spinlock in ptlp - as
350 * pte_offset_map_lock() does, but in this case without locking it. This helps
351 * the caller to avoid a later pte_lockptr(mm, *pmd), which might by that time
352 * act on a changed *pmd: pte_offset_map_nolock() provides the correct spinlock
353 * pointer for the page table that it returns. In principle, the caller should
354 * recheck *pmd once the lock is taken; in practice, no callsite needs that -
355 * either the mmap_lock for write, or pte_same() check on contents, is enough.
356 *
357 * Note that free_pgtables(), used after unmapping detached vmas, or when
358 * exiting the whole mm, does not take page table lock before freeing a page
359 * table, and may not use RCU at all: "outsiders" like khugepaged should avoid
360 * pte_offset_map() and co once the vma is detached from mm or mm_users is zero.
361 */
362pte_t *__pte_offset_map_lock(struct mm_struct *mm, pmd_t *pmd,
363 unsigned long addr, spinlock_t **ptlp)
364{
365 spinlock_t *ptl;
366 pmd_t pmdval;
367 pte_t *pte;
368again:
369 pte = __pte_offset_map(pmd, addr, &pmdval);
370 if (unlikely(!pte))
371 return pte;
372 ptl = pte_lockptr(mm, &pmdval);
373 spin_lock(ptl);
374 if (likely(pmd_same(pmdval, pmdp_get_lockless(pmd)))) {
375 *ptlp = ptl;
376 return pte;
377 }
378 pte_unmap_unlock(pte, ptl);
379 goto again;
380}