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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * This file contains common routines for dealing with free of page tables
4 * Along with common page table handling code
5 *
6 * Derived from arch/powerpc/mm/tlb_64.c:
7 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
8 *
9 * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
10 * and Cort Dougan (PReP) (cort@cs.nmt.edu)
11 * Copyright (C) 1996 Paul Mackerras
12 *
13 * Derived from "arch/i386/mm/init.c"
14 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
15 *
16 * Dave Engebretsen <engebret@us.ibm.com>
17 * Rework for PPC64 port.
18 */
19
20#include <linux/kernel.h>
21#include <linux/gfp.h>
22#include <linux/mm.h>
23#include <linux/percpu.h>
24#include <linux/hardirq.h>
25#include <linux/hugetlb.h>
26#include <asm/tlbflush.h>
27#include <asm/tlb.h>
28#include <asm/hugetlb.h>
29#include <asm/pte-walk.h>
30
31#ifdef CONFIG_PPC64
32#define PGD_ALIGN (sizeof(pgd_t) * MAX_PTRS_PER_PGD)
33#else
34#define PGD_ALIGN PAGE_SIZE
35#endif
36
37pgd_t swapper_pg_dir[MAX_PTRS_PER_PGD] __section(".bss..page_aligned") __aligned(PGD_ALIGN);
38
39static inline int is_exec_fault(void)
40{
41 return current->thread.regs && TRAP(current->thread.regs) == 0x400;
42}
43
44/* We only try to do i/d cache coherency on stuff that looks like
45 * reasonably "normal" PTEs. We currently require a PTE to be present
46 * and we avoid _PAGE_SPECIAL and cache inhibited pte. We also only do that
47 * on userspace PTEs
48 */
49static inline int pte_looks_normal(pte_t pte, unsigned long addr)
50{
51
52 if (pte_present(pte) && !pte_special(pte)) {
53 if (pte_ci(pte))
54 return 0;
55 if (!is_kernel_addr(addr))
56 return 1;
57 }
58 return 0;
59}
60
61static struct folio *maybe_pte_to_folio(pte_t pte)
62{
63 unsigned long pfn = pte_pfn(pte);
64 struct page *page;
65
66 if (unlikely(!pfn_valid(pfn)))
67 return NULL;
68 page = pfn_to_page(pfn);
69 if (PageReserved(page))
70 return NULL;
71 return page_folio(page);
72}
73
74#ifdef CONFIG_PPC_BOOK3S
75
76/* Server-style MMU handles coherency when hashing if HW exec permission
77 * is supposed per page (currently 64-bit only). If not, then, we always
78 * flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec
79 * support falls into the same category.
80 */
81
82static pte_t set_pte_filter_hash(pte_t pte, unsigned long addr)
83{
84 pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
85 if (pte_looks_normal(pte, addr) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
86 cpu_has_feature(CPU_FTR_NOEXECUTE))) {
87 struct folio *folio = maybe_pte_to_folio(pte);
88 if (!folio)
89 return pte;
90 if (!test_bit(PG_dcache_clean, &folio->flags)) {
91 flush_dcache_icache_folio(folio);
92 set_bit(PG_dcache_clean, &folio->flags);
93 }
94 }
95 return pte;
96}
97
98#else /* CONFIG_PPC_BOOK3S */
99
100static pte_t set_pte_filter_hash(pte_t pte, unsigned long addr) { return pte; }
101
102#endif /* CONFIG_PPC_BOOK3S */
103
104/* Embedded type MMU with HW exec support. This is a bit more complicated
105 * as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
106 * instead we "filter out" the exec permission for non clean pages.
107 *
108 * This is also called once for the folio. So only work with folio->flags here.
109 */
110static inline pte_t set_pte_filter(pte_t pte, unsigned long addr)
111{
112 struct folio *folio;
113
114 if (radix_enabled())
115 return pte;
116
117 if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
118 return set_pte_filter_hash(pte, addr);
119
120 /* No exec permission in the first place, move on */
121 if (!pte_exec(pte) || !pte_looks_normal(pte, addr))
122 return pte;
123
124 /* If you set _PAGE_EXEC on weird pages you're on your own */
125 folio = maybe_pte_to_folio(pte);
126 if (unlikely(!folio))
127 return pte;
128
129 /* If the page clean, we move on */
130 if (test_bit(PG_dcache_clean, &folio->flags))
131 return pte;
132
133 /* If it's an exec fault, we flush the cache and make it clean */
134 if (is_exec_fault()) {
135 flush_dcache_icache_folio(folio);
136 set_bit(PG_dcache_clean, &folio->flags);
137 return pte;
138 }
139
140 /* Else, we filter out _PAGE_EXEC */
141 return pte_exprotect(pte);
142}
143
144static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
145 int dirty)
146{
147 struct folio *folio;
148
149 if (IS_ENABLED(CONFIG_PPC_BOOK3S_64))
150 return pte;
151
152 if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
153 return pte;
154
155 /* So here, we only care about exec faults, as we use them
156 * to recover lost _PAGE_EXEC and perform I$/D$ coherency
157 * if necessary. Also if _PAGE_EXEC is already set, same deal,
158 * we just bail out
159 */
160 if (dirty || pte_exec(pte) || !is_exec_fault())
161 return pte;
162
163#ifdef CONFIG_DEBUG_VM
164 /* So this is an exec fault, _PAGE_EXEC is not set. If it was
165 * an error we would have bailed out earlier in do_page_fault()
166 * but let's make sure of it
167 */
168 if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
169 return pte;
170#endif /* CONFIG_DEBUG_VM */
171
172 /* If you set _PAGE_EXEC on weird pages you're on your own */
173 folio = maybe_pte_to_folio(pte);
174 if (unlikely(!folio))
175 goto bail;
176
177 /* If the page is already clean, we move on */
178 if (test_bit(PG_dcache_clean, &folio->flags))
179 goto bail;
180
181 /* Clean the page and set PG_dcache_clean */
182 flush_dcache_icache_folio(folio);
183 set_bit(PG_dcache_clean, &folio->flags);
184
185 bail:
186 return pte_mkexec(pte);
187}
188
189/*
190 * set_pte stores a linux PTE into the linux page table.
191 */
192void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
193 pte_t pte, unsigned int nr)
194{
195
196 /* Note: mm->context.id might not yet have been assigned as
197 * this context might not have been activated yet when this
198 * is called. Filter the pte value and use the filtered value
199 * to setup all the ptes in the range.
200 */
201 pte = set_pte_filter(pte, addr);
202
203 /*
204 * We don't need to call arch_enter/leave_lazy_mmu_mode()
205 * because we expect set_ptes to be only be used on not present
206 * and not hw_valid ptes. Hence there is no translation cache flush
207 * involved that need to be batched.
208 */
209 for (;;) {
210
211 /*
212 * Make sure hardware valid bit is not set. We don't do
213 * tlb flush for this update.
214 */
215 VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
216
217 /* Perform the setting of the PTE */
218 __set_pte_at(mm, addr, ptep, pte, 0);
219 if (--nr == 0)
220 break;
221 ptep++;
222 addr += PAGE_SIZE;
223 /*
224 * increment the pfn.
225 */
226 pte = pfn_pte(pte_pfn(pte) + 1, pte_pgprot((pte)));
227 }
228}
229
230void unmap_kernel_page(unsigned long va)
231{
232 pmd_t *pmdp = pmd_off_k(va);
233 pte_t *ptep = pte_offset_kernel(pmdp, va);
234
235 pte_clear(&init_mm, va, ptep);
236 flush_tlb_kernel_range(va, va + PAGE_SIZE);
237}
238
239/*
240 * This is called when relaxing access to a PTE. It's also called in the page
241 * fault path when we don't hit any of the major fault cases, ie, a minor
242 * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
243 * handled those two for us, we additionally deal with missing execute
244 * permission here on some processors
245 */
246int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
247 pte_t *ptep, pte_t entry, int dirty)
248{
249 int changed;
250 entry = set_access_flags_filter(entry, vma, dirty);
251 changed = !pte_same(*(ptep), entry);
252 if (changed) {
253 assert_pte_locked(vma->vm_mm, address);
254 __ptep_set_access_flags(vma, ptep, entry,
255 address, mmu_virtual_psize);
256 }
257 return changed;
258}
259
260#ifdef CONFIG_HUGETLB_PAGE
261int huge_ptep_set_access_flags(struct vm_area_struct *vma,
262 unsigned long addr, pte_t *ptep,
263 pte_t pte, int dirty)
264{
265#ifdef HUGETLB_NEED_PRELOAD
266 /*
267 * The "return 1" forces a call of update_mmu_cache, which will write a
268 * TLB entry. Without this, platforms that don't do a write of the TLB
269 * entry in the TLB miss handler asm will fault ad infinitum.
270 */
271 ptep_set_access_flags(vma, addr, ptep, pte, dirty);
272 return 1;
273#else
274 int changed, psize;
275
276 pte = set_access_flags_filter(pte, vma, dirty);
277 changed = !pte_same(*(ptep), pte);
278 if (changed) {
279
280#ifdef CONFIG_PPC_BOOK3S_64
281 struct hstate *h = hstate_vma(vma);
282
283 psize = hstate_get_psize(h);
284#ifdef CONFIG_DEBUG_VM
285 assert_spin_locked(huge_pte_lockptr(h, vma->vm_mm, ptep));
286#endif
287
288#else
289 /*
290 * Not used on non book3s64 platforms.
291 * 8xx compares it with mmu_virtual_psize to
292 * know if it is a huge page or not.
293 */
294 psize = MMU_PAGE_COUNT;
295#endif
296 __ptep_set_access_flags(vma, ptep, pte, addr, psize);
297 }
298 return changed;
299#endif
300}
301
302#if defined(CONFIG_PPC_8xx)
303void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
304 pte_t pte, unsigned long sz)
305{
306 pmd_t *pmd = pmd_off(mm, addr);
307 pte_basic_t val;
308 pte_basic_t *entry = (pte_basic_t *)ptep;
309 int num, i;
310
311 /*
312 * Make sure hardware valid bit is not set. We don't do
313 * tlb flush for this update.
314 */
315 VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
316
317 pte = set_pte_filter(pte, addr);
318
319 val = pte_val(pte);
320
321 num = number_of_cells_per_pte(pmd, val, 1);
322
323 for (i = 0; i < num; i++, entry++, val += SZ_4K)
324 *entry = val;
325}
326#endif
327#endif /* CONFIG_HUGETLB_PAGE */
328
329#ifdef CONFIG_DEBUG_VM
330void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
331{
332 pgd_t *pgd;
333 p4d_t *p4d;
334 pud_t *pud;
335 pmd_t *pmd;
336 pte_t *pte;
337 spinlock_t *ptl;
338
339 if (mm == &init_mm)
340 return;
341 pgd = mm->pgd + pgd_index(addr);
342 BUG_ON(pgd_none(*pgd));
343 p4d = p4d_offset(pgd, addr);
344 BUG_ON(p4d_none(*p4d));
345 pud = pud_offset(p4d, addr);
346 BUG_ON(pud_none(*pud));
347 pmd = pmd_offset(pud, addr);
348 /*
349 * khugepaged to collapse normal pages to hugepage, first set
350 * pmd to none to force page fault/gup to take mmap_lock. After
351 * pmd is set to none, we do a pte_clear which does this assertion
352 * so if we find pmd none, return.
353 */
354 if (pmd_none(*pmd))
355 return;
356 pte = pte_offset_map_nolock(mm, pmd, addr, &ptl);
357 BUG_ON(!pte);
358 assert_spin_locked(ptl);
359 pte_unmap(pte);
360}
361#endif /* CONFIG_DEBUG_VM */
362
363unsigned long vmalloc_to_phys(void *va)
364{
365 unsigned long pfn = vmalloc_to_pfn(va);
366
367 BUG_ON(!pfn);
368 return __pa(pfn_to_kaddr(pfn)) + offset_in_page(va);
369}
370EXPORT_SYMBOL_GPL(vmalloc_to_phys);
371
372/*
373 * We have 4 cases for pgds and pmds:
374 * (1) invalid (all zeroes)
375 * (2) pointer to next table, as normal; bottom 6 bits == 0
376 * (3) leaf pte for huge page _PAGE_PTE set
377 * (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] indicate size of table
378 *
379 * So long as we atomically load page table pointers we are safe against teardown,
380 * we can follow the address down to the page and take a ref on it.
381 * This function need to be called with interrupts disabled. We use this variant
382 * when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED
383 */
384pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
385 bool *is_thp, unsigned *hpage_shift)
386{
387 pgd_t *pgdp;
388 p4d_t p4d, *p4dp;
389 pud_t pud, *pudp;
390 pmd_t pmd, *pmdp;
391 pte_t *ret_pte;
392 hugepd_t *hpdp = NULL;
393 unsigned pdshift;
394
395 if (hpage_shift)
396 *hpage_shift = 0;
397
398 if (is_thp)
399 *is_thp = false;
400
401 /*
402 * Always operate on the local stack value. This make sure the
403 * value don't get updated by a parallel THP split/collapse,
404 * page fault or a page unmap. The return pte_t * is still not
405 * stable. So should be checked there for above conditions.
406 * Top level is an exception because it is folded into p4d.
407 */
408 pgdp = pgdir + pgd_index(ea);
409 p4dp = p4d_offset(pgdp, ea);
410 p4d = READ_ONCE(*p4dp);
411 pdshift = P4D_SHIFT;
412
413 if (p4d_none(p4d))
414 return NULL;
415
416 if (p4d_is_leaf(p4d)) {
417 ret_pte = (pte_t *)p4dp;
418 goto out;
419 }
420
421 if (is_hugepd(__hugepd(p4d_val(p4d)))) {
422 hpdp = (hugepd_t *)&p4d;
423 goto out_huge;
424 }
425
426 /*
427 * Even if we end up with an unmap, the pgtable will not
428 * be freed, because we do an rcu free and here we are
429 * irq disabled
430 */
431 pdshift = PUD_SHIFT;
432 pudp = pud_offset(&p4d, ea);
433 pud = READ_ONCE(*pudp);
434
435 if (pud_none(pud))
436 return NULL;
437
438 if (pud_is_leaf(pud)) {
439 ret_pte = (pte_t *)pudp;
440 goto out;
441 }
442
443 if (is_hugepd(__hugepd(pud_val(pud)))) {
444 hpdp = (hugepd_t *)&pud;
445 goto out_huge;
446 }
447
448 pdshift = PMD_SHIFT;
449 pmdp = pmd_offset(&pud, ea);
450 pmd = READ_ONCE(*pmdp);
451
452 /*
453 * A hugepage collapse is captured by this condition, see
454 * pmdp_collapse_flush.
455 */
456 if (pmd_none(pmd))
457 return NULL;
458
459#ifdef CONFIG_PPC_BOOK3S_64
460 /*
461 * A hugepage split is captured by this condition, see
462 * pmdp_invalidate.
463 *
464 * Huge page modification can be caught here too.
465 */
466 if (pmd_is_serializing(pmd))
467 return NULL;
468#endif
469
470 if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
471 if (is_thp)
472 *is_thp = true;
473 ret_pte = (pte_t *)pmdp;
474 goto out;
475 }
476
477 if (pmd_is_leaf(pmd)) {
478 ret_pte = (pte_t *)pmdp;
479 goto out;
480 }
481
482 if (is_hugepd(__hugepd(pmd_val(pmd)))) {
483 hpdp = (hugepd_t *)&pmd;
484 goto out_huge;
485 }
486
487 return pte_offset_kernel(&pmd, ea);
488
489out_huge:
490 if (!hpdp)
491 return NULL;
492
493 ret_pte = hugepte_offset(*hpdp, ea, pdshift);
494 pdshift = hugepd_shift(*hpdp);
495out:
496 if (hpage_shift)
497 *hpage_shift = pdshift;
498 return ret_pte;
499}
500EXPORT_SYMBOL_GPL(__find_linux_pte);
501
502/* Note due to the way vm flags are laid out, the bits are XWR */
503const pgprot_t protection_map[16] = {
504 [VM_NONE] = PAGE_NONE,
505 [VM_READ] = PAGE_READONLY,
506 [VM_WRITE] = PAGE_COPY,
507 [VM_WRITE | VM_READ] = PAGE_COPY,
508 [VM_EXEC] = PAGE_EXECONLY_X,
509 [VM_EXEC | VM_READ] = PAGE_READONLY_X,
510 [VM_EXEC | VM_WRITE] = PAGE_COPY_X,
511 [VM_EXEC | VM_WRITE | VM_READ] = PAGE_COPY_X,
512 [VM_SHARED] = PAGE_NONE,
513 [VM_SHARED | VM_READ] = PAGE_READONLY,
514 [VM_SHARED | VM_WRITE] = PAGE_SHARED,
515 [VM_SHARED | VM_WRITE | VM_READ] = PAGE_SHARED,
516 [VM_SHARED | VM_EXEC] = PAGE_EXECONLY_X,
517 [VM_SHARED | VM_EXEC | VM_READ] = PAGE_READONLY_X,
518 [VM_SHARED | VM_EXEC | VM_WRITE] = PAGE_SHARED_X,
519 [VM_SHARED | VM_EXEC | VM_WRITE | VM_READ] = PAGE_SHARED_X
520};
521
522#ifndef CONFIG_PPC_BOOK3S_64
523DECLARE_VM_GET_PAGE_PROT
524#endif
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * This file contains common routines for dealing with free of page tables
4 * Along with common page table handling code
5 *
6 * Derived from arch/powerpc/mm/tlb_64.c:
7 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
8 *
9 * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
10 * and Cort Dougan (PReP) (cort@cs.nmt.edu)
11 * Copyright (C) 1996 Paul Mackerras
12 *
13 * Derived from "arch/i386/mm/init.c"
14 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
15 *
16 * Dave Engebretsen <engebret@us.ibm.com>
17 * Rework for PPC64 port.
18 */
19
20#include <linux/kernel.h>
21#include <linux/gfp.h>
22#include <linux/mm.h>
23#include <linux/percpu.h>
24#include <linux/hardirq.h>
25#include <linux/hugetlb.h>
26#include <asm/tlbflush.h>
27#include <asm/tlb.h>
28#include <asm/hugetlb.h>
29
30static inline int is_exec_fault(void)
31{
32 return current->thread.regs && TRAP(current->thread.regs) == 0x400;
33}
34
35/* We only try to do i/d cache coherency on stuff that looks like
36 * reasonably "normal" PTEs. We currently require a PTE to be present
37 * and we avoid _PAGE_SPECIAL and cache inhibited pte. We also only do that
38 * on userspace PTEs
39 */
40static inline int pte_looks_normal(pte_t pte)
41{
42
43 if (pte_present(pte) && !pte_special(pte)) {
44 if (pte_ci(pte))
45 return 0;
46 if (pte_user(pte))
47 return 1;
48 }
49 return 0;
50}
51
52static struct page *maybe_pte_to_page(pte_t pte)
53{
54 unsigned long pfn = pte_pfn(pte);
55 struct page *page;
56
57 if (unlikely(!pfn_valid(pfn)))
58 return NULL;
59 page = pfn_to_page(pfn);
60 if (PageReserved(page))
61 return NULL;
62 return page;
63}
64
65#ifdef CONFIG_PPC_BOOK3S
66
67/* Server-style MMU handles coherency when hashing if HW exec permission
68 * is supposed per page (currently 64-bit only). If not, then, we always
69 * flush the cache for valid PTEs in set_pte. Embedded CPU without HW exec
70 * support falls into the same category.
71 */
72
73static pte_t set_pte_filter_hash(pte_t pte)
74{
75 if (radix_enabled())
76 return pte;
77
78 pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
79 if (pte_looks_normal(pte) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
80 cpu_has_feature(CPU_FTR_NOEXECUTE))) {
81 struct page *pg = maybe_pte_to_page(pte);
82 if (!pg)
83 return pte;
84 if (!test_bit(PG_arch_1, &pg->flags)) {
85 flush_dcache_icache_page(pg);
86 set_bit(PG_arch_1, &pg->flags);
87 }
88 }
89 return pte;
90}
91
92#else /* CONFIG_PPC_BOOK3S */
93
94static pte_t set_pte_filter_hash(pte_t pte) { return pte; }
95
96#endif /* CONFIG_PPC_BOOK3S */
97
98/* Embedded type MMU with HW exec support. This is a bit more complicated
99 * as we don't have two bits to spare for _PAGE_EXEC and _PAGE_HWEXEC so
100 * instead we "filter out" the exec permission for non clean pages.
101 */
102static inline pte_t set_pte_filter(pte_t pte)
103{
104 struct page *pg;
105
106 if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
107 return set_pte_filter_hash(pte);
108
109 /* No exec permission in the first place, move on */
110 if (!pte_exec(pte) || !pte_looks_normal(pte))
111 return pte;
112
113 /* If you set _PAGE_EXEC on weird pages you're on your own */
114 pg = maybe_pte_to_page(pte);
115 if (unlikely(!pg))
116 return pte;
117
118 /* If the page clean, we move on */
119 if (test_bit(PG_arch_1, &pg->flags))
120 return pte;
121
122 /* If it's an exec fault, we flush the cache and make it clean */
123 if (is_exec_fault()) {
124 flush_dcache_icache_page(pg);
125 set_bit(PG_arch_1, &pg->flags);
126 return pte;
127 }
128
129 /* Else, we filter out _PAGE_EXEC */
130 return pte_exprotect(pte);
131}
132
133static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
134 int dirty)
135{
136 struct page *pg;
137
138 if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
139 return pte;
140
141 /* So here, we only care about exec faults, as we use them
142 * to recover lost _PAGE_EXEC and perform I$/D$ coherency
143 * if necessary. Also if _PAGE_EXEC is already set, same deal,
144 * we just bail out
145 */
146 if (dirty || pte_exec(pte) || !is_exec_fault())
147 return pte;
148
149#ifdef CONFIG_DEBUG_VM
150 /* So this is an exec fault, _PAGE_EXEC is not set. If it was
151 * an error we would have bailed out earlier in do_page_fault()
152 * but let's make sure of it
153 */
154 if (WARN_ON(!(vma->vm_flags & VM_EXEC)))
155 return pte;
156#endif /* CONFIG_DEBUG_VM */
157
158 /* If you set _PAGE_EXEC on weird pages you're on your own */
159 pg = maybe_pte_to_page(pte);
160 if (unlikely(!pg))
161 goto bail;
162
163 /* If the page is already clean, we move on */
164 if (test_bit(PG_arch_1, &pg->flags))
165 goto bail;
166
167 /* Clean the page and set PG_arch_1 */
168 flush_dcache_icache_page(pg);
169 set_bit(PG_arch_1, &pg->flags);
170
171 bail:
172 return pte_mkexec(pte);
173}
174
175/*
176 * set_pte stores a linux PTE into the linux page table.
177 */
178void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
179 pte_t pte)
180{
181 /*
182 * Make sure hardware valid bit is not set. We don't do
183 * tlb flush for this update.
184 */
185 VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
186
187 /* Add the pte bit when trying to set a pte */
188 pte = pte_mkpte(pte);
189
190 /* Note: mm->context.id might not yet have been assigned as
191 * this context might not have been activated yet when this
192 * is called.
193 */
194 pte = set_pte_filter(pte);
195
196 /* Perform the setting of the PTE */
197 __set_pte_at(mm, addr, ptep, pte, 0);
198}
199
200/*
201 * This is called when relaxing access to a PTE. It's also called in the page
202 * fault path when we don't hit any of the major fault cases, ie, a minor
203 * update of _PAGE_ACCESSED, _PAGE_DIRTY, etc... The generic code will have
204 * handled those two for us, we additionally deal with missing execute
205 * permission here on some processors
206 */
207int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
208 pte_t *ptep, pte_t entry, int dirty)
209{
210 int changed;
211 entry = set_access_flags_filter(entry, vma, dirty);
212 changed = !pte_same(*(ptep), entry);
213 if (changed) {
214 assert_pte_locked(vma->vm_mm, address);
215 __ptep_set_access_flags(vma, ptep, entry,
216 address, mmu_virtual_psize);
217 }
218 return changed;
219}
220
221#ifdef CONFIG_HUGETLB_PAGE
222int huge_ptep_set_access_flags(struct vm_area_struct *vma,
223 unsigned long addr, pte_t *ptep,
224 pte_t pte, int dirty)
225{
226#ifdef HUGETLB_NEED_PRELOAD
227 /*
228 * The "return 1" forces a call of update_mmu_cache, which will write a
229 * TLB entry. Without this, platforms that don't do a write of the TLB
230 * entry in the TLB miss handler asm will fault ad infinitum.
231 */
232 ptep_set_access_flags(vma, addr, ptep, pte, dirty);
233 return 1;
234#else
235 int changed, psize;
236
237 pte = set_access_flags_filter(pte, vma, dirty);
238 changed = !pte_same(*(ptep), pte);
239 if (changed) {
240
241#ifdef CONFIG_PPC_BOOK3S_64
242 struct hstate *h = hstate_vma(vma);
243
244 psize = hstate_get_psize(h);
245#ifdef CONFIG_DEBUG_VM
246 assert_spin_locked(huge_pte_lockptr(h, vma->vm_mm, ptep));
247#endif
248
249#else
250 /*
251 * Not used on non book3s64 platforms.
252 * 8xx compares it with mmu_virtual_psize to
253 * know if it is a huge page or not.
254 */
255 psize = MMU_PAGE_COUNT;
256#endif
257 __ptep_set_access_flags(vma, ptep, pte, addr, psize);
258 }
259 return changed;
260#endif
261}
262
263#if defined(CONFIG_PPC_8xx)
264void set_huge_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte)
265{
266 pmd_t *pmd = pmd_off(mm, addr);
267 pte_basic_t val;
268 pte_basic_t *entry = &ptep->pte;
269 int num = is_hugepd(*((hugepd_t *)pmd)) ? 1 : SZ_512K / SZ_4K;
270 int i;
271
272 /*
273 * Make sure hardware valid bit is not set. We don't do
274 * tlb flush for this update.
275 */
276 VM_WARN_ON(pte_hw_valid(*ptep) && !pte_protnone(*ptep));
277
278 pte = pte_mkpte(pte);
279
280 pte = set_pte_filter(pte);
281
282 val = pte_val(pte);
283 for (i = 0; i < num; i++, entry++, val += SZ_4K)
284 *entry = val;
285}
286#endif
287#endif /* CONFIG_HUGETLB_PAGE */
288
289#ifdef CONFIG_DEBUG_VM
290void assert_pte_locked(struct mm_struct *mm, unsigned long addr)
291{
292 pgd_t *pgd;
293 p4d_t *p4d;
294 pud_t *pud;
295 pmd_t *pmd;
296
297 if (mm == &init_mm)
298 return;
299 pgd = mm->pgd + pgd_index(addr);
300 BUG_ON(pgd_none(*pgd));
301 p4d = p4d_offset(pgd, addr);
302 BUG_ON(p4d_none(*p4d));
303 pud = pud_offset(p4d, addr);
304 BUG_ON(pud_none(*pud));
305 pmd = pmd_offset(pud, addr);
306 /*
307 * khugepaged to collapse normal pages to hugepage, first set
308 * pmd to none to force page fault/gup to take mmap_lock. After
309 * pmd is set to none, we do a pte_clear which does this assertion
310 * so if we find pmd none, return.
311 */
312 if (pmd_none(*pmd))
313 return;
314 BUG_ON(!pmd_present(*pmd));
315 assert_spin_locked(pte_lockptr(mm, pmd));
316}
317#endif /* CONFIG_DEBUG_VM */
318
319unsigned long vmalloc_to_phys(void *va)
320{
321 unsigned long pfn = vmalloc_to_pfn(va);
322
323 BUG_ON(!pfn);
324 return __pa(pfn_to_kaddr(pfn)) + offset_in_page(va);
325}
326EXPORT_SYMBOL_GPL(vmalloc_to_phys);
327
328/*
329 * We have 4 cases for pgds and pmds:
330 * (1) invalid (all zeroes)
331 * (2) pointer to next table, as normal; bottom 6 bits == 0
332 * (3) leaf pte for huge page _PAGE_PTE set
333 * (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] indicate size of table
334 *
335 * So long as we atomically load page table pointers we are safe against teardown,
336 * we can follow the address down to the the page and take a ref on it.
337 * This function need to be called with interrupts disabled. We use this variant
338 * when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED
339 */
340pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
341 bool *is_thp, unsigned *hpage_shift)
342{
343 pgd_t *pgdp;
344 p4d_t p4d, *p4dp;
345 pud_t pud, *pudp;
346 pmd_t pmd, *pmdp;
347 pte_t *ret_pte;
348 hugepd_t *hpdp = NULL;
349 unsigned pdshift;
350
351 if (hpage_shift)
352 *hpage_shift = 0;
353
354 if (is_thp)
355 *is_thp = false;
356
357 /*
358 * Always operate on the local stack value. This make sure the
359 * value don't get updated by a parallel THP split/collapse,
360 * page fault or a page unmap. The return pte_t * is still not
361 * stable. So should be checked there for above conditions.
362 * Top level is an exception because it is folded into p4d.
363 */
364 pgdp = pgdir + pgd_index(ea);
365 p4dp = p4d_offset(pgdp, ea);
366 p4d = READ_ONCE(*p4dp);
367 pdshift = P4D_SHIFT;
368
369 if (p4d_none(p4d))
370 return NULL;
371
372 if (p4d_is_leaf(p4d)) {
373 ret_pte = (pte_t *)p4dp;
374 goto out;
375 }
376
377 if (is_hugepd(__hugepd(p4d_val(p4d)))) {
378 hpdp = (hugepd_t *)&p4d;
379 goto out_huge;
380 }
381
382 /*
383 * Even if we end up with an unmap, the pgtable will not
384 * be freed, because we do an rcu free and here we are
385 * irq disabled
386 */
387 pdshift = PUD_SHIFT;
388 pudp = pud_offset(&p4d, ea);
389 pud = READ_ONCE(*pudp);
390
391 if (pud_none(pud))
392 return NULL;
393
394 if (pud_is_leaf(pud)) {
395 ret_pte = (pte_t *)pudp;
396 goto out;
397 }
398
399 if (is_hugepd(__hugepd(pud_val(pud)))) {
400 hpdp = (hugepd_t *)&pud;
401 goto out_huge;
402 }
403
404 pdshift = PMD_SHIFT;
405 pmdp = pmd_offset(&pud, ea);
406 pmd = READ_ONCE(*pmdp);
407
408 /*
409 * A hugepage collapse is captured by this condition, see
410 * pmdp_collapse_flush.
411 */
412 if (pmd_none(pmd))
413 return NULL;
414
415#ifdef CONFIG_PPC_BOOK3S_64
416 /*
417 * A hugepage split is captured by this condition, see
418 * pmdp_invalidate.
419 *
420 * Huge page modification can be caught here too.
421 */
422 if (pmd_is_serializing(pmd))
423 return NULL;
424#endif
425
426 if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
427 if (is_thp)
428 *is_thp = true;
429 ret_pte = (pte_t *)pmdp;
430 goto out;
431 }
432
433 if (pmd_is_leaf(pmd)) {
434 ret_pte = (pte_t *)pmdp;
435 goto out;
436 }
437
438 if (is_hugepd(__hugepd(pmd_val(pmd)))) {
439 hpdp = (hugepd_t *)&pmd;
440 goto out_huge;
441 }
442
443 return pte_offset_kernel(&pmd, ea);
444
445out_huge:
446 if (!hpdp)
447 return NULL;
448
449 ret_pte = hugepte_offset(*hpdp, ea, pdshift);
450 pdshift = hugepd_shift(*hpdp);
451out:
452 if (hpage_shift)
453 *hpage_shift = pdshift;
454 return ret_pte;
455}
456EXPORT_SYMBOL_GPL(__find_linux_pte);