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Linux/arch/arm64/mm/hugetlbpage.c

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  1 /*
  2  * arch/arm64/mm/hugetlbpage.c
  3  *
  4  * Copyright (C) 2013 Linaro Ltd.
  5  *
  6  * Based on arch/x86/mm/hugetlbpage.c.
  7  *
  8  * This program is free software; you can redistribute it and/or modify
  9  * it under the terms of the GNU General Public License version 2 as
 10  * published by the Free Software Foundation.
 11  *
 12  * This program is distributed in the hope that it will be useful,
 13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 15  * GNU General Public License for more details.
 16  */
 17 
 18 #include <linux/init.h>
 19 #include <linux/fs.h>
 20 #include <linux/mm.h>
 21 #include <linux/hugetlb.h>
 22 #include <linux/pagemap.h>
 23 #include <linux/err.h>
 24 #include <linux/sysctl.h>
 25 #include <asm/mman.h>
 26 #include <asm/tlb.h>
 27 #include <asm/tlbflush.h>
 28 #include <asm/pgalloc.h>
 29 
 30 int pmd_huge(pmd_t pmd)
 31 {
 32         return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
 33 }
 34 
 35 int pud_huge(pud_t pud)
 36 {
 37 #ifndef __PAGETABLE_PMD_FOLDED
 38         return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
 39 #else
 40         return 0;
 41 #endif
 42 }
 43 
 44 static int find_num_contig(struct mm_struct *mm, unsigned long addr,
 45                            pte_t *ptep, pte_t pte, size_t *pgsize)
 46 {
 47         pgd_t *pgd = pgd_offset(mm, addr);
 48         pud_t *pud;
 49         pmd_t *pmd;
 50 
 51         *pgsize = PAGE_SIZE;
 52         if (!pte_cont(pte))
 53                 return 1;
 54         pud = pud_offset(pgd, addr);
 55         pmd = pmd_offset(pud, addr);
 56         if ((pte_t *)pmd == ptep) {
 57                 *pgsize = PMD_SIZE;
 58                 return CONT_PMDS;
 59         }
 60         return CONT_PTES;
 61 }
 62 
 63 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
 64                             pte_t *ptep, pte_t pte)
 65 {
 66         size_t pgsize;
 67         int i;
 68         int ncontig = find_num_contig(mm, addr, ptep, pte, &pgsize);
 69         unsigned long pfn;
 70         pgprot_t hugeprot;
 71 
 72         if (ncontig == 1) {
 73                 set_pte_at(mm, addr, ptep, pte);
 74                 return;
 75         }
 76 
 77         pfn = pte_pfn(pte);
 78         hugeprot = __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
 79         for (i = 0; i < ncontig; i++) {
 80                 pr_debug("%s: set pte %p to 0x%llx\n", __func__, ptep,
 81                          pte_val(pfn_pte(pfn, hugeprot)));
 82                 set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
 83                 ptep++;
 84                 pfn += pgsize >> PAGE_SHIFT;
 85                 addr += pgsize;
 86         }
 87 }
 88 
 89 pte_t *huge_pte_alloc(struct mm_struct *mm,
 90                       unsigned long addr, unsigned long sz)
 91 {
 92         pgd_t *pgd;
 93         pud_t *pud;
 94         pte_t *pte = NULL;
 95 
 96         pr_debug("%s: addr:0x%lx sz:0x%lx\n", __func__, addr, sz);
 97         pgd = pgd_offset(mm, addr);
 98         pud = pud_alloc(mm, pgd, addr);
 99         if (!pud)
100                 return NULL;
101 
102         if (sz == PUD_SIZE) {
103                 pte = (pte_t *)pud;
104         } else if (sz == (PAGE_SIZE * CONT_PTES)) {
105                 pmd_t *pmd = pmd_alloc(mm, pud, addr);
106 
107                 WARN_ON(addr & (sz - 1));
108                 /*
109                  * Note that if this code were ever ported to the
110                  * 32-bit arm platform then it will cause trouble in
111                  * the case where CONFIG_HIGHPTE is set, since there
112                  * will be no pte_unmap() to correspond with this
113                  * pte_alloc_map().
114                  */
115                 pte = pte_alloc_map(mm, pmd, addr);
116         } else if (sz == PMD_SIZE) {
117                 if (IS_ENABLED(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) &&
118                     pud_none(*pud))
119                         pte = huge_pmd_share(mm, addr, pud);
120                 else
121                         pte = (pte_t *)pmd_alloc(mm, pud, addr);
122         } else if (sz == (PMD_SIZE * CONT_PMDS)) {
123                 pmd_t *pmd;
124 
125                 pmd = pmd_alloc(mm, pud, addr);
126                 WARN_ON(addr & (sz - 1));
127                 return (pte_t *)pmd;
128         }
129 
130         pr_debug("%s: addr:0x%lx sz:0x%lx ret pte=%p/0x%llx\n", __func__, addr,
131                sz, pte, pte_val(*pte));
132         return pte;
133 }
134 
135 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
136 {
137         pgd_t *pgd;
138         pud_t *pud;
139         pmd_t *pmd = NULL;
140         pte_t *pte = NULL;
141 
142         pgd = pgd_offset(mm, addr);
143         pr_debug("%s: addr:0x%lx pgd:%p\n", __func__, addr, pgd);
144         if (!pgd_present(*pgd))
145                 return NULL;
146         pud = pud_offset(pgd, addr);
147         if (!pud_present(*pud))
148                 return NULL;
149 
150         if (pud_huge(*pud))
151                 return (pte_t *)pud;
152         pmd = pmd_offset(pud, addr);
153         if (!pmd_present(*pmd))
154                 return NULL;
155 
156         if (pte_cont(pmd_pte(*pmd))) {
157                 pmd = pmd_offset(
158                         pud, (addr & CONT_PMD_MASK));
159                 return (pte_t *)pmd;
160         }
161         if (pmd_huge(*pmd))
162                 return (pte_t *)pmd;
163         pte = pte_offset_kernel(pmd, addr);
164         if (pte_present(*pte) && pte_cont(*pte)) {
165                 pte = pte_offset_kernel(
166                         pmd, (addr & CONT_PTE_MASK));
167                 return pte;
168         }
169         return NULL;
170 }
171 
172 pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
173                          struct page *page, int writable)
174 {
175         size_t pagesize = huge_page_size(hstate_vma(vma));
176 
177         if (pagesize == CONT_PTE_SIZE) {
178                 entry = pte_mkcont(entry);
179         } else if (pagesize == CONT_PMD_SIZE) {
180                 entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
181         } else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
182                 pr_warn("%s: unrecognized huge page size 0x%lx\n",
183                         __func__, pagesize);
184         }
185         return entry;
186 }
187 
188 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
189                               unsigned long addr, pte_t *ptep)
190 {
191         pte_t pte;
192 
193         if (pte_cont(*ptep)) {
194                 int ncontig, i;
195                 size_t pgsize;
196                 pte_t *cpte;
197                 bool is_dirty = false;
198 
199                 cpte = huge_pte_offset(mm, addr);
200                 ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
201                 /* save the 1st pte to return */
202                 pte = ptep_get_and_clear(mm, addr, cpte);
203                 for (i = 1, addr += pgsize; i < ncontig; ++i, addr += pgsize) {
204                         /*
205                          * If HW_AFDBM is enabled, then the HW could
206                          * turn on the dirty bit for any of the page
207                          * in the set, so check them all.
208                          */
209                         ++cpte;
210                         if (pte_dirty(ptep_get_and_clear(mm, addr, cpte)))
211                                 is_dirty = true;
212                 }
213                 if (is_dirty)
214                         return pte_mkdirty(pte);
215                 else
216                         return pte;
217         } else {
218                 return ptep_get_and_clear(mm, addr, ptep);
219         }
220 }
221 
222 int 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         pte_t *cpte;
227 
228         if (pte_cont(pte)) {
229                 int ncontig, i, changed = 0;
230                 size_t pgsize = 0;
231                 unsigned long pfn = pte_pfn(pte);
232                 /* Select all bits except the pfn */
233                 pgprot_t hugeprot =
234                         __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^
235                                  pte_val(pte));
236 
237                 cpte = huge_pte_offset(vma->vm_mm, addr);
238                 pfn = pte_pfn(*cpte);
239                 ncontig = find_num_contig(vma->vm_mm, addr, cpte,
240                                           *cpte, &pgsize);
241                 for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize) {
242                         changed |= ptep_set_access_flags(vma, addr, cpte,
243                                                         pfn_pte(pfn,
244                                                                 hugeprot),
245                                                         dirty);
246                         pfn += pgsize >> PAGE_SHIFT;
247                 }
248                 return changed;
249         } else {
250                 return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
251         }
252 }
253 
254 void huge_ptep_set_wrprotect(struct mm_struct *mm,
255                              unsigned long addr, pte_t *ptep)
256 {
257         if (pte_cont(*ptep)) {
258                 int ncontig, i;
259                 pte_t *cpte;
260                 size_t pgsize = 0;
261 
262                 cpte = huge_pte_offset(mm, addr);
263                 ncontig = find_num_contig(mm, addr, cpte, *cpte, &pgsize);
264                 for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize)
265                         ptep_set_wrprotect(mm, addr, cpte);
266         } else {
267                 ptep_set_wrprotect(mm, addr, ptep);
268         }
269 }
270 
271 void huge_ptep_clear_flush(struct vm_area_struct *vma,
272                            unsigned long addr, pte_t *ptep)
273 {
274         if (pte_cont(*ptep)) {
275                 int ncontig, i;
276                 pte_t *cpte;
277                 size_t pgsize = 0;
278 
279                 cpte = huge_pte_offset(vma->vm_mm, addr);
280                 ncontig = find_num_contig(vma->vm_mm, addr, cpte,
281                                           *cpte, &pgsize);
282                 for (i = 0; i < ncontig; ++i, ++cpte, addr += pgsize)
283                         ptep_clear_flush(vma, addr, cpte);
284         } else {
285                 ptep_clear_flush(vma, addr, ptep);
286         }
287 }
288 
289 static __init int setup_hugepagesz(char *opt)
290 {
291         unsigned long ps = memparse(opt, &opt);
292 
293         if (ps == PMD_SIZE) {
294                 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
295         } else if (ps == PUD_SIZE) {
296                 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
297         } else if (ps == (PAGE_SIZE * CONT_PTES)) {
298                 hugetlb_add_hstate(CONT_PTE_SHIFT);
299         } else if (ps == (PMD_SIZE * CONT_PMDS)) {
300                 hugetlb_add_hstate((PMD_SHIFT + CONT_PMD_SHIFT) - PAGE_SHIFT);
301         } else {
302                 hugetlb_bad_size();
303                 pr_err("hugepagesz: Unsupported page size %lu K\n", ps >> 10);
304                 return 0;
305         }
306         return 1;
307 }
308 __setup("hugepagesz=", setup_hugepagesz);
309 
310 #ifdef CONFIG_ARM64_64K_PAGES
311 static __init int add_default_hugepagesz(void)
312 {
313         if (size_to_hstate(CONT_PTES * PAGE_SIZE) == NULL)
314                 hugetlb_add_hstate(CONT_PTE_SHIFT);
315         return 0;
316 }
317 arch_initcall(add_default_hugepagesz);
318 #endif
319 

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