~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/arch/s390/mm/pgalloc.c

Version: ~ [ linux-5.13-rc5 ] ~ [ linux-5.12.9 ] ~ [ linux-5.11.22 ] ~ [ linux-5.10.42 ] ~ [ linux-5.9.16 ] ~ [ linux-5.8.18 ] ~ [ linux-5.7.19 ] ~ [ linux-5.6.19 ] ~ [ linux-5.5.19 ] ~ [ linux-5.4.124 ] ~ [ linux-5.3.18 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.193 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.235 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.271 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.271 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.18.140 ] ~ [ linux-3.16.85 ] ~ [ linux-3.14.79 ] ~ [ linux-3.12.74 ] ~ [ linux-3.10.108 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 // SPDX-License-Identifier: GPL-2.0
  2 /*
  3  *  Page table allocation functions
  4  *
  5  *    Copyright IBM Corp. 2016
  6  *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
  7  */
  8 
  9 #include <linux/mm.h>
 10 #include <linux/sysctl.h>
 11 #include <asm/mmu_context.h>
 12 #include <asm/pgalloc.h>
 13 #include <asm/gmap.h>
 14 #include <asm/tlb.h>
 15 #include <asm/tlbflush.h>
 16 
 17 #ifdef CONFIG_PGSTE
 18 
 19 static int page_table_allocate_pgste_min = 0;
 20 static int page_table_allocate_pgste_max = 1;
 21 int page_table_allocate_pgste = 0;
 22 EXPORT_SYMBOL(page_table_allocate_pgste);
 23 
 24 static struct ctl_table page_table_sysctl[] = {
 25         {
 26                 .procname       = "allocate_pgste",
 27                 .data           = &page_table_allocate_pgste,
 28                 .maxlen         = sizeof(int),
 29                 .mode           = S_IRUGO | S_IWUSR,
 30                 .proc_handler   = proc_dointvec,
 31                 .extra1         = &page_table_allocate_pgste_min,
 32                 .extra2         = &page_table_allocate_pgste_max,
 33         },
 34         { }
 35 };
 36 
 37 static struct ctl_table page_table_sysctl_dir[] = {
 38         {
 39                 .procname       = "vm",
 40                 .maxlen         = 0,
 41                 .mode           = 0555,
 42                 .child          = page_table_sysctl,
 43         },
 44         { }
 45 };
 46 
 47 static int __init page_table_register_sysctl(void)
 48 {
 49         return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM;
 50 }
 51 __initcall(page_table_register_sysctl);
 52 
 53 #endif /* CONFIG_PGSTE */
 54 
 55 unsigned long *crst_table_alloc(struct mm_struct *mm)
 56 {
 57         struct page *page = alloc_pages(GFP_KERNEL, 2);
 58 
 59         if (!page)
 60                 return NULL;
 61         arch_set_page_dat(page, 2);
 62         return (unsigned long *) page_to_phys(page);
 63 }
 64 
 65 void crst_table_free(struct mm_struct *mm, unsigned long *table)
 66 {
 67         free_pages((unsigned long) table, 2);
 68 }
 69 
 70 static void __crst_table_upgrade(void *arg)
 71 {
 72         struct mm_struct *mm = arg;
 73 
 74         if (current->active_mm == mm)
 75                 set_user_asce(mm);
 76         __tlb_flush_local();
 77 }
 78 
 79 int crst_table_upgrade(struct mm_struct *mm, unsigned long end)
 80 {
 81         unsigned long *table, *pgd;
 82         int rc, notify;
 83 
 84         /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */
 85         VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE);
 86         rc = 0;
 87         notify = 0;
 88         while (mm->context.asce_limit < end) {
 89                 table = crst_table_alloc(mm);
 90                 if (!table) {
 91                         rc = -ENOMEM;
 92                         break;
 93                 }
 94                 spin_lock_bh(&mm->page_table_lock);
 95                 pgd = (unsigned long *) mm->pgd;
 96                 if (mm->context.asce_limit == _REGION2_SIZE) {
 97                         crst_table_init(table, _REGION2_ENTRY_EMPTY);
 98                         p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd);
 99                         mm->pgd = (pgd_t *) table;
100                         mm->context.asce_limit = _REGION1_SIZE;
101                         mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
102                                 _ASCE_USER_BITS | _ASCE_TYPE_REGION2;
103                 } else {
104                         crst_table_init(table, _REGION1_ENTRY_EMPTY);
105                         pgd_populate(mm, (pgd_t *) table, (p4d_t *) pgd);
106                         mm->pgd = (pgd_t *) table;
107                         mm->context.asce_limit = -PAGE_SIZE;
108                         mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
109                                 _ASCE_USER_BITS | _ASCE_TYPE_REGION1;
110                 }
111                 notify = 1;
112                 spin_unlock_bh(&mm->page_table_lock);
113         }
114         if (notify)
115                 on_each_cpu(__crst_table_upgrade, mm, 0);
116         return rc;
117 }
118 
119 void crst_table_downgrade(struct mm_struct *mm)
120 {
121         pgd_t *pgd;
122 
123         /* downgrade should only happen from 3 to 2 levels (compat only) */
124         VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE);
125 
126         if (current->active_mm == mm) {
127                 clear_user_asce();
128                 __tlb_flush_mm(mm);
129         }
130 
131         pgd = mm->pgd;
132         mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN);
133         mm->context.asce_limit = _REGION3_SIZE;
134         mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH |
135                            _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT;
136         crst_table_free(mm, (unsigned long *) pgd);
137 
138         if (current->active_mm == mm)
139                 set_user_asce(mm);
140 }
141 
142 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits)
143 {
144         unsigned int old, new;
145 
146         do {
147                 old = atomic_read(v);
148                 new = old ^ bits;
149         } while (atomic_cmpxchg(v, old, new) != old);
150         return new;
151 }
152 
153 #ifdef CONFIG_PGSTE
154 
155 struct page *page_table_alloc_pgste(struct mm_struct *mm)
156 {
157         struct page *page;
158         u64 *table;
159 
160         page = alloc_page(GFP_KERNEL);
161         if (page) {
162                 table = (u64 *)page_to_phys(page);
163                 memset64(table, _PAGE_INVALID, PTRS_PER_PTE);
164                 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
165         }
166         return page;
167 }
168 
169 void page_table_free_pgste(struct page *page)
170 {
171         __free_page(page);
172 }
173 
174 #endif /* CONFIG_PGSTE */
175 
176 /*
177  * page table entry allocation/free routines.
178  */
179 unsigned long *page_table_alloc(struct mm_struct *mm)
180 {
181         unsigned long *table;
182         struct page *page;
183         unsigned int mask, bit;
184 
185         /* Try to get a fragment of a 4K page as a 2K page table */
186         if (!mm_alloc_pgste(mm)) {
187                 table = NULL;
188                 spin_lock_bh(&mm->context.lock);
189                 if (!list_empty(&mm->context.pgtable_list)) {
190                         page = list_first_entry(&mm->context.pgtable_list,
191                                                 struct page, lru);
192                         mask = atomic_read(&page->_mapcount);
193                         mask = (mask | (mask >> 4)) & 3;
194                         if (mask != 3) {
195                                 table = (unsigned long *) page_to_phys(page);
196                                 bit = mask & 1;         /* =1 -> second 2K */
197                                 if (bit)
198                                         table += PTRS_PER_PTE;
199                                 atomic_xor_bits(&page->_mapcount, 1U << bit);
200                                 list_del(&page->lru);
201                         }
202                 }
203                 spin_unlock_bh(&mm->context.lock);
204                 if (table)
205                         return table;
206         }
207         /* Allocate a fresh page */
208         page = alloc_page(GFP_KERNEL);
209         if (!page)
210                 return NULL;
211         if (!pgtable_page_ctor(page)) {
212                 __free_page(page);
213                 return NULL;
214         }
215         arch_set_page_dat(page, 0);
216         /* Initialize page table */
217         table = (unsigned long *) page_to_phys(page);
218         if (mm_alloc_pgste(mm)) {
219                 /* Return 4K page table with PGSTEs */
220                 atomic_set(&page->_mapcount, 3);
221                 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE);
222                 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE);
223         } else {
224                 /* Return the first 2K fragment of the page */
225                 atomic_set(&page->_mapcount, 1);
226                 memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE);
227                 spin_lock_bh(&mm->context.lock);
228                 list_add(&page->lru, &mm->context.pgtable_list);
229                 spin_unlock_bh(&mm->context.lock);
230         }
231         return table;
232 }
233 
234 void page_table_free(struct mm_struct *mm, unsigned long *table)
235 {
236         struct page *page;
237         unsigned int bit, mask;
238 
239         page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
240         if (!mm_alloc_pgste(mm)) {
241                 /* Free 2K page table fragment of a 4K page */
242                 bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t));
243                 spin_lock_bh(&mm->context.lock);
244                 mask = atomic_xor_bits(&page->_mapcount, 1U << bit);
245                 if (mask & 3)
246                         list_add(&page->lru, &mm->context.pgtable_list);
247                 else
248                         list_del(&page->lru);
249                 spin_unlock_bh(&mm->context.lock);
250                 if (mask != 0)
251                         return;
252         }
253 
254         pgtable_page_dtor(page);
255         atomic_set(&page->_mapcount, -1);
256         __free_page(page);
257 }
258 
259 void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table,
260                          unsigned long vmaddr)
261 {
262         struct mm_struct *mm;
263         struct page *page;
264         unsigned int bit, mask;
265 
266         mm = tlb->mm;
267         page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
268         if (mm_alloc_pgste(mm)) {
269                 gmap_unlink(mm, table, vmaddr);
270                 table = (unsigned long *) (__pa(table) | 3);
271                 tlb_remove_table(tlb, table);
272                 return;
273         }
274         bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t));
275         spin_lock_bh(&mm->context.lock);
276         mask = atomic_xor_bits(&page->_mapcount, 0x11U << bit);
277         if (mask & 3)
278                 list_add_tail(&page->lru, &mm->context.pgtable_list);
279         else
280                 list_del(&page->lru);
281         spin_unlock_bh(&mm->context.lock);
282         table = (unsigned long *) (__pa(table) | (1U << bit));
283         tlb_remove_table(tlb, table);
284 }
285 
286 static void __tlb_remove_table(void *_table)
287 {
288         unsigned int mask = (unsigned long) _table & 3;
289         void *table = (void *)((unsigned long) _table ^ mask);
290         struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT);
291 
292         switch (mask) {
293         case 0:         /* pmd, pud, or p4d */
294                 free_pages((unsigned long) table, 2);
295                 break;
296         case 1:         /* lower 2K of a 4K page table */
297         case 2:         /* higher 2K of a 4K page table */
298                 if (atomic_xor_bits(&page->_mapcount, mask << 4) != 0)
299                         break;
300                 /* fallthrough */
301         case 3:         /* 4K page table with pgstes */
302                 pgtable_page_dtor(page);
303                 atomic_set(&page->_mapcount, -1);
304                 __free_page(page);
305                 break;
306         }
307 }
308 
309 static void tlb_remove_table_smp_sync(void *arg)
310 {
311         /* Simply deliver the interrupt */
312 }
313 
314 static void tlb_remove_table_one(void *table)
315 {
316         /*
317          * This isn't an RCU grace period and hence the page-tables cannot be
318          * assumed to be actually RCU-freed.
319          *
320          * It is however sufficient for software page-table walkers that rely
321          * on IRQ disabling. See the comment near struct mmu_table_batch.
322          */
323         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
324         __tlb_remove_table(table);
325 }
326 
327 static void tlb_remove_table_rcu(struct rcu_head *head)
328 {
329         struct mmu_table_batch *batch;
330         int i;
331 
332         batch = container_of(head, struct mmu_table_batch, rcu);
333 
334         for (i = 0; i < batch->nr; i++)
335                 __tlb_remove_table(batch->tables[i]);
336 
337         free_page((unsigned long)batch);
338 }
339 
340 void tlb_table_flush(struct mmu_gather *tlb)
341 {
342         struct mmu_table_batch **batch = &tlb->batch;
343 
344         if (*batch) {
345                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
346                 *batch = NULL;
347         }
348 }
349 
350 void tlb_remove_table(struct mmu_gather *tlb, void *table)
351 {
352         struct mmu_table_batch **batch = &tlb->batch;
353 
354         tlb->mm->context.flush_mm = 1;
355         if (*batch == NULL) {
356                 *batch = (struct mmu_table_batch *)
357                         __get_free_page(GFP_NOWAIT | __GFP_NOWARN);
358                 if (*batch == NULL) {
359                         __tlb_flush_mm_lazy(tlb->mm);
360                         tlb_remove_table_one(table);
361                         return;
362                 }
363                 (*batch)->nr = 0;
364         }
365         (*batch)->tables[(*batch)->nr++] = table;
366         if ((*batch)->nr == MAX_TABLE_BATCH)
367                 tlb_flush_mmu(tlb);
368 }
369 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp