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