1 /*
2 * Copyright IBM Corporation, 2015
3 * Author Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of version 2 of the GNU Lesser General Public License
7 * as published by the Free Software Foundation.
8 *
9 * This program is distributed in the hope that it would be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
12 *
13 */
14
15 #include <linux/mm.h>
16 #include <asm/machdep.h>
17 #include <asm/mmu.h>
18
19 #include "internal.h"
20
21 /*
22 * Return true, if the entry has a slot value which
23 * the software considers as invalid.
24 */
25 static inline bool hpte_soft_invalid(unsigned long hidx)
26 {
27 return ((hidx & 0xfUL) == 0xfUL);
28 }
29
30 /*
31 * index from 0 - 15
32 */
33 bool __rpte_sub_valid(real_pte_t rpte, unsigned long index)
34 {
35 return !(hpte_soft_invalid(__rpte_to_hidx(rpte, index)));
36 }
37
38 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
39 pte_t *ptep, unsigned long trap, unsigned long flags,
40 int ssize, int subpg_prot)
41 {
42 real_pte_t rpte;
43 unsigned long hpte_group;
44 unsigned int subpg_index;
45 unsigned long rflags, pa;
46 unsigned long old_pte, new_pte, subpg_pte;
47 unsigned long vpn, hash, slot, gslot;
48 unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
49
50 /*
51 * atomically mark the linux large page PTE busy and dirty
52 */
53 do {
54 pte_t pte = READ_ONCE(*ptep);
55
56 old_pte = pte_val(pte);
57 /* If PTE busy, retry the access */
58 if (unlikely(old_pte & H_PAGE_BUSY))
59 return 0;
60 /* If PTE permissions don't match, take page fault */
61 if (unlikely(!check_pte_access(access, old_pte)))
62 return 1;
63 /*
64 * Try to lock the PTE, add ACCESSED and DIRTY if it was
65 * a write access. Since this is 4K insert of 64K page size
66 * also add H_PAGE_COMBO
67 */
68 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED | H_PAGE_COMBO;
69 if (access & _PAGE_WRITE)
70 new_pte |= _PAGE_DIRTY;
71 } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
72
73 /*
74 * Handle the subpage protection bits
75 */
76 subpg_pte = new_pte & ~subpg_prot;
77 rflags = htab_convert_pte_flags(subpg_pte, flags);
78
79 if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
80 !cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
81
82 /*
83 * No CPU has hugepages but lacks no execute, so we
84 * don't need to worry about that case
85 */
86 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
87 }
88
89 subpg_index = (ea & (PAGE_SIZE - 1)) >> shift;
90 vpn = hpt_vpn(ea, vsid, ssize);
91 rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
92 /*
93 *None of the sub 4k page is hashed
94 */
95 if (!(old_pte & H_PAGE_HASHPTE))
96 goto htab_insert_hpte;
97 /*
98 * Check if the pte was already inserted into the hash table
99 * as a 64k HW page, and invalidate the 64k HPTE if so.
100 */
101 if (!(old_pte & H_PAGE_COMBO)) {
102 flush_hash_page(vpn, rpte, MMU_PAGE_64K, ssize, flags);
103 /*
104 * clear the old slot details from the old and new pte.
105 * On hash insert failure we use old pte value and we don't
106 * want slot information there if we have a insert failure.
107 */
108 old_pte &= ~H_PAGE_HASHPTE;
109 new_pte &= ~H_PAGE_HASHPTE;
110 goto htab_insert_hpte;
111 }
112 /*
113 * Check for sub page valid and update
114 */
115 if (__rpte_sub_valid(rpte, subpg_index)) {
116 int ret;
117
118 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte,
119 subpg_index);
120 ret = mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn,
121 MMU_PAGE_4K, MMU_PAGE_4K,
122 ssize, flags);
123
124 /*
125 * If we failed because typically the HPTE wasn't really here
126 * we try an insertion.
127 */
128 if (ret == -1)
129 goto htab_insert_hpte;
130
131 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
132 return 0;
133 }
134
135 htab_insert_hpte:
136
137 /*
138 * Initialize all hidx entries to invalid value, the first time
139 * the PTE is about to allocate a 4K HPTE.
140 */
141 if (!(old_pte & H_PAGE_COMBO))
142 rpte.hidx = INVALID_RPTE_HIDX;
143
144 /*
145 * handle H_PAGE_4K_PFN case
146 */
147 if (old_pte & H_PAGE_4K_PFN) {
148 /*
149 * All the sub 4k page have the same
150 * physical address.
151 */
152 pa = pte_pfn(__pte(old_pte)) << HW_PAGE_SHIFT;
153 } else {
154 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
155 pa += (subpg_index << shift);
156 }
157 hash = hpt_hash(vpn, shift, ssize);
158 repeat:
159 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
160
161 /* Insert into the hash table, primary slot */
162 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
163 MMU_PAGE_4K, MMU_PAGE_4K, ssize);
164 /*
165 * Primary is full, try the secondary
166 */
167 if (unlikely(slot == -1)) {
168 bool soft_invalid;
169
170 hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
171 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
172 rflags, HPTE_V_SECONDARY,
173 MMU_PAGE_4K, MMU_PAGE_4K,
174 ssize);
175
176 soft_invalid = hpte_soft_invalid(slot);
177 if (unlikely(soft_invalid)) {
178 /*
179 * We got a valid slot from a hardware point of view.
180 * but we cannot use it, because we use this special
181 * value; as defined by hpte_soft_invalid(), to track
182 * invalid slots. We cannot use it. So invalidate it.
183 */
184 gslot = slot & _PTEIDX_GROUP_IX;
185 mmu_hash_ops.hpte_invalidate(hpte_group + gslot, vpn,
186 MMU_PAGE_4K, MMU_PAGE_4K,
187 ssize, 0);
188 }
189
190 if (unlikely(slot == -1 || soft_invalid)) {
191 /*
192 * For soft invalid slot, let's ensure that we release a
193 * slot from the primary, with the hope that we will
194 * acquire that slot next time we try. This will ensure
195 * that we do not get the same soft-invalid slot.
196 */
197 if (soft_invalid || (mftb() & 0x1))
198 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
199
200 mmu_hash_ops.hpte_remove(hpte_group);
201 /*
202 * FIXME!! Should be try the group from which we removed ?
203 */
204 goto repeat;
205 }
206 }
207 /*
208 * Hypervisor failure. Restore old pte and return -1
209 * similar to __hash_page_*
210 */
211 if (unlikely(slot == -2)) {
212 *ptep = __pte(old_pte);
213 hash_failure_debug(ea, access, vsid, trap, ssize,
214 MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
215 return -1;
216 }
217
218 new_pte |= pte_set_hidx(ptep, rpte, subpg_index, slot, PTRS_PER_PTE);
219 new_pte |= H_PAGE_HASHPTE;
220
221 if (stress_hpt())
222 hpt_do_stress(ea, hpte_group);
223
224 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
225 return 0;
226 }
227
228 int __hash_page_64K(unsigned long ea, unsigned long access,
229 unsigned long vsid, pte_t *ptep, unsigned long trap,
230 unsigned long flags, int ssize)
231 {
232 real_pte_t rpte;
233 unsigned long hpte_group;
234 unsigned long rflags, pa;
235 unsigned long old_pte, new_pte;
236 unsigned long vpn, hash, slot;
237 unsigned long shift = mmu_psize_defs[MMU_PAGE_64K].shift;
238
239 /*
240 * atomically mark the linux large page PTE busy and dirty
241 */
242 do {
243 pte_t pte = READ_ONCE(*ptep);
244
245 old_pte = pte_val(pte);
246 /* If PTE busy, retry the access */
247 if (unlikely(old_pte & H_PAGE_BUSY))
248 return 0;
249 /* If PTE permissions don't match, take page fault */
250 if (unlikely(!check_pte_access(access, old_pte)))
251 return 1;
252 /*
253 * Check if PTE has the cache-inhibit bit set
254 * If so, bail out and refault as a 4k page
255 */
256 if (!mmu_has_feature(MMU_FTR_CI_LARGE_PAGE) &&
257 unlikely(pte_ci(pte)))
258 return 0;
259 /*
260 * Try to lock the PTE, add ACCESSED and DIRTY if it was
261 * a write access.
262 */
263 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
264 if (access & _PAGE_WRITE)
265 new_pte |= _PAGE_DIRTY;
266 } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
267
268 rflags = htab_convert_pte_flags(new_pte, flags);
269 rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
270
271 if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
272 !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
273 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
274
275 vpn = hpt_vpn(ea, vsid, ssize);
276 if (unlikely(old_pte & H_PAGE_HASHPTE)) {
277 unsigned long gslot;
278
279 /*
280 * There MIGHT be an HPTE for this pte
281 */
282 gslot = pte_get_hash_gslot(vpn, shift, ssize, rpte, 0);
283 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_64K,
284 MMU_PAGE_64K, ssize,
285 flags) == -1)
286 old_pte &= ~_PAGE_HPTEFLAGS;
287 }
288
289 if (likely(!(old_pte & H_PAGE_HASHPTE))) {
290
291 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
292 hash = hpt_hash(vpn, shift, ssize);
293
294 repeat:
295 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
296
297 /* Insert into the hash table, primary slot */
298 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
299 MMU_PAGE_64K, MMU_PAGE_64K,
300 ssize);
301 /*
302 * Primary is full, try the secondary
303 */
304 if (unlikely(slot == -1)) {
305 hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
306 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
307 rflags,
308 HPTE_V_SECONDARY,
309 MMU_PAGE_64K,
310 MMU_PAGE_64K, ssize);
311 if (slot == -1) {
312 if (mftb() & 0x1)
313 hpte_group = (hash & htab_hash_mask) *
314 HPTES_PER_GROUP;
315 mmu_hash_ops.hpte_remove(hpte_group);
316 /*
317 * FIXME!! Should be try the group from which we removed ?
318 */
319 goto repeat;
320 }
321 }
322 /*
323 * Hypervisor failure. Restore old pte and return -1
324 * similar to __hash_page_*
325 */
326 if (unlikely(slot == -2)) {
327 *ptep = __pte(old_pte);
328 hash_failure_debug(ea, access, vsid, trap, ssize,
329 MMU_PAGE_64K, MMU_PAGE_64K, old_pte);
330 return -1;
331 }
332
333 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
334 new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
335
336 if (stress_hpt())
337 hpt_do_stress(ea, hpte_group);
338 }
339
340 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
341
342 return 0;
343 }
344
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