1 /*
2 * Copyright IBM Corporation, 2013
3 * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
4 *
5 * This program is free software; you can redistribute it and/or modify it
6 * under the terms of version 2.1 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 /*
16 * PPC64 THP Support for hash based MMUs
17 */
18 #include <linux/mm.h>
19 #include <asm/machdep.h>
20
__hash_page_thp(unsigned long ea,unsigned long access,unsigned long vsid,pmd_t * pmdp,unsigned long trap,unsigned long flags,int ssize,unsigned int psize)21 int __hash_page_thp(unsigned long ea, unsigned long access, unsigned long vsid,
22 pmd_t *pmdp, unsigned long trap, unsigned long flags,
23 int ssize, unsigned int psize)
24 {
25 unsigned int index, valid;
26 unsigned char *hpte_slot_array;
27 unsigned long rflags, pa, hidx;
28 unsigned long old_pmd, new_pmd;
29 int ret, lpsize = MMU_PAGE_16M;
30 unsigned long vpn, hash, shift, slot;
31
32 /*
33 * atomically mark the linux large page PMD busy and dirty
34 */
35 do {
36 pmd_t pmd = READ_ONCE(*pmdp);
37
38 old_pmd = pmd_val(pmd);
39 /* If PMD busy, retry the access */
40 if (unlikely(old_pmd & _PAGE_BUSY))
41 return 0;
42 /* If PMD is trans splitting retry the access */
43 if (unlikely(old_pmd & _PAGE_SPLITTING))
44 return 0;
45 /* If PMD permissions don't match, take page fault */
46 if (unlikely(access & ~old_pmd))
47 return 1;
48 /*
49 * Try to lock the PTE, add ACCESSED and DIRTY if it was
50 * a write access
51 */
52 new_pmd = old_pmd | _PAGE_BUSY | _PAGE_ACCESSED;
53 if (access & _PAGE_RW)
54 new_pmd |= _PAGE_DIRTY;
55 } while (old_pmd != __cmpxchg_u64((unsigned long *)pmdp,
56 old_pmd, new_pmd));
57 /*
58 * PP bits. _PAGE_USER is already PP bit 0x2, so we only
59 * need to add in 0x1 if it's a read-only user page
60 */
61 rflags = new_pmd & _PAGE_USER;
62 if ((new_pmd & _PAGE_USER) && !((new_pmd & _PAGE_RW) &&
63 (new_pmd & _PAGE_DIRTY)))
64 rflags |= 0x1;
65 /*
66 * _PAGE_EXEC -> HW_NO_EXEC since it's inverted
67 */
68 rflags |= ((new_pmd & _PAGE_EXEC) ? 0 : HPTE_R_N);
69
70 #if 0
71 if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE)) {
72
73 /*
74 * No CPU has hugepages but lacks no execute, so we
75 * don't need to worry about that case
76 */
77 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
78 }
79 #endif
80 /*
81 * Find the slot index details for this ea, using base page size.
82 */
83 shift = mmu_psize_defs[psize].shift;
84 index = (ea & ~HPAGE_PMD_MASK) >> shift;
85 BUG_ON(index >= 4096);
86
87 vpn = hpt_vpn(ea, vsid, ssize);
88 hpte_slot_array = get_hpte_slot_array(pmdp);
89 if (psize == MMU_PAGE_4K) {
90 /*
91 * invalidate the old hpte entry if we have that mapped via 64K
92 * base page size. This is because demote_segment won't flush
93 * hash page table entries.
94 */
95 if ((old_pmd & _PAGE_HASHPTE) && !(old_pmd & _PAGE_COMBO))
96 flush_hash_hugepage(vsid, ea, pmdp, MMU_PAGE_64K,
97 ssize, flags);
98 }
99
100 valid = hpte_valid(hpte_slot_array, index);
101 if (valid) {
102 /* update the hpte bits */
103 hash = hpt_hash(vpn, shift, ssize);
104 hidx = hpte_hash_index(hpte_slot_array, index);
105 if (hidx & _PTEIDX_SECONDARY)
106 hash = ~hash;
107 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
108 slot += hidx & _PTEIDX_GROUP_IX;
109
110 ret = ppc_md.hpte_updatepp(slot, rflags, vpn,
111 psize, lpsize, ssize, flags);
112 /*
113 * We failed to update, try to insert a new entry.
114 */
115 if (ret == -1) {
116 /*
117 * large pte is marked busy, so we can be sure
118 * nobody is looking at hpte_slot_array. hence we can
119 * safely update this here.
120 */
121 valid = 0;
122 hpte_slot_array[index] = 0;
123 }
124 }
125
126 if (!valid) {
127 unsigned long hpte_group;
128
129 hash = hpt_hash(vpn, shift, ssize);
130 /* insert new entry */
131 pa = pmd_pfn(__pmd(old_pmd)) << PAGE_SHIFT;
132 new_pmd |= _PAGE_HASHPTE;
133
134 /* Add in WIMG bits */
135 rflags |= (new_pmd & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
136 _PAGE_GUARDED));
137 /*
138 * enable the memory coherence always
139 */
140 rflags |= HPTE_R_M;
141 repeat:
142 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
143
144 /* Insert into the hash table, primary slot */
145 slot = ppc_md.hpte_insert(hpte_group, vpn, pa, rflags, 0,
146 psize, lpsize, ssize);
147 /*
148 * Primary is full, try the secondary
149 */
150 if (unlikely(slot == -1)) {
151 hpte_group = ((~hash & htab_hash_mask) *
152 HPTES_PER_GROUP) & ~0x7UL;
153 slot = ppc_md.hpte_insert(hpte_group, vpn, pa,
154 rflags, HPTE_V_SECONDARY,
155 psize, lpsize, ssize);
156 if (slot == -1) {
157 if (mftb() & 0x1)
158 hpte_group = ((hash & htab_hash_mask) *
159 HPTES_PER_GROUP) & ~0x7UL;
160
161 ppc_md.hpte_remove(hpte_group);
162 goto repeat;
163 }
164 }
165 /*
166 * Hypervisor failure. Restore old pmd and return -1
167 * similar to __hash_page_*
168 */
169 if (unlikely(slot == -2)) {
170 *pmdp = __pmd(old_pmd);
171 hash_failure_debug(ea, access, vsid, trap, ssize,
172 psize, lpsize, old_pmd);
173 return -1;
174 }
175 /*
176 * large pte is marked busy, so we can be sure
177 * nobody is looking at hpte_slot_array. hence we can
178 * safely update this here.
179 */
180 mark_hpte_slot_valid(hpte_slot_array, index, slot);
181 }
182 /*
183 * Mark the pte with _PAGE_COMBO, if we are trying to hash it with
184 * base page size 4k.
185 */
186 if (psize == MMU_PAGE_4K)
187 new_pmd |= _PAGE_COMBO;
188 /*
189 * The hpte valid is stored in the pgtable whose address is in the
190 * second half of the PMD. Order this against clearing of the busy bit in
191 * huge pmd.
192 */
193 smp_wmb();
194 *pmdp = __pmd(new_pmd & ~_PAGE_BUSY);
195 return 0;
196 }
197