1 /*
2 * Copyright IBM Corporation, 2015
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 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
__hash_page_4K(unsigned long ea,unsigned long access,unsigned long vsid,pte_t * ptep,unsigned long trap,unsigned long flags,int ssize,int subpg_prot)19 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
20 pte_t *ptep, unsigned long trap, unsigned long flags,
21 int ssize, int subpg_prot)
22 {
23 unsigned long hpte_group;
24 unsigned long rflags, pa;
25 unsigned long old_pte, new_pte;
26 unsigned long vpn, hash, slot;
27 unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
28
29 /*
30 * atomically mark the linux large page PTE busy and dirty
31 */
32 do {
33 pte_t pte = READ_ONCE(*ptep);
34
35 old_pte = pte_val(pte);
36 /* If PTE busy, retry the access */
37 if (unlikely(old_pte & H_PAGE_BUSY))
38 return 0;
39 /* If PTE permissions don't match, take page fault */
40 if (unlikely(!check_pte_access(access, old_pte)))
41 return 1;
42 /*
43 * Try to lock the PTE, add ACCESSED and DIRTY if it was
44 * a write access. Since this is 4K insert of 64K page size
45 * also add H_PAGE_COMBO
46 */
47 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
48 if (access & _PAGE_WRITE)
49 new_pte |= _PAGE_DIRTY;
50 } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
51
52 /*
53 * PP bits. _PAGE_USER is already PP bit 0x2, so we only
54 * need to add in 0x1 if it's a read-only user page
55 */
56 rflags = htab_convert_pte_flags(new_pte);
57
58 if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
59 !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
60 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
61
62 vpn = hpt_vpn(ea, vsid, ssize);
63 if (unlikely(old_pte & H_PAGE_HASHPTE)) {
64 /*
65 * There MIGHT be an HPTE for this pte
66 */
67 hash = hpt_hash(vpn, shift, ssize);
68 if (old_pte & H_PAGE_F_SECOND)
69 hash = ~hash;
70 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
71 slot += (old_pte & H_PAGE_F_GIX) >> H_PAGE_F_GIX_SHIFT;
72
73 if (mmu_hash_ops.hpte_updatepp(slot, rflags, vpn, MMU_PAGE_4K,
74 MMU_PAGE_4K, ssize, flags) == -1)
75 old_pte &= ~_PAGE_HPTEFLAGS;
76 }
77
78 if (likely(!(old_pte & H_PAGE_HASHPTE))) {
79
80 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
81 hash = hpt_hash(vpn, shift, ssize);
82
83 repeat:
84 hpte_group = ((hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
85
86 /* Insert into the hash table, primary slot */
87 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
88 MMU_PAGE_4K, MMU_PAGE_4K, ssize);
89 /*
90 * Primary is full, try the secondary
91 */
92 if (unlikely(slot == -1)) {
93 hpte_group = ((~hash & htab_hash_mask) * HPTES_PER_GROUP) & ~0x7UL;
94 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
95 rflags,
96 HPTE_V_SECONDARY,
97 MMU_PAGE_4K,
98 MMU_PAGE_4K, ssize);
99 if (slot == -1) {
100 if (mftb() & 0x1)
101 hpte_group = ((hash & htab_hash_mask) *
102 HPTES_PER_GROUP) & ~0x7UL;
103 mmu_hash_ops.hpte_remove(hpte_group);
104 /*
105 * FIXME!! Should be try the group from which we removed ?
106 */
107 goto repeat;
108 }
109 }
110 /*
111 * Hypervisor failure. Restore old pte and return -1
112 * similar to __hash_page_*
113 */
114 if (unlikely(slot == -2)) {
115 *ptep = __pte(old_pte);
116 hash_failure_debug(ea, access, vsid, trap, ssize,
117 MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
118 return -1;
119 }
120 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
121 new_pte |= (slot << H_PAGE_F_GIX_SHIFT) &
122 (H_PAGE_F_SECOND | H_PAGE_F_GIX);
123 }
124 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
125 return 0;
126 }
127