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
__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)21 int __hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid,
22 pte_t *ptep, unsigned long trap, unsigned long flags,
23 int ssize, int subpg_prot)
24 {
25 real_pte_t rpte;
26 unsigned long hpte_group;
27 unsigned long rflags, pa;
28 unsigned long old_pte, new_pte;
29 unsigned long vpn, hash, slot;
30 unsigned long shift = mmu_psize_defs[MMU_PAGE_4K].shift;
31
32 /*
33 * atomically mark the linux large page PTE busy and dirty
34 */
35 do {
36 pte_t pte = READ_ONCE(*ptep);
37
38 old_pte = pte_val(pte);
39 /* If PTE busy, retry the access */
40 if (unlikely(old_pte & H_PAGE_BUSY))
41 return 0;
42 /* If PTE permissions don't match, take page fault */
43 if (unlikely(!check_pte_access(access, old_pte)))
44 return 1;
45 /*
46 * Try to lock the PTE, add ACCESSED and DIRTY if it was
47 * a write access. Since this is 4K insert of 64K page size
48 * also add H_PAGE_COMBO
49 */
50 new_pte = old_pte | H_PAGE_BUSY | _PAGE_ACCESSED;
51 if (access & _PAGE_WRITE)
52 new_pte |= _PAGE_DIRTY;
53 } while (!pte_xchg(ptep, __pte(old_pte), __pte(new_pte)));
54
55 /*
56 * PP bits. _PAGE_USER is already PP bit 0x2, so we only
57 * need to add in 0x1 if it's a read-only user page
58 */
59 rflags = htab_convert_pte_flags(new_pte, flags);
60 rpte = __real_pte(__pte(old_pte), ptep, PTRS_PER_PTE);
61
62 if (cpu_has_feature(CPU_FTR_NOEXECUTE) &&
63 !cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
64 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
65
66 vpn = hpt_vpn(ea, vsid, ssize);
67 if (unlikely(old_pte & H_PAGE_HASHPTE)) {
68 /*
69 * There MIGHT be an HPTE for this pte
70 */
71 unsigned long gslot = pte_get_hash_gslot(vpn, shift, ssize,
72 rpte, 0);
73
74 if (mmu_hash_ops.hpte_updatepp(gslot, rflags, vpn, MMU_PAGE_4K,
75 MMU_PAGE_4K, ssize, flags) == -1)
76 old_pte &= ~_PAGE_HPTEFLAGS;
77 }
78
79 if (likely(!(old_pte & H_PAGE_HASHPTE))) {
80
81 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
82 hash = hpt_hash(vpn, shift, ssize);
83
84 repeat:
85 hpte_group = (hash & htab_hash_mask) * HPTES_PER_GROUP;
86
87 /* Insert into the hash table, primary slot */
88 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa, rflags, 0,
89 MMU_PAGE_4K, MMU_PAGE_4K, ssize);
90 /*
91 * Primary is full, try the secondary
92 */
93 if (unlikely(slot == -1)) {
94 hpte_group = (~hash & htab_hash_mask) * HPTES_PER_GROUP;
95 slot = mmu_hash_ops.hpte_insert(hpte_group, vpn, pa,
96 rflags,
97 HPTE_V_SECONDARY,
98 MMU_PAGE_4K,
99 MMU_PAGE_4K, ssize);
100 if (slot == -1) {
101 if (mftb() & 0x1)
102 hpte_group = (hash & htab_hash_mask) *
103 HPTES_PER_GROUP;
104 mmu_hash_ops.hpte_remove(hpte_group);
105 /*
106 * FIXME!! Should be try the group from which we removed ?
107 */
108 goto repeat;
109 }
110 }
111 /*
112 * Hypervisor failure. Restore old pte and return -1
113 * similar to __hash_page_*
114 */
115 if (unlikely(slot == -2)) {
116 *ptep = __pte(old_pte);
117 hash_failure_debug(ea, access, vsid, trap, ssize,
118 MMU_PAGE_4K, MMU_PAGE_4K, old_pte);
119 return -1;
120 }
121 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | H_PAGE_HASHPTE;
122 new_pte |= pte_set_hidx(ptep, rpte, 0, slot, PTRS_PER_PTE);
123
124 if (stress_hpt())
125 hpt_do_stress(ea, hpte_group);
126 }
127 *ptep = __pte(new_pte & ~H_PAGE_BUSY);
128 return 0;
129 }
130