1 /*
2 * PPC64 Huge TLB Page Support for hash based MMUs (POWER4 and later)
3 *
4 * Copyright (C) 2003 David Gibson, IBM Corporation.
5 *
6 * Based on the IA-32 version:
7 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
8 */
9
10 #include <linux/mm.h>
11 #include <linux/hugetlb.h>
12 #include <asm/pgtable.h>
13 #include <asm/pgalloc.h>
14 #include <asm/cacheflush.h>
15 #include <asm/machdep.h>
16
17 extern long hpte_insert_repeating(unsigned long hash, unsigned long vpn,
18 unsigned long pa, unsigned long rlags,
19 unsigned long vflags, int psize, int ssize);
20
__hash_page_huge(unsigned long ea,unsigned long access,unsigned long vsid,pte_t * ptep,unsigned long trap,unsigned long flags,int ssize,unsigned int shift,unsigned int mmu_psize)21 int __hash_page_huge(unsigned long ea, unsigned long access, unsigned long vsid,
22 pte_t *ptep, unsigned long trap, unsigned long flags,
23 int ssize, unsigned int shift, unsigned int mmu_psize)
24 {
25 unsigned long vpn;
26 unsigned long old_pte, new_pte;
27 unsigned long rflags, pa, sz;
28 long slot;
29
30 BUG_ON(shift != mmu_psize_defs[mmu_psize].shift);
31
32 /* Search the Linux page table for a match with va */
33 vpn = hpt_vpn(ea, vsid, ssize);
34
35 /* At this point, we have a pte (old_pte) which can be used to build
36 * or update an HPTE. There are 2 cases:
37 *
38 * 1. There is a valid (present) pte with no associated HPTE (this is
39 * the most common case)
40 * 2. There is a valid (present) pte with an associated HPTE. The
41 * current values of the pp bits in the HPTE prevent access
42 * because we are doing software DIRTY bit management and the
43 * page is currently not DIRTY.
44 */
45
46
47 do {
48 old_pte = pte_val(*ptep);
49 /* If PTE busy, retry the access */
50 if (unlikely(old_pte & _PAGE_BUSY))
51 return 0;
52 /* If PTE permissions don't match, take page fault */
53 if (unlikely(access & ~old_pte))
54 return 1;
55 /* Try to lock the PTE, add ACCESSED and DIRTY if it was
56 * a write access */
57 new_pte = old_pte | _PAGE_BUSY | _PAGE_ACCESSED;
58 if (access & _PAGE_RW)
59 new_pte |= _PAGE_DIRTY;
60 } while(old_pte != __cmpxchg_u64((unsigned long *)ptep,
61 old_pte, new_pte));
62
63 rflags = 0x2 | (!(new_pte & _PAGE_RW));
64 /* _PAGE_EXEC -> HW_NO_EXEC since it's inverted */
65 rflags |= ((new_pte & _PAGE_EXEC) ? 0 : HPTE_R_N);
66 sz = ((1UL) << shift);
67 if (!cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
68 /* No CPU has hugepages but lacks no execute, so we
69 * don't need to worry about that case */
70 rflags = hash_page_do_lazy_icache(rflags, __pte(old_pte), trap);
71
72 /* Check if pte already has an hpte (case 2) */
73 if (unlikely(old_pte & _PAGE_HASHPTE)) {
74 /* There MIGHT be an HPTE for this pte */
75 unsigned long hash, slot;
76
77 hash = hpt_hash(vpn, shift, ssize);
78 if (old_pte & _PAGE_F_SECOND)
79 hash = ~hash;
80 slot = (hash & htab_hash_mask) * HPTES_PER_GROUP;
81 slot += (old_pte & _PAGE_F_GIX) >> 12;
82
83 if (ppc_md.hpte_updatepp(slot, rflags, vpn, mmu_psize,
84 mmu_psize, ssize, flags) == -1)
85 old_pte &= ~_PAGE_HPTEFLAGS;
86 }
87
88 if (likely(!(old_pte & _PAGE_HASHPTE))) {
89 unsigned long hash = hpt_hash(vpn, shift, ssize);
90
91 pa = pte_pfn(__pte(old_pte)) << PAGE_SHIFT;
92
93 /* clear HPTE slot informations in new PTE */
94 #ifdef CONFIG_PPC_64K_PAGES
95 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HPTE_SUB0;
96 #else
97 new_pte = (new_pte & ~_PAGE_HPTEFLAGS) | _PAGE_HASHPTE;
98 #endif
99 /* Add in WIMG bits */
100 rflags |= (new_pte & (_PAGE_WRITETHRU | _PAGE_NO_CACHE |
101 _PAGE_COHERENT | _PAGE_GUARDED));
102 /*
103 * enable the memory coherence always
104 */
105 rflags |= HPTE_R_M;
106
107 slot = hpte_insert_repeating(hash, vpn, pa, rflags, 0,
108 mmu_psize, ssize);
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_psize, mmu_psize, old_pte);
118 return -1;
119 }
120
121 new_pte |= (slot << 12) & (_PAGE_F_SECOND | _PAGE_F_GIX);
122 }
123
124 /*
125 * No need to use ldarx/stdcx here
126 */
127 *ptep = __pte(new_pte & ~_PAGE_BUSY);
128 return 0;
129 }
130