xref: /openbmc/linux/arch/powerpc/mm/book3s64/hash_4k.c (revision 2a598d0b)
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 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