xref: /openbmc/linux/arch/s390/mm/hugetlbpage.c (revision 9b9c2cd4)
1 /*
2  *  IBM System z Huge TLB Page Support for Kernel.
3  *
4  *    Copyright IBM Corp. 2007
5  *    Author(s): Gerald Schaefer <gerald.schaefer@de.ibm.com>
6  */
7 
8 #include <linux/mm.h>
9 #include <linux/hugetlb.h>
10 
11 static inline pmd_t __pte_to_pmd(pte_t pte)
12 {
13 	pmd_t pmd;
14 
15 	/*
16 	 * Convert encoding		  pte bits	   pmd bits
17 	 *				lIR.uswrdy.p	dy..R...I...wr
18 	 * empty			010.000000.0 -> 00..0...1...00
19 	 * prot-none, clean, old	111.000000.1 -> 00..1...1...00
20 	 * prot-none, clean, young	111.000001.1 -> 01..1...1...00
21 	 * prot-none, dirty, old	111.000010.1 -> 10..1...1...00
22 	 * prot-none, dirty, young	111.000011.1 -> 11..1...1...00
23 	 * read-only, clean, old	111.000100.1 -> 00..1...1...01
24 	 * read-only, clean, young	101.000101.1 -> 01..1...0...01
25 	 * read-only, dirty, old	111.000110.1 -> 10..1...1...01
26 	 * read-only, dirty, young	101.000111.1 -> 11..1...0...01
27 	 * read-write, clean, old	111.001100.1 -> 00..1...1...11
28 	 * read-write, clean, young	101.001101.1 -> 01..1...0...11
29 	 * read-write, dirty, old	110.001110.1 -> 10..0...1...11
30 	 * read-write, dirty, young	100.001111.1 -> 11..0...0...11
31 	 * HW-bits: R read-only, I invalid
32 	 * SW-bits: p present, y young, d dirty, r read, w write, s special,
33 	 *	    u unused, l large
34 	 */
35 	if (pte_present(pte)) {
36 		pmd_val(pmd) = pte_val(pte) & PAGE_MASK;
37 		pmd_val(pmd) |= (pte_val(pte) & _PAGE_READ) >> 4;
38 		pmd_val(pmd) |= (pte_val(pte) & _PAGE_WRITE) >> 4;
39 		pmd_val(pmd) |=	(pte_val(pte) & _PAGE_INVALID) >> 5;
40 		pmd_val(pmd) |= (pte_val(pte) & _PAGE_PROTECT);
41 		pmd_val(pmd) |= (pte_val(pte) & _PAGE_DIRTY) << 10;
42 		pmd_val(pmd) |= (pte_val(pte) & _PAGE_YOUNG) << 10;
43 		pmd_val(pmd) |= (pte_val(pte) & _PAGE_SOFT_DIRTY) << 13;
44 	} else
45 		pmd_val(pmd) = _SEGMENT_ENTRY_INVALID;
46 	return pmd;
47 }
48 
49 static inline pte_t __pmd_to_pte(pmd_t pmd)
50 {
51 	pte_t pte;
52 
53 	/*
54 	 * Convert encoding		   pmd bits	    pte bits
55 	 *				dy..R...I...wr	  lIR.uswrdy.p
56 	 * empty			00..0...1...00 -> 010.000000.0
57 	 * prot-none, clean, old	00..1...1...00 -> 111.000000.1
58 	 * prot-none, clean, young	01..1...1...00 -> 111.000001.1
59 	 * prot-none, dirty, old	10..1...1...00 -> 111.000010.1
60 	 * prot-none, dirty, young	11..1...1...00 -> 111.000011.1
61 	 * read-only, clean, old	00..1...1...01 -> 111.000100.1
62 	 * read-only, clean, young	01..1...0...01 -> 101.000101.1
63 	 * read-only, dirty, old	10..1...1...01 -> 111.000110.1
64 	 * read-only, dirty, young	11..1...0...01 -> 101.000111.1
65 	 * read-write, clean, old	00..1...1...11 -> 111.001100.1
66 	 * read-write, clean, young	01..1...0...11 -> 101.001101.1
67 	 * read-write, dirty, old	10..0...1...11 -> 110.001110.1
68 	 * read-write, dirty, young	11..0...0...11 -> 100.001111.1
69 	 * HW-bits: R read-only, I invalid
70 	 * SW-bits: p present, y young, d dirty, r read, w write, s special,
71 	 *	    u unused, l large
72 	 */
73 	if (pmd_present(pmd)) {
74 		pte_val(pte) = pmd_val(pmd) & _SEGMENT_ENTRY_ORIGIN_LARGE;
75 		pte_val(pte) |= _PAGE_LARGE | _PAGE_PRESENT;
76 		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_READ) << 4;
77 		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_WRITE) << 4;
78 		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_INVALID) << 5;
79 		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_PROTECT);
80 		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_DIRTY) >> 10;
81 		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_YOUNG) >> 10;
82 		pte_val(pte) |= (pmd_val(pmd) & _SEGMENT_ENTRY_SOFT_DIRTY) >> 13;
83 	} else
84 		pte_val(pte) = _PAGE_INVALID;
85 	return pte;
86 }
87 
88 void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
89 		     pte_t *ptep, pte_t pte)
90 {
91 	pmd_t pmd = __pte_to_pmd(pte);
92 
93 	pmd_val(pmd) |= _SEGMENT_ENTRY_LARGE;
94 	*(pmd_t *) ptep = pmd;
95 }
96 
97 pte_t huge_ptep_get(pte_t *ptep)
98 {
99 	pmd_t pmd = *(pmd_t *) ptep;
100 
101 	return __pmd_to_pte(pmd);
102 }
103 
104 pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
105 			      unsigned long addr, pte_t *ptep)
106 {
107 	pmd_t *pmdp = (pmd_t *) ptep;
108 	pte_t pte = huge_ptep_get(ptep);
109 
110 	pmdp_flush_direct(mm, addr, pmdp);
111 	pmd_val(*pmdp) = _SEGMENT_ENTRY_EMPTY;
112 	return pte;
113 }
114 
115 pte_t *huge_pte_alloc(struct mm_struct *mm,
116 			unsigned long addr, unsigned long sz)
117 {
118 	pgd_t *pgdp;
119 	pud_t *pudp;
120 	pmd_t *pmdp = NULL;
121 
122 	pgdp = pgd_offset(mm, addr);
123 	pudp = pud_alloc(mm, pgdp, addr);
124 	if (pudp)
125 		pmdp = pmd_alloc(mm, pudp, addr);
126 	return (pte_t *) pmdp;
127 }
128 
129 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
130 {
131 	pgd_t *pgdp;
132 	pud_t *pudp;
133 	pmd_t *pmdp = NULL;
134 
135 	pgdp = pgd_offset(mm, addr);
136 	if (pgd_present(*pgdp)) {
137 		pudp = pud_offset(pgdp, addr);
138 		if (pud_present(*pudp))
139 			pmdp = pmd_offset(pudp, addr);
140 	}
141 	return (pte_t *) pmdp;
142 }
143 
144 int pmd_huge(pmd_t pmd)
145 {
146 	return pmd_large(pmd);
147 }
148 
149 int pud_huge(pud_t pud)
150 {
151 	return 0;
152 }
153