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fa28237c PM |
1 | /* |
2 | * Copyright 2007-2008 Paul Mackerras, IBM Corp. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version | |
7 | * 2 of the License, or (at your option) any later version. | |
8 | */ | |
9 | ||
10 | #include <linux/errno.h> | |
11 | #include <linux/kernel.h> | |
12 | #include <linux/gfp.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/types.h> | |
15 | #include <linux/mm.h> | |
16 | #include <linux/hugetlb.h> | |
17 | ||
18 | #include <asm/pgtable.h> | |
19 | #include <asm/uaccess.h> | |
20 | #include <asm/tlbflush.h> | |
21 | ||
22 | /* | |
23 | * Free all pages allocated for subpage protection maps and pointers. | |
24 | * Also makes sure that the subpage_prot_table structure is | |
25 | * reinitialized for the next user. | |
26 | */ | |
5a7b4193 | 27 | void subpage_prot_free(pgd_t *pgd) |
fa28237c | 28 | { |
5a7b4193 | 29 | struct subpage_prot_table *spt = pgd_subpage_prot(pgd); |
fa28237c PM |
30 | unsigned long i, j, addr; |
31 | u32 **p; | |
32 | ||
33 | for (i = 0; i < 4; ++i) { | |
34 | if (spt->low_prot[i]) { | |
35 | free_page((unsigned long)spt->low_prot[i]); | |
36 | spt->low_prot[i] = NULL; | |
37 | } | |
38 | } | |
39 | addr = 0; | |
40 | for (i = 0; i < 2; ++i) { | |
41 | p = spt->protptrs[i]; | |
42 | if (!p) | |
43 | continue; | |
44 | spt->protptrs[i] = NULL; | |
45 | for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr; | |
46 | ++j, addr += PAGE_SIZE) | |
47 | if (p[j]) | |
48 | free_page((unsigned long)p[j]); | |
49 | free_page((unsigned long)p); | |
50 | } | |
51 | spt->maxaddr = 0; | |
52 | } | |
53 | ||
54 | static void hpte_flush_range(struct mm_struct *mm, unsigned long addr, | |
55 | int npages) | |
56 | { | |
57 | pgd_t *pgd; | |
58 | pud_t *pud; | |
59 | pmd_t *pmd; | |
60 | pte_t *pte; | |
61 | spinlock_t *ptl; | |
62 | ||
63 | pgd = pgd_offset(mm, addr); | |
64 | if (pgd_none(*pgd)) | |
65 | return; | |
66 | pud = pud_offset(pgd, addr); | |
67 | if (pud_none(*pud)) | |
68 | return; | |
69 | pmd = pmd_offset(pud, addr); | |
70 | if (pmd_none(*pmd)) | |
71 | return; | |
72 | pte = pte_offset_map_lock(mm, pmd, addr, &ptl); | |
73 | arch_enter_lazy_mmu_mode(); | |
74 | for (; npages > 0; --npages) { | |
75 | pte_update(mm, addr, pte, 0, 0); | |
76 | addr += PAGE_SIZE; | |
77 | ++pte; | |
78 | } | |
79 | arch_leave_lazy_mmu_mode(); | |
80 | pte_unmap_unlock(pte - 1, ptl); | |
81 | } | |
82 | ||
83 | /* | |
84 | * Clear the subpage protection map for an address range, allowing | |
85 | * all accesses that are allowed by the pte permissions. | |
86 | */ | |
87 | static void subpage_prot_clear(unsigned long addr, unsigned long len) | |
88 | { | |
89 | struct mm_struct *mm = current->mm; | |
5a7b4193 | 90 | struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd); |
fa28237c PM |
91 | u32 **spm, *spp; |
92 | int i, nw; | |
93 | unsigned long next, limit; | |
94 | ||
95 | down_write(&mm->mmap_sem); | |
96 | limit = addr + len; | |
97 | if (limit > spt->maxaddr) | |
98 | limit = spt->maxaddr; | |
99 | for (; addr < limit; addr = next) { | |
100 | next = pmd_addr_end(addr, limit); | |
101 | if (addr < 0x100000000) { | |
102 | spm = spt->low_prot; | |
103 | } else { | |
104 | spm = spt->protptrs[addr >> SBP_L3_SHIFT]; | |
105 | if (!spm) | |
106 | continue; | |
107 | } | |
108 | spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)]; | |
109 | if (!spp) | |
110 | continue; | |
111 | spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); | |
112 | ||
113 | i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); | |
114 | nw = PTRS_PER_PTE - i; | |
115 | if (addr + (nw << PAGE_SHIFT) > next) | |
116 | nw = (next - addr) >> PAGE_SHIFT; | |
117 | ||
118 | memset(spp, 0, nw * sizeof(u32)); | |
119 | ||
120 | /* now flush any existing HPTEs for the range */ | |
121 | hpte_flush_range(mm, addr, nw); | |
122 | } | |
123 | up_write(&mm->mmap_sem); | |
124 | } | |
125 | ||
126 | /* | |
127 | * Copy in a subpage protection map for an address range. | |
128 | * The map has 2 bits per 4k subpage, so 32 bits per 64k page. | |
129 | * Each 2-bit field is 0 to allow any access, 1 to prevent writes, | |
130 | * 2 or 3 to prevent all accesses. | |
131 | * Note that the normal page protections also apply; the subpage | |
132 | * protection mechanism is an additional constraint, so putting 0 | |
133 | * in a 2-bit field won't allow writes to a page that is otherwise | |
134 | * write-protected. | |
135 | */ | |
136 | long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map) | |
137 | { | |
138 | struct mm_struct *mm = current->mm; | |
5a7b4193 | 139 | struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd); |
fa28237c PM |
140 | u32 **spm, *spp; |
141 | int i, nw; | |
142 | unsigned long next, limit; | |
143 | int err; | |
144 | ||
145 | /* Check parameters */ | |
146 | if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) || | |
147 | addr >= TASK_SIZE || len >= TASK_SIZE || addr + len > TASK_SIZE) | |
148 | return -EINVAL; | |
149 | ||
150 | if (is_hugepage_only_range(mm, addr, len)) | |
151 | return -EINVAL; | |
152 | ||
153 | if (!map) { | |
154 | /* Clear out the protection map for the address range */ | |
155 | subpage_prot_clear(addr, len); | |
156 | return 0; | |
157 | } | |
158 | ||
159 | if (!access_ok(VERIFY_READ, map, (len >> PAGE_SHIFT) * sizeof(u32))) | |
160 | return -EFAULT; | |
161 | ||
162 | down_write(&mm->mmap_sem); | |
163 | for (limit = addr + len; addr < limit; addr = next) { | |
164 | next = pmd_addr_end(addr, limit); | |
165 | err = -ENOMEM; | |
166 | if (addr < 0x100000000) { | |
167 | spm = spt->low_prot; | |
168 | } else { | |
169 | spm = spt->protptrs[addr >> SBP_L3_SHIFT]; | |
170 | if (!spm) { | |
171 | spm = (u32 **)get_zeroed_page(GFP_KERNEL); | |
172 | if (!spm) | |
173 | goto out; | |
174 | spt->protptrs[addr >> SBP_L3_SHIFT] = spm; | |
175 | } | |
176 | } | |
177 | spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1); | |
178 | spp = *spm; | |
179 | if (!spp) { | |
180 | spp = (u32 *)get_zeroed_page(GFP_KERNEL); | |
181 | if (!spp) | |
182 | goto out; | |
183 | *spm = spp; | |
184 | } | |
185 | spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); | |
186 | ||
187 | local_irq_disable(); | |
188 | demote_segment_4k(mm, addr); | |
189 | local_irq_enable(); | |
190 | ||
191 | i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); | |
192 | nw = PTRS_PER_PTE - i; | |
193 | if (addr + (nw << PAGE_SHIFT) > next) | |
194 | nw = (next - addr) >> PAGE_SHIFT; | |
195 | ||
196 | up_write(&mm->mmap_sem); | |
197 | err = -EFAULT; | |
198 | if (__copy_from_user(spp, map, nw * sizeof(u32))) | |
199 | goto out2; | |
200 | map += nw; | |
201 | down_write(&mm->mmap_sem); | |
202 | ||
203 | /* now flush any existing HPTEs for the range */ | |
204 | hpte_flush_range(mm, addr, nw); | |
205 | } | |
206 | if (limit > spt->maxaddr) | |
207 | spt->maxaddr = limit; | |
208 | err = 0; | |
209 | out: | |
210 | up_write(&mm->mmap_sem); | |
211 | out2: | |
212 | return err; | |
213 | } |