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/types.h>
14 #include <linux/mm.h>
15 #include <linux/hugetlb.h>
16
17 #include <asm/pgtable.h>
18 #include <asm/uaccess.h>
19 #include <asm/tlbflush.h>
20
21 /*
22 * Free all pages allocated for subpage protection maps and pointers.
23 * Also makes sure that the subpage_prot_table structure is
24 * reinitialized for the next user.
25 */
subpage_prot_free(struct mm_struct * mm)26 void subpage_prot_free(struct mm_struct *mm)
27 {
28 struct subpage_prot_table *spt = &mm->context.spt;
29 unsigned long i, j, addr;
30 u32 **p;
31
32 for (i = 0; i < 4; ++i) {
33 if (spt->low_prot[i]) {
34 free_page((unsigned long)spt->low_prot[i]);
35 spt->low_prot[i] = NULL;
36 }
37 }
38 addr = 0;
39 for (i = 0; i < 2; ++i) {
40 p = spt->protptrs[i];
41 if (!p)
42 continue;
43 spt->protptrs[i] = NULL;
44 for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr;
45 ++j, addr += PAGE_SIZE)
46 if (p[j])
47 free_page((unsigned long)p[j]);
48 free_page((unsigned long)p);
49 }
50 spt->maxaddr = 0;
51 }
52
subpage_prot_init_new_context(struct mm_struct * mm)53 void subpage_prot_init_new_context(struct mm_struct *mm)
54 {
55 struct subpage_prot_table *spt = &mm->context.spt;
56
57 memset(spt, 0, sizeof(*spt));
58 }
59
hpte_flush_range(struct mm_struct * mm,unsigned long addr,int npages)60 static void hpte_flush_range(struct mm_struct *mm, unsigned long addr,
61 int npages)
62 {
63 pgd_t *pgd;
64 pud_t *pud;
65 pmd_t *pmd;
66 pte_t *pte;
67 spinlock_t *ptl;
68
69 pgd = pgd_offset(mm, addr);
70 if (pgd_none(*pgd))
71 return;
72 pud = pud_offset(pgd, addr);
73 if (pud_none(*pud))
74 return;
75 pmd = pmd_offset(pud, addr);
76 if (pmd_none(*pmd))
77 return;
78 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
79 arch_enter_lazy_mmu_mode();
80 for (; npages > 0; --npages) {
81 pte_update(mm, addr, pte, 0, 0, 0);
82 addr += PAGE_SIZE;
83 ++pte;
84 }
85 arch_leave_lazy_mmu_mode();
86 pte_unmap_unlock(pte - 1, ptl);
87 }
88
89 /*
90 * Clear the subpage protection map for an address range, allowing
91 * all accesses that are allowed by the pte permissions.
92 */
subpage_prot_clear(unsigned long addr,unsigned long len)93 static void subpage_prot_clear(unsigned long addr, unsigned long len)
94 {
95 struct mm_struct *mm = current->mm;
96 struct subpage_prot_table *spt = &mm->context.spt;
97 u32 **spm, *spp;
98 unsigned long i;
99 size_t nw;
100 unsigned long next, limit;
101
102 down_write(&mm->mmap_sem);
103 limit = addr + len;
104 if (limit > spt->maxaddr)
105 limit = spt->maxaddr;
106 for (; addr < limit; addr = next) {
107 next = pmd_addr_end(addr, limit);
108 if (addr < 0x100000000UL) {
109 spm = spt->low_prot;
110 } else {
111 spm = spt->protptrs[addr >> SBP_L3_SHIFT];
112 if (!spm)
113 continue;
114 }
115 spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)];
116 if (!spp)
117 continue;
118 spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);
119
120 i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
121 nw = PTRS_PER_PTE - i;
122 if (addr + (nw << PAGE_SHIFT) > next)
123 nw = (next - addr) >> PAGE_SHIFT;
124
125 memset(spp, 0, nw * sizeof(u32));
126
127 /* now flush any existing HPTEs for the range */
128 hpte_flush_range(mm, addr, nw);
129 }
130 up_write(&mm->mmap_sem);
131 }
132
133 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
subpage_walk_pmd_entry(pmd_t * pmd,unsigned long addr,unsigned long end,struct mm_walk * walk)134 static int subpage_walk_pmd_entry(pmd_t *pmd, unsigned long addr,
135 unsigned long end, struct mm_walk *walk)
136 {
137 struct vm_area_struct *vma = walk->vma;
138 split_huge_page_pmd(vma, addr, pmd);
139 return 0;
140 }
141
subpage_mark_vma_nohuge(struct mm_struct * mm,unsigned long addr,unsigned long len)142 static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
143 unsigned long len)
144 {
145 struct vm_area_struct *vma;
146 struct mm_walk subpage_proto_walk = {
147 .mm = mm,
148 .pmd_entry = subpage_walk_pmd_entry,
149 };
150
151 /*
152 * We don't try too hard, we just mark all the vma in that range
153 * VM_NOHUGEPAGE and split them.
154 */
155 vma = find_vma(mm, addr);
156 /*
157 * If the range is in unmapped range, just return
158 */
159 if (vma && ((addr + len) <= vma->vm_start))
160 return;
161
162 while (vma) {
163 if (vma->vm_start >= (addr + len))
164 break;
165 vma->vm_flags |= VM_NOHUGEPAGE;
166 walk_page_vma(vma, &subpage_proto_walk);
167 vma = vma->vm_next;
168 }
169 }
170 #else
subpage_mark_vma_nohuge(struct mm_struct * mm,unsigned long addr,unsigned long len)171 static void subpage_mark_vma_nohuge(struct mm_struct *mm, unsigned long addr,
172 unsigned long len)
173 {
174 return;
175 }
176 #endif
177
178 /*
179 * Copy in a subpage protection map for an address range.
180 * The map has 2 bits per 4k subpage, so 32 bits per 64k page.
181 * Each 2-bit field is 0 to allow any access, 1 to prevent writes,
182 * 2 or 3 to prevent all accesses.
183 * Note that the normal page protections also apply; the subpage
184 * protection mechanism is an additional constraint, so putting 0
185 * in a 2-bit field won't allow writes to a page that is otherwise
186 * write-protected.
187 */
sys_subpage_prot(unsigned long addr,unsigned long len,u32 __user * map)188 long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map)
189 {
190 struct mm_struct *mm = current->mm;
191 struct subpage_prot_table *spt = &mm->context.spt;
192 u32 **spm, *spp;
193 unsigned long i;
194 size_t nw;
195 unsigned long next, limit;
196 int err;
197
198 /* Check parameters */
199 if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) ||
200 addr >= TASK_SIZE || len >= TASK_SIZE || addr + len > TASK_SIZE)
201 return -EINVAL;
202
203 if (is_hugepage_only_range(mm, addr, len))
204 return -EINVAL;
205
206 if (!map) {
207 /* Clear out the protection map for the address range */
208 subpage_prot_clear(addr, len);
209 return 0;
210 }
211
212 if (!access_ok(VERIFY_READ, map, (len >> PAGE_SHIFT) * sizeof(u32)))
213 return -EFAULT;
214
215 down_write(&mm->mmap_sem);
216 subpage_mark_vma_nohuge(mm, addr, len);
217 for (limit = addr + len; addr < limit; addr = next) {
218 next = pmd_addr_end(addr, limit);
219 err = -ENOMEM;
220 if (addr < 0x100000000UL) {
221 spm = spt->low_prot;
222 } else {
223 spm = spt->protptrs[addr >> SBP_L3_SHIFT];
224 if (!spm) {
225 spm = (u32 **)get_zeroed_page(GFP_KERNEL);
226 if (!spm)
227 goto out;
228 spt->protptrs[addr >> SBP_L3_SHIFT] = spm;
229 }
230 }
231 spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1);
232 spp = *spm;
233 if (!spp) {
234 spp = (u32 *)get_zeroed_page(GFP_KERNEL);
235 if (!spp)
236 goto out;
237 *spm = spp;
238 }
239 spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1);
240
241 local_irq_disable();
242 demote_segment_4k(mm, addr);
243 local_irq_enable();
244
245 i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
246 nw = PTRS_PER_PTE - i;
247 if (addr + (nw << PAGE_SHIFT) > next)
248 nw = (next - addr) >> PAGE_SHIFT;
249
250 up_write(&mm->mmap_sem);
251 err = -EFAULT;
252 if (__copy_from_user(spp, map, nw * sizeof(u32)))
253 goto out2;
254 map += nw;
255 down_write(&mm->mmap_sem);
256
257 /* now flush any existing HPTEs for the range */
258 hpte_flush_range(mm, addr, nw);
259 }
260 if (limit > spt->maxaddr)
261 spt->maxaddr = limit;
262 err = 0;
263 out:
264 up_write(&mm->mmap_sem);
265 out2:
266 return err;
267 }
268