Merge branch 'for_linus' of git://git.infradead.org/~dedekind/ubifs-2.6
[linux-2.6] / arch / x86 / mm / pgtable.c
1 #include <linux/mm.h>
2 #include <asm/pgalloc.h>
3 #include <asm/pgtable.h>
4 #include <asm/tlb.h>
5 #include <asm/fixmap.h>
6
7 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
8 {
9         return (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
10 }
11
12 pgtable_t pte_alloc_one(struct mm_struct *mm, unsigned long address)
13 {
14         struct page *pte;
15
16 #ifdef CONFIG_HIGHPTE
17         pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
18 #else
19         pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
20 #endif
21         if (pte)
22                 pgtable_page_ctor(pte);
23         return pte;
24 }
25
26 void __pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
27 {
28         pgtable_page_dtor(pte);
29         paravirt_release_pte(page_to_pfn(pte));
30         tlb_remove_page(tlb, pte);
31 }
32
33 #if PAGETABLE_LEVELS > 2
34 void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
35 {
36         paravirt_release_pmd(__pa(pmd) >> PAGE_SHIFT);
37         tlb_remove_page(tlb, virt_to_page(pmd));
38 }
39
40 #if PAGETABLE_LEVELS > 3
41 void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud)
42 {
43         paravirt_release_pud(__pa(pud) >> PAGE_SHIFT);
44         tlb_remove_page(tlb, virt_to_page(pud));
45 }
46 #endif  /* PAGETABLE_LEVELS > 3 */
47 #endif  /* PAGETABLE_LEVELS > 2 */
48
49 static inline void pgd_list_add(pgd_t *pgd)
50 {
51         struct page *page = virt_to_page(pgd);
52
53         list_add(&page->lru, &pgd_list);
54 }
55
56 static inline void pgd_list_del(pgd_t *pgd)
57 {
58         struct page *page = virt_to_page(pgd);
59
60         list_del(&page->lru);
61 }
62
63 #define UNSHARED_PTRS_PER_PGD                           \
64         (SHARED_KERNEL_PMD ? KERNEL_PGD_BOUNDARY : PTRS_PER_PGD)
65
66 static void pgd_ctor(void *p)
67 {
68         pgd_t *pgd = p;
69
70         /* If the pgd points to a shared pagetable level (either the
71            ptes in non-PAE, or shared PMD in PAE), then just copy the
72            references from swapper_pg_dir. */
73         if (PAGETABLE_LEVELS == 2 ||
74             (PAGETABLE_LEVELS == 3 && SHARED_KERNEL_PMD) ||
75             PAGETABLE_LEVELS == 4) {
76                 clone_pgd_range(pgd + KERNEL_PGD_BOUNDARY,
77                                 swapper_pg_dir + KERNEL_PGD_BOUNDARY,
78                                 KERNEL_PGD_PTRS);
79                 paravirt_alloc_pmd_clone(__pa(pgd) >> PAGE_SHIFT,
80                                          __pa(swapper_pg_dir) >> PAGE_SHIFT,
81                                          KERNEL_PGD_BOUNDARY,
82                                          KERNEL_PGD_PTRS);
83         }
84
85         /* list required to sync kernel mapping updates */
86         if (!SHARED_KERNEL_PMD)
87                 pgd_list_add(pgd);
88 }
89
90 static void pgd_dtor(void *pgd)
91 {
92         unsigned long flags; /* can be called from interrupt context */
93
94         if (SHARED_KERNEL_PMD)
95                 return;
96
97         spin_lock_irqsave(&pgd_lock, flags);
98         pgd_list_del(pgd);
99         spin_unlock_irqrestore(&pgd_lock, flags);
100 }
101
102 /*
103  * List of all pgd's needed for non-PAE so it can invalidate entries
104  * in both cached and uncached pgd's; not needed for PAE since the
105  * kernel pmd is shared. If PAE were not to share the pmd a similar
106  * tactic would be needed. This is essentially codepath-based locking
107  * against pageattr.c; it is the unique case in which a valid change
108  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
109  * vmalloc faults work because attached pagetables are never freed.
110  * -- wli
111  */
112
113 #ifdef CONFIG_X86_PAE
114 /*
115  * In PAE mode, we need to do a cr3 reload (=tlb flush) when
116  * updating the top-level pagetable entries to guarantee the
117  * processor notices the update.  Since this is expensive, and
118  * all 4 top-level entries are used almost immediately in a
119  * new process's life, we just pre-populate them here.
120  *
121  * Also, if we're in a paravirt environment where the kernel pmd is
122  * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
123  * and initialize the kernel pmds here.
124  */
125 #define PREALLOCATED_PMDS       UNSHARED_PTRS_PER_PGD
126
127 void pud_populate(struct mm_struct *mm, pud_t *pudp, pmd_t *pmd)
128 {
129         paravirt_alloc_pmd(mm, __pa(pmd) >> PAGE_SHIFT);
130
131         /* Note: almost everything apart from _PAGE_PRESENT is
132            reserved at the pmd (PDPT) level. */
133         set_pud(pudp, __pud(__pa(pmd) | _PAGE_PRESENT));
134
135         /*
136          * According to Intel App note "TLBs, Paging-Structure Caches,
137          * and Their Invalidation", April 2007, document 317080-001,
138          * section 8.1: in PAE mode we explicitly have to flush the
139          * TLB via cr3 if the top-level pgd is changed...
140          */
141         if (mm == current->active_mm)
142                 write_cr3(read_cr3());
143 }
144 #else  /* !CONFIG_X86_PAE */
145
146 /* No need to prepopulate any pagetable entries in non-PAE modes. */
147 #define PREALLOCATED_PMDS       0
148
149 #endif  /* CONFIG_X86_PAE */
150
151 static void free_pmds(pmd_t *pmds[])
152 {
153         int i;
154
155         for(i = 0; i < PREALLOCATED_PMDS; i++)
156                 if (pmds[i])
157                         free_page((unsigned long)pmds[i]);
158 }
159
160 static int preallocate_pmds(pmd_t *pmds[])
161 {
162         int i;
163         bool failed = false;
164
165         for(i = 0; i < PREALLOCATED_PMDS; i++) {
166                 pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL|__GFP_REPEAT);
167                 if (pmd == NULL)
168                         failed = true;
169                 pmds[i] = pmd;
170         }
171
172         if (failed) {
173                 free_pmds(pmds);
174                 return -ENOMEM;
175         }
176
177         return 0;
178 }
179
180 /*
181  * Mop up any pmd pages which may still be attached to the pgd.
182  * Normally they will be freed by munmap/exit_mmap, but any pmd we
183  * preallocate which never got a corresponding vma will need to be
184  * freed manually.
185  */
186 static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
187 {
188         int i;
189
190         for(i = 0; i < PREALLOCATED_PMDS; i++) {
191                 pgd_t pgd = pgdp[i];
192
193                 if (pgd_val(pgd) != 0) {
194                         pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
195
196                         pgdp[i] = native_make_pgd(0);
197
198                         paravirt_release_pmd(pgd_val(pgd) >> PAGE_SHIFT);
199                         pmd_free(mm, pmd);
200                 }
201         }
202 }
203
204 static void pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd, pmd_t *pmds[])
205 {
206         pud_t *pud;
207         unsigned long addr;
208         int i;
209
210         pud = pud_offset(pgd, 0);
211
212         for (addr = i = 0; i < PREALLOCATED_PMDS;
213              i++, pud++, addr += PUD_SIZE) {
214                 pmd_t *pmd = pmds[i];
215
216                 if (i >= KERNEL_PGD_BOUNDARY)
217                         memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
218                                sizeof(pmd_t) * PTRS_PER_PMD);
219
220                 pud_populate(mm, pud, pmd);
221         }
222 }
223
224 pgd_t *pgd_alloc(struct mm_struct *mm)
225 {
226         pgd_t *pgd;
227         pmd_t *pmds[PREALLOCATED_PMDS];
228         unsigned long flags;
229
230         pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
231
232         if (pgd == NULL)
233                 goto out;
234
235         mm->pgd = pgd;
236
237         if (preallocate_pmds(pmds) != 0)
238                 goto out_free_pgd;
239
240         if (paravirt_pgd_alloc(mm) != 0)
241                 goto out_free_pmds;
242
243         /*
244          * Make sure that pre-populating the pmds is atomic with
245          * respect to anything walking the pgd_list, so that they
246          * never see a partially populated pgd.
247          */
248         spin_lock_irqsave(&pgd_lock, flags);
249
250         pgd_ctor(pgd);
251         pgd_prepopulate_pmd(mm, pgd, pmds);
252
253         spin_unlock_irqrestore(&pgd_lock, flags);
254
255         return pgd;
256
257 out_free_pmds:
258         free_pmds(pmds);
259 out_free_pgd:
260         free_page((unsigned long)pgd);
261 out:
262         return NULL;
263 }
264
265 void pgd_free(struct mm_struct *mm, pgd_t *pgd)
266 {
267         pgd_mop_up_pmds(mm, pgd);
268         pgd_dtor(pgd);
269         paravirt_pgd_free(mm, pgd);
270         free_page((unsigned long)pgd);
271 }
272
273 int ptep_set_access_flags(struct vm_area_struct *vma,
274                           unsigned long address, pte_t *ptep,
275                           pte_t entry, int dirty)
276 {
277         int changed = !pte_same(*ptep, entry);
278
279         if (changed && dirty) {
280                 *ptep = entry;
281                 pte_update_defer(vma->vm_mm, address, ptep);
282                 flush_tlb_page(vma, address);
283         }
284
285         return changed;
286 }
287
288 int ptep_test_and_clear_young(struct vm_area_struct *vma,
289                               unsigned long addr, pte_t *ptep)
290 {
291         int ret = 0;
292
293         if (pte_young(*ptep))
294                 ret = test_and_clear_bit(_PAGE_BIT_ACCESSED,
295                                          (unsigned long *) &ptep->pte);
296
297         if (ret)
298                 pte_update(vma->vm_mm, addr, ptep);
299
300         return ret;
301 }
302
303 int ptep_clear_flush_young(struct vm_area_struct *vma,
304                            unsigned long address, pte_t *ptep)
305 {
306         int young;
307
308         young = ptep_test_and_clear_young(vma, address, ptep);
309         if (young)
310                 flush_tlb_page(vma, address);
311
312         return young;
313 }
314
315 int fixmaps_set;
316
317 void __native_set_fixmap(enum fixed_addresses idx, pte_t pte)
318 {
319         unsigned long address = __fix_to_virt(idx);
320
321         if (idx >= __end_of_fixed_addresses) {
322                 BUG();
323                 return;
324         }
325         set_pte_vaddr(address, pte);
326         fixmaps_set++;
327 }
328
329 void native_set_fixmap(enum fixed_addresses idx, unsigned long phys, pgprot_t flags)
330 {
331         __native_set_fixmap(idx, pfn_pte(phys >> PAGE_SHIFT, flags));
332 }