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