arch/i386/mm/pgtable.c

   1 /*
   2  *  linux/arch/i386/mm/pgtable.c
   3  */
   4
   5 #include <linux/sched.h>
   6 #include <linux/kernel.h>
   7 #include <linux/errno.h>
   8 #include <linux/mm.h>
   9 #include <linux/swap.h>
  10 #include <linux/smp.h>
  11 #include <linux/highmem.h>
  12 #include <linux/slab.h>
  13 #include <linux/pagemap.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/module.h>
  16
  17 #include <asm/system.h>
  18 #include <asm/pgtable.h>
  19 #include <asm/pgalloc.h>
  20 #include <asm/fixmap.h>
  21 #include <asm/e820.h>
  22 #include <asm/tlb.h>
  23 #include <asm/tlbflush.h>
  24
  25 void show_mem(void)
  26 {
  27         int total = 0, reserved = 0;
  28         int shared = 0, cached = 0;
  29         int highmem = 0;
  30         struct page *page;
  31         pg_data_t *pgdat;
  32         unsigned long i;
  33         unsigned long flags;
  34
  35         printk(KERN_INFO "Mem-info:\n");
  36         show_free_areas();
  37         printk(KERN_INFO "Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
  38         for_each_online_pgdat(pgdat) {
  39                 pgdat_resize_lock(pgdat, &flags);
  40                 for (i = 0; i < pgdat->node_spanned_pages; ++i) {
  41                         page = pgdat_page_nr(pgdat, i);
  42                         total++;
  43                         if (PageHighMem(page))
  44                                 highmem++;
  45                         if (PageReserved(page))
  46                                 reserved++;
  47                         else if (PageSwapCache(page))
  48                                 cached++;
  49                         else if (page_count(page))
  50                                 shared += page_count(page) - 1;
  51                 }
  52                 pgdat_resize_unlock(pgdat, &flags);
  53         }
  54         printk(KERN_INFO "%d pages of RAM\n", total);
  55         printk(KERN_INFO "%d pages of HIGHMEM\n", highmem);
  56         printk(KERN_INFO "%d reserved pages\n", reserved);
  57         printk(KERN_INFO "%d pages shared\n", shared);
  58         printk(KERN_INFO "%d pages swap cached\n", cached);
  59
  60         printk(KERN_INFO "%lu pages dirty\n", global_page_state(NR_FILE_DIRTY));
  61         printk(KERN_INFO "%lu pages writeback\n",
  62                                         global_page_state(NR_WRITEBACK));
  63         printk(KERN_INFO "%lu pages mapped\n", global_page_state(NR_FILE_MAPPED));
  64         printk(KERN_INFO "%lu pages slab\n",
  65                 global_page_state(NR_SLAB_RECLAIMABLE) +
  66                 global_page_state(NR_SLAB_UNRECLAIMABLE));
  67         printk(KERN_INFO "%lu pages pagetables\n",
  68                                         global_page_state(NR_PAGETABLE));
  69 }
  70
  71 /*
  72  * Associate a virtual page frame with a given physical page frame
  73  * and protection flags for that frame.
  74  */
  75 static void set_pte_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
  76 {
  77         pgd_t *pgd;
  78         pud_t *pud;
  79         pmd_t *pmd;
  80         pte_t *pte;
  81
  82         pgd = swapper_pg_dir + pgd_index(vaddr);
  83         if (pgd_none(*pgd)) {
  84                 BUG();
  85                 return;
  86         }
  87         pud = pud_offset(pgd, vaddr);
  88         if (pud_none(*pud)) {
  89                 BUG();
  90                 return;
  91         }
  92         pmd = pmd_offset(pud, vaddr);
  93         if (pmd_none(*pmd)) {
  94                 BUG();
  95                 return;
  96         }
  97         pte = pte_offset_kernel(pmd, vaddr);
  98         if (pgprot_val(flags))
  99                 /* <pfn,flags> stored as-is, to permit clearing entries */
 100                 set_pte(pte, pfn_pte(pfn, flags));
 101         else
 102                 pte_clear(&init_mm, vaddr, pte);
 103
 104         /*
 105          * It's enough to flush this one mapping.
 106          * (PGE mappings get flushed as well)
 107          */
 108         __flush_tlb_one(vaddr);
 109 }
 110
 111 /*
 112  * Associate a large virtual page frame with a given physical page frame
 113  * and protection flags for that frame. pfn is for the base of the page,
 114  * vaddr is what the page gets mapped to - both must be properly aligned.
 115  * The pmd must already be instantiated. Assumes PAE mode.
 116  */
 117 void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
 118 {
 119         pgd_t *pgd;
 120         pud_t *pud;
 121         pmd_t *pmd;
 122
 123         if (vaddr & (PMD_SIZE-1)) {             /* vaddr is misaligned */
 124                 printk(KERN_WARNING "set_pmd_pfn: vaddr misaligned\n");
 125                 return; /* BUG(); */
 126         }
 127         if (pfn & (PTRS_PER_PTE-1)) {           /* pfn is misaligned */
 128                 printk(KERN_WARNING "set_pmd_pfn: pfn misaligned\n");
 129                 return; /* BUG(); */
 130         }
 131         pgd = swapper_pg_dir + pgd_index(vaddr);
 132         if (pgd_none(*pgd)) {
 133                 printk(KERN_WARNING "set_pmd_pfn: pgd_none\n");
 134                 return; /* BUG(); */
 135         }
 136         pud = pud_offset(pgd, vaddr);
 137         pmd = pmd_offset(pud, vaddr);
 138         set_pmd(pmd, pfn_pmd(pfn, flags));
 139         /*
 140          * It's enough to flush this one mapping.
 141          * (PGE mappings get flushed as well)
 142          */
 143         __flush_tlb_one(vaddr);
 144 }
 145
 146 static int fixmaps;
 147 unsigned long __FIXADDR_TOP = 0xfffff000;
 148 EXPORT_SYMBOL(__FIXADDR_TOP);
 149
 150 void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags)
 151 {
 152         unsigned long address = __fix_to_virt(idx);
 153
 154         if (idx >= __end_of_fixed_addresses) {
 155                 BUG();
 156                 return;
 157         }
 158         set_pte_pfn(address, phys >> PAGE_SHIFT, flags);
 159         fixmaps++;
 160 }
 161
 162 /**
 163  * reserve_top_address - reserves a hole in the top of kernel address space
 164  * @reserve - size of hole to reserve
 165  *
 166  * Can be used to relocate the fixmap area and poke a hole in the top
 167  * of kernel address space to make room for a hypervisor.
 168  */
 169 void reserve_top_address(unsigned long reserve)
 170 {
 171         BUG_ON(fixmaps > 0);
 172         printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
 173                (int)-reserve);
 174         __FIXADDR_TOP = -reserve - PAGE_SIZE;
 175         __VMALLOC_RESERVE += reserve;
 176 }
 177
 178 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 179 {
 180         return (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
 181 }
 182
 183 struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
 184 {
 185         struct page *pte;
 186
 187 #ifdef CONFIG_HIGHPTE
 188         pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
 189 #else
 190         pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
 191 #endif
 192         return pte;
 193 }
 194
 195 void pmd_ctor(void *pmd, struct kmem_cache *cache, unsigned long flags)
 196 {
 197         memset(pmd, 0, PTRS_PER_PMD*sizeof(pmd_t));
 198 }
 199
 200 /*
 201  * List of all pgd's needed for non-PAE so it can invalidate entries
 202  * in both cached and uncached pgd's; not needed for PAE since the
 203  * kernel pmd is shared. If PAE were not to share the pmd a similar
 204  * tactic would be needed. This is essentially codepath-based locking
 205  * against pageattr.c; it is the unique case in which a valid change
 206  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 207  * vmalloc faults work because attached pagetables are never freed.
 208  * The locking scheme was chosen on the basis of manfred's
 209  * recommendations and having no core impact whatsoever.
 210  * -- wli
 211  */
 212 DEFINE_SPINLOCK(pgd_lock);
 213 struct page *pgd_list;
 214
 215 static inline void pgd_list_add(pgd_t *pgd)
 216 {
 217         struct page *page = virt_to_page(pgd);
 218         page->index = (unsigned long)pgd_list;
 219         if (pgd_list)
 220                 set_page_private(pgd_list, (unsigned long)&page->index);
 221         pgd_list = page;
 222         set_page_private(page, (unsigned long)&pgd_list);
 223 }
 224
 225 static inline void pgd_list_del(pgd_t *pgd)
 226 {
 227         struct page *next, **pprev, *page = virt_to_page(pgd);
 228         next = (struct page *)page->index;
 229         pprev = (struct page **)page_private(page);
 230         *pprev = next;
 231         if (next)
 232                 set_page_private(next, (unsigned long)pprev);
 233 }
 234
 235 #if (PTRS_PER_PMD == 1)
 236 /* Non-PAE pgd constructor */
 237 void pgd_ctor(void *pgd, struct kmem_cache *cache, unsigned long unused)
 238 {
 239         unsigned long flags;
 240
 241         /* !PAE, no pagetable sharing */
 242         memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
 243
 244         spin_lock_irqsave(&pgd_lock, flags);
 245
 246         /* must happen under lock */
 247         clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
 248                         swapper_pg_dir + USER_PTRS_PER_PGD,
 249                         KERNEL_PGD_PTRS);
 250         paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT,
 251                                 __pa(swapper_pg_dir) >> PAGE_SHIFT,
 252                                 USER_PTRS_PER_PGD,
 253                                 KERNEL_PGD_PTRS);
 254         pgd_list_add(pgd);
 255         spin_unlock_irqrestore(&pgd_lock, flags);
 256 }
 257 #else  /* PTRS_PER_PMD > 1 */
 258 /* PAE pgd constructor */
 259 void pgd_ctor(void *pgd, struct kmem_cache *cache, unsigned long unused)
 260 {
 261         /* PAE, kernel PMD may be shared */
 262
 263         if (SHARED_KERNEL_PMD) {
 264                 clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
 265                                 swapper_pg_dir + USER_PTRS_PER_PGD,
 266                                 KERNEL_PGD_PTRS);
 267         } else {
 268                 unsigned long flags;
 269
 270                 memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
 271                 spin_lock_irqsave(&pgd_lock, flags);
 272                 pgd_list_add(pgd);
 273                 spin_unlock_irqrestore(&pgd_lock, flags);
 274         }
 275 }
 276 #endif  /* PTRS_PER_PMD */
 277
 278 void pgd_dtor(void *pgd, struct kmem_cache *cache, unsigned long unused)
 279 {
 280         unsigned long flags; /* can be called from interrupt context */
 281
 282         BUG_ON(SHARED_KERNEL_PMD);
 283
 284         paravirt_release_pd(__pa(pgd) >> PAGE_SHIFT);
 285         spin_lock_irqsave(&pgd_lock, flags);
 286         pgd_list_del(pgd);
 287         spin_unlock_irqrestore(&pgd_lock, flags);
 288 }
 289
 290 #define UNSHARED_PTRS_PER_PGD                           \
 291         (SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)
 292
 293 /* If we allocate a pmd for part of the kernel address space, then
 294    make sure its initialized with the appropriate kernel mappings.
 295    Otherwise use a cached zeroed pmd.  */
 296 static pmd_t *pmd_cache_alloc(int idx)
 297 {
 298         pmd_t *pmd;
 299
 300         if (idx >= USER_PTRS_PER_PGD) {
 301                 pmd = (pmd_t *)__get_free_page(GFP_KERNEL);
 302
 303                 if (pmd)
 304                         memcpy(pmd,
 305                                (void *)pgd_page_vaddr(swapper_pg_dir[idx]),
 306                                sizeof(pmd_t) * PTRS_PER_PMD);
 307         } else
 308                 pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
 309
 310         return pmd;
 311 }
 312
 313 static void pmd_cache_free(pmd_t *pmd, int idx)
 314 {
 315         if (idx >= USER_PTRS_PER_PGD)
 316                 free_page((unsigned long)pmd);
 317         else
 318                 kmem_cache_free(pmd_cache, pmd);
 319 }
 320
 321 pgd_t *pgd_alloc(struct mm_struct *mm)
 322 {
 323         int i;
 324         pgd_t *pgd = kmem_cache_alloc(pgd_cache, GFP_KERNEL);
 325
 326         if (PTRS_PER_PMD == 1 || !pgd)
 327                 return pgd;
 328
 329         for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
 330                 pmd_t *pmd = pmd_cache_alloc(i);
 331
 332                 if (!pmd)
 333                         goto out_oom;
 334
 335                 paravirt_alloc_pd(__pa(pmd) >> PAGE_SHIFT);
 336                 set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
 337         }
 338         return pgd;
 339
 340 out_oom:
 341         for (i--; i >= 0; i--) {
 342                 pgd_t pgdent = pgd[i];
 343                 void* pmd = (void *)__va(pgd_val(pgdent)-1);
 344                 paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
 345                 pmd_cache_free(pmd, i);
 346         }
 347         kmem_cache_free(pgd_cache, pgd);
 348         return NULL;
 349 }
 350
 351 void pgd_free(pgd_t *pgd)
 352 {
 353         int i;
 354
 355         /* in the PAE case user pgd entries are overwritten before usage */
 356         if (PTRS_PER_PMD > 1)
 357                 for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
 358                         pgd_t pgdent = pgd[i];
 359                         void* pmd = (void *)__va(pgd_val(pgdent)-1);
 360                         paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
 361                         pmd_cache_free(pmd, i);
 362                 }
 363         /* in the non-PAE case, free_pgtables() clears user pgd entries */
 364         kmem_cache_free(pgd_cache, pgd);
 365 }