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   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/nmi.h>
  10 #include <linux/swap.h>
  11 #include <linux/smp.h>
  12 #include <linux/highmem.h>
  13 #include <linux/slab.h>
  14 #include <linux/pagemap.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/module.h>
  17 #include <linux/quicklist.h>
  18
  19 #include <asm/system.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/pgalloc.h>
  22 #include <asm/fixmap.h>
  23 #include <asm/e820.h>
  24 #include <asm/tlb.h>
  25 #include <asm/tlbflush.h>
  26
  27 void show_mem(void)
  28 {
  29         int total = 0, reserved = 0;
  30         int shared = 0, cached = 0;
  31         int highmem = 0;
  32         struct page *page;
  33         pg_data_t *pgdat;
  34         unsigned long i;
  35         unsigned long flags;
  36
  37         printk(KERN_INFO "Mem-info:\n");
  38         show_free_areas();
  39         printk(KERN_INFO "Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
  40         for_each_online_pgdat(pgdat) {
  41                 pgdat_resize_lock(pgdat, &flags);
  42                 for (i = 0; i < pgdat->node_spanned_pages; ++i) {
  43                         if (unlikely(i % MAX_ORDER_NR_PAGES == 0))
  44                                 touch_nmi_watchdog();
  45                         page = pgdat_page_nr(pgdat, i);
  46                         total++;
  47                         if (PageHighMem(page))
  48                                 highmem++;
  49                         if (PageReserved(page))
  50                                 reserved++;
  51                         else if (PageSwapCache(page))
  52                                 cached++;
  53                         else if (page_count(page))
  54                                 shared += page_count(page) - 1;
  55                 }
  56                 pgdat_resize_unlock(pgdat, &flags);
  57         }
  58         printk(KERN_INFO "%d pages of RAM\n", total);
  59         printk(KERN_INFO "%d pages of HIGHMEM\n", highmem);
  60         printk(KERN_INFO "%d reserved pages\n", reserved);
  61         printk(KERN_INFO "%d pages shared\n", shared);
  62         printk(KERN_INFO "%d pages swap cached\n", cached);
  63
  64         printk(KERN_INFO "%lu pages dirty\n", global_page_state(NR_FILE_DIRTY));
  65         printk(KERN_INFO "%lu pages writeback\n",
  66                                         global_page_state(NR_WRITEBACK));
  67         printk(KERN_INFO "%lu pages mapped\n", global_page_state(NR_FILE_MAPPED));
  68         printk(KERN_INFO "%lu pages slab\n",
  69                 global_page_state(NR_SLAB_RECLAIMABLE) +
  70                 global_page_state(NR_SLAB_UNRECLAIMABLE));
  71         printk(KERN_INFO "%lu pages pagetables\n",
  72                                         global_page_state(NR_PAGETABLE));
  73 }
  74
  75 /*
  76  * Associate a virtual page frame with a given physical page frame
  77  * and protection flags for that frame.
  78  */
  79 static void set_pte_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
  80 {
  81         pgd_t *pgd;
  82         pud_t *pud;
  83         pmd_t *pmd;
  84         pte_t *pte;
  85
  86         pgd = swapper_pg_dir + pgd_index(vaddr);
  87         if (pgd_none(*pgd)) {
  88                 BUG();
  89                 return;
  90         }
  91         pud = pud_offset(pgd, vaddr);
  92         if (pud_none(*pud)) {
  93                 BUG();
  94                 return;
  95         }
  96         pmd = pmd_offset(pud, vaddr);
  97         if (pmd_none(*pmd)) {
  98                 BUG();
  99                 return;
 100         }
 101         pte = pte_offset_kernel(pmd, vaddr);
 102         if (pgprot_val(flags))
 103                 set_pte_present(&init_mm, vaddr, pte, pfn_pte(pfn, flags));
 104         else
 105                 pte_clear(&init_mm, vaddr, pte);
 106
 107         /*
 108          * It's enough to flush this one mapping.
 109          * (PGE mappings get flushed as well)
 110          */
 111         __flush_tlb_one(vaddr);
 112 }
 113
 114 /*
 115  * Associate a large virtual page frame with a given physical page frame
 116  * and protection flags for that frame. pfn is for the base of the page,
 117  * vaddr is what the page gets mapped to - both must be properly aligned.
 118  * The pmd must already be instantiated. Assumes PAE mode.
 119  */
 120 void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
 121 {
 122         pgd_t *pgd;
 123         pud_t *pud;
 124         pmd_t *pmd;
 125
 126         if (vaddr & (PMD_SIZE-1)) {             /* vaddr is misaligned */
 127                 printk(KERN_WARNING "set_pmd_pfn: vaddr misaligned\n");
 128                 return; /* BUG(); */
 129         }
 130         if (pfn & (PTRS_PER_PTE-1)) {           /* pfn is misaligned */
 131                 printk(KERN_WARNING "set_pmd_pfn: pfn misaligned\n");
 132                 return; /* BUG(); */
 133         }
 134         pgd = swapper_pg_dir + pgd_index(vaddr);
 135         if (pgd_none(*pgd)) {
 136                 printk(KERN_WARNING "set_pmd_pfn: pgd_none\n");
 137                 return; /* BUG(); */
 138         }
 139         pud = pud_offset(pgd, vaddr);
 140         pmd = pmd_offset(pud, vaddr);
 141         set_pmd(pmd, pfn_pmd(pfn, flags));
 142         /*
 143          * It's enough to flush this one mapping.
 144          * (PGE mappings get flushed as well)
 145          */
 146         __flush_tlb_one(vaddr);
 147 }
 148
 149 static int fixmaps;
 150 unsigned long __FIXADDR_TOP = 0xfffff000;
 151 EXPORT_SYMBOL(__FIXADDR_TOP);
 152
 153 void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags)
 154 {
 155         unsigned long address = __fix_to_virt(idx);
 156
 157         if (idx >= __end_of_fixed_addresses) {
 158                 BUG();
 159                 return;
 160         }
 161         set_pte_pfn(address, phys >> PAGE_SHIFT, flags);
 162         fixmaps++;
 163 }
 164
 165 /**
 166  * reserve_top_address - reserves a hole in the top of kernel address space
 167  * @reserve - size of hole to reserve
 168  *
 169  * Can be used to relocate the fixmap area and poke a hole in the top
 170  * of kernel address space to make room for a hypervisor.
 171  */
 172 void reserve_top_address(unsigned long reserve)
 173 {
 174         BUG_ON(fixmaps > 0);
 175         printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
 176                (int)-reserve);
 177         __FIXADDR_TOP = -reserve - PAGE_SIZE;
 178         __VMALLOC_RESERVE += reserve;
 179 }
 180
 181 pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 182 {
 183         return (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
 184 }
 185
 186 struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
 187 {
 188         struct page *pte;
 189
 190 #ifdef CONFIG_HIGHPTE
 191         pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
 192 #else
 193         pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
 194 #endif
 195         return pte;
 196 }
 197
 198 void pmd_ctor(struct kmem_cache *cache, void *pmd)
 199 {
 200         memset(pmd, 0, PTRS_PER_PMD*sizeof(pmd_t));
 201 }
 202
 203 /*
 204  * List of all pgd's needed for non-PAE so it can invalidate entries
 205  * in both cached and uncached pgd's; not needed for PAE since the
 206  * kernel pmd is shared. If PAE were not to share the pmd a similar
 207  * tactic would be needed. This is essentially codepath-based locking
 208  * against pageattr.c; it is the unique case in which a valid change
 209  * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 210  * vmalloc faults work because attached pagetables are never freed.
 211  * -- wli
 212  */
 213 DEFINE_SPINLOCK(pgd_lock);
 214 struct page *pgd_list;
 215
 216 static inline void pgd_list_add(pgd_t *pgd)
 217 {
 218         struct page *page = virt_to_page(pgd);
 219         page->index = (unsigned long)pgd_list;
 220         if (pgd_list)
 221                 set_page_private(pgd_list, (unsigned long)&page->index);
 222         pgd_list = page;
 223         set_page_private(page, (unsigned long)&pgd_list);
 224 }
 225
 226 static inline void pgd_list_del(pgd_t *pgd)
 227 {
 228         struct page *next, **pprev, *page = virt_to_page(pgd);
 229         next = (struct page *)page->index;
 230         pprev = (struct page **)page_private(page);
 231         *pprev = next;
 232         if (next)
 233                 set_page_private(next, (unsigned long)pprev);
 234 }
 235
 236
 237
 238 #if (PTRS_PER_PMD == 1)
 239 /* Non-PAE pgd constructor */
 240 static void pgd_ctor(void *pgd)
 241 {
 242         unsigned long flags;
 243
 244         /* !PAE, no pagetable sharing */
 245         memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
 246
 247         spin_lock_irqsave(&pgd_lock, flags);
 248
 249         /* must happen under lock */
 250         clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
 251                         swapper_pg_dir + USER_PTRS_PER_PGD,
 252                         KERNEL_PGD_PTRS);
 253         paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT,
 254                                 __pa(swapper_pg_dir) >> PAGE_SHIFT,
 255                                 USER_PTRS_PER_PGD,
 256                                 KERNEL_PGD_PTRS);
 257         pgd_list_add(pgd);
 258         spin_unlock_irqrestore(&pgd_lock, flags);
 259 }
 260 #else  /* PTRS_PER_PMD > 1 */
 261 /* PAE pgd constructor */
 262 static void pgd_ctor(void *pgd)
 263 {
 264         /* PAE, kernel PMD may be shared */
 265
 266         if (SHARED_KERNEL_PMD) {
 267                 clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
 268                                 swapper_pg_dir + USER_PTRS_PER_PGD,
 269                                 KERNEL_PGD_PTRS);
 270         } else {
 271                 unsigned long flags;
 272
 273                 memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
 274                 spin_lock_irqsave(&pgd_lock, flags);
 275                 pgd_list_add(pgd);
 276                 spin_unlock_irqrestore(&pgd_lock, flags);
 277         }
 278 }
 279 #endif  /* PTRS_PER_PMD */
 280
 281 static void pgd_dtor(void *pgd)
 282 {
 283         unsigned long flags; /* can be called from interrupt context */
 284
 285         if (SHARED_KERNEL_PMD)
 286                 return;
 287
 288         paravirt_release_pd(__pa(pgd) >> PAGE_SHIFT);
 289         spin_lock_irqsave(&pgd_lock, flags);
 290         pgd_list_del(pgd);
 291         spin_unlock_irqrestore(&pgd_lock, flags);
 292 }
 293
 294 #define UNSHARED_PTRS_PER_PGD                           \
 295         (SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)
 296
 297 #ifdef CONFIG_X86_PAE
 298 /*
 299  * Mop up any pmd pages which may still be attached to the pgd.
 300  * Normally they will be freed by munmap/exit_mmap, but any pmd we
 301  * preallocate which never got a corresponding vma will need to be
 302  * freed manually.
 303  */
 304 static void pgd_mop_up_pmds(pgd_t *pgdp)
 305 {
 306         int i;
 307
 308         for(i = 0; i < USER_PTRS_PER_PGD; i++) {
 309                 pgd_t pgd = pgdp[i];
 310
 311                 if (pgd_val(pgd) != 0) {
 312                         pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);
 313
 314                         pgdp[i] = native_make_pgd(0);
 315
 316                         paravirt_release_pd(pgd_val(pgd) >> PAGE_SHIFT);
 317                         pmd_free(pmd);
 318                 }
 319         }
 320 }
 321
 322 /*
 323  * In PAE mode, we need to do a cr3 reload (=tlb flush) when
 324  * updating the top-level pagetable entries to guarantee the
 325  * processor notices the update.  Since this is expensive, and
 326  * all 4 top-level entries are used almost immediately in a
 327  * new process's life, we just pre-populate them here.
 328  */
 329 static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd)
 330 {
 331         pud_t *pud;
 332         unsigned long addr;
 333         int i;
 334
 335         pud = pud_offset(pgd, 0);
 336         for (addr = i = 0; i < USER_PTRS_PER_PGD; i++, pud++, addr += PUD_SIZE) {
 337                 pmd_t *pmd = pmd_alloc_one(mm, addr);
 338
 339                 if (!pmd) {
 340                         pgd_mop_up_pmds(pgd);
 341                         return 0;
 342                 }
 343
 344                 pud_populate(mm, pud, pmd);
 345         }
 346
 347         return 1;
 348 }
 349 #else  /* !CONFIG_X86_PAE */
 350 /* No need to prepopulate any pagetable entries in non-PAE modes. */
 351 static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd)
 352 {
 353         return 1;
 354 }
 355
 356 static void pgd_mop_up_pmds(pgd_t *pgd)
 357 {
 358 }
 359 #endif  /* CONFIG_X86_PAE */
 360
 361 /* If we allocate a pmd for part of the kernel address space, then
 362    make sure its initialized with the appropriate kernel mappings.
 363    Otherwise use a cached zeroed pmd.  */
 364 static pmd_t *pmd_cache_alloc(int idx)
 365 {
 366         pmd_t *pmd;
 367
 368         if (idx >= USER_PTRS_PER_PGD) {
 369                 pmd = (pmd_t *)__get_free_page(GFP_KERNEL);
 370
 371                 if (pmd)
 372                         memcpy(pmd,
 373                                (void *)pgd_page_vaddr(swapper_pg_dir[idx]),
 374                                sizeof(pmd_t) * PTRS_PER_PMD);
 375         } else
 376                 pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
 377
 378         return pmd;
 379 }
 380
 381 static void pmd_cache_free(pmd_t *pmd, int idx)
 382 {
 383         if (idx >= USER_PTRS_PER_PGD)
 384                 free_page((unsigned long)pmd);
 385         else
 386                 kmem_cache_free(pmd_cache, pmd);
 387 }
 388
 389 pgd_t *pgd_alloc(struct mm_struct *mm)
 390 {
 391         int i;
 392         pgd_t *pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
 393
 394         if (PTRS_PER_PMD == 1 || !pgd)
 395                 return pgd;
 396
 397         mm->pgd = pgd;          /* so that alloc_pd can use it */
 398
 399         for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
 400                 pmd_t *pmd = pmd_cache_alloc(i);
 401
 402                 if (!pmd)
 403                         goto out_oom;
 404
 405                 paravirt_alloc_pd(mm, __pa(pmd) >> PAGE_SHIFT);
 406                 set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
 407         }
 408         if (pgd && !pgd_prepopulate_pmd(mm, pgd)) {
 409                 quicklist_free(0, pgd_dtor, pgd);
 410                 pgd = NULL;
 411         }
 412
 413         return pgd;
 414
 415 out_oom:
 416         for (i--; i >= 0; i--) {
 417                 pgd_t pgdent = pgd[i];
 418                 void* pmd = (void *)__va(pgd_val(pgdent)-1);
 419                 paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
 420                 pmd_cache_free(pmd, i);
 421         }
 422         quicklist_free(0, pgd_dtor, pgd);
 423         return NULL;
 424 }
 425
 426 void pgd_free(pgd_t *pgd)
 427 {
 428         int i;
 429
 430         /* in the PAE case user pgd entries are overwritten before usage */
 431         if (PTRS_PER_PMD > 1)
 432                 for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
 433                         pgd_t pgdent = pgd[i];
 434                         void* pmd = (void *)__va(pgd_val(pgdent)-1);
 435                         paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
 436                         pmd_cache_free(pmd, i);
 437                 }
 438         /* in the non-PAE case, free_pgtables() clears user pgd entries */
 439         pgd_mop_up_pmds(pgd);
 440         quicklist_free(0, pgd_dtor, pgd);
 441 }
 442
 443 void check_pgt_cache(void)
 444 {
 445         quicklist_trim(0, pgd_dtor, 25, 16);
 446 }
 447