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