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pgtable_32.c

/*
 *  linux/arch/i386/mm/pgtable.c
 */

#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/mm.h>
#include <linux/nmi.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/quicklist.h>

#include <asm/system.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/fixmap.h>
#include <asm/e820.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>

void show_mem(void)
{
      int total = 0, reserved = 0;
      int shared = 0, cached = 0;
      int highmem = 0;
      struct page *page;
      pg_data_t *pgdat;
      unsigned long i;
      unsigned long flags;

      printk(KERN_INFO "Mem-info:\n");
      show_free_areas();
      printk(KERN_INFO "Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
      for_each_online_pgdat(pgdat) {
            pgdat_resize_lock(pgdat, &flags);
            for (i = 0; i < pgdat->node_spanned_pages; ++i) {
                  if (unlikely(i % MAX_ORDER_NR_PAGES == 0))
                        touch_nmi_watchdog();
                  page = pgdat_page_nr(pgdat, i);
                  total++;
                  if (PageHighMem(page))
                        highmem++;
                  if (PageReserved(page))
                        reserved++;
                  else if (PageSwapCache(page))
                        cached++;
                  else if (page_count(page))
                        shared += page_count(page) - 1;
            }
            pgdat_resize_unlock(pgdat, &flags);
      }
      printk(KERN_INFO "%d pages of RAM\n", total);
      printk(KERN_INFO "%d pages of HIGHMEM\n", highmem);
      printk(KERN_INFO "%d reserved pages\n", reserved);
      printk(KERN_INFO "%d pages shared\n", shared);
      printk(KERN_INFO "%d pages swap cached\n", cached);

      printk(KERN_INFO "%lu pages dirty\n", global_page_state(NR_FILE_DIRTY));
      printk(KERN_INFO "%lu pages writeback\n",
                              global_page_state(NR_WRITEBACK));
      printk(KERN_INFO "%lu pages mapped\n", global_page_state(NR_FILE_MAPPED));
      printk(KERN_INFO "%lu pages slab\n",
            global_page_state(NR_SLAB_RECLAIMABLE) +
            global_page_state(NR_SLAB_UNRECLAIMABLE));
      printk(KERN_INFO "%lu pages pagetables\n",
                              global_page_state(NR_PAGETABLE));
}

/*
 * Associate a virtual page frame with a given physical page frame 
 * and protection flags for that frame.
 */ 
static void set_pte_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
{
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;
      pte_t *pte;

      pgd = swapper_pg_dir + pgd_index(vaddr);
      if (pgd_none(*pgd)) {
            BUG();
            return;
      }
      pud = pud_offset(pgd, vaddr);
      if (pud_none(*pud)) {
            BUG();
            return;
      }
      pmd = pmd_offset(pud, vaddr);
      if (pmd_none(*pmd)) {
            BUG();
            return;
      }
      pte = pte_offset_kernel(pmd, vaddr);
      if (pgprot_val(flags))
            set_pte_present(&init_mm, vaddr, pte, pfn_pte(pfn, flags));
      else
            pte_clear(&init_mm, vaddr, pte);

      /*
       * It's enough to flush this one mapping.
       * (PGE mappings get flushed as well)
       */
      __flush_tlb_one(vaddr);
}

/*
 * Associate a large virtual page frame with a given physical page frame 
 * and protection flags for that frame. pfn is for the base of the page,
 * vaddr is what the page gets mapped to - both must be properly aligned. 
 * The pmd must already be instantiated. Assumes PAE mode.
 */ 
void set_pmd_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
{
      pgd_t *pgd;
      pud_t *pud;
      pmd_t *pmd;

      if (vaddr & (PMD_SIZE-1)) {         /* vaddr is misaligned */
            printk(KERN_WARNING "set_pmd_pfn: vaddr misaligned\n");
            return; /* BUG(); */
      }
      if (pfn & (PTRS_PER_PTE-1)) {       /* pfn is misaligned */
            printk(KERN_WARNING "set_pmd_pfn: pfn misaligned\n");
            return; /* BUG(); */
      }
      pgd = swapper_pg_dir + pgd_index(vaddr);
      if (pgd_none(*pgd)) {
            printk(KERN_WARNING "set_pmd_pfn: pgd_none\n");
            return; /* BUG(); */
      }
      pud = pud_offset(pgd, vaddr);
      pmd = pmd_offset(pud, vaddr);
      set_pmd(pmd, pfn_pmd(pfn, flags));
      /*
       * It's enough to flush this one mapping.
       * (PGE mappings get flushed as well)
       */
      __flush_tlb_one(vaddr);
}

static int fixmaps;
unsigned long __FIXADDR_TOP = 0xfffff000;
EXPORT_SYMBOL(__FIXADDR_TOP);

void __set_fixmap (enum fixed_addresses idx, unsigned long phys, pgprot_t flags)
{
      unsigned long address = __fix_to_virt(idx);

      if (idx >= __end_of_fixed_addresses) {
            BUG();
            return;
      }
      set_pte_pfn(address, phys >> PAGE_SHIFT, flags);
      fixmaps++;
}

/**
 * reserve_top_address - reserves a hole in the top of kernel address space
 * @reserve - size of hole to reserve
 *
 * Can be used to relocate the fixmap area and poke a hole in the top
 * of kernel address space to make room for a hypervisor.
 */
void reserve_top_address(unsigned long reserve)
{
      BUG_ON(fixmaps > 0);
      printk(KERN_INFO "Reserving virtual address space above 0x%08x\n",
             (int)-reserve);
      __FIXADDR_TOP = -reserve - PAGE_SIZE;
      __VMALLOC_RESERVE += reserve;
}

pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
      return (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO);
}

struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
{
      struct page *pte;

#ifdef CONFIG_HIGHPTE
      pte = alloc_pages(GFP_KERNEL|__GFP_HIGHMEM|__GFP_REPEAT|__GFP_ZERO, 0);
#else
      pte = alloc_pages(GFP_KERNEL|__GFP_REPEAT|__GFP_ZERO, 0);
#endif
      return pte;
}

void pmd_ctor(struct kmem_cache *cache, void *pmd)
{
      memset(pmd, 0, PTRS_PER_PMD*sizeof(pmd_t));
}

/*
 * List of all pgd's needed for non-PAE so it can invalidate entries
 * in both cached and uncached pgd's; not needed for PAE since the
 * kernel pmd is shared. If PAE were not to share the pmd a similar
 * tactic would be needed. This is essentially codepath-based locking
 * against pageattr.c; it is the unique case in which a valid change
 * of kernel pagetables can't be lazily synchronized by vmalloc faults.
 * vmalloc faults work because attached pagetables are never freed.
 * -- wli
 */
DEFINE_SPINLOCK(pgd_lock);
struct page *pgd_list;

static inline void pgd_list_add(pgd_t *pgd)
{
      struct page *page = virt_to_page(pgd);
      page->index = (unsigned long)pgd_list;
      if (pgd_list)
            set_page_private(pgd_list, (unsigned long)&page->index);
      pgd_list = page;
      set_page_private(page, (unsigned long)&pgd_list);
}

static inline void pgd_list_del(pgd_t *pgd)
{
      struct page *next, **pprev, *page = virt_to_page(pgd);
      next = (struct page *)page->index;
      pprev = (struct page **)page_private(page);
      *pprev = next;
      if (next)
            set_page_private(next, (unsigned long)pprev);
}



#if (PTRS_PER_PMD == 1)
/* Non-PAE pgd constructor */
static void pgd_ctor(void *pgd)
{
      unsigned long flags;

      /* !PAE, no pagetable sharing */
      memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));

      spin_lock_irqsave(&pgd_lock, flags);

      /* must happen under lock */
      clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
                  swapper_pg_dir + USER_PTRS_PER_PGD,
                  KERNEL_PGD_PTRS);
      paravirt_alloc_pd_clone(__pa(pgd) >> PAGE_SHIFT,
                        __pa(swapper_pg_dir) >> PAGE_SHIFT,
                        USER_PTRS_PER_PGD,
                        KERNEL_PGD_PTRS);
      pgd_list_add(pgd);
      spin_unlock_irqrestore(&pgd_lock, flags);
}
#else  /* PTRS_PER_PMD > 1 */
/* PAE pgd constructor */
static void pgd_ctor(void *pgd)
{
      /* PAE, kernel PMD may be shared */

      if (SHARED_KERNEL_PMD) {
            clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
                        swapper_pg_dir + USER_PTRS_PER_PGD,
                        KERNEL_PGD_PTRS);
      } else {
            unsigned long flags;

            memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
            spin_lock_irqsave(&pgd_lock, flags);
            pgd_list_add(pgd);
            spin_unlock_irqrestore(&pgd_lock, flags);
      }
}
#endif      /* PTRS_PER_PMD */

static void pgd_dtor(void *pgd)
{
      unsigned long flags; /* can be called from interrupt context */

      if (SHARED_KERNEL_PMD)
            return;

      paravirt_release_pd(__pa(pgd) >> PAGE_SHIFT);
      spin_lock_irqsave(&pgd_lock, flags);
      pgd_list_del(pgd);
      spin_unlock_irqrestore(&pgd_lock, flags);
}

#define UNSHARED_PTRS_PER_PGD                   \
      (SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)

/* If we allocate a pmd for part of the kernel address space, then
   make sure its initialized with the appropriate kernel mappings.
   Otherwise use a cached zeroed pmd.  */
static pmd_t *pmd_cache_alloc(int idx)
{
      pmd_t *pmd;

      if (idx >= USER_PTRS_PER_PGD) {
            pmd = (pmd_t *)__get_free_page(GFP_KERNEL);

            if (pmd)
                  memcpy(pmd,
                         (void *)pgd_page_vaddr(swapper_pg_dir[idx]),
                         sizeof(pmd_t) * PTRS_PER_PMD);
      } else
            pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);

      return pmd;
}

static void pmd_cache_free(pmd_t *pmd, int idx)
{
      if (idx >= USER_PTRS_PER_PGD)
            free_page((unsigned long)pmd);
      else
            kmem_cache_free(pmd_cache, pmd);
}

pgd_t *pgd_alloc(struct mm_struct *mm)
{
      int i;
      pgd_t *pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);

      if (PTRS_PER_PMD == 1 || !pgd)
            return pgd;

      for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
            pmd_t *pmd = pmd_cache_alloc(i);

            if (!pmd)
                  goto out_oom;

            paravirt_alloc_pd(__pa(pmd) >> PAGE_SHIFT);
            set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
      }
      return pgd;

out_oom:
      for (i--; i >= 0; i--) {
            pgd_t pgdent = pgd[i];
            void* pmd = (void *)__va(pgd_val(pgdent)-1);
            paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
            pmd_cache_free(pmd, i);
      }
      quicklist_free(0, pgd_dtor, pgd);
      return NULL;
}

void pgd_free(pgd_t *pgd)
{
      int i;

      /* in the PAE case user pgd entries are overwritten before usage */
      if (PTRS_PER_PMD > 1)
            for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
                  pgd_t pgdent = pgd[i];
                  void* pmd = (void *)__va(pgd_val(pgdent)-1);
                  paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
                  pmd_cache_free(pmd, i);
            }
      /* in the non-PAE case, free_pgtables() clears user pgd entries */
      quicklist_free(0, pgd_dtor, pgd);
}

void check_pgt_cache(void)
{
      quicklist_trim(0, pgd_dtor, 25, 16);
}


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