source: trunk/packages/xen-3.1/xen-3.1/linux-2.6-xen-sparse/include/asm-x86_64/mach-xen/asm/pgalloc.h @ 34

#ifndef _X86_64_PGALLOC_H
#define _X86_64_PGALLOC_H

#include <asm/fixmap.h>
#include <asm/pda.h>
#include <linux/threads.h>
#include <linux/mm.h>
#include <asm/io.h>             /* for phys_to_virt and page_to_pseudophys */

#include <xen/features.h>
void make_page_readonly(void *va, unsigned int feature);
void make_page_writable(void *va, unsigned int feature);
void make_pages_readonly(void *va, unsigned int nr, unsigned int feature);
void make_pages_writable(void *va, unsigned int nr, unsigned int feature);

#define __user_pgd(pgd) ((pgd) + PTRS_PER_PGD)

static inline void pmd_populate_kernel(struct mm_struct *mm, pmd_t *pmd, pte_t *pte)
{
        set_pmd(pmd, __pmd(_PAGE_TABLE | __pa(pte)));
}

static inline void pmd_populate(struct mm_struct *mm, pmd_t *pmd, struct page *pte)
{
        if (unlikely((mm)->context.pinned)) {
                BUG_ON(HYPERVISOR_update_va_mapping(
                               (unsigned long)__va(page_to_pfn(pte) << PAGE_SHIFT),
                               pfn_pte(page_to_pfn(pte), PAGE_KERNEL_RO), 0));
                set_pmd(pmd, __pmd(_PAGE_TABLE | (page_to_pfn(pte) << PAGE_SHIFT)));
        } else {
                *(pmd) = __pmd(_PAGE_TABLE | (page_to_pfn(pte) << PAGE_SHIFT));
        }
}

static inline void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
{
        if (unlikely((mm)->context.pinned)) {
                BUG_ON(HYPERVISOR_update_va_mapping(
                               (unsigned long)pmd,
                               pfn_pte(virt_to_phys(pmd)>>PAGE_SHIFT, 
                                       PAGE_KERNEL_RO), 0));
                set_pud(pud, __pud(_PAGE_TABLE | __pa(pmd)));
        } else {
                *(pud) =  __pud(_PAGE_TABLE | __pa(pmd));
        }
}

/*
 * We need to use the batch mode here, but pgd_pupulate() won't be
 * be called frequently.
 */
static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, pud_t *pud)
{
        if (unlikely((mm)->context.pinned)) {
                BUG_ON(HYPERVISOR_update_va_mapping(
                               (unsigned long)pud,
                               pfn_pte(virt_to_phys(pud)>>PAGE_SHIFT, 
                                       PAGE_KERNEL_RO), 0));
                set_pgd(pgd, __pgd(_PAGE_TABLE | __pa(pud)));
                set_pgd(__user_pgd(pgd), __pgd(_PAGE_TABLE | __pa(pud)));
        } else {
                *(pgd) =  __pgd(_PAGE_TABLE | __pa(pud));
                *(__user_pgd(pgd)) = *(pgd);
        }
}

extern struct page *pte_alloc_one(struct mm_struct *mm, unsigned long addr);
extern void pte_free(struct page *pte);

static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
{
        struct page *pg;

        pg = pte_alloc_one(mm, addr);
        return pg ? page_address(pg) : NULL;
}

static inline void pmd_free(pmd_t *pmd)
{
        BUG_ON((unsigned long)pmd & (PAGE_SIZE-1));
        pte_free(virt_to_page(pmd));
}

static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long addr)
{
        struct page *pg;

        pg = pte_alloc_one(mm, addr);
        return pg ? page_address(pg) : NULL;
}

static inline void pud_free(pud_t *pud)
{
        BUG_ON((unsigned long)pud & (PAGE_SIZE-1));
        pte_free(virt_to_page(pud));
}

static inline void pgd_list_add(pgd_t *pgd)
{
        struct page *page = virt_to_page(pgd);

        spin_lock(&pgd_lock);
        page->index = (pgoff_t)pgd_list;
        if (pgd_list)
                pgd_list->private = (unsigned long)&page->index;
        pgd_list = page;
        page->private = (unsigned long)&pgd_list;
        spin_unlock(&pgd_lock);
}

static inline void pgd_list_del(pgd_t *pgd)
{
        struct page *next, **pprev, *page = virt_to_page(pgd);

        spin_lock(&pgd_lock);
        next = (struct page *)page->index;
        pprev = (struct page **)page->private;
        *pprev = next;
        if (next)
                next->private = (unsigned long)pprev;
        spin_unlock(&pgd_lock);
}

static inline pgd_t *pgd_alloc(struct mm_struct *mm)
{
        /*
         * We allocate two contiguous pages for kernel and user.
         */
        unsigned boundary;
        pgd_t *pgd = (pgd_t *)__get_free_pages(GFP_KERNEL|__GFP_REPEAT, 1);
        if (!pgd)
                return NULL;
        pgd_list_add(pgd);
        /*
         * Copy kernel pointers in from init.
         * Could keep a freelist or slab cache of those because the kernel
         * part never changes.
         */
        boundary = pgd_index(__PAGE_OFFSET);
        memset(pgd, 0, boundary * sizeof(pgd_t));
        memcpy(pgd + boundary,
               init_level4_pgt + boundary,
               (PTRS_PER_PGD - boundary) * sizeof(pgd_t));

        memset(__user_pgd(pgd), 0, PAGE_SIZE); /* clean up user pgd */
        /*
         * Set level3_user_pgt for vsyscall area
         */
        set_pgd(__user_pgd(pgd) + pgd_index(VSYSCALL_START), 
                mk_kernel_pgd(__pa_symbol(level3_user_pgt)));
        return pgd;
}

static inline void pgd_free(pgd_t *pgd)
{
        pte_t *ptep = virt_to_ptep(pgd);

        if (!pte_write(*ptep)) {
                xen_pgd_unpin(__pa(pgd));
                BUG_ON(HYPERVISOR_update_va_mapping(
                               (unsigned long)pgd,
                               pfn_pte(virt_to_phys(pgd)>>PAGE_SHIFT, PAGE_KERNEL),
                               0));
        }

        ptep = virt_to_ptep(__user_pgd(pgd));

        if (!pte_write(*ptep)) {
                xen_pgd_unpin(__pa(__user_pgd(pgd)));
                BUG_ON(HYPERVISOR_update_va_mapping(
                               (unsigned long)__user_pgd(pgd),
                               pfn_pte(virt_to_phys(__user_pgd(pgd))>>PAGE_SHIFT, 
                                       PAGE_KERNEL),
                               0));
        }

        pgd_list_del(pgd);
        free_pages((unsigned long)pgd, 1);
}

static inline pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
{
        pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL|__GFP_REPEAT);
        if (pte)
                make_page_readonly(pte, XENFEAT_writable_page_tables);

        return pte;
}

/* Should really implement gc for free page table pages. This could be
   done with a reference count in struct page. */

static inline void pte_free_kernel(pte_t *pte)
{
        BUG_ON((unsigned long)pte & (PAGE_SIZE-1));
        make_page_writable(pte, XENFEAT_writable_page_tables);
        free_page((unsigned long)pte); 
}

#define __pte_free_tlb(tlb,pte) tlb_remove_page((tlb),(pte))
#define __pmd_free_tlb(tlb,x)   tlb_remove_page((tlb),virt_to_page(x))
#define __pud_free_tlb(tlb,x)   tlb_remove_page((tlb),virt_to_page(x))

#endif /* _X86_64_PGALLOC_H */