/*
 *  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);
}

pgtable_t 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
        if (pte)
                pgtable_page_ctor(pte);
        return pte;
}

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

        list_add(&page->lru, &pgd_list);
}

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

        list_del(&page->lru);
}

#define UNSHARED_PTRS_PER_PGD                           \
        (SHARED_KERNEL_PMD ? USER_PTRS_PER_PGD : PTRS_PER_PGD)

static void pgd_ctor(void *p)
{
        pgd_t *pgd = p;
        unsigned long flags;

        /* Clear usermode parts of PGD */
        memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));

        spin_lock_irqsave(&pgd_lock, flags);

        /* If the pgd points to a shared pagetable level (either the
           ptes in non-PAE, or shared PMD in PAE), then just copy the
           references from swapper_pg_dir. */
        if (PAGETABLE_LEVELS == 2 ||
            (PAGETABLE_LEVELS == 3 && SHARED_KERNEL_PMD)) {
                clone_pgd_range(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);
        }

        /* list required to sync kernel mapping updates */
        if (!SHARED_KERNEL_PMD)
                pgd_list_add(pgd);

        spin_unlock_irqrestore(&pgd_lock, flags);
}

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

        if (SHARED_KERNEL_PMD)
                return;

        spin_lock_irqsave(&pgd_lock, flags);
        pgd_list_del(pgd);
        spin_unlock_irqrestore(&pgd_lock, flags);
}

#ifdef CONFIG_X86_PAE
/*
 * Mop up any pmd pages which may still be attached to the pgd.
 * Normally they will be freed by munmap/exit_mmap, but any pmd we
 * preallocate which never got a corresponding vma will need to be
 * freed manually.
 */
static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
{
        int i;

        for(i = 0; i < UNSHARED_PTRS_PER_PGD; i++) {
                pgd_t pgd = pgdp[i];

                if (pgd_val(pgd) != 0) {
                        pmd_t *pmd = (pmd_t *)pgd_page_vaddr(pgd);

                        pgdp[i] = native_make_pgd(0);

                        paravirt_release_pd(pgd_val(pgd) >> PAGE_SHIFT);
                        pmd_free(mm, pmd);
                }
        }
}

/*
 * In PAE mode, we need to do a cr3 reload (=tlb flush) when
 * updating the top-level pagetable entries to guarantee the
 * processor notices the update.  Since this is expensive, and
 * all 4 top-level entries are used almost immediately in a
 * new process's life, we just pre-populate them here.
 *
 * Also, if we're in a paravirt environment where the kernel pmd is
 * not shared between pagetables (!SHARED_KERNEL_PMDS), we allocate
 * and initialize the kernel pmds here.
 */
static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd)
{
        pud_t *pud;
        unsigned long addr;
        int i;

        pud = pud_offset(pgd, 0);
        for (addr = i = 0; i < UNSHARED_PTRS_PER_PGD;
             i++, pud++, addr += PUD_SIZE) {
                pmd_t *pmd = pmd_alloc_one(mm, addr);

                if (!pmd) {
                        pgd_mop_up_pmds(mm, pgd);
                        return 0;
                }

                if (i >= USER_PTRS_PER_PGD)
                        memcpy(pmd, (pmd_t *)pgd_page_vaddr(swapper_pg_dir[i]),
                               sizeof(pmd_t) * PTRS_PER_PMD);

                pud_populate(mm, pud, pmd);
        }

        return 1;
}
#else  /* !CONFIG_X86_PAE */
/* No need to prepopulate any pagetable entries in non-PAE modes. */
static int pgd_prepopulate_pmd(struct mm_struct *mm, pgd_t *pgd)
{
        return 1;
}

static void pgd_mop_up_pmds(struct mm_struct *mm, pgd_t *pgdp)
{
}
#endif  /* CONFIG_X86_PAE */

pgd_t *pgd_alloc(struct mm_struct *mm)
{
        pgd_t *pgd = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);

        /* so that alloc_pd can use it */
        mm->pgd = pgd;
        if (pgd)
                pgd_ctor(pgd);

        if (pgd && !pgd_prepopulate_pmd(mm, pgd)) {
                pgd_dtor(pgd);
                free_page((unsigned long)pgd);
                pgd = NULL;
        }

        return pgd;
}

void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
        pgd_mop_up_pmds(mm, pgd);
        pgd_dtor(pgd);
        free_page((unsigned long)pgd);
}

void __pte_free_tlb(struct mmu_gather *tlb, struct page *pte)
{
        pgtable_page_dtor(pte);
        paravirt_release_pt(page_to_pfn(pte));
        tlb_remove_page(tlb, pte);
}

#ifdef CONFIG_X86_PAE

void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmd)
{
        paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
        tlb_remove_page(tlb, virt_to_page(pmd));
}

#endif