/*
 * PPC64 (POWER4) Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2003 David Gibson, IBM Corporation.
 *
 * Based on the IA-32 version:
 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
 */

#include <linux/mm.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>

#define PAGE_SHIFT_64K  16
#define PAGE_SHIFT_16M  24
#define PAGE_SHIFT_16G  34

#define MAX_NUMBER_GPAGES       1024

/* Tracks the 16G pages after the device tree is scanned and before the
 * huge_boot_pages list is ready.  */
static unsigned long gpage_freearray[MAX_NUMBER_GPAGES];
static unsigned nr_gpages;

/* Flag to mark huge PD pointers.  This means pmd_bad() and pud_bad()
 * will choke on pointers to hugepte tables, which is handy for
 * catching screwups early. */

static inline int shift_to_mmu_psize(unsigned int shift)
{
        int psize;

        for (psize = 0; psize < MMU_PAGE_COUNT; ++psize)
                if (mmu_psize_defs[psize].shift == shift)
                        return psize;
        return -1;
}

static inline unsigned int mmu_psize_to_shift(unsigned int mmu_psize)
{
        if (mmu_psize_defs[mmu_psize].shift)
                return mmu_psize_defs[mmu_psize].shift;
        BUG();
}

#define hugepd_none(hpd)        ((hpd).pd == 0)

static inline pte_t *hugepd_page(hugepd_t hpd)
{
        BUG_ON(!hugepd_ok(hpd));
        return (pte_t *)((hpd.pd & ~HUGEPD_SHIFT_MASK) | 0xc000000000000000);
}

static inline unsigned int hugepd_shift(hugepd_t hpd)
{
        return hpd.pd & HUGEPD_SHIFT_MASK;
}

static inline pte_t *hugepte_offset(hugepd_t *hpdp, unsigned long addr, unsigned pdshift)
{
        unsigned long idx = (addr & ((1UL << pdshift) - 1)) >> hugepd_shift(*hpdp);
        pte_t *dir = hugepd_page(*hpdp);

        return dir + idx;
}

pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, unsigned *shift)
{
        pgd_t *pg;
        pud_t *pu;
        pmd_t *pm;
        hugepd_t *hpdp = NULL;
        unsigned pdshift = PGDIR_SHIFT;

        if (shift)
                *shift = 0;

        pg = pgdir + pgd_index(ea);
        if (is_hugepd(pg)) {
                hpdp = (hugepd_t *)pg;
        } else if (!pgd_none(*pg)) {
                pdshift = PUD_SHIFT;
                pu = pud_offset(pg, ea);
                if (is_hugepd(pu))
                        hpdp = (hugepd_t *)pu;
                else if (!pud_none(*pu)) {
                        pdshift = PMD_SHIFT;
                        pm = pmd_offset(pu, ea);
                        if (is_hugepd(pm))
                                hpdp = (hugepd_t *)pm;
                        else if (!pmd_none(*pm)) {
                                return pte_offset_map(pm, ea);
                        }
                }
        }

        if (!hpdp)
                return NULL;

        if (shift)
                *shift = hugepd_shift(*hpdp);
        return hugepte_offset(hpdp, ea, pdshift);
}

pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr)
{
        return find_linux_pte_or_hugepte(mm->pgd, addr, NULL);
}

static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
                           unsigned long address, unsigned pdshift, unsigned pshift)
{
        pte_t *new = kmem_cache_zalloc(PGT_CACHE(pdshift - pshift),
                                       GFP_KERNEL|__GFP_REPEAT);

        BUG_ON(pshift > HUGEPD_SHIFT_MASK);
        BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);

        if (! new)
                return -ENOMEM;

        spin_lock(&mm->page_table_lock);
        if (!hugepd_none(*hpdp))
                kmem_cache_free(PGT_CACHE(pdshift - pshift), new);
        else
                hpdp->pd = ((unsigned long)new & ~0x8000000000000000) | pshift;
        spin_unlock(&mm->page_table_lock);
        return 0;
}

pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
{
        pgd_t *pg;
        pud_t *pu;
        pmd_t *pm;
        hugepd_t *hpdp = NULL;
        unsigned pshift = __ffs(sz);
        unsigned pdshift = PGDIR_SHIFT;

        addr &= ~(sz-1);

        pg = pgd_offset(mm, addr);
        if (pshift >= PUD_SHIFT) {
                hpdp = (hugepd_t *)pg;
        } else {
                pdshift = PUD_SHIFT;
                pu = pud_alloc(mm, pg, addr);
                if (pshift >= PMD_SHIFT) {
                        hpdp = (hugepd_t *)pu;
                } else {
                        pdshift = PMD_SHIFT;
                        pm = pmd_alloc(mm, pu, addr);
                        hpdp = (hugepd_t *)pm;
                }
        }

        if (!hpdp)
                return NULL;

        BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));

        if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr, pdshift, pshift))
                return NULL;

        return hugepte_offset(hpdp, addr, pdshift);
}

/* Build list of addresses of gigantic pages.  This function is used in early
 * boot before the buddy or bootmem allocator is setup.
 */
void add_gpage(unsigned long addr, unsigned long page_size,
        unsigned long number_of_pages)
{
        if (!addr)
                return;
        while (number_of_pages > 0) {
                gpage_freearray[nr_gpages] = addr;
                nr_gpages++;
                number_of_pages--;
                addr += page_size;
        }
}

/* Moves the gigantic page addresses from the temporary list to the
 * huge_boot_pages list.
 */
int alloc_bootmem_huge_page(struct hstate *hstate)
{
        struct huge_bootmem_page *m;
        if (nr_gpages == 0)
                return 0;
        m = phys_to_virt(gpage_freearray[--nr_gpages]);
        gpage_freearray[nr_gpages] = 0;
        list_add(&m->list, &huge_boot_pages);
        m->hstate = hstate;
        return 1;
}

int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep)
{
        return 0;
}

static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshift,
                              unsigned long start, unsigned long end,
                              unsigned long floor, unsigned long ceiling)
{
        pte_t *hugepte = hugepd_page(*hpdp);
        unsigned shift = hugepd_shift(*hpdp);
        unsigned long pdmask = ~((1UL << pdshift) - 1);

        start &= pdmask;
        if (start < floor)
                return;
        if (ceiling) {
                ceiling &= pdmask;
                if (! ceiling)
                        return;
        }
        if (end - 1 > ceiling - 1)
                return;

        hpdp->pd = 0;
        tlb->need_flush = 1;
        pgtable_free_tlb(tlb, hugepte, pdshift - shift);
}

static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
                                   unsigned long addr, unsigned long end,
                                   unsigned long floor, unsigned long ceiling)
{
        pmd_t *pmd;
        unsigned long next;
        unsigned long start;

        start = addr;
        pmd = pmd_offset(pud, addr);
        do {
                next = pmd_addr_end(addr, end);
                if (pmd_none(*pmd))
                        continue;
                free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
                                  addr, next, floor, ceiling);
        } while (pmd++, addr = next, addr != end);

        start &= PUD_MASK;
        if (start < floor)
                return;
        if (ceiling) {
                ceiling &= PUD_MASK;
                if (!ceiling)
                        return;
        }
        if (end - 1 > ceiling - 1)
                return;

        pmd = pmd_offset(pud, start);
        pud_clear(pud);
        pmd_free_tlb(tlb, pmd, start);
}

static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
                                   unsigned long addr, unsigned long end,
                                   unsigned long floor, unsigned long ceiling)
{
        pud_t *pud;
        unsigned long next;
        unsigned long start;

        start = addr;
        pud = pud_offset(pgd, addr);
        do {
                next = pud_addr_end(addr, end);
                if (!is_hugepd(pud)) {
                        if (pud_none_or_clear_bad(pud))
                                continue;
                        hugetlb_free_pmd_range(tlb, pud, addr, next, floor,
                                               ceiling);
                } else {
                        free_hugepd_range(tlb, (hugepd_t *)pud, PUD_SHIFT,
                                          addr, next, floor, ceiling);
                }
        } while (pud++, addr = next, addr != end);

        start &= PGDIR_MASK;
        if (start < floor)
                return;
        if (ceiling) {
                ceiling &= PGDIR_MASK;
                if (!ceiling)
                        return;
        }
        if (end - 1 > ceiling - 1)
                return;

        pud = pud_offset(pgd, start);
        pgd_clear(pgd);
        pud_free_tlb(tlb, pud, start);
}

/*
 * This function frees user-level page tables of a process.
 *
 * Must be called with pagetable lock held.
 */
void hugetlb_free_pgd_range(struct mmu_gather *tlb,
                            unsigned long addr, unsigned long end,
                            unsigned long floor, unsigned long ceiling)
{
        pgd_t *pgd;
        unsigned long next;

        /*
         * Because there are a number of different possible pagetable
         * layouts for hugepage ranges, we limit knowledge of how
         * things should be laid out to the allocation path
         * (huge_pte_alloc(), above).  Everything else works out the
         * structure as it goes from information in the hugepd
         * pointers.  That means that we can't here use the
         * optimization used in the normal page free_pgd_range(), of
         * checking whether we're actually covering a large enough
         * range to have to do anything at the top level of the walk
         * instead of at the bottom.
         *
         * To make sense of this, you should probably go read the big
         * block comment at the top of the normal free_pgd_range(),
         * too.
         */

        pgd = pgd_offset(tlb->mm, addr);
        do {
                next = pgd_addr_end(addr, end);
                if (!is_hugepd(pgd)) {
                        if (pgd_none_or_clear_bad(pgd))
                                continue;
                        hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
                } else {
                        free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
                                          addr, next, floor, ceiling);
                }
        } while (pgd++, addr = next, addr != end);
}

struct page *
follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
{
        pte_t *ptep;
        struct page *page;
        unsigned shift;
        unsigned long mask;

        ptep = find_linux_pte_or_hugepte(mm->pgd, address, &shift);

        /* Verify it is a huge page else bail. */
        if (!ptep || !shift)
                return ERR_PTR(-EINVAL);

        mask = (1UL << shift) - 1;
        page = pte_page(*ptep);
        if (page)
                page += (address & mask) / PAGE_SIZE;

        return page;
}

int pmd_huge(pmd_t pmd)
{
        return 0;
}

int pud_huge(pud_t pud)
{
        return 0;
}

struct page *
follow_huge_pmd(struct mm_struct *mm, unsigned long address,
                pmd_t *pmd, int write)
{
        BUG();
        return NULL;
}

static noinline int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
                       unsigned long end, int write, struct page **pages, int *nr)
{
        unsigned long mask;
        unsigned long pte_end;
        struct page *head, *page;
        pte_t pte;
        int refs;

        pte_end = (addr + sz) & ~(sz-1);
        if (pte_end < end)
                end = pte_end;

        pte = *ptep;
        mask = _PAGE_PRESENT | _PAGE_USER;
        if (write)
                mask |= _PAGE_RW;

        if ((pte_val(pte) & mask) != mask)
                return 0;

        /* hugepages are never "special" */
        VM_BUG_ON(!pfn_valid(pte_pfn(pte)));

        refs = 0;
        head = pte_page(pte);

        page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
        do {
                VM_BUG_ON(compound_head(page) != head);
                pages[*nr] = page;
                (*nr)++;
                page++;
                refs++;
        } while (addr += PAGE_SIZE, addr != end);

        if (!page_cache_add_speculative(head, refs)) {
                *nr -= refs;
                return 0;
        }

        if (unlikely(pte_val(pte) != pte_val(*ptep))) {
                /* Could be optimized better */
                while (*nr) {
                        put_page(page);
                        (*nr)--;
                }
        }

        return 1;
}

static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
                                      unsigned long sz)
{
        unsigned long __boundary = (addr + sz) & ~(sz-1);
        return (__boundary - 1 < end - 1) ? __boundary : end;
}

int gup_hugepd(hugepd_t *hugepd, unsigned pdshift,
               unsigned long addr, unsigned long end,
               int write, struct page **pages, int *nr)
{
        pte_t *ptep;
        unsigned long sz = 1UL << hugepd_shift(*hugepd);
        unsigned long next;

        ptep = hugepte_offset(hugepd, addr, pdshift);
        do {
                next = hugepte_addr_end(addr, end, sz);
                if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
                        return 0;
        } while (ptep++, addr = next, addr != end);

        return 1;
}

unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
                                        unsigned long len, unsigned long pgoff,
                                        unsigned long flags)
{
        struct hstate *hstate = hstate_file(file);
        int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));

        return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1, 0);
}

unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
        unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);

        return 1UL << mmu_psize_to_shift(psize);
}

static int __init add_huge_page_size(unsigned long long size)
{
        int shift = __ffs(size);
        int mmu_psize;

        /* Check that it is a page size supported by the hardware and
         * that it fits within pagetable and slice limits. */
        if (!is_power_of_2(size)
            || (shift > SLICE_HIGH_SHIFT) || (shift <= PAGE_SHIFT))
                return -EINVAL;

        if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
                return -EINVAL;

#ifdef CONFIG_SPU_FS_64K_LS
        /* Disable support for 64K huge pages when 64K SPU local store
         * support is enabled as the current implementation conflicts.
         */
        if (shift == PAGE_SHIFT_64K)
                return -EINVAL;
#endif /* CONFIG_SPU_FS_64K_LS */

        BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);

        /* Return if huge page size has already been setup */
        if (size_to_hstate(size))
                return 0;

        hugetlb_add_hstate(shift - PAGE_SHIFT);

        return 0;
}

static int __init hugepage_setup_sz(char *str)
{
        unsigned long long size;

        size = memparse(str, &str);

        if (add_huge_page_size(size) != 0)
                printk(KERN_WARNING "Invalid huge page size specified(%llu)\n", size);

        return 1;
}
__setup("hugepagesz=", hugepage_setup_sz);

static int __init hugetlbpage_init(void)
{
        int psize;

        if (!cpu_has_feature(CPU_FTR_16M_PAGE))
                return -ENODEV;

        for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
                unsigned shift;
                unsigned pdshift;

                if (!mmu_psize_defs[psize].shift)
                        continue;

                shift = mmu_psize_to_shift(psize);

                if (add_huge_page_size(1ULL << shift) < 0)
                        continue;

                if (shift < PMD_SHIFT)
                        pdshift = PMD_SHIFT;
                else if (shift < PUD_SHIFT)
                        pdshift = PUD_SHIFT;
                else
                        pdshift = PGDIR_SHIFT;

                pgtable_cache_add(pdshift - shift, NULL);
                if (!PGT_CACHE(pdshift - shift))
                        panic("hugetlbpage_init(): could not create "
                              "pgtable cache for %d bit pagesize\n", shift);
        }

        /* Set default large page size. Currently, we pick 16M or 1M
         * depending on what is available
         */
        if (mmu_psize_defs[MMU_PAGE_16M].shift)
                HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
        else if (mmu_psize_defs[MMU_PAGE_1M].shift)
                HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;

        return 0;
}

module_init(hugetlbpage_init);

void flush_dcache_icache_hugepage(struct page *page)
{
        int i;

        BUG_ON(!PageCompound(page));

        for (i = 0; i < (1UL << compound_order(page)); i++)
                __flush_dcache_icache(page_address(page+i));
}