// SPDX-License-Identifier: GPL-2.0
/*
 * arch/metag/mm/hugetlbpage.c
 *
 * METAG HugeTLB page support.
 *
 * Cloned from SuperH
 *
 * Cloned from sparc64 by Paul Mundt.
 *
 * Copyright (C) 2002, 2003 David S. Miller (davem@redhat.com)
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/sysctl.h>

#include <asm/mman.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
#include <asm/cacheflush.h>

/*
 * If the arch doesn't supply something else, assume that hugepage
 * size aligned regions are ok without further preparation.
 */
int prepare_hugepage_range(struct file *file, unsigned long addr,
                                                unsigned long len)
{
        struct mm_struct *mm = current->mm;
        struct hstate *h = hstate_file(file);
        struct vm_area_struct *vma;

        if (len & ~huge_page_mask(h))
                return -EINVAL;
        if (addr & ~huge_page_mask(h))
                return -EINVAL;
        if (TASK_SIZE - len < addr)
                return -EINVAL;

        vma = find_vma(mm, ALIGN_HUGEPT(addr));
        if (vma && !(vma->vm_flags & MAP_HUGETLB))
                return -EINVAL;

        vma = find_vma(mm, addr);
        if (vma) {
                if (addr + len > vma->vm_start)
                        return -EINVAL;
                if (!(vma->vm_flags & MAP_HUGETLB) &&
                    (ALIGN_HUGEPT(addr + len) > vma->vm_start))
                        return -EINVAL;
        }
        return 0;
}

pte_t *huge_pte_alloc(struct mm_struct *mm,
                        unsigned long addr, unsigned long sz)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        pgd = pgd_offset(mm, addr);
        pud = pud_offset(pgd, addr);
        pmd = pmd_offset(pud, addr);
        pte = pte_alloc_map(mm, pmd, addr);
        pgd->pgd &= ~_PAGE_SZ_MASK;
        pgd->pgd |= _PAGE_SZHUGE;

        return pte;
}

pte_t *huge_pte_offset(struct mm_struct *mm,
                       unsigned long addr, unsigned long sz)
{
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte = NULL;

        pgd = pgd_offset(mm, addr);
        pud = pud_offset(pgd, addr);
        pmd = pmd_offset(pud, addr);
        pte = pte_offset_kernel(pmd, addr);

        return pte;
}

int pmd_huge(pmd_t pmd)
{
        return pmd_page_shift(pmd) > PAGE_SHIFT;
}

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)
{
        return NULL;
}

#ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA

/*
 * Look for an unmapped area starting after another hugetlb vma.
 * There are guaranteed to be no huge pte's spare if all the huge pages are
 * full size (4MB), so in that case compile out this search.
 */
#if HPAGE_SHIFT == HUGEPT_SHIFT
static inline unsigned long
hugetlb_get_unmapped_area_existing(unsigned long len)
{
        return 0;
}
#else
static unsigned long
hugetlb_get_unmapped_area_existing(unsigned long len)
{
        struct mm_struct *mm = current->mm;
        struct vm_area_struct *vma;
        unsigned long start_addr, addr;
        int after_huge;

        if (mm->context.part_huge) {
                start_addr = mm->context.part_huge;
                after_huge = 1;
        } else {
                start_addr = TASK_UNMAPPED_BASE;
                after_huge = 0;
        }
new_search:
        addr = start_addr;

        for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
                if ((!vma && !after_huge) || TASK_SIZE - len < addr) {
                        /*
                         * Start a new search - just in case we missed
                         * some holes.
                         */
                        if (start_addr != TASK_UNMAPPED_BASE) {
                                start_addr = TASK_UNMAPPED_BASE;
                                goto new_search;
                        }
                        return 0;
                }
                /* skip ahead if we've aligned right over some vmas */
                if (vma && vma->vm_end <= addr)
                        continue;
                /* space before the next vma? */
                if (after_huge && (!vma || ALIGN_HUGEPT(addr + len)
                            <= vma->vm_start)) {
                        unsigned long end = addr + len;
                        if (end & HUGEPT_MASK)
                                mm->context.part_huge = end;
                        else if (addr == mm->context.part_huge)
                                mm->context.part_huge = 0;
                        return addr;
                }
                if (vma->vm_flags & MAP_HUGETLB) {
                        /* space after a huge vma in 2nd level page table? */
                        if (vma->vm_end & HUGEPT_MASK) {
                                after_huge = 1;
                                /* no need to align to the next PT block */
                                addr = vma->vm_end;
                                continue;
                        }
                }
                after_huge = 0;
                addr = ALIGN_HUGEPT(vma->vm_end);
        }
}
#endif

/* Do a full search to find an area without any nearby normal pages. */
static unsigned long
hugetlb_get_unmapped_area_new_pmd(unsigned long len)
{
        struct vm_unmapped_area_info info;

        info.flags = 0;
        info.length = len;
        info.low_limit = TASK_UNMAPPED_BASE;
        info.high_limit = TASK_SIZE;
        info.align_mask = PAGE_MASK & HUGEPT_MASK;
        info.align_offset = 0;
        return vm_unmapped_area(&info);
}

unsigned long
hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
                unsigned long len, unsigned long pgoff, unsigned long flags)
{
        struct hstate *h = hstate_file(file);

        if (len & ~huge_page_mask(h))
                return -EINVAL;
        if (len > TASK_SIZE)
                return -ENOMEM;

        if (flags & MAP_FIXED) {
                if (prepare_hugepage_range(file, addr, len))
                        return -EINVAL;
                return addr;
        }

        if (addr) {
                addr = ALIGN(addr, huge_page_size(h));
                if (!prepare_hugepage_range(file, addr, len))
                        return addr;
        }

        /*
         * Look for an existing hugetlb vma with space after it (this is to to
         * minimise fragmentation caused by huge pages.
         */
        addr = hugetlb_get_unmapped_area_existing(len);
        if (addr)
                return addr;

        /*
         * Find an unmapped naturally aligned set of 4MB blocks that we can use
         * for huge pages.
         */
        return hugetlb_get_unmapped_area_new_pmd(len);
}

#endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/

/* necessary for boot time 4MB huge page allocation */
static __init int setup_hugepagesz(char *opt)
{
        unsigned long ps = memparse(opt, &opt);
        if (ps == (1 << HPAGE_SHIFT)) {
                hugetlb_add_hstate(HPAGE_SHIFT - PAGE_SHIFT);
        } else {
                hugetlb_bad_size();
                pr_err("hugepagesz: Unsupported page size %lu M\n",
                       ps >> 20);
                return 0;
        }
        return 1;
}
__setup("hugepagesz=", setup_hugepagesz);