// SPDX-License-Identifier: GPL-2.0
/*
 * IA-64 Huge TLB Page Support for Kernel.
 *
 * Copyright (C) 2002-2004 Rohit Seth <rohit.seth@intel.com>
 * Copyright (C) 2003-2004 Ken Chen <kenneth.w.chen@intel.com>
 *
 * Sep, 2003: add numa support
 * Feb, 2004: dynamic hugetlb page size via boot parameter
 */

#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/module.h>
#include <linux/sysctl.h>
#include <linux/log2.h>
#include <asm/mman.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>

unsigned int hpage_shift = HPAGE_SHIFT_DEFAULT;
EXPORT_SYMBOL(hpage_shift);

pte_t *
huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
               unsigned long addr, unsigned long sz)
{
        unsigned long taddr = htlbpage_to_page(addr);
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte = NULL;

        pgd = pgd_offset(mm, taddr);
        p4d = p4d_offset(pgd, taddr);
        pud = pud_alloc(mm, p4d, taddr);
        if (pud) {
                pmd = pmd_alloc(mm, pud, taddr);
                if (pmd)
                        pte = pte_alloc_map(mm, pmd, taddr);
        }
        return pte;
}

pte_t *
huge_pte_offset (struct mm_struct *mm, unsigned long addr, unsigned long sz)
{
        unsigned long taddr = htlbpage_to_page(addr);
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte = NULL;

        pgd = pgd_offset(mm, taddr);
        if (pgd_present(*pgd)) {
                p4d = p4d_offset(pgd, addr);
                if (p4d_present(*p4d)) {
                        pud = pud_offset(p4d, taddr);
                        if (pud_present(*pud)) {
                                pmd = pmd_offset(pud, taddr);
                                if (pmd_present(*pmd))
                                        pte = pte_offset_map(pmd, taddr);
                        }
                }
        }

        return pte;
}

#define mk_pte_huge(entry) { pte_val(entry) |= _PAGE_P; }

/*
 * Don't actually need to do any preparation, but need to make sure
 * the address is in the right region.
 */
int prepare_hugepage_range(struct file *file,
                        unsigned long addr, unsigned long len)
{
        if (len & ~HPAGE_MASK)
                return -EINVAL;
        if (addr & ~HPAGE_MASK)
                return -EINVAL;
        if (REGION_NUMBER(addr) != RGN_HPAGE)
                return -EINVAL;

        return 0;
}

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

        if (REGION_NUMBER(addr) != RGN_HPAGE)
                return ERR_PTR(-EINVAL);

        ptep = huge_pte_offset(mm, addr, HPAGE_SIZE);
        if (!ptep || pte_none(*ptep))
                return NULL;
        page = pte_page(*ptep);
        page += ((addr & ~HPAGE_MASK) >> PAGE_SHIFT);
        return page;
}
int pmd_huge(pmd_t pmd)
{
        return 0;
}

int pud_huge(pud_t pud)
{
        return 0;
}

void hugetlb_free_pgd_range(struct mmu_gather *tlb,
                        unsigned long addr, unsigned long end,
                        unsigned long floor, unsigned long ceiling)
{
        /*
         * This is called to free hugetlb page tables.
         *
         * The offset of these addresses from the base of the hugetlb
         * region must be scaled down by HPAGE_SIZE/PAGE_SIZE so that
         * the standard free_pgd_range will free the right page tables.
         *
         * If floor and ceiling are also in the hugetlb region, they
         * must likewise be scaled down; but if outside, left unchanged.
         */

        addr = htlbpage_to_page(addr);
        end  = htlbpage_to_page(end);
        if (REGION_NUMBER(floor) == RGN_HPAGE)
                floor = htlbpage_to_page(floor);
        if (REGION_NUMBER(ceiling) == RGN_HPAGE)
                ceiling = htlbpage_to_page(ceiling);

        free_pgd_range(tlb, addr, end, floor, ceiling);
}

unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
                unsigned long pgoff, unsigned long flags)
{
        struct vm_unmapped_area_info info;

        if (len > RGN_MAP_LIMIT)
                return -ENOMEM;
        if (len & ~HPAGE_MASK)
                return -EINVAL;

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

        /* This code assumes that RGN_HPAGE != 0. */
        if ((REGION_NUMBER(addr) != RGN_HPAGE) || (addr & (HPAGE_SIZE - 1)))
                addr = HPAGE_REGION_BASE;

        info.flags = 0;
        info.length = len;
        info.low_limit = addr;
        info.high_limit = HPAGE_REGION_BASE + RGN_MAP_LIMIT;
        info.align_mask = PAGE_MASK & (HPAGE_SIZE - 1);
        info.align_offset = 0;
        return vm_unmapped_area(&info);
}

static int __init hugetlb_setup_sz(char *str)
{
        u64 tr_pages;
        unsigned long long size;

        if (ia64_pal_vm_page_size(&tr_pages, NULL) != 0)
                /*
                 * shouldn't happen, but just in case.
                 */
                tr_pages = 0x15557000UL;

        size = memparse(str, &str);
        if (*str || !is_power_of_2(size) || !(tr_pages & size) ||
                size <= PAGE_SIZE ||
                size >= (1UL << PAGE_SHIFT << MAX_ORDER)) {
                printk(KERN_WARNING "Invalid huge page size specified\n");
                return 1;
        }

        hpage_shift = __ffs(size);
        /*
         * boot cpu already executed ia64_mmu_init, and has HPAGE_SHIFT_DEFAULT
         * override here with new page shift.
         */
        ia64_set_rr(HPAGE_REGION_BASE, hpage_shift << 2);
        return 0;
}
early_param("hugepagesz", hugetlb_setup_sz);