// SPDX-License-Identifier: GPL-2.0
/*
 * PARISC64 Huge TLB page support.
 *
 * This parisc implementation is heavily based on the SPARC and x86 code.
 *
 * Copyright (C) 2015 Helge Deller <deller@gmx.de>
 */

#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/sched/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>
#include <asm/mmu_context.h>


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;

        if (addr)
                addr = ALIGN(addr, huge_page_size(h));

        /* we need to make sure the colouring is OK */
        return arch_get_unmapped_area(file, addr, len, pgoff, flags);
}


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 = NULL;

        /* We must align the address, because our caller will run
         * set_huge_pte_at() on whatever we return, which writes out
         * all of the sub-ptes for the hugepage range.  So we have
         * to give it the first such sub-pte.
         */
        addr &= HPAGE_MASK;

        pgd = pgd_offset(mm, addr);
        pud = pud_alloc(mm, pgd, addr);
        if (pud) {
                pmd = pmd_alloc(mm, pud, addr);
                if (pmd)
                        pte = pte_alloc_map(mm, pmd, addr);
        }
        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;

        addr &= HPAGE_MASK;

        pgd = pgd_offset(mm, addr);
        if (!pgd_none(*pgd)) {
                pud = pud_offset(pgd, addr);
                if (!pud_none(*pud)) {
                        pmd = pmd_offset(pud, addr);
                        if (!pmd_none(*pmd))
                                pte = pte_offset_map(pmd, addr);
                }
        }
        return pte;
}

/* Purge data and instruction TLB entries.  Must be called holding
 * the pa_tlb_lock.  The TLB purge instructions are slow on SMP
 * machines since the purge must be broadcast to all CPUs.
 */
static inline void purge_tlb_entries_huge(struct mm_struct *mm, unsigned long addr)
{
        int i;

        /* We may use multiple physical huge pages (e.g. 2x1 MB) to emulate
         * Linux standard huge pages (e.g. 2 MB) */
        BUILD_BUG_ON(REAL_HPAGE_SHIFT > HPAGE_SHIFT);

        addr &= HPAGE_MASK;
        addr |= _HUGE_PAGE_SIZE_ENCODING_DEFAULT;

        for (i = 0; i < (1 << (HPAGE_SHIFT-REAL_HPAGE_SHIFT)); i++) {
                purge_tlb_entries(mm, addr);
                addr += (1UL << REAL_HPAGE_SHIFT);
        }
}

/* __set_huge_pte_at() must be called holding the pa_tlb_lock. */
static void __set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
                     pte_t *ptep, pte_t entry)
{
        unsigned long addr_start;
        int i;

        addr &= HPAGE_MASK;
        addr_start = addr;

        for (i = 0; i < (1 << HUGETLB_PAGE_ORDER); i++) {
                set_pte(ptep, entry);
                ptep++;

                addr += PAGE_SIZE;
                pte_val(entry) += PAGE_SIZE;
        }

        purge_tlb_entries_huge(mm, addr_start);
}

void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
                     pte_t *ptep, pte_t entry)
{
        unsigned long flags;

        spin_lock_irqsave(pgd_spinlock((mm)->pgd), flags);
        __set_huge_pte_at(mm, addr, ptep, entry);
        spin_unlock_irqrestore(pgd_spinlock((mm)->pgd), flags);
}


pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
                              pte_t *ptep)
{
        unsigned long flags;
        pte_t entry;

        spin_lock_irqsave(pgd_spinlock((mm)->pgd), flags);
        entry = *ptep;
        __set_huge_pte_at(mm, addr, ptep, __pte(0));
        spin_unlock_irqrestore(pgd_spinlock((mm)->pgd), flags);

        return entry;
}


void huge_ptep_set_wrprotect(struct mm_struct *mm,
                                unsigned long addr, pte_t *ptep)
{
        unsigned long flags;
        pte_t old_pte;

        spin_lock_irqsave(pgd_spinlock((mm)->pgd), flags);
        old_pte = *ptep;
        __set_huge_pte_at(mm, addr, ptep, pte_wrprotect(old_pte));
        spin_unlock_irqrestore(pgd_spinlock((mm)->pgd), flags);
}

int huge_ptep_set_access_flags(struct vm_area_struct *vma,
                                unsigned long addr, pte_t *ptep,
                                pte_t pte, int dirty)
{
        unsigned long flags;
        int changed;
        struct mm_struct *mm = vma->vm_mm;

        spin_lock_irqsave(pgd_spinlock((mm)->pgd), flags);
        changed = !pte_same(*ptep, pte);
        if (changed) {
                __set_huge_pte_at(mm, addr, ptep, pte);
        }
        spin_unlock_irqrestore(pgd_spinlock((mm)->pgd), flags);
        return changed;
}


int pmd_huge(pmd_t pmd)
{
        return 0;
}

int pud_huge(pud_t pud)
{
        return 0;
}