// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/mm/pgd.c
 *
 *  Copyright (C) 1998-2005 Russell King
 */
#include <linux/mm.h>
#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/slab.h>

#include <asm/cp15.h>
#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/tlbflush.h>

#include "mm.h"

#ifdef CONFIG_ARM_LPAE
#define __pgd_alloc()   kmalloc_array(PTRS_PER_PGD, sizeof(pgd_t), GFP_KERNEL)
#define __pgd_free(pgd) kfree(pgd)
#else
#define __pgd_alloc()   (pgd_t *)__get_free_pages(GFP_KERNEL, 2)
#define __pgd_free(pgd) free_pages((unsigned long)pgd, 2)
#endif

/*
 * need to get a 16k page for level 1
 */
pgd_t *pgd_alloc(struct mm_struct *mm)
{
        pgd_t *new_pgd, *init_pgd;
        p4d_t *new_p4d, *init_p4d;
        pud_t *new_pud, *init_pud;
        pmd_t *new_pmd, *init_pmd;
        pte_t *new_pte, *init_pte;

        new_pgd = __pgd_alloc();
        if (!new_pgd)
                goto no_pgd;

        memset(new_pgd, 0, USER_PTRS_PER_PGD * sizeof(pgd_t));

        /*
         * Copy over the kernel and IO PGD entries
         */
        init_pgd = pgd_offset_k(0);
        memcpy(new_pgd + USER_PTRS_PER_PGD, init_pgd + USER_PTRS_PER_PGD,
                       (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));

        clean_dcache_area(new_pgd, PTRS_PER_PGD * sizeof(pgd_t));

#ifdef CONFIG_ARM_LPAE
        /*
         * Allocate PMD table for modules and pkmap mappings.
         */
        new_p4d = p4d_alloc(mm, new_pgd + pgd_index(MODULES_VADDR),
                            MODULES_VADDR);
        if (!new_p4d)
                goto no_p4d;

        new_pud = pud_alloc(mm, new_p4d, MODULES_VADDR);
        if (!new_pud)
                goto no_pud;

        new_pmd = pmd_alloc(mm, new_pud, 0);
        if (!new_pmd)
                goto no_pmd;
#ifdef CONFIG_KASAN
        /*
         * Copy PMD table for KASAN shadow mappings.
         */
        init_pgd = pgd_offset_k(TASK_SIZE);
        init_p4d = p4d_offset(init_pgd, TASK_SIZE);
        init_pud = pud_offset(init_p4d, TASK_SIZE);
        init_pmd = pmd_offset(init_pud, TASK_SIZE);
        new_pmd = pmd_offset(new_pud, TASK_SIZE);
        memcpy(new_pmd, init_pmd,
               (pmd_index(MODULES_VADDR) - pmd_index(TASK_SIZE))
               * sizeof(pmd_t));
        clean_dcache_area(new_pmd, PTRS_PER_PMD * sizeof(pmd_t));
#endif /* CONFIG_KASAN */
#endif /* CONFIG_LPAE */

        if (!vectors_high()) {
                /*
                 * On ARM, first page must always be allocated since it
                 * contains the machine vectors. The vectors are always high
                 * with LPAE.
                 */
                new_p4d = p4d_alloc(mm, new_pgd, 0);
                if (!new_p4d)
                        goto no_p4d;

                new_pud = pud_alloc(mm, new_p4d, 0);
                if (!new_pud)
                        goto no_pud;

                new_pmd = pmd_alloc(mm, new_pud, 0);
                if (!new_pmd)
                        goto no_pmd;

                new_pte = pte_alloc_map(mm, new_pmd, 0);
                if (!new_pte)
                        goto no_pte;

#ifndef CONFIG_ARM_LPAE
                /*
                 * Modify the PTE pointer to have the correct domain.  This
                 * needs to be the vectors domain to avoid the low vectors
                 * being unmapped.
                 */
                pmd_val(*new_pmd) &= ~PMD_DOMAIN_MASK;
                pmd_val(*new_pmd) |= PMD_DOMAIN(DOMAIN_VECTORS);
#endif

                init_p4d = p4d_offset(init_pgd, 0);
                init_pud = pud_offset(init_p4d, 0);
                init_pmd = pmd_offset(init_pud, 0);
                init_pte = pte_offset_map(init_pmd, 0);
                set_pte_ext(new_pte + 0, init_pte[0], 0);
                set_pte_ext(new_pte + 1, init_pte[1], 0);
                pte_unmap(init_pte);
                pte_unmap(new_pte);
        }

        return new_pgd;

no_pte:
        pmd_free(mm, new_pmd);
        mm_dec_nr_pmds(mm);
no_pmd:
        pud_free(mm, new_pud);
no_pud:
        p4d_free(mm, new_p4d);
no_p4d:
        __pgd_free(new_pgd);
no_pgd:
        return NULL;
}

void pgd_free(struct mm_struct *mm, pgd_t *pgd_base)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pgtable_t pte;

        if (!pgd_base)
                return;

        pgd = pgd_base + pgd_index(0);
        if (pgd_none_or_clear_bad(pgd))
                goto no_pgd;

        p4d = p4d_offset(pgd, 0);
        if (p4d_none_or_clear_bad(p4d))
                goto no_p4d;

        pud = pud_offset(p4d, 0);
        if (pud_none_or_clear_bad(pud))
                goto no_pud;

        pmd = pmd_offset(pud, 0);
        if (pmd_none_or_clear_bad(pmd))
                goto no_pmd;

        pte = pmd_pgtable(*pmd);
        pmd_clear(pmd);
        pte_free(mm, pte);
        mm_dec_nr_ptes(mm);
no_pmd:
        pud_clear(pud);
        pmd_free(mm, pmd);
        mm_dec_nr_pmds(mm);
no_pud:
        p4d_clear(p4d);
        pud_free(mm, pud);
no_p4d:
        pgd_clear(pgd);
        p4d_free(mm, p4d);
no_pgd:
#ifdef CONFIG_ARM_LPAE
        /*
         * Free modules/pkmap or identity pmd tables.
         */
        for (pgd = pgd_base; pgd < pgd_base + PTRS_PER_PGD; pgd++) {
                if (pgd_none_or_clear_bad(pgd))
                        continue;
                if (pgd_val(*pgd) & L_PGD_SWAPPER)
                        continue;
                p4d = p4d_offset(pgd, 0);
                if (p4d_none_or_clear_bad(p4d))
                        continue;
                pud = pud_offset(p4d, 0);
                if (pud_none_or_clear_bad(pud))
                        continue;
                pmd = pmd_offset(pud, 0);
                pud_clear(pud);
                pmd_free(mm, pmd);
                mm_dec_nr_pmds(mm);
                p4d_clear(p4d);
                pud_free(mm, pud);
                mm_dec_nr_puds(mm);
                pgd_clear(pgd);
                p4d_free(mm, p4d);
        }
#endif
        __pgd_free(pgd_base);
}