// SPDX-License-Identifier: GPL-2.0-only
/*
 * Based on arch/arm/mm/mmu.c
 *
 * Copyright (C) 1995-2005 Russell King
 * Copyright (C) 2012 ARM Ltd.
 */

#include <linux/cache.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/kexec.h>
#include <linux/libfdt.h>
#include <linux/mman.h>
#include <linux/nodemask.h>
#include <linux/memblock.h>
#include <linux/memremap.h>
#include <linux/memory.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/set_memory.h>
#include <linux/kfence.h>
#include <linux/pkeys.h>
#include <linux/mm_inline.h>
#include <linux/pagewalk.h>
#include <linux/stop_machine.h>

#include <asm/barrier.h>
#include <asm/cputype.h>
#include <asm/fixmap.h>
#include <asm/kasan.h>
#include <asm/kernel-pgtable.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <linux/sizes.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/ptdump.h>
#include <asm/tlbflush.h>
#include <asm/pgalloc.h>
#include <asm/kfence.h>

#define NO_BLOCK_MAPPINGS       BIT(0)
#define NO_CONT_MAPPINGS        BIT(1)
#define NO_EXEC_MAPPINGS        BIT(2)  /* assumes FEAT_HPDS is not used */

DEFINE_STATIC_KEY_FALSE(arm64_ptdump_lock_key);

u64 kimage_voffset __ro_after_init;
EXPORT_SYMBOL(kimage_voffset);

u32 __boot_cpu_mode[] = { BOOT_CPU_MODE_EL2, BOOT_CPU_MODE_EL1 };

static bool rodata_is_rw __ro_after_init = true;

/*
 * The booting CPU updates the failed status @__early_cpu_boot_status,
 * with MMU turned off.
 */
long __section(".mmuoff.data.write") __early_cpu_boot_status;

/*
 * Empty_zero_page is a special page that is used for zero-initialized data
 * and COW.
 */
unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
EXPORT_SYMBOL(empty_zero_page);

static DEFINE_SPINLOCK(swapper_pgdir_lock);
static DEFINE_MUTEX(fixmap_lock);

void noinstr set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
{
        pgd_t *fixmap_pgdp;

        /*
         * Don't bother with the fixmap if swapper_pg_dir is still mapped
         * writable in the kernel mapping.
         */
        if (rodata_is_rw) {
                WRITE_ONCE(*pgdp, pgd);
                dsb(ishst);
                isb();
                return;
        }

        spin_lock(&swapper_pgdir_lock);
        fixmap_pgdp = pgd_set_fixmap(__pa_symbol(pgdp));
        WRITE_ONCE(*fixmap_pgdp, pgd);
        /*
         * We need dsb(ishst) here to ensure the page-table-walker sees
         * our new entry before set_p?d() returns. The fixmap's
         * flush_tlb_kernel_range() via clear_fixmap() does this for us.
         */
        pgd_clear_fixmap();
        spin_unlock(&swapper_pgdir_lock);
}

pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
                              unsigned long size, pgprot_t vma_prot)
{
        if (!pfn_is_map_memory(pfn))
                return pgprot_noncached(vma_prot);
        else if (file->f_flags & O_SYNC)
                return pgprot_writecombine(vma_prot);
        return vma_prot;
}
EXPORT_SYMBOL(phys_mem_access_prot);

static phys_addr_t __init early_pgtable_alloc(enum pgtable_type pgtable_type)
{
        phys_addr_t phys;

        phys = memblock_phys_alloc_range(PAGE_SIZE, PAGE_SIZE, 0,
                                         MEMBLOCK_ALLOC_NOLEAKTRACE);
        if (!phys)
                panic("Failed to allocate page table page\n");

        return phys;
}

bool pgattr_change_is_safe(pteval_t old, pteval_t new)
{
        /*
         * The following mapping attributes may be updated in live
         * kernel mappings without the need for break-before-make.
         */
        pteval_t mask = PTE_PXN | PTE_RDONLY | PTE_WRITE | PTE_NG |
                        PTE_SWBITS_MASK;

        /* creating or taking down mappings is always safe */
        if (!pte_valid(__pte(old)) || !pte_valid(__pte(new)))
                return true;

        /* A live entry's pfn should not change */
        if (pte_pfn(__pte(old)) != pte_pfn(__pte(new)))
                return false;

        /* live contiguous mappings may not be manipulated at all */
        if ((old | new) & PTE_CONT)
                return false;

        /* Transitioning from Non-Global to Global is unsafe */
        if (old & ~new & PTE_NG)
                return false;

        /*
         * Changing the memory type between Normal and Normal-Tagged is safe
         * since Tagged is considered a permission attribute from the
         * mismatched attribute aliases perspective.
         */
        if (((old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) ||
             (old & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)) &&
            ((new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL) ||
             (new & PTE_ATTRINDX_MASK) == PTE_ATTRINDX(MT_NORMAL_TAGGED)))
                mask |= PTE_ATTRINDX_MASK;

        return ((old ^ new) & ~mask) == 0;
}

static void init_clear_pgtable(void *table)
{
        clear_page(table);

        /* Ensure the zeroing is observed by page table walks. */
        dsb(ishst);
}

static void init_pte(pte_t *ptep, unsigned long addr, unsigned long end,
                     phys_addr_t phys, pgprot_t prot)
{
        do {
                pte_t old_pte = __ptep_get(ptep);

                /*
                 * Required barriers to make this visible to the table walker
                 * are deferred to the end of alloc_init_cont_pte().
                 */
                __set_pte_nosync(ptep, pfn_pte(__phys_to_pfn(phys), prot));

                /*
                 * After the PTE entry has been populated once, we
                 * only allow updates to the permission attributes.
                 */
                BUG_ON(!pgattr_change_is_safe(pte_val(old_pte),
                                              pte_val(__ptep_get(ptep))));

                phys += PAGE_SIZE;
        } while (ptep++, addr += PAGE_SIZE, addr != end);
}

static int alloc_init_cont_pte(pmd_t *pmdp, unsigned long addr,
                               unsigned long end, phys_addr_t phys,
                               pgprot_t prot,
                               phys_addr_t (*pgtable_alloc)(enum pgtable_type),
                               int flags)
{
        unsigned long next;
        pmd_t pmd = READ_ONCE(*pmdp);
        pte_t *ptep;

        BUG_ON(pmd_sect(pmd));
        if (pmd_none(pmd)) {
                pmdval_t pmdval = PMD_TYPE_TABLE | PMD_TABLE_UXN | PMD_TABLE_AF;
                phys_addr_t pte_phys;

                if (flags & NO_EXEC_MAPPINGS)
                        pmdval |= PMD_TABLE_PXN;
                BUG_ON(!pgtable_alloc);
                pte_phys = pgtable_alloc(TABLE_PTE);
                if (pte_phys == INVALID_PHYS_ADDR)
                        return -ENOMEM;
                ptep = pte_set_fixmap(pte_phys);
                init_clear_pgtable(ptep);
                ptep += pte_index(addr);
                __pmd_populate(pmdp, pte_phys, pmdval);
        } else {
                BUG_ON(pmd_bad(pmd));
                ptep = pte_set_fixmap_offset(pmdp, addr);
        }

        do {
                pgprot_t __prot = prot;

                next = pte_cont_addr_end(addr, end);

                /* use a contiguous mapping if the range is suitably aligned */
                if ((((addr | next | phys) & ~CONT_PTE_MASK) == 0) &&
                    (flags & NO_CONT_MAPPINGS) == 0)
                        __prot = __pgprot(pgprot_val(prot) | PTE_CONT);

                init_pte(ptep, addr, next, phys, __prot);

                ptep += pte_index(next) - pte_index(addr);
                phys += next - addr;
        } while (addr = next, addr != end);

        /*
         * Note: barriers and maintenance necessary to clear the fixmap slot
         * ensure that all previous pgtable writes are visible to the table
         * walker.
         */
        pte_clear_fixmap();

        return 0;
}

static int init_pmd(pmd_t *pmdp, unsigned long addr, unsigned long end,
                    phys_addr_t phys, pgprot_t prot,
                    phys_addr_t (*pgtable_alloc)(enum pgtable_type), int flags)
{
        unsigned long next;

        do {
                pmd_t old_pmd = READ_ONCE(*pmdp);

                next = pmd_addr_end(addr, end);

                /* try section mapping first */
                if (((addr | next | phys) & ~PMD_MASK) == 0 &&
                    (flags & NO_BLOCK_MAPPINGS) == 0) {
                        pmd_set_huge(pmdp, phys, prot);

                        /*
                         * After the PMD entry has been populated once, we
                         * only allow updates to the permission attributes.
                         */
                        BUG_ON(!pgattr_change_is_safe(pmd_val(old_pmd),
                                                      READ_ONCE(pmd_val(*pmdp))));
                } else {
                        int ret;

                        ret = alloc_init_cont_pte(pmdp, addr, next, phys, prot,
                                                  pgtable_alloc, flags);
                        if (ret)
                                return ret;

                        BUG_ON(pmd_val(old_pmd) != 0 &&
                               pmd_val(old_pmd) != READ_ONCE(pmd_val(*pmdp)));
                }
                phys += next - addr;
        } while (pmdp++, addr = next, addr != end);

        return 0;
}

static int alloc_init_cont_pmd(pud_t *pudp, unsigned long addr,
                               unsigned long end, phys_addr_t phys,
                               pgprot_t prot,
                               phys_addr_t (*pgtable_alloc)(enum pgtable_type),
                               int flags)
{
        int ret;
        unsigned long next;
        pud_t pud = READ_ONCE(*pudp);
        pmd_t *pmdp;

        /*
         * Check for initial section mappings in the pgd/pud.
         */
        BUG_ON(pud_sect(pud));
        if (pud_none(pud)) {
                pudval_t pudval = PUD_TYPE_TABLE | PUD_TABLE_UXN | PUD_TABLE_AF;
                phys_addr_t pmd_phys;

                if (flags & NO_EXEC_MAPPINGS)
                        pudval |= PUD_TABLE_PXN;
                BUG_ON(!pgtable_alloc);
                pmd_phys = pgtable_alloc(TABLE_PMD);
                if (pmd_phys == INVALID_PHYS_ADDR)
                        return -ENOMEM;
                pmdp = pmd_set_fixmap(pmd_phys);
                init_clear_pgtable(pmdp);
                pmdp += pmd_index(addr);
                __pud_populate(pudp, pmd_phys, pudval);
        } else {
                BUG_ON(pud_bad(pud));
                pmdp = pmd_set_fixmap_offset(pudp, addr);
        }

        do {
                pgprot_t __prot = prot;

                next = pmd_cont_addr_end(addr, end);

                /* use a contiguous mapping if the range is suitably aligned */
                if ((((addr | next | phys) & ~CONT_PMD_MASK) == 0) &&
                    (flags & NO_CONT_MAPPINGS) == 0)
                        __prot = __pgprot(pgprot_val(prot) | PTE_CONT);

                ret = init_pmd(pmdp, addr, next, phys, __prot, pgtable_alloc, flags);
                if (ret)
                        goto out;

                pmdp += pmd_index(next) - pmd_index(addr);
                phys += next - addr;
        } while (addr = next, addr != end);

out:
        pmd_clear_fixmap();

        return ret;
}

static int alloc_init_pud(p4d_t *p4dp, unsigned long addr, unsigned long end,
                          phys_addr_t phys, pgprot_t prot,
                          phys_addr_t (*pgtable_alloc)(enum pgtable_type),
                          int flags)
{
        int ret = 0;
        unsigned long next;
        p4d_t p4d = READ_ONCE(*p4dp);
        pud_t *pudp;

        if (p4d_none(p4d)) {
                p4dval_t p4dval = P4D_TYPE_TABLE | P4D_TABLE_UXN | P4D_TABLE_AF;
                phys_addr_t pud_phys;

                if (flags & NO_EXEC_MAPPINGS)
                        p4dval |= P4D_TABLE_PXN;
                BUG_ON(!pgtable_alloc);
                pud_phys = pgtable_alloc(TABLE_PUD);
                if (pud_phys == INVALID_PHYS_ADDR)
                        return -ENOMEM;
                pudp = pud_set_fixmap(pud_phys);
                init_clear_pgtable(pudp);
                pudp += pud_index(addr);
                __p4d_populate(p4dp, pud_phys, p4dval);
        } else {
                BUG_ON(p4d_bad(p4d));
                pudp = pud_set_fixmap_offset(p4dp, addr);
        }

        do {
                pud_t old_pud = READ_ONCE(*pudp);

                next = pud_addr_end(addr, end);

                /*
                 * For 4K granule only, attempt to put down a 1GB block
                 */
                if (pud_sect_supported() &&
                   ((addr | next | phys) & ~PUD_MASK) == 0 &&
                    (flags & NO_BLOCK_MAPPINGS) == 0) {
                        pud_set_huge(pudp, phys, prot);

                        /*
                         * After the PUD entry has been populated once, we
                         * only allow updates to the permission attributes.
                         */
                        BUG_ON(!pgattr_change_is_safe(pud_val(old_pud),
                                                      READ_ONCE(pud_val(*pudp))));
                } else {
                        ret = alloc_init_cont_pmd(pudp, addr, next, phys, prot,
                                                  pgtable_alloc, flags);
                        if (ret)
                                goto out;

                        BUG_ON(pud_val(old_pud) != 0 &&
                               pud_val(old_pud) != READ_ONCE(pud_val(*pudp)));
                }
                phys += next - addr;
        } while (pudp++, addr = next, addr != end);

out:
        pud_clear_fixmap();

        return ret;
}

static int alloc_init_p4d(pgd_t *pgdp, unsigned long addr, unsigned long end,
                          phys_addr_t phys, pgprot_t prot,
                          phys_addr_t (*pgtable_alloc)(enum pgtable_type),
                          int flags)
{
        int ret;
        unsigned long next;
        pgd_t pgd = READ_ONCE(*pgdp);
        p4d_t *p4dp;

        if (pgd_none(pgd)) {
                pgdval_t pgdval = PGD_TYPE_TABLE | PGD_TABLE_UXN | PGD_TABLE_AF;
                phys_addr_t p4d_phys;

                if (flags & NO_EXEC_MAPPINGS)
                        pgdval |= PGD_TABLE_PXN;
                BUG_ON(!pgtable_alloc);
                p4d_phys = pgtable_alloc(TABLE_P4D);
                if (p4d_phys == INVALID_PHYS_ADDR)
                        return -ENOMEM;
                p4dp = p4d_set_fixmap(p4d_phys);
                init_clear_pgtable(p4dp);
                p4dp += p4d_index(addr);
                __pgd_populate(pgdp, p4d_phys, pgdval);
        } else {
                BUG_ON(pgd_bad(pgd));
                p4dp = p4d_set_fixmap_offset(pgdp, addr);
        }

        do {
                p4d_t old_p4d = READ_ONCE(*p4dp);

                next = p4d_addr_end(addr, end);

                ret = alloc_init_pud(p4dp, addr, next, phys, prot,
                                     pgtable_alloc, flags);
                if (ret)
                        goto out;

                BUG_ON(p4d_val(old_p4d) != 0 &&
                       p4d_val(old_p4d) != READ_ONCE(p4d_val(*p4dp)));

                phys += next - addr;
        } while (p4dp++, addr = next, addr != end);

out:
        p4d_clear_fixmap();

        return ret;
}

static int __create_pgd_mapping_locked(pgd_t *pgdir, phys_addr_t phys,
                                       unsigned long virt, phys_addr_t size,
                                       pgprot_t prot,
                                       phys_addr_t (*pgtable_alloc)(enum pgtable_type),
                                       int flags)
{
        int ret;
        unsigned long addr, end, next;
        pgd_t *pgdp = pgd_offset_pgd(pgdir, virt);

        /*
         * If the virtual and physical address don't have the same offset
         * within a page, we cannot map the region as the caller expects.
         */
        if (WARN_ON((phys ^ virt) & ~PAGE_MASK))
                return -EINVAL;

        phys &= PAGE_MASK;
        addr = virt & PAGE_MASK;
        end = PAGE_ALIGN(virt + size);

        do {
                next = pgd_addr_end(addr, end);
                ret = alloc_init_p4d(pgdp, addr, next, phys, prot, pgtable_alloc,
                                     flags);
                if (ret)
                        return ret;
                phys += next - addr;
        } while (pgdp++, addr = next, addr != end);

        return 0;
}

static int __create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
                                unsigned long virt, phys_addr_t size,
                                pgprot_t prot,
                                phys_addr_t (*pgtable_alloc)(enum pgtable_type),
                                int flags)
{
        int ret;

        mutex_lock(&fixmap_lock);
        ret = __create_pgd_mapping_locked(pgdir, phys, virt, size, prot,
                                          pgtable_alloc, flags);
        mutex_unlock(&fixmap_lock);

        return ret;
}

static void early_create_pgd_mapping(pgd_t *pgdir, phys_addr_t phys,
                                     unsigned long virt, phys_addr_t size,
                                     pgprot_t prot,
                                     phys_addr_t (*pgtable_alloc)(enum pgtable_type),
                                     int flags)
{
        int ret;

        ret = __create_pgd_mapping(pgdir, phys, virt, size, prot, pgtable_alloc,
                                   flags);
        if (ret)
                panic("Failed to create page tables\n");
}

static phys_addr_t __pgd_pgtable_alloc(struct mm_struct *mm, gfp_t gfp,
                                       enum pgtable_type pgtable_type)
{
        /* Page is zeroed by init_clear_pgtable() so don't duplicate effort. */
        struct ptdesc *ptdesc = pagetable_alloc(gfp & ~__GFP_ZERO, 0);
        phys_addr_t pa;

        if (!ptdesc)
                return INVALID_PHYS_ADDR;

        pa = page_to_phys(ptdesc_page(ptdesc));

        switch (pgtable_type) {
        case TABLE_PTE:
                BUG_ON(!pagetable_pte_ctor(mm, ptdesc));
                break;
        case TABLE_PMD:
                BUG_ON(!pagetable_pmd_ctor(mm, ptdesc));
                break;
        case TABLE_PUD:
                pagetable_pud_ctor(ptdesc);
                break;
        case TABLE_P4D:
                pagetable_p4d_ctor(ptdesc);
                break;
        }

        return pa;
}

static phys_addr_t
pgd_pgtable_alloc_init_mm_gfp(enum pgtable_type pgtable_type, gfp_t gfp)
{
        return __pgd_pgtable_alloc(&init_mm, gfp, pgtable_type);
}

static phys_addr_t __maybe_unused
pgd_pgtable_alloc_init_mm(enum pgtable_type pgtable_type)
{
        return pgd_pgtable_alloc_init_mm_gfp(pgtable_type, GFP_PGTABLE_KERNEL);
}

static phys_addr_t
pgd_pgtable_alloc_special_mm(enum pgtable_type pgtable_type)
{
        return  __pgd_pgtable_alloc(NULL, GFP_PGTABLE_KERNEL, pgtable_type);
}

static void split_contpte(pte_t *ptep)
{
        int i;

        ptep = PTR_ALIGN_DOWN(ptep, sizeof(*ptep) * CONT_PTES);
        for (i = 0; i < CONT_PTES; i++, ptep++)
                __set_pte(ptep, pte_mknoncont(__ptep_get(ptep)));
}

static int split_pmd(pmd_t *pmdp, pmd_t pmd, gfp_t gfp, bool to_cont)
{
        pmdval_t tableprot = PMD_TYPE_TABLE | PMD_TABLE_UXN | PMD_TABLE_AF;
        unsigned long pfn = pmd_pfn(pmd);
        pgprot_t prot = pmd_pgprot(pmd);
        phys_addr_t pte_phys;
        pte_t *ptep;
        int i;

        pte_phys = pgd_pgtable_alloc_init_mm_gfp(TABLE_PTE, gfp);
        if (pte_phys == INVALID_PHYS_ADDR)
                return -ENOMEM;
        ptep = (pte_t *)phys_to_virt(pte_phys);

        if (pgprot_val(prot) & PMD_SECT_PXN)
                tableprot |= PMD_TABLE_PXN;

        prot = __pgprot((pgprot_val(prot) & ~PTE_TYPE_MASK) | PTE_TYPE_PAGE);
        prot = __pgprot(pgprot_val(prot) & ~PTE_CONT);
        if (to_cont)
                prot = __pgprot(pgprot_val(prot) | PTE_CONT);

        for (i = 0; i < PTRS_PER_PTE; i++, ptep++, pfn++)
                __set_pte(ptep, pfn_pte(pfn, prot));

        /*
         * Ensure the pte entries are visible to the table walker by the time
         * the pmd entry that points to the ptes is visible.
         */
        dsb(ishst);
        __pmd_populate(pmdp, pte_phys, tableprot);

        return 0;
}

static void split_contpmd(pmd_t *pmdp)
{
        int i;

        pmdp = PTR_ALIGN_DOWN(pmdp, sizeof(*pmdp) * CONT_PMDS);
        for (i = 0; i < CONT_PMDS; i++, pmdp++)
                set_pmd(pmdp, pmd_mknoncont(pmdp_get(pmdp)));
}

static int split_pud(pud_t *pudp, pud_t pud, gfp_t gfp, bool to_cont)
{
        pudval_t tableprot = PUD_TYPE_TABLE | PUD_TABLE_UXN | PUD_TABLE_AF;
        unsigned int step = PMD_SIZE >> PAGE_SHIFT;
        unsigned long pfn = pud_pfn(pud);
        pgprot_t prot = pud_pgprot(pud);
        phys_addr_t pmd_phys;
        pmd_t *pmdp;
        int i;

        pmd_phys = pgd_pgtable_alloc_init_mm_gfp(TABLE_PMD, gfp);
        if (pmd_phys == INVALID_PHYS_ADDR)
                return -ENOMEM;
        pmdp = (pmd_t *)phys_to_virt(pmd_phys);

        if (pgprot_val(prot) & PMD_SECT_PXN)
                tableprot |= PUD_TABLE_PXN;

        prot = __pgprot((pgprot_val(prot) & ~PMD_TYPE_MASK) | PMD_TYPE_SECT);
        prot = __pgprot(pgprot_val(prot) & ~PTE_CONT);
        if (to_cont)
                prot = __pgprot(pgprot_val(prot) | PTE_CONT);

        for (i = 0; i < PTRS_PER_PMD; i++, pmdp++, pfn += step)
                set_pmd(pmdp, pfn_pmd(pfn, prot));

        /*
         * Ensure the pmd entries are visible to the table walker by the time
         * the pud entry that points to the pmds is visible.
         */
        dsb(ishst);
        __pud_populate(pudp, pmd_phys, tableprot);

        return 0;
}

static int split_kernel_leaf_mapping_locked(unsigned long addr)
{
        pgd_t *pgdp, pgd;
        p4d_t *p4dp, p4d;
        pud_t *pudp, pud;
        pmd_t *pmdp, pmd;
        pte_t *ptep, pte;
        int ret = 0;

        /*
         * PGD: If addr is PGD aligned then addr already describes a leaf
         * boundary. If not present then there is nothing to split.
         */
        if (ALIGN_DOWN(addr, PGDIR_SIZE) == addr)
                goto out;
        pgdp = pgd_offset_k(addr);
        pgd = pgdp_get(pgdp);
        if (!pgd_present(pgd))
                goto out;

        /*
         * P4D: If addr is P4D aligned then addr already describes a leaf
         * boundary. If not present then there is nothing to split.
         */
        if (ALIGN_DOWN(addr, P4D_SIZE) == addr)
                goto out;
        p4dp = p4d_offset(pgdp, addr);
        p4d = p4dp_get(p4dp);
        if (!p4d_present(p4d))
                goto out;

        /*
         * PUD: If addr is PUD aligned then addr already describes a leaf
         * boundary. If not present then there is nothing to split. Otherwise,
         * if we have a pud leaf, split to contpmd.
         */
        if (ALIGN_DOWN(addr, PUD_SIZE) == addr)
                goto out;
        pudp = pud_offset(p4dp, addr);
        pud = pudp_get(pudp);
        if (!pud_present(pud))
                goto out;
        if (pud_leaf(pud)) {
                ret = split_pud(pudp, pud, GFP_PGTABLE_KERNEL, true);
                if (ret)
                        goto out;
        }

        /*
         * CONTPMD: If addr is CONTPMD aligned then addr already describes a
         * leaf boundary. If not present then there is nothing to split.
         * Otherwise, if we have a contpmd leaf, split to pmd.
         */
        if (ALIGN_DOWN(addr, CONT_PMD_SIZE) == addr)
                goto out;
        pmdp = pmd_offset(pudp, addr);
        pmd = pmdp_get(pmdp);
        if (!pmd_present(pmd))
                goto out;
        if (pmd_leaf(pmd)) {
                if (pmd_cont(pmd))
                        split_contpmd(pmdp);
                /*
                 * PMD: If addr is PMD aligned then addr already describes a
                 * leaf boundary. Otherwise, split to contpte.
                 */
                if (ALIGN_DOWN(addr, PMD_SIZE) == addr)
                        goto out;
                ret = split_pmd(pmdp, pmd, GFP_PGTABLE_KERNEL, true);
                if (ret)
                        goto out;
        }

        /*
         * CONTPTE: If addr is CONTPTE aligned then addr already describes a
         * leaf boundary. If not present then there is nothing to split.
         * Otherwise, if we have a contpte leaf, split to pte.
         */
        if (ALIGN_DOWN(addr, CONT_PTE_SIZE) == addr)
                goto out;
        ptep = pte_offset_kernel(pmdp, addr);
        pte = __ptep_get(ptep);
        if (!pte_present(pte))
                goto out;
        if (pte_cont(pte))
                split_contpte(ptep);

out:
        return ret;
}

static inline bool force_pte_mapping(void)
{
        const bool bbml2 = system_capabilities_finalized() ?
                system_supports_bbml2_noabort() : cpu_supports_bbml2_noabort();

        if (debug_pagealloc_enabled())
                return true;
        if (bbml2)
                return false;
        return rodata_full || arm64_kfence_can_set_direct_map() || is_realm_world();
}

static DEFINE_MUTEX(pgtable_split_lock);

int split_kernel_leaf_mapping(unsigned long start, unsigned long end)
{
        int ret;

        /*
         * !BBML2_NOABORT systems should not be trying to change permissions on
         * anything that is not pte-mapped in the first place. Just return early
         * and let the permission change code raise a warning if not already
         * pte-mapped.
         */
        if (!system_supports_bbml2_noabort())
                return 0;

        /*
         * If the region is within a pte-mapped area, there is no need to try to
         * split. Additionally, CONFIG_DEBUG_PAGEALLOC and CONFIG_KFENCE may
         * change permissions from atomic context so for those cases (which are
         * always pte-mapped), we must not go any further because taking the
         * mutex below may sleep.
         */
        if (force_pte_mapping() || is_kfence_address((void *)start))
                return 0;

        /*
         * Ensure start and end are at least page-aligned since this is the
         * finest granularity we can split to.
         */
        if (start != PAGE_ALIGN(start) || end != PAGE_ALIGN(end))
                return -EINVAL;

        mutex_lock(&pgtable_split_lock);
        lazy_mmu_mode_enable();

        /*
         * The split_kernel_leaf_mapping_locked() may sleep, it is not a
         * problem for ARM64 since ARM64's lazy MMU implementation allows
         * sleeping.
         *
         * Optimize for the common case of splitting out a single page from a
         * larger mapping. Here we can just split on the "least aligned" of
         * start and end and this will guarantee that there must also be a split
         * on the more aligned address since the both addresses must be in the
         * same contpte block and it must have been split to ptes.
         */
        if (end - start == PAGE_SIZE) {
                start = __ffs(start) < __ffs(end) ? start : end;
                ret = split_kernel_leaf_mapping_locked(start);
        } else {
                ret = split_kernel_leaf_mapping_locked(start);
                if (!ret)
                        ret = split_kernel_leaf_mapping_locked(end);
        }

        lazy_mmu_mode_disable();
        mutex_unlock(&pgtable_split_lock);
        return ret;
}

static int split_to_ptes_pud_entry(pud_t *pudp, unsigned long addr,
                                   unsigned long next, struct mm_walk *walk)
{
        gfp_t gfp = *(gfp_t *)walk->private;
        pud_t pud = pudp_get(pudp);
        int ret = 0;

        if (pud_leaf(pud))
                ret = split_pud(pudp, pud, gfp, false);

        return ret;
}

static int split_to_ptes_pmd_entry(pmd_t *pmdp, unsigned long addr,
                                   unsigned long next, struct mm_walk *walk)
{
        gfp_t gfp = *(gfp_t *)walk->private;
        pmd_t pmd = pmdp_get(pmdp);
        int ret = 0;

        if (pmd_leaf(pmd)) {
                if (pmd_cont(pmd))
                        split_contpmd(pmdp);
                ret = split_pmd(pmdp, pmd, gfp, false);

                /*
                 * We have split the pmd directly to ptes so there is no need to
                 * visit each pte to check if they are contpte.
                 */
                walk->action = ACTION_CONTINUE;
        }

        return ret;
}

static int split_to_ptes_pte_entry(pte_t *ptep, unsigned long addr,
                                   unsigned long next, struct mm_walk *walk)
{
        pte_t pte = __ptep_get(ptep);

        if (pte_cont(pte))
                split_contpte(ptep);

        return 0;
}

static const struct mm_walk_ops split_to_ptes_ops = {
        .pud_entry      = split_to_ptes_pud_entry,
        .pmd_entry      = split_to_ptes_pmd_entry,
        .pte_entry      = split_to_ptes_pte_entry,
};

static int range_split_to_ptes(unsigned long start, unsigned long end, gfp_t gfp)
{
        int ret;

        lazy_mmu_mode_enable();
        ret = walk_kernel_page_table_range_lockless(start, end,
                                        &split_to_ptes_ops, NULL, &gfp);
        lazy_mmu_mode_disable();

        return ret;
}

static bool linear_map_requires_bbml2 __initdata;

u32 idmap_kpti_bbml2_flag;

static void __init init_idmap_kpti_bbml2_flag(void)
{
        WRITE_ONCE(idmap_kpti_bbml2_flag, 1);
        /* Must be visible to other CPUs before stop_machine() is called. */
        smp_mb();
}

static int __init linear_map_split_to_ptes(void *__unused)
{
        /*
         * Repainting the linear map must be done by CPU0 (the boot CPU) because
         * that's the only CPU that we know supports BBML2. The other CPUs will
         * be held in a waiting area with the idmap active.
         */
        if (!smp_processor_id()) {
                unsigned long lstart = _PAGE_OFFSET(vabits_actual);
                unsigned long lend = PAGE_END;
                unsigned long kstart = (unsigned long)lm_alias(_stext);
                unsigned long kend = (unsigned long)lm_alias(__init_begin);
                int ret;

                /*
                 * Wait for all secondary CPUs to be put into the waiting area.
                 */
                smp_cond_load_acquire(&idmap_kpti_bbml2_flag, VAL == num_online_cpus());

                /*
                 * Walk all of the linear map [lstart, lend), except the kernel
                 * linear map alias [kstart, kend), and split all mappings to
                 * PTE. The kernel alias remains static throughout runtime so
                 * can continue to be safely mapped with large mappings.
                 */
                ret = range_split_to_ptes(lstart, kstart, GFP_ATOMIC);
                if (!ret)
                        ret = range_split_to_ptes(kend, lend, GFP_ATOMIC);
                if (ret)
                        panic("Failed to split linear map\n");
                flush_tlb_kernel_range(lstart, lend);

                /*
                 * Relies on dsb in flush_tlb_kernel_range() to avoid reordering
                 * before any page table split operations.
                 */
                WRITE_ONCE(idmap_kpti_bbml2_flag, 0);
        } else {
                typedef void (wait_split_fn)(void);
                extern wait_split_fn wait_linear_map_split_to_ptes;
                wait_split_fn *wait_fn;

                wait_fn = (void *)__pa_symbol(wait_linear_map_split_to_ptes);

                /*
                 * At least one secondary CPU doesn't support BBML2 so cannot
                 * tolerate the size of the live mappings changing. So have the
                 * secondary CPUs wait for the boot CPU to make the changes
                 * with the idmap active and init_mm inactive.
                 */
                cpu_install_idmap();
                wait_fn();
                cpu_uninstall_idmap();
        }

        return 0;
}

void __init linear_map_maybe_split_to_ptes(void)
{
        if (linear_map_requires_bbml2 && !system_supports_bbml2_noabort()) {
                init_idmap_kpti_bbml2_flag();
                stop_machine(linear_map_split_to_ptes, NULL, cpu_online_mask);
        }
}

/*
 * This function can only be used to modify existing table entries,
 * without allocating new levels of table. Note that this permits the
 * creation of new section or page entries.
 */
void __init create_mapping_noalloc(phys_addr_t phys, unsigned long virt,
                                   phys_addr_t size, pgprot_t prot)
{
        if (virt < PAGE_OFFSET) {
                pr_warn("BUG: not creating mapping for %pa at 0x%016lx - outside kernel range\n",
                        &phys, virt);
                return;
        }
        early_create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL,
                                 NO_CONT_MAPPINGS);
}

void __init create_pgd_mapping(struct mm_struct *mm, phys_addr_t phys,
                               unsigned long virt, phys_addr_t size,
                               pgprot_t prot, bool page_mappings_only)
{
        int flags = 0;

        BUG_ON(mm == &init_mm);

        if (page_mappings_only)
                flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;

        early_create_pgd_mapping(mm->pgd, phys, virt, size, prot,
                                 pgd_pgtable_alloc_special_mm, flags);
}

static void update_mapping_prot(phys_addr_t phys, unsigned long virt,
                                phys_addr_t size, pgprot_t prot)
{
        if (virt < PAGE_OFFSET) {
                pr_warn("BUG: not updating mapping for %pa at 0x%016lx - outside kernel range\n",
                        &phys, virt);
                return;
        }

        early_create_pgd_mapping(init_mm.pgd, phys, virt, size, prot, NULL,
                                 NO_CONT_MAPPINGS);

        /* flush the TLBs after updating live kernel mappings */
        flush_tlb_kernel_range(virt, virt + size);
}

static void __init __map_memblock(pgd_t *pgdp, phys_addr_t start,
                                  phys_addr_t end, pgprot_t prot, int flags)
{
        early_create_pgd_mapping(pgdp, start, __phys_to_virt(start), end - start,
                                 prot, early_pgtable_alloc, flags);
}

void __init mark_linear_text_alias_ro(void)
{
        /*
         * Remove the write permissions from the linear alias of .text/.rodata
         */
        update_mapping_prot(__pa_symbol(_text), (unsigned long)lm_alias(_text),
                            (unsigned long)__init_begin - (unsigned long)_text,
                            PAGE_KERNEL_RO);
}

#ifdef CONFIG_KFENCE

bool __ro_after_init kfence_early_init = !!CONFIG_KFENCE_SAMPLE_INTERVAL;

/* early_param() will be parsed before map_mem() below. */
static int __init parse_kfence_early_init(char *arg)
{
        int val;

        if (get_option(&arg, &val))
                kfence_early_init = !!val;
        return 0;
}
early_param("kfence.sample_interval", parse_kfence_early_init);

static phys_addr_t __init arm64_kfence_alloc_pool(void)
{
        phys_addr_t kfence_pool;

        if (!kfence_early_init)
                return 0;

        kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE);
        if (!kfence_pool) {
                pr_err("failed to allocate kfence pool\n");
                kfence_early_init = false;
                return 0;
        }

        /* Temporarily mark as NOMAP. */
        memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE);

        return kfence_pool;
}

static void __init arm64_kfence_map_pool(phys_addr_t kfence_pool, pgd_t *pgdp)
{
        if (!kfence_pool)
                return;

        /* KFENCE pool needs page-level mapping. */
        __map_memblock(pgdp, kfence_pool, kfence_pool + KFENCE_POOL_SIZE,
                        pgprot_tagged(PAGE_KERNEL),
                        NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS);
        memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE);
        __kfence_pool = phys_to_virt(kfence_pool);
}

bool arch_kfence_init_pool(void)
{
        unsigned long start = (unsigned long)__kfence_pool;
        unsigned long end = start + KFENCE_POOL_SIZE;
        int ret;

        /* Exit early if we know the linear map is already pte-mapped. */
        if (force_pte_mapping())
                return true;

        /* Kfence pool is already pte-mapped for the early init case. */
        if (kfence_early_init)
                return true;

        mutex_lock(&pgtable_split_lock);
        ret = range_split_to_ptes(start, end, GFP_PGTABLE_KERNEL);
        mutex_unlock(&pgtable_split_lock);

        /*
         * Since the system supports bbml2_noabort, tlb invalidation is not
         * required here; the pgtable mappings have been split to pte but larger
         * entries may safely linger in the TLB.
         */

        return !ret;
}
#else /* CONFIG_KFENCE */

static inline phys_addr_t arm64_kfence_alloc_pool(void) { return 0; }
static inline void arm64_kfence_map_pool(phys_addr_t kfence_pool, pgd_t *pgdp) { }

#endif /* CONFIG_KFENCE */

static void __init map_mem(pgd_t *pgdp)
{
        static const u64 direct_map_end = _PAGE_END(VA_BITS_MIN);
        phys_addr_t kernel_start = __pa_symbol(_text);
        phys_addr_t kernel_end = __pa_symbol(__init_begin);
        phys_addr_t start, end;
        phys_addr_t early_kfence_pool;
        int flags = NO_EXEC_MAPPINGS;
        u64 i;

        /*
         * Setting hierarchical PXNTable attributes on table entries covering
         * the linear region is only possible if it is guaranteed that no table
         * entries at any level are being shared between the linear region and
         * the vmalloc region. Check whether this is true for the PGD level, in
         * which case it is guaranteed to be true for all other levels as well.
         * (Unless we are running with support for LPA2, in which case the
         * entire reduced VA space is covered by a single pgd_t which will have
         * been populated without the PXNTable attribute by the time we get here.)
         */
        BUILD_BUG_ON(pgd_index(direct_map_end - 1) == pgd_index(direct_map_end) &&
                     pgd_index(_PAGE_OFFSET(VA_BITS_MIN)) != PTRS_PER_PGD - 1);

        early_kfence_pool = arm64_kfence_alloc_pool();

        linear_map_requires_bbml2 = !force_pte_mapping() && can_set_direct_map();

        if (force_pte_mapping())
                flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;

        /*
         * Take care not to create a writable alias for the
         * read-only text and rodata sections of the kernel image.
         * So temporarily mark them as NOMAP to skip mappings in
         * the following for-loop
         */
        memblock_mark_nomap(kernel_start, kernel_end - kernel_start);

        /* map all the memory banks */
        for_each_mem_range(i, &start, &end) {
                if (start >= end)
                        break;
                /*
                 * The linear map must allow allocation tags reading/writing
                 * if MTE is present. Otherwise, it has the same attributes as
                 * PAGE_KERNEL.
                 */
                __map_memblock(pgdp, start, end, pgprot_tagged(PAGE_KERNEL),
                               flags);
        }

        /*
         * Map the linear alias of the [_text, __init_begin) interval
         * as non-executable now, and remove the write permission in
         * mark_linear_text_alias_ro() below (which will be called after
         * alternative patching has completed). This makes the contents
         * of the region accessible to subsystems such as hibernate,
         * but protects it from inadvertent modification or execution.
         * Note that contiguous mappings cannot be remapped in this way,
         * so we should avoid them here.
         */
        __map_memblock(pgdp, kernel_start, kernel_end,
                       PAGE_KERNEL, NO_CONT_MAPPINGS);
        memblock_clear_nomap(kernel_start, kernel_end - kernel_start);
        arm64_kfence_map_pool(early_kfence_pool, pgdp);
}

void mark_rodata_ro(void)
{
        unsigned long section_size;

        /*
         * mark .rodata as read only. Use __init_begin rather than __end_rodata
         * to cover NOTES and EXCEPTION_TABLE.
         */
        section_size = (unsigned long)__init_begin - (unsigned long)__start_rodata;
        WRITE_ONCE(rodata_is_rw, false);
        update_mapping_prot(__pa_symbol(__start_rodata), (unsigned long)__start_rodata,
                            section_size, PAGE_KERNEL_RO);
        /* mark the range between _text and _stext as read only. */
        update_mapping_prot(__pa_symbol(_text), (unsigned long)_text,
                            (unsigned long)_stext - (unsigned long)_text,
                            PAGE_KERNEL_RO);
}

static void __init declare_vma(struct vm_struct *vma,
                               void *va_start, void *va_end,
                               unsigned long vm_flags)
{
        phys_addr_t pa_start = __pa_symbol(va_start);
        unsigned long size = va_end - va_start;

        BUG_ON(!PAGE_ALIGNED(pa_start));
        BUG_ON(!PAGE_ALIGNED(size));

        if (!(vm_flags & VM_NO_GUARD))
                size += PAGE_SIZE;

        vma->addr       = va_start;
        vma->phys_addr  = pa_start;
        vma->size       = size;
        vma->flags      = VM_MAP | vm_flags;
        vma->caller     = __builtin_return_address(0);

        vm_area_add_early(vma);
}

#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
#define KPTI_NG_TEMP_VA         (-(1UL << PMD_SHIFT))

static phys_addr_t kpti_ng_temp_alloc __initdata;

static phys_addr_t __init kpti_ng_pgd_alloc(enum pgtable_type type)
{
        kpti_ng_temp_alloc -= PAGE_SIZE;
        return kpti_ng_temp_alloc;
}

static int __init __kpti_install_ng_mappings(void *__unused)
{
        typedef void (kpti_remap_fn)(int, int, phys_addr_t, unsigned long);
        extern kpti_remap_fn idmap_kpti_install_ng_mappings;
        kpti_remap_fn *remap_fn;

        int cpu = smp_processor_id();
        int levels = CONFIG_PGTABLE_LEVELS;
        int order = order_base_2(levels);
        u64 kpti_ng_temp_pgd_pa = 0;
        pgd_t *kpti_ng_temp_pgd;
        u64 alloc = 0;

        if (levels == 5 && !pgtable_l5_enabled())
                levels = 4;
        else if (levels == 4 && !pgtable_l4_enabled())
                levels = 3;

        remap_fn = (void *)__pa_symbol(idmap_kpti_install_ng_mappings);

        if (!cpu) {
                int ret;

                alloc = __get_free_pages(GFP_ATOMIC | __GFP_ZERO, order);
                kpti_ng_temp_pgd = (pgd_t *)(alloc + (levels - 1) * PAGE_SIZE);
                kpti_ng_temp_alloc = kpti_ng_temp_pgd_pa = __pa(kpti_ng_temp_pgd);

                //
                // Create a minimal page table hierarchy that permits us to map
                // the swapper page tables temporarily as we traverse them.
                //
                // The physical pages are laid out as follows:
                //
                // +--------+-/-------+-/------ +-/------ +-\\\--------+
                // :  PTE[] : | PMD[] : | PUD[] : | P4D[] : ||| PGD[]  :
                // +--------+-\-------+-\------ +-\------ +-///--------+
                //      ^
                // The first page is mapped into this hierarchy at a PMD_SHIFT
                // aligned virtual address, so that we can manipulate the PTE
                // level entries while the mapping is active. The first entry
                // covers the PTE[] page itself, the remaining entries are free
                // to be used as a ad-hoc fixmap.
                //
                ret = __create_pgd_mapping_locked(kpti_ng_temp_pgd, __pa(alloc),
                                                  KPTI_NG_TEMP_VA, PAGE_SIZE, PAGE_KERNEL,
                                                  kpti_ng_pgd_alloc, 0);
                if (ret)
                        panic("Failed to create page tables\n");
        }

        cpu_install_idmap();
        remap_fn(cpu, num_online_cpus(), kpti_ng_temp_pgd_pa, KPTI_NG_TEMP_VA);
        cpu_uninstall_idmap();

        if (!cpu) {
                free_pages(alloc, order);
                arm64_use_ng_mappings = true;
        }

        return 0;
}

void __init kpti_install_ng_mappings(void)
{
        /* Check whether KPTI is going to be used */
        if (!arm64_kernel_unmapped_at_el0())
                return;

        /*
         * We don't need to rewrite the page-tables if either we've done
         * it already or we have KASLR enabled and therefore have not
         * created any global mappings at all.
         */
        if (arm64_use_ng_mappings)
                return;

        init_idmap_kpti_bbml2_flag();
        stop_machine(__kpti_install_ng_mappings, NULL, cpu_online_mask);
}

static pgprot_t __init kernel_exec_prot(void)
{
        return rodata_enabled ? PAGE_KERNEL_ROX : PAGE_KERNEL_EXEC;
}

static int __init map_entry_trampoline(void)
{
        int i;

        if (!arm64_kernel_unmapped_at_el0())
                return 0;

        pgprot_t prot = kernel_exec_prot();
        phys_addr_t pa_start = __pa_symbol(__entry_tramp_text_start);

        /* The trampoline is always mapped and can therefore be global */
        pgprot_val(prot) &= ~PTE_NG;

        /* Map only the text into the trampoline page table */
        memset(tramp_pg_dir, 0, PGD_SIZE);
        early_create_pgd_mapping(tramp_pg_dir, pa_start, TRAMP_VALIAS,
                                 entry_tramp_text_size(), prot,
                                 pgd_pgtable_alloc_init_mm, NO_BLOCK_MAPPINGS);

        /* Map both the text and data into the kernel page table */
        for (i = 0; i < DIV_ROUND_UP(entry_tramp_text_size(), PAGE_SIZE); i++)
                __set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i,
                             pa_start + i * PAGE_SIZE, prot);

        if (IS_ENABLED(CONFIG_RELOCATABLE))
                __set_fixmap(FIX_ENTRY_TRAMP_TEXT1 - i,
                             pa_start + i * PAGE_SIZE, PAGE_KERNEL_RO);

        return 0;
}
core_initcall(map_entry_trampoline);
#endif

/*
 * Declare the VMA areas for the kernel
 */
static void __init declare_kernel_vmas(void)
{
        static struct vm_struct vmlinux_seg[KERNEL_SEGMENT_COUNT];

        declare_vma(&vmlinux_seg[0], _text, _etext, VM_NO_GUARD);
        declare_vma(&vmlinux_seg[1], __start_rodata, __inittext_begin, VM_NO_GUARD);
        declare_vma(&vmlinux_seg[2], __inittext_begin, __inittext_end, VM_NO_GUARD);
        declare_vma(&vmlinux_seg[3], __initdata_begin, __initdata_end, VM_NO_GUARD);
        declare_vma(&vmlinux_seg[4], _data, _end, 0);
}

void __pi_map_range(phys_addr_t *pte, u64 start, u64 end, phys_addr_t pa,
                    pgprot_t prot, int level, pte_t *tbl, bool may_use_cont,
                    u64 va_offset);

static u8 idmap_ptes[IDMAP_LEVELS - 1][PAGE_SIZE] __aligned(PAGE_SIZE) __ro_after_init,
          kpti_bbml2_ptes[IDMAP_LEVELS - 1][PAGE_SIZE] __aligned(PAGE_SIZE) __ro_after_init;

static void __init create_idmap(void)
{
        phys_addr_t start = __pa_symbol(__idmap_text_start);
        phys_addr_t end   = __pa_symbol(__idmap_text_end);
        phys_addr_t ptep  = __pa_symbol(idmap_ptes);

        __pi_map_range(&ptep, start, end, start, PAGE_KERNEL_ROX,
                       IDMAP_ROOT_LEVEL, (pte_t *)idmap_pg_dir, false,
                       __phys_to_virt(ptep) - ptep);

        if (linear_map_requires_bbml2 ||
            (IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0) && !arm64_use_ng_mappings)) {
                phys_addr_t pa = __pa_symbol(&idmap_kpti_bbml2_flag);

                /*
                 * The KPTI G-to-nG conversion code needs a read-write mapping
                 * of its synchronization flag in the ID map. This is also used
                 * when splitting the linear map to ptes if a secondary CPU
                 * doesn't support bbml2.
                 */
                ptep = __pa_symbol(kpti_bbml2_ptes);
                __pi_map_range(&ptep, pa, pa + sizeof(u32), pa, PAGE_KERNEL,
                               IDMAP_ROOT_LEVEL, (pte_t *)idmap_pg_dir, false,
                               __phys_to_virt(ptep) - ptep);
        }
}

void __init paging_init(void)
{
        map_mem(swapper_pg_dir);

        memblock_allow_resize();

        create_idmap();
        declare_kernel_vmas();
}

#ifdef CONFIG_MEMORY_HOTPLUG
static void free_hotplug_page_range(struct page *page, size_t size,
                                    struct vmem_altmap *altmap)
{
        if (altmap) {
                vmem_altmap_free(altmap, size >> PAGE_SHIFT);
        } else {
                WARN_ON(PageReserved(page));
                __free_pages(page, get_order(size));
        }
}

static void free_hotplug_pgtable_page(struct page *page)
{
        free_hotplug_page_range(page, PAGE_SIZE, NULL);
}

static bool pgtable_range_aligned(unsigned long start, unsigned long end,
                                  unsigned long floor, unsigned long ceiling,
                                  unsigned long mask)
{
        start &= mask;
        if (start < floor)
                return false;

        if (ceiling) {
                ceiling &= mask;
                if (!ceiling)
                        return false;
        }

        if (end - 1 > ceiling - 1)
                return false;
        return true;
}

static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr,
                                    unsigned long end, bool free_mapped,
                                    struct vmem_altmap *altmap)
{
        pte_t *ptep, pte;

        do {
                ptep = pte_offset_kernel(pmdp, addr);
                pte = __ptep_get(ptep);
                if (pte_none(pte))
                        continue;

                WARN_ON(!pte_present(pte));
                __pte_clear(&init_mm, addr, ptep);
                flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
                if (free_mapped)
                        free_hotplug_page_range(pte_page(pte),
                                                PAGE_SIZE, altmap);
        } while (addr += PAGE_SIZE, addr < end);
}

static void unmap_hotplug_pmd_range(pud_t *pudp, unsigned long addr,
                                    unsigned long end, bool free_mapped,
                                    struct vmem_altmap *altmap)
{
        unsigned long next;
        pmd_t *pmdp, pmd;

        do {
                next = pmd_addr_end(addr, end);
                pmdp = pmd_offset(pudp, addr);
                pmd = READ_ONCE(*pmdp);
                if (pmd_none(pmd))
                        continue;

                WARN_ON(!pmd_present(pmd));
                if (pmd_sect(pmd)) {
                        pmd_clear(pmdp);

                        /*
                         * One TLBI should be sufficient here as the PMD_SIZE
                         * range is mapped with a single block entry.
                         */
                        flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
                        if (free_mapped)
                                free_hotplug_page_range(pmd_page(pmd),
                                                        PMD_SIZE, altmap);
                        continue;
                }
                WARN_ON(!pmd_table(pmd));
                unmap_hotplug_pte_range(pmdp, addr, next, free_mapped, altmap);
        } while (addr = next, addr < end);
}

static void unmap_hotplug_pud_range(p4d_t *p4dp, unsigned long addr,
                                    unsigned long end, bool free_mapped,
                                    struct vmem_altmap *altmap)
{
        unsigned long next;
        pud_t *pudp, pud;

        do {
                next = pud_addr_end(addr, end);
                pudp = pud_offset(p4dp, addr);
                pud = READ_ONCE(*pudp);
                if (pud_none(pud))
                        continue;

                WARN_ON(!pud_present(pud));
                if (pud_sect(pud)) {
                        pud_clear(pudp);

                        /*
                         * One TLBI should be sufficient here as the PUD_SIZE
                         * range is mapped with a single block entry.
                         */
                        flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
                        if (free_mapped)
                                free_hotplug_page_range(pud_page(pud),
                                                        PUD_SIZE, altmap);
                        continue;
                }
                WARN_ON(!pud_table(pud));
                unmap_hotplug_pmd_range(pudp, addr, next, free_mapped, altmap);
        } while (addr = next, addr < end);
}

static void unmap_hotplug_p4d_range(pgd_t *pgdp, unsigned long addr,
                                    unsigned long end, bool free_mapped,
                                    struct vmem_altmap *altmap)
{
        unsigned long next;
        p4d_t *p4dp, p4d;

        do {
                next = p4d_addr_end(addr, end);
                p4dp = p4d_offset(pgdp, addr);
                p4d = READ_ONCE(*p4dp);
                if (p4d_none(p4d))
                        continue;

                WARN_ON(!p4d_present(p4d));
                unmap_hotplug_pud_range(p4dp, addr, next, free_mapped, altmap);
        } while (addr = next, addr < end);
}

static void unmap_hotplug_range(unsigned long addr, unsigned long end,
                                bool free_mapped, struct vmem_altmap *altmap)
{
        unsigned long next;
        pgd_t *pgdp, pgd;

        /*
         * altmap can only be used as vmemmap mapping backing memory.
         * In case the backing memory itself is not being freed, then
         * altmap is irrelevant. Warn about this inconsistency when
         * encountered.
         */
        WARN_ON(!free_mapped && altmap);

        do {
                next = pgd_addr_end(addr, end);
                pgdp = pgd_offset_k(addr);
                pgd = READ_ONCE(*pgdp);
                if (pgd_none(pgd))
                        continue;

                WARN_ON(!pgd_present(pgd));
                unmap_hotplug_p4d_range(pgdp, addr, next, free_mapped, altmap);
        } while (addr = next, addr < end);
}

static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr,
                                 unsigned long end, unsigned long floor,
                                 unsigned long ceiling)
{
        pte_t *ptep, pte;
        unsigned long i, start = addr;

        do {
                ptep = pte_offset_kernel(pmdp, addr);
                pte = __ptep_get(ptep);

                /*
                 * This is just a sanity check here which verifies that
                 * pte clearing has been done by earlier unmap loops.
                 */
                WARN_ON(!pte_none(pte));
        } while (addr += PAGE_SIZE, addr < end);

        if (!pgtable_range_aligned(start, end, floor, ceiling, PMD_MASK))
                return;

        /*
         * Check whether we can free the pte page if the rest of the
         * entries are empty. Overlap with other regions have been
         * handled by the floor/ceiling check.
         */
        ptep = pte_offset_kernel(pmdp, 0UL);
        for (i = 0; i < PTRS_PER_PTE; i++) {
                if (!pte_none(__ptep_get(&ptep[i])))
                        return;
        }

        pmd_clear(pmdp);
        __flush_tlb_kernel_pgtable(start);
        free_hotplug_pgtable_page(virt_to_page(ptep));
}

static void free_empty_pmd_table(pud_t *pudp, unsigned long addr,
                                 unsigned long end, unsigned long floor,
                                 unsigned long ceiling)
{
        pmd_t *pmdp, pmd;
        unsigned long i, next, start = addr;

        do {
                next = pmd_addr_end(addr, end);
                pmdp = pmd_offset(pudp, addr);
                pmd = READ_ONCE(*pmdp);
                if (pmd_none(pmd))
                        continue;

                WARN_ON(!pmd_present(pmd) || !pmd_table(pmd) || pmd_sect(pmd));
                free_empty_pte_table(pmdp, addr, next, floor, ceiling);
        } while (addr = next, addr < end);

        if (CONFIG_PGTABLE_LEVELS <= 2)
                return;

        if (!pgtable_range_aligned(start, end, floor, ceiling, PUD_MASK))
                return;

        /*
         * Check whether we can free the pmd page if the rest of the
         * entries are empty. Overlap with other regions have been
         * handled by the floor/ceiling check.
         */
        pmdp = pmd_offset(pudp, 0UL);
        for (i = 0; i < PTRS_PER_PMD; i++) {
                if (!pmd_none(READ_ONCE(pmdp[i])))
                        return;
        }

        pud_clear(pudp);
        __flush_tlb_kernel_pgtable(start);
        free_hotplug_pgtable_page(virt_to_page(pmdp));
}

static void free_empty_pud_table(p4d_t *p4dp, unsigned long addr,
                                 unsigned long end, unsigned long floor,
                                 unsigned long ceiling)
{
        pud_t *pudp, pud;
        unsigned long i, next, start = addr;

        do {
                next = pud_addr_end(addr, end);
                pudp = pud_offset(p4dp, addr);
                pud = READ_ONCE(*pudp);
                if (pud_none(pud))
                        continue;

                WARN_ON(!pud_present(pud) || !pud_table(pud) || pud_sect(pud));
                free_empty_pmd_table(pudp, addr, next, floor, ceiling);
        } while (addr = next, addr < end);

        if (!pgtable_l4_enabled())
                return;

        if (!pgtable_range_aligned(start, end, floor, ceiling, P4D_MASK))
                return;

        /*
         * Check whether we can free the pud page if the rest of the
         * entries are empty. Overlap with other regions have been
         * handled by the floor/ceiling check.
         */
        pudp = pud_offset(p4dp, 0UL);
        for (i = 0; i < PTRS_PER_PUD; i++) {
                if (!pud_none(READ_ONCE(pudp[i])))
                        return;
        }

        p4d_clear(p4dp);
        __flush_tlb_kernel_pgtable(start);
        free_hotplug_pgtable_page(virt_to_page(pudp));
}

static void free_empty_p4d_table(pgd_t *pgdp, unsigned long addr,
                                 unsigned long end, unsigned long floor,
                                 unsigned long ceiling)
{
        p4d_t *p4dp, p4d;
        unsigned long i, next, start = addr;

        do {
                next = p4d_addr_end(addr, end);
                p4dp = p4d_offset(pgdp, addr);
                p4d = READ_ONCE(*p4dp);
                if (p4d_none(p4d))
                        continue;

                WARN_ON(!p4d_present(p4d));
                free_empty_pud_table(p4dp, addr, next, floor, ceiling);
        } while (addr = next, addr < end);

        if (!pgtable_l5_enabled())
                return;

        if (!pgtable_range_aligned(start, end, floor, ceiling, PGDIR_MASK))
                return;

        /*
         * Check whether we can free the p4d page if the rest of the
         * entries are empty. Overlap with other regions have been
         * handled by the floor/ceiling check.
         */
        p4dp = p4d_offset(pgdp, 0UL);
        for (i = 0; i < PTRS_PER_P4D; i++) {
                if (!p4d_none(READ_ONCE(p4dp[i])))
                        return;
        }

        pgd_clear(pgdp);
        __flush_tlb_kernel_pgtable(start);
        free_hotplug_pgtable_page(virt_to_page(p4dp));
}

static void free_empty_tables(unsigned long addr, unsigned long end,
                              unsigned long floor, unsigned long ceiling)
{
        unsigned long next;
        pgd_t *pgdp, pgd;

        do {
                next = pgd_addr_end(addr, end);
                pgdp = pgd_offset_k(addr);
                pgd = READ_ONCE(*pgdp);
                if (pgd_none(pgd))
                        continue;

                WARN_ON(!pgd_present(pgd));
                free_empty_p4d_table(pgdp, addr, next, floor, ceiling);
        } while (addr = next, addr < end);
}
#endif

void __meminit vmemmap_set_pmd(pmd_t *pmdp, void *p, int node,
                               unsigned long addr, unsigned long next)
{
        pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL));
}

int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
                                unsigned long addr, unsigned long next)
{
        vmemmap_verify((pte_t *)pmdp, node, addr, next);

        return pmd_sect(READ_ONCE(*pmdp));
}

int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
                struct vmem_altmap *altmap)
{
        WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));
        /* [start, end] should be within one section */
        WARN_ON_ONCE(end - start > PAGES_PER_SECTION * sizeof(struct page));

        if (!IS_ENABLED(CONFIG_ARM64_4K_PAGES) ||
            (end - start < PAGES_PER_SECTION * sizeof(struct page)))
                return vmemmap_populate_basepages(start, end, node, altmap);
        else
                return vmemmap_populate_hugepages(start, end, node, altmap);
}

#ifdef CONFIG_MEMORY_HOTPLUG
void vmemmap_free(unsigned long start, unsigned long end,
                struct vmem_altmap *altmap)
{
        WARN_ON((start < VMEMMAP_START) || (end > VMEMMAP_END));

        unmap_hotplug_range(start, end, true, altmap);
        free_empty_tables(start, end, VMEMMAP_START, VMEMMAP_END);
}
#endif /* CONFIG_MEMORY_HOTPLUG */

int pud_set_huge(pud_t *pudp, phys_addr_t phys, pgprot_t prot)
{
        pud_t new_pud = pfn_pud(__phys_to_pfn(phys), mk_pud_sect_prot(prot));

        /* Only allow permission changes for now */
        if (!pgattr_change_is_safe(READ_ONCE(pud_val(*pudp)),
                                   pud_val(new_pud)))
                return 0;

        VM_BUG_ON(phys & ~PUD_MASK);
        set_pud(pudp, new_pud);
        return 1;
}

int pmd_set_huge(pmd_t *pmdp, phys_addr_t phys, pgprot_t prot)
{
        pmd_t new_pmd = pfn_pmd(__phys_to_pfn(phys), mk_pmd_sect_prot(prot));

        /* Only allow permission changes for now */
        if (!pgattr_change_is_safe(READ_ONCE(pmd_val(*pmdp)),
                                   pmd_val(new_pmd)))
                return 0;

        VM_BUG_ON(phys & ~PMD_MASK);
        set_pmd(pmdp, new_pmd);
        return 1;
}

#ifndef __PAGETABLE_P4D_FOLDED
void p4d_clear_huge(p4d_t *p4dp)
{
}
#endif

int pud_clear_huge(pud_t *pudp)
{
        if (!pud_sect(READ_ONCE(*pudp)))
                return 0;
        pud_clear(pudp);
        return 1;
}

int pmd_clear_huge(pmd_t *pmdp)
{
        if (!pmd_sect(READ_ONCE(*pmdp)))
                return 0;
        pmd_clear(pmdp);
        return 1;
}

static int __pmd_free_pte_page(pmd_t *pmdp, unsigned long addr,
                               bool acquire_mmap_lock)
{
        pte_t *table;
        pmd_t pmd;

        pmd = READ_ONCE(*pmdp);

        if (!pmd_table(pmd)) {
                VM_WARN_ON(1);
                return 1;
        }

        /* See comment in pud_free_pmd_page for static key logic */
        table = pte_offset_kernel(pmdp, addr);
        pmd_clear(pmdp);
        __flush_tlb_kernel_pgtable(addr);
        if (static_branch_unlikely(&arm64_ptdump_lock_key) && acquire_mmap_lock) {
                mmap_read_lock(&init_mm);
                mmap_read_unlock(&init_mm);
        }

        pte_free_kernel(NULL, table);
        return 1;
}

int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
{
        /* If ptdump is walking the pagetables, acquire init_mm.mmap_lock */
        return __pmd_free_pte_page(pmdp, addr, /* acquire_mmap_lock = */ true);
}

int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
{
        pmd_t *table;
        pmd_t *pmdp;
        pud_t pud;
        unsigned long next, end;

        pud = READ_ONCE(*pudp);

        if (!pud_table(pud)) {
                VM_WARN_ON(1);
                return 1;
        }

        table = pmd_offset(pudp, addr);

        /*
         * Our objective is to prevent ptdump from reading a PMD table which has
         * been freed. In this race, if pud_free_pmd_page observes the key on
         * (which got flipped by ptdump) then the mmap lock sequence here will,
         * as a result of the mmap write lock/unlock sequence in ptdump, give
         * us the correct synchronization. If not, this means that ptdump has
         * yet not started walking the pagetables - the sequence of barriers
         * issued by __flush_tlb_kernel_pgtable() guarantees that ptdump will
         * observe an empty PUD.
         */
        pud_clear(pudp);
        __flush_tlb_kernel_pgtable(addr);
        if (static_branch_unlikely(&arm64_ptdump_lock_key)) {
                mmap_read_lock(&init_mm);
                mmap_read_unlock(&init_mm);
        }

        pmdp = table;
        next = addr;
        end = addr + PUD_SIZE;
        do {
                if (pmd_present(pmdp_get(pmdp)))
                        /*
                         * PMD has been isolated, so ptdump won't see it. No
                         * need to acquire init_mm.mmap_lock.
                         */
                        __pmd_free_pte_page(pmdp, next, /* acquire_mmap_lock = */ false);
        } while (pmdp++, next += PMD_SIZE, next != end);

        pmd_free(NULL, table);
        return 1;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static void __remove_pgd_mapping(pgd_t *pgdir, unsigned long start, u64 size)
{
        unsigned long end = start + size;

        WARN_ON(pgdir != init_mm.pgd);
        WARN_ON((start < PAGE_OFFSET) || (end > PAGE_END));

        unmap_hotplug_range(start, end, false, NULL);
        free_empty_tables(start, end, PAGE_OFFSET, PAGE_END);
}

struct range arch_get_mappable_range(void)
{
        struct range mhp_range;
        phys_addr_t start_linear_pa = __pa(_PAGE_OFFSET(vabits_actual));
        phys_addr_t end_linear_pa = __pa(PAGE_END - 1);

        if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) {
                /*
                 * Check for a wrap, it is possible because of randomized linear
                 * mapping the start physical address is actually bigger than
                 * the end physical address. In this case set start to zero
                 * because [0, end_linear_pa] range must still be able to cover
                 * all addressable physical addresses.
                 */
                if (start_linear_pa > end_linear_pa)
                        start_linear_pa = 0;
        }

        WARN_ON(start_linear_pa > end_linear_pa);

        /*
         * Linear mapping region is the range [PAGE_OFFSET..(PAGE_END - 1)]
         * accommodating both its ends but excluding PAGE_END. Max physical
         * range which can be mapped inside this linear mapping range, must
         * also be derived from its end points.
         */
        mhp_range.start = start_linear_pa;
        mhp_range.end =  end_linear_pa;

        return mhp_range;
}

int arch_add_memory(int nid, u64 start, u64 size,
                    struct mhp_params *params)
{
        int ret, flags = NO_EXEC_MAPPINGS;

        VM_BUG_ON(!mhp_range_allowed(start, size, true));

        if (force_pte_mapping())
                flags |= NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;

        ret = __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
                                   size, params->pgprot, pgd_pgtable_alloc_init_mm,
                                   flags);
        if (ret)
                goto err;

        memblock_clear_nomap(start, size);

        ret = __add_pages(nid, start >> PAGE_SHIFT, size >> PAGE_SHIFT,
                           params);
        if (ret)
                goto err;

        /* Address of hotplugged memory can be smaller */
        max_pfn = max(max_pfn, PFN_UP(start + size));
        max_low_pfn = max_pfn;

        return 0;

err:
        __remove_pgd_mapping(swapper_pg_dir,
                             __phys_to_virt(start), size);
        return ret;
}

void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
{
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;

        __remove_pages(start_pfn, nr_pages, altmap);
        __remove_pgd_mapping(swapper_pg_dir, __phys_to_virt(start), size);
}

/*
 * This memory hotplug notifier helps prevent boot memory from being
 * inadvertently removed as it blocks pfn range offlining process in
 * __offline_pages(). Hence this prevents both offlining as well as
 * removal process for boot memory which is initially always online.
 * In future if and when boot memory could be removed, this notifier
 * should be dropped and free_hotplug_page_range() should handle any
 * reserved pages allocated during boot.
 */
static int prevent_bootmem_remove_notifier(struct notifier_block *nb,
                                           unsigned long action, void *data)
{
        struct mem_section *ms;
        struct memory_notify *arg = data;
        unsigned long end_pfn = arg->start_pfn + arg->nr_pages;
        unsigned long pfn = arg->start_pfn;

        if ((action != MEM_GOING_OFFLINE) && (action != MEM_OFFLINE))
                return NOTIFY_OK;

        for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
                unsigned long start = PFN_PHYS(pfn);
                unsigned long end = start + (1UL << PA_SECTION_SHIFT);

                ms = __pfn_to_section(pfn);
                if (!early_section(ms))
                        continue;

                if (action == MEM_GOING_OFFLINE) {
                        /*
                         * Boot memory removal is not supported. Prevent
                         * it via blocking any attempted offline request
                         * for the boot memory and just report it.
                         */
                        pr_warn("Boot memory [%lx %lx] offlining attempted\n", start, end);
                        return NOTIFY_BAD;
                } else if (action == MEM_OFFLINE) {
                        /*
                         * This should have never happened. Boot memory
                         * offlining should have been prevented by this
                         * very notifier. Probably some memory removal
                         * procedure might have changed which would then
                         * require further debug.
                         */
                        pr_err("Boot memory [%lx %lx] offlined\n", start, end);

                        /*
                         * Core memory hotplug does not process a return
                         * code from the notifier for MEM_OFFLINE events.
                         * The error condition has been reported. Return
                         * from here as if ignored.
                         */
                        return NOTIFY_DONE;
                }
        }
        return NOTIFY_OK;
}

static struct notifier_block prevent_bootmem_remove_nb = {
        .notifier_call = prevent_bootmem_remove_notifier,
};

/*
 * This ensures that boot memory sections on the platform are online
 * from early boot. Memory sections could not be prevented from being
 * offlined, unless for some reason they are not online to begin with.
 * This helps validate the basic assumption on which the above memory
 * event notifier works to prevent boot memory section offlining and
 * its possible removal.
 */
static void validate_bootmem_online(void)
{
        phys_addr_t start, end, addr;
        struct mem_section *ms;
        u64 i;

        /*
         * Scanning across all memblock might be expensive
         * on some big memory systems. Hence enable this
         * validation only with DEBUG_VM.
         */
        if (!IS_ENABLED(CONFIG_DEBUG_VM))
                return;

        for_each_mem_range(i, &start, &end) {
                for (addr = start; addr < end; addr += (1UL << PA_SECTION_SHIFT)) {
                        ms = __pfn_to_section(PHYS_PFN(addr));

                        /*
                         * All memory ranges in the system at this point
                         * should have been marked as early sections.
                         */
                        WARN_ON(!early_section(ms));

                        /*
                         * Memory notifier mechanism here to prevent boot
                         * memory offlining depends on the fact that each
                         * early section memory on the system is initially
                         * online. Otherwise a given memory section which
                         * is already offline will be overlooked and can
                         * be removed completely. Call out such sections.
                         */
                        if (!online_section(ms))
                                pr_err("Boot memory [%llx %llx] is offline, can be removed\n",
                                        addr, addr + (1UL << PA_SECTION_SHIFT));
                }
        }
}

static int __init prevent_bootmem_remove_init(void)
{
        int ret = 0;

        if (!IS_ENABLED(CONFIG_MEMORY_HOTREMOVE))
                return ret;

        validate_bootmem_online();
        ret = register_memory_notifier(&prevent_bootmem_remove_nb);
        if (ret)
                pr_err("%s: Notifier registration failed %d\n", __func__, ret);

        return ret;
}
early_initcall(prevent_bootmem_remove_init);
#endif

pte_t modify_prot_start_ptes(struct vm_area_struct *vma, unsigned long addr,
                             pte_t *ptep, unsigned int nr)
{
        pte_t pte = get_and_clear_ptes(vma->vm_mm, addr, ptep, nr);

        if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) {
                /*
                 * Break-before-make (BBM) is required for all user space mappings
                 * when the permission changes from executable to non-executable
                 * in cases where cpu is affected with errata #2645198.
                 */
                if (pte_accessible(vma->vm_mm, pte) && pte_user_exec(pte))
                        __flush_tlb_range(vma, addr, nr * PAGE_SIZE,
                                          PAGE_SIZE, true, 3);
        }

        return pte;
}

pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep)
{
        return modify_prot_start_ptes(vma, addr, ptep, 1);
}

void modify_prot_commit_ptes(struct vm_area_struct *vma, unsigned long addr,
                             pte_t *ptep, pte_t old_pte, pte_t pte,
                             unsigned int nr)
{
        set_ptes(vma->vm_mm, addr, ptep, pte, nr);
}

void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep,
                             pte_t old_pte, pte_t pte)
{
        modify_prot_commit_ptes(vma, addr, ptep, old_pte, pte, 1);
}

/*
 * Atomically replaces the active TTBR1_EL1 PGD with a new VA-compatible PGD,
 * avoiding the possibility of conflicting TLB entries being allocated.
 */
void __cpu_replace_ttbr1(pgd_t *pgdp, bool cnp)
{
        typedef void (ttbr_replace_func)(phys_addr_t);
        extern ttbr_replace_func idmap_cpu_replace_ttbr1;
        ttbr_replace_func *replace_phys;
        unsigned long daif;

        /* phys_to_ttbr() zeros lower 2 bits of ttbr with 52-bit PA */
        phys_addr_t ttbr1 = phys_to_ttbr(virt_to_phys(pgdp));

        if (cnp)
                ttbr1 |= TTBR_CNP_BIT;

        replace_phys = (void *)__pa_symbol(idmap_cpu_replace_ttbr1);

        cpu_install_idmap();

        /*
         * We really don't want to take *any* exceptions while TTBR1 is
         * in the process of being replaced so mask everything.
         */
        daif = local_daif_save();
        replace_phys(ttbr1);
        local_daif_restore(daif);

        cpu_uninstall_idmap();
}

#ifdef CONFIG_ARCH_HAS_PKEYS
int arch_set_user_pkey_access(struct task_struct *tsk, int pkey, unsigned long init_val)
{
        u64 new_por;
        u64 old_por;

        if (!system_supports_poe())
                return -ENOSPC;

        /*
         * This code should only be called with valid 'pkey'
         * values originating from in-kernel users.  Complain
         * if a bad value is observed.
         */
        if (WARN_ON_ONCE(pkey >= arch_max_pkey()))
                return -EINVAL;

        /* Set the bits we need in POR:  */
        new_por = POE_RWX;
        if (init_val & PKEY_DISABLE_WRITE)
                new_por &= ~POE_W;
        if (init_val & PKEY_DISABLE_ACCESS)
                new_por &= ~POE_RW;
        if (init_val & PKEY_DISABLE_READ)
                new_por &= ~POE_R;
        if (init_val & PKEY_DISABLE_EXECUTE)
                new_por &= ~POE_X;

        /* Shift the bits in to the correct place in POR for pkey: */
        new_por = POR_ELx_PERM_PREP(pkey, new_por);

        /* Get old POR and mask off any old bits in place: */
        old_por = read_sysreg_s(SYS_POR_EL0);
        old_por &= ~(POE_MASK << POR_ELx_PERM_SHIFT(pkey));

        /* Write old part along with new part: */
        write_sysreg_s(old_por | new_por, SYS_POR_EL0);

        return 0;
}
#endif