mm: hugetlb: add a kernel parameter hugetlb_free_vmemmap

[mirror_ubuntu-jammy-kernel.git] / arch / x86 / mm / init_64.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/x86_64/mm/init.c
 *
 *  Copyright (C) 1995  Linus Torvalds
 *  Copyright (C) 2000  Pavel Machek <pavel@ucw.cz>
 *  Copyright (C) 2002,2003 Andi Kleen <ak@suse.de>
 */

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/initrd.h>
#include <linux/pagemap.h>
#include <linux/memblock.h>
#include <linux/proc_fs.h>
#include <linux/pci.h>
#include <linux/pfn.h>
#include <linux/poison.h>
#include <linux/dma-mapping.h>
#include <linux/memory.h>
#include <linux/memory_hotplug.h>
#include <linux/memremap.h>
#include <linux/nmi.h>
#include <linux/gfp.h>
#include <linux/kcore.h>
#include <linux/bootmem_info.h>
#include <linux/hugetlb.h>

#include <asm/processor.h>
#include <asm/bios_ebda.h>
#include <linux/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/dma.h>
#include <asm/fixmap.h>
#include <asm/e820/api.h>
#include <asm/apic.h>
#include <asm/tlb.h>
#include <asm/mmu_context.h>
#include <asm/proto.h>
#include <asm/smp.h>
#include <asm/sections.h>
#include <asm/kdebug.h>
#include <asm/numa.h>
#include <asm/set_memory.h>
#include <asm/init.h>
#include <asm/uv/uv.h>
#include <asm/setup.h>
#include <asm/ftrace.h>

#include "mm_internal.h"

#include "ident_map.c"

#define DEFINE_POPULATE(fname, type1, type2, init)              \
static inline void fname##_init(struct mm_struct *mm,           \
                type1##_t *arg1, type2##_t *arg2, bool init)    \
{                                                               \
        if (init)                                               \
                fname##_safe(mm, arg1, arg2);                   \
        else                                                    \
                fname(mm, arg1, arg2);                          \
}

DEFINE_POPULATE(p4d_populate, p4d, pud, init)
DEFINE_POPULATE(pgd_populate, pgd, p4d, init)
DEFINE_POPULATE(pud_populate, pud, pmd, init)
DEFINE_POPULATE(pmd_populate_kernel, pmd, pte, init)

#define DEFINE_ENTRY(type1, type2, init)                        \
static inline void set_##type1##_init(type1##_t *arg1,          \
                        type2##_t arg2, bool init)              \
{                                                               \
        if (init)                                               \
                set_##type1##_safe(arg1, arg2);                 \
        else                                                    \
                set_##type1(arg1, arg2);                        \
}

DEFINE_ENTRY(p4d, p4d, init)
DEFINE_ENTRY(pud, pud, init)
DEFINE_ENTRY(pmd, pmd, init)
DEFINE_ENTRY(pte, pte, init)


/*
 * NOTE: pagetable_init alloc all the fixmap pagetables contiguous on the
 * physical space so we can cache the place of the first one and move
 * around without checking the pgd every time.
 */

/* Bits supported by the hardware: */
pteval_t __supported_pte_mask __read_mostly = ~0;
/* Bits allowed in normal kernel mappings: */
pteval_t __default_kernel_pte_mask __read_mostly = ~0;
EXPORT_SYMBOL_GPL(__supported_pte_mask);
/* Used in PAGE_KERNEL_* macros which are reasonably used out-of-tree: */
EXPORT_SYMBOL(__default_kernel_pte_mask);

int force_personality32;

/*
 * noexec32=on|off
 * Control non executable heap for 32bit processes.
 * To control the stack too use noexec=off
 *
 * on   PROT_READ does not imply PROT_EXEC for 32-bit processes (default)
 * off  PROT_READ implies PROT_EXEC
 */
static int __init nonx32_setup(char *str)
{
        if (!strcmp(str, "on"))
                force_personality32 &= ~READ_IMPLIES_EXEC;
        else if (!strcmp(str, "off"))
                force_personality32 |= READ_IMPLIES_EXEC;
        return 1;
}
__setup("noexec32=", nonx32_setup);

static void sync_global_pgds_l5(unsigned long start, unsigned long end)
{
        unsigned long addr;

        for (addr = start; addr <= end; addr = ALIGN(addr + 1, PGDIR_SIZE)) {
                const pgd_t *pgd_ref = pgd_offset_k(addr);
                struct page *page;

                /* Check for overflow */
                if (addr < start)
                        break;

                if (pgd_none(*pgd_ref))
                        continue;

                spin_lock(&pgd_lock);
                list_for_each_entry(page, &pgd_list, lru) {
                        pgd_t *pgd;
                        spinlock_t *pgt_lock;

                        pgd = (pgd_t *)page_address(page) + pgd_index(addr);
                        /* the pgt_lock only for Xen */
                        pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
                        spin_lock(pgt_lock);

                        if (!pgd_none(*pgd_ref) && !pgd_none(*pgd))
                                BUG_ON(pgd_page_vaddr(*pgd) != pgd_page_vaddr(*pgd_ref));

                        if (pgd_none(*pgd))
                                set_pgd(pgd, *pgd_ref);

                        spin_unlock(pgt_lock);
                }
                spin_unlock(&pgd_lock);
        }
}

static void sync_global_pgds_l4(unsigned long start, unsigned long end)
{
        unsigned long addr;

        for (addr = start; addr <= end; addr = ALIGN(addr + 1, PGDIR_SIZE)) {
                pgd_t *pgd_ref = pgd_offset_k(addr);
                const p4d_t *p4d_ref;
                struct page *page;

                /*
                 * With folded p4d, pgd_none() is always false, we need to
                 * handle synchronization on p4d level.
                 */
                MAYBE_BUILD_BUG_ON(pgd_none(*pgd_ref));
                p4d_ref = p4d_offset(pgd_ref, addr);

                if (p4d_none(*p4d_ref))
                        continue;

                spin_lock(&pgd_lock);
                list_for_each_entry(page, &pgd_list, lru) {
                        pgd_t *pgd;
                        p4d_t *p4d;
                        spinlock_t *pgt_lock;

                        pgd = (pgd_t *)page_address(page) + pgd_index(addr);
                        p4d = p4d_offset(pgd, addr);
                        /* the pgt_lock only for Xen */
                        pgt_lock = &pgd_page_get_mm(page)->page_table_lock;
                        spin_lock(pgt_lock);

                        if (!p4d_none(*p4d_ref) && !p4d_none(*p4d))
                                BUG_ON(p4d_page_vaddr(*p4d)
                                       != p4d_page_vaddr(*p4d_ref));

                        if (p4d_none(*p4d))
                                set_p4d(p4d, *p4d_ref);

                        spin_unlock(pgt_lock);
                }
                spin_unlock(&pgd_lock);
        }
}

/*
 * When memory was added make sure all the processes MM have
 * suitable PGD entries in the local PGD level page.
 */
static void sync_global_pgds(unsigned long start, unsigned long end)
{
        if (pgtable_l5_enabled())
                sync_global_pgds_l5(start, end);
        else
                sync_global_pgds_l4(start, end);
}

/*
 * NOTE: This function is marked __ref because it calls __init function
 * (alloc_bootmem_pages). It's safe to do it ONLY when after_bootmem == 0.
 */
static __ref void *spp_getpage(void)
{
        void *ptr;

        if (after_bootmem)
                ptr = (void *) get_zeroed_page(GFP_ATOMIC);
        else
                ptr = memblock_alloc(PAGE_SIZE, PAGE_SIZE);

        if (!ptr || ((unsigned long)ptr & ~PAGE_MASK)) {
                panic("set_pte_phys: cannot allocate page data %s\n",
                        after_bootmem ? "after bootmem" : "");
        }

        pr_debug("spp_getpage %p\n", ptr);

        return ptr;
}

static p4d_t *fill_p4d(pgd_t *pgd, unsigned long vaddr)
{
        if (pgd_none(*pgd)) {
                p4d_t *p4d = (p4d_t *)spp_getpage();
                pgd_populate(&init_mm, pgd, p4d);
                if (p4d != p4d_offset(pgd, 0))
                        printk(KERN_ERR "PAGETABLE BUG #00! %p <-> %p\n",
                               p4d, p4d_offset(pgd, 0));
        }
        return p4d_offset(pgd, vaddr);
}

static pud_t *fill_pud(p4d_t *p4d, unsigned long vaddr)
{
        if (p4d_none(*p4d)) {
                pud_t *pud = (pud_t *)spp_getpage();
                p4d_populate(&init_mm, p4d, pud);
                if (pud != pud_offset(p4d, 0))
                        printk(KERN_ERR "PAGETABLE BUG #01! %p <-> %p\n",
                               pud, pud_offset(p4d, 0));
        }
        return pud_offset(p4d, vaddr);
}

static pmd_t *fill_pmd(pud_t *pud, unsigned long vaddr)
{
        if (pud_none(*pud)) {
                pmd_t *pmd = (pmd_t *) spp_getpage();
                pud_populate(&init_mm, pud, pmd);
                if (pmd != pmd_offset(pud, 0))
                        printk(KERN_ERR "PAGETABLE BUG #02! %p <-> %p\n",
                               pmd, pmd_offset(pud, 0));
        }
        return pmd_offset(pud, vaddr);
}

static pte_t *fill_pte(pmd_t *pmd, unsigned long vaddr)
{
        if (pmd_none(*pmd)) {
                pte_t *pte = (pte_t *) spp_getpage();
                pmd_populate_kernel(&init_mm, pmd, pte);
                if (pte != pte_offset_kernel(pmd, 0))
                        printk(KERN_ERR "PAGETABLE BUG #03!\n");
        }
        return pte_offset_kernel(pmd, vaddr);
}

static void __set_pte_vaddr(pud_t *pud, unsigned long vaddr, pte_t new_pte)
{
        pmd_t *pmd = fill_pmd(pud, vaddr);
        pte_t *pte = fill_pte(pmd, vaddr);

        set_pte(pte, new_pte);

        /*
         * It's enough to flush this one mapping.
         * (PGE mappings get flushed as well)
         */
        flush_tlb_one_kernel(vaddr);
}

void set_pte_vaddr_p4d(p4d_t *p4d_page, unsigned long vaddr, pte_t new_pte)
{
        p4d_t *p4d = p4d_page + p4d_index(vaddr);
        pud_t *pud = fill_pud(p4d, vaddr);

        __set_pte_vaddr(pud, vaddr, new_pte);
}

void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte)
{
        pud_t *pud = pud_page + pud_index(vaddr);

        __set_pte_vaddr(pud, vaddr, new_pte);
}

void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
{
        pgd_t *pgd;
        p4d_t *p4d_page;

        pr_debug("set_pte_vaddr %lx to %lx\n", vaddr, native_pte_val(pteval));

        pgd = pgd_offset_k(vaddr);
        if (pgd_none(*pgd)) {
                printk(KERN_ERR
                        "PGD FIXMAP MISSING, it should be setup in head.S!\n");
                return;
        }

        p4d_page = p4d_offset(pgd, 0);
        set_pte_vaddr_p4d(p4d_page, vaddr, pteval);
}

pmd_t * __init populate_extra_pmd(unsigned long vaddr)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;

        pgd = pgd_offset_k(vaddr);
        p4d = fill_p4d(pgd, vaddr);
        pud = fill_pud(p4d, vaddr);
        return fill_pmd(pud, vaddr);
}

pte_t * __init populate_extra_pte(unsigned long vaddr)
{
        pmd_t *pmd;

        pmd = populate_extra_pmd(vaddr);
        return fill_pte(pmd, vaddr);
}

/*
 * Create large page table mappings for a range of physical addresses.
 */
static void __init __init_extra_mapping(unsigned long phys, unsigned long size,
                                        enum page_cache_mode cache)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pgprot_t prot;

        pgprot_val(prot) = pgprot_val(PAGE_KERNEL_LARGE) |
                protval_4k_2_large(cachemode2protval(cache));
        BUG_ON((phys & ~PMD_MASK) || (size & ~PMD_MASK));
        for (; size; phys += PMD_SIZE, size -= PMD_SIZE) {
                pgd = pgd_offset_k((unsigned long)__va(phys));
                if (pgd_none(*pgd)) {
                        p4d = (p4d_t *) spp_getpage();
                        set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE |
                                                _PAGE_USER));
                }
                p4d = p4d_offset(pgd, (unsigned long)__va(phys));
                if (p4d_none(*p4d)) {
                        pud = (pud_t *) spp_getpage();
                        set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE |
                                                _PAGE_USER));
                }
                pud = pud_offset(p4d, (unsigned long)__va(phys));
                if (pud_none(*pud)) {
                        pmd = (pmd_t *) spp_getpage();
                        set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE |
                                                _PAGE_USER));
                }
                pmd = pmd_offset(pud, phys);
                BUG_ON(!pmd_none(*pmd));
                set_pmd(pmd, __pmd(phys | pgprot_val(prot)));
        }
}

void __init init_extra_mapping_wb(unsigned long phys, unsigned long size)
{
        __init_extra_mapping(phys, size, _PAGE_CACHE_MODE_WB);
}

void __init init_extra_mapping_uc(unsigned long phys, unsigned long size)
{
        __init_extra_mapping(phys, size, _PAGE_CACHE_MODE_UC);
}

/*
 * The head.S code sets up the kernel high mapping:
 *
 *   from __START_KERNEL_map to __START_KERNEL_map + size (== _end-_text)
 *
 * phys_base holds the negative offset to the kernel, which is added
 * to the compile time generated pmds. This results in invalid pmds up
 * to the point where we hit the physaddr 0 mapping.
 *
 * We limit the mappings to the region from _text to _brk_end.  _brk_end
 * is rounded up to the 2MB boundary. This catches the invalid pmds as
 * well, as they are located before _text:
 */
void __init cleanup_highmap(void)
{
        unsigned long vaddr = __START_KERNEL_map;
        unsigned long vaddr_end = __START_KERNEL_map + KERNEL_IMAGE_SIZE;
        unsigned long end = roundup((unsigned long)_brk_end, PMD_SIZE) - 1;
        pmd_t *pmd = level2_kernel_pgt;

        /*
         * Native path, max_pfn_mapped is not set yet.
         * Xen has valid max_pfn_mapped set in
         *      arch/x86/xen/mmu.c:xen_setup_kernel_pagetable().
         */
        if (max_pfn_mapped)
                vaddr_end = __START_KERNEL_map + (max_pfn_mapped << PAGE_SHIFT);

        for (; vaddr + PMD_SIZE - 1 < vaddr_end; pmd++, vaddr += PMD_SIZE) {
                if (pmd_none(*pmd))
                        continue;
                if (vaddr < (unsigned long) _text || vaddr > end)
                        set_pmd(pmd, __pmd(0));
        }
}

/*
 * Create PTE level page table mapping for physical addresses.
 * It returns the last physical address mapped.
 */
static unsigned long __meminit
phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end,
              pgprot_t prot, bool init)
{
        unsigned long pages = 0, paddr_next;
        unsigned long paddr_last = paddr_end;
        pte_t *pte;
        int i;

        pte = pte_page + pte_index(paddr);
        i = pte_index(paddr);

        for (; i < PTRS_PER_PTE; i++, paddr = paddr_next, pte++) {
                paddr_next = (paddr & PAGE_MASK) + PAGE_SIZE;
                if (paddr >= paddr_end) {
                        if (!after_bootmem &&
                            !e820__mapped_any(paddr & PAGE_MASK, paddr_next,
                                             E820_TYPE_RAM) &&
                            !e820__mapped_any(paddr & PAGE_MASK, paddr_next,
                                             E820_TYPE_RESERVED_KERN))
                                set_pte_init(pte, __pte(0), init);
                        continue;
                }

                /*
                 * We will re-use the existing mapping.
                 * Xen for example has some special requirements, like mapping
                 * pagetable pages as RO. So assume someone who pre-setup
                 * these mappings are more intelligent.
                 */
                if (!pte_none(*pte)) {
                        if (!after_bootmem)
                                pages++;
                        continue;
                }

                if (0)
                        pr_info("   pte=%p addr=%lx pte=%016lx\n", pte, paddr,
                                pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL).pte);
                pages++;
                set_pte_init(pte, pfn_pte(paddr >> PAGE_SHIFT, prot), init);
                paddr_last = (paddr & PAGE_MASK) + PAGE_SIZE;
        }

        update_page_count(PG_LEVEL_4K, pages);

        return paddr_last;
}

/*
 * Create PMD level page table mapping for physical addresses. The virtual
 * and physical address have to be aligned at this level.
 * It returns the last physical address mapped.
 */
static unsigned long __meminit
phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end,
              unsigned long page_size_mask, pgprot_t prot, bool init)
{
        unsigned long pages = 0, paddr_next;
        unsigned long paddr_last = paddr_end;

        int i = pmd_index(paddr);

        for (; i < PTRS_PER_PMD; i++, paddr = paddr_next) {
                pmd_t *pmd = pmd_page + pmd_index(paddr);
                pte_t *pte;
                pgprot_t new_prot = prot;

                paddr_next = (paddr & PMD_MASK) + PMD_SIZE;
                if (paddr >= paddr_end) {
                        if (!after_bootmem &&
                            !e820__mapped_any(paddr & PMD_MASK, paddr_next,
                                             E820_TYPE_RAM) &&
                            !e820__mapped_any(paddr & PMD_MASK, paddr_next,
                                             E820_TYPE_RESERVED_KERN))
                                set_pmd_init(pmd, __pmd(0), init);
                        continue;
                }

                if (!pmd_none(*pmd)) {
                        if (!pmd_large(*pmd)) {
                                spin_lock(&init_mm.page_table_lock);
                                pte = (pte_t *)pmd_page_vaddr(*pmd);
                                paddr_last = phys_pte_init(pte, paddr,
                                                           paddr_end, prot,
                                                           init);
                                spin_unlock(&init_mm.page_table_lock);
                                continue;
                        }
                        /*
                         * If we are ok with PG_LEVEL_2M mapping, then we will
                         * use the existing mapping,
                         *
                         * Otherwise, we will split the large page mapping but
                         * use the same existing protection bits except for
                         * large page, so that we don't violate Intel's TLB
                         * Application note (317080) which says, while changing
                         * the page sizes, new and old translations should
                         * not differ with respect to page frame and
                         * attributes.
                         */
                        if (page_size_mask & (1 << PG_LEVEL_2M)) {
                                if (!after_bootmem)
                                        pages++;
                                paddr_last = paddr_next;
                                continue;
                        }
                        new_prot = pte_pgprot(pte_clrhuge(*(pte_t *)pmd));
                }

                if (page_size_mask & (1<<PG_LEVEL_2M)) {
                        pages++;
                        spin_lock(&init_mm.page_table_lock);
                        set_pte_init((pte_t *)pmd,
                                     pfn_pte((paddr & PMD_MASK) >> PAGE_SHIFT,
                                             __pgprot(pgprot_val(prot) | _PAGE_PSE)),
                                     init);
                        spin_unlock(&init_mm.page_table_lock);
                        paddr_last = paddr_next;
                        continue;
                }

                pte = alloc_low_page();
                paddr_last = phys_pte_init(pte, paddr, paddr_end, new_prot, init);

                spin_lock(&init_mm.page_table_lock);
                pmd_populate_kernel_init(&init_mm, pmd, pte, init);
                spin_unlock(&init_mm.page_table_lock);
        }
        update_page_count(PG_LEVEL_2M, pages);
        return paddr_last;
}

/*
 * Create PUD level page table mapping for physical addresses. The virtual
 * and physical address do not have to be aligned at this level. KASLR can
 * randomize virtual addresses up to this level.
 * It returns the last physical address mapped.
 */
static unsigned long __meminit
phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end,
              unsigned long page_size_mask, pgprot_t _prot, bool init)
{
        unsigned long pages = 0, paddr_next;
        unsigned long paddr_last = paddr_end;
        unsigned long vaddr = (unsigned long)__va(paddr);
        int i = pud_index(vaddr);

        for (; i < PTRS_PER_PUD; i++, paddr = paddr_next) {
                pud_t *pud;
                pmd_t *pmd;
                pgprot_t prot = _prot;

                vaddr = (unsigned long)__va(paddr);
                pud = pud_page + pud_index(vaddr);
                paddr_next = (paddr & PUD_MASK) + PUD_SIZE;

                if (paddr >= paddr_end) {
                        if (!after_bootmem &&
                            !e820__mapped_any(paddr & PUD_MASK, paddr_next,
                                             E820_TYPE_RAM) &&
                            !e820__mapped_any(paddr & PUD_MASK, paddr_next,
                                             E820_TYPE_RESERVED_KERN))
                                set_pud_init(pud, __pud(0), init);
                        continue;
                }

                if (!pud_none(*pud)) {
                        if (!pud_large(*pud)) {
                                pmd = pmd_offset(pud, 0);
                                paddr_last = phys_pmd_init(pmd, paddr,
                                                           paddr_end,
                                                           page_size_mask,
                                                           prot, init);
                                continue;
                        }
                        /*
                         * If we are ok with PG_LEVEL_1G mapping, then we will
                         * use the existing mapping.
                         *
                         * Otherwise, we will split the gbpage mapping but use
                         * the same existing protection  bits except for large
                         * page, so that we don't violate Intel's TLB
                         * Application note (317080) which says, while changing
                         * the page sizes, new and old translations should
                         * not differ with respect to page frame and
                         * attributes.
                         */
                        if (page_size_mask & (1 << PG_LEVEL_1G)) {
                                if (!after_bootmem)
                                        pages++;
                                paddr_last = paddr_next;
                                continue;
                        }
                        prot = pte_pgprot(pte_clrhuge(*(pte_t *)pud));
                }

                if (page_size_mask & (1<<PG_LEVEL_1G)) {
                        pages++;
                        spin_lock(&init_mm.page_table_lock);

                        prot = __pgprot(pgprot_val(prot) | __PAGE_KERNEL_LARGE);

                        set_pte_init((pte_t *)pud,
                                     pfn_pte((paddr & PUD_MASK) >> PAGE_SHIFT,
                                             prot),
                                     init);
                        spin_unlock(&init_mm.page_table_lock);
                        paddr_last = paddr_next;
                        continue;
                }

                pmd = alloc_low_page();
                paddr_last = phys_pmd_init(pmd, paddr, paddr_end,
                                           page_size_mask, prot, init);

                spin_lock(&init_mm.page_table_lock);
                pud_populate_init(&init_mm, pud, pmd, init);
                spin_unlock(&init_mm.page_table_lock);
        }

        update_page_count(PG_LEVEL_1G, pages);

        return paddr_last;
}

static unsigned long __meminit
phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end,
              unsigned long page_size_mask, pgprot_t prot, bool init)
{
        unsigned long vaddr, vaddr_end, vaddr_next, paddr_next, paddr_last;

        paddr_last = paddr_end;
        vaddr = (unsigned long)__va(paddr);
        vaddr_end = (unsigned long)__va(paddr_end);

        if (!pgtable_l5_enabled())
                return phys_pud_init((pud_t *) p4d_page, paddr, paddr_end,
                                     page_size_mask, prot, init);

        for (; vaddr < vaddr_end; vaddr = vaddr_next) {
                p4d_t *p4d = p4d_page + p4d_index(vaddr);
                pud_t *pud;

                vaddr_next = (vaddr & P4D_MASK) + P4D_SIZE;
                paddr = __pa(vaddr);

                if (paddr >= paddr_end) {
                        paddr_next = __pa(vaddr_next);
                        if (!after_bootmem &&
                            !e820__mapped_any(paddr & P4D_MASK, paddr_next,
                                             E820_TYPE_RAM) &&
                            !e820__mapped_any(paddr & P4D_MASK, paddr_next,
                                             E820_TYPE_RESERVED_KERN))
                                set_p4d_init(p4d, __p4d(0), init);
                        continue;
                }

                if (!p4d_none(*p4d)) {
                        pud = pud_offset(p4d, 0);
                        paddr_last = phys_pud_init(pud, paddr, __pa(vaddr_end),
                                        page_size_mask, prot, init);
                        continue;
                }

                pud = alloc_low_page();
                paddr_last = phys_pud_init(pud, paddr, __pa(vaddr_end),
                                           page_size_mask, prot, init);

                spin_lock(&init_mm.page_table_lock);
                p4d_populate_init(&init_mm, p4d, pud, init);
                spin_unlock(&init_mm.page_table_lock);
        }

        return paddr_last;
}

static unsigned long __meminit
__kernel_physical_mapping_init(unsigned long paddr_start,
                               unsigned long paddr_end,
                               unsigned long page_size_mask,
                               pgprot_t prot, bool init)
{
        bool pgd_changed = false;
        unsigned long vaddr, vaddr_start, vaddr_end, vaddr_next, paddr_last;

        paddr_last = paddr_end;
        vaddr = (unsigned long)__va(paddr_start);
        vaddr_end = (unsigned long)__va(paddr_end);
        vaddr_start = vaddr;

        for (; vaddr < vaddr_end; vaddr = vaddr_next) {
                pgd_t *pgd = pgd_offset_k(vaddr);
                p4d_t *p4d;

                vaddr_next = (vaddr & PGDIR_MASK) + PGDIR_SIZE;

                if (pgd_val(*pgd)) {
                        p4d = (p4d_t *)pgd_page_vaddr(*pgd);
                        paddr_last = phys_p4d_init(p4d, __pa(vaddr),
                                                   __pa(vaddr_end),
                                                   page_size_mask,
                                                   prot, init);
                        continue;
                }

                p4d = alloc_low_page();
                paddr_last = phys_p4d_init(p4d, __pa(vaddr), __pa(vaddr_end),
                                           page_size_mask, prot, init);

                spin_lock(&init_mm.page_table_lock);
                if (pgtable_l5_enabled())
                        pgd_populate_init(&init_mm, pgd, p4d, init);
                else
                        p4d_populate_init(&init_mm, p4d_offset(pgd, vaddr),
                                          (pud_t *) p4d, init);

                spin_unlock(&init_mm.page_table_lock);
                pgd_changed = true;
        }

        if (pgd_changed)
                sync_global_pgds(vaddr_start, vaddr_end - 1);

        return paddr_last;
}


/*
 * Create page table mapping for the physical memory for specific physical
 * addresses. Note that it can only be used to populate non-present entries.
 * The virtual and physical addresses have to be aligned on PMD level
 * down. It returns the last physical address mapped.
 */
unsigned long __meminit
kernel_physical_mapping_init(unsigned long paddr_start,
                             unsigned long paddr_end,
                             unsigned long page_size_mask, pgprot_t prot)
{
        return __kernel_physical_mapping_init(paddr_start, paddr_end,
                                              page_size_mask, prot, true);
}

/*
 * This function is similar to kernel_physical_mapping_init() above with the
 * exception that it uses set_{pud,pmd}() instead of the set_{pud,pte}_safe()
 * when updating the mapping. The caller is responsible to flush the TLBs after
 * the function returns.
 */
unsigned long __meminit
kernel_physical_mapping_change(unsigned long paddr_start,
                               unsigned long paddr_end,
                               unsigned long page_size_mask)
{
        return __kernel_physical_mapping_init(paddr_start, paddr_end,
                                              page_size_mask, PAGE_KERNEL,
                                              false);
}

#ifndef CONFIG_NUMA
void __init initmem_init(void)
{
        memblock_set_node(0, PHYS_ADDR_MAX, &memblock.memory, 0);
}
#endif

void __init paging_init(void)
{
        sparse_init();

        /*
         * clear the default setting with node 0
         * note: don't use nodes_clear here, that is really clearing when
         *       numa support is not compiled in, and later node_set_state
         *       will not set it back.
         */
        node_clear_state(0, N_MEMORY);
        node_clear_state(0, N_NORMAL_MEMORY);

        zone_sizes_init();
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
#define PAGE_UNUSED 0xFD

/*
 * The unused vmemmap range, which was not yet memset(PAGE_UNUSED), ranges
 * from unused_pmd_start to next PMD_SIZE boundary.
 */
static unsigned long unused_pmd_start __meminitdata;

static void __meminit vmemmap_flush_unused_pmd(void)
{
        if (!unused_pmd_start)
                return;
        /*
         * Clears (unused_pmd_start, PMD_END]
         */
        memset((void *)unused_pmd_start, PAGE_UNUSED,
               ALIGN(unused_pmd_start, PMD_SIZE) - unused_pmd_start);
        unused_pmd_start = 0;
}

#ifdef CONFIG_MEMORY_HOTPLUG
/* Returns true if the PMD is completely unused and thus it can be freed */
static bool __meminit vmemmap_pmd_is_unused(unsigned long addr, unsigned long end)
{
        unsigned long start = ALIGN_DOWN(addr, PMD_SIZE);

        /*
         * Flush the unused range cache to ensure that memchr_inv() will work
         * for the whole range.
         */
        vmemmap_flush_unused_pmd();
        memset((void *)addr, PAGE_UNUSED, end - addr);

        return !memchr_inv((void *)start, PAGE_UNUSED, PMD_SIZE);
}
#endif

static void __meminit __vmemmap_use_sub_pmd(unsigned long start)
{
        /*
         * As we expect to add in the same granularity as we remove, it's
         * sufficient to mark only some piece used to block the memmap page from
         * getting removed when removing some other adjacent memmap (just in
         * case the first memmap never gets initialized e.g., because the memory
         * block never gets onlined).
         */
        memset((void *)start, 0, sizeof(struct page));
}

static void __meminit vmemmap_use_sub_pmd(unsigned long start, unsigned long end)
{
        /*
         * We only optimize if the new used range directly follows the
         * previously unused range (esp., when populating consecutive sections).
         */
        if (unused_pmd_start == start) {
                if (likely(IS_ALIGNED(end, PMD_SIZE)))
                        unused_pmd_start = 0;
                else
                        unused_pmd_start = end;
                return;
        }

        /*
         * If the range does not contiguously follows previous one, make sure
         * to mark the unused range of the previous one so it can be removed.
         */
        vmemmap_flush_unused_pmd();
        __vmemmap_use_sub_pmd(start);
}


static void __meminit vmemmap_use_new_sub_pmd(unsigned long start, unsigned long end)
{
        vmemmap_flush_unused_pmd();

        /*
         * Could be our memmap page is filled with PAGE_UNUSED already from a
         * previous remove. Make sure to reset it.
         */
        __vmemmap_use_sub_pmd(start);

        /*
         * Mark with PAGE_UNUSED the unused parts of the new memmap range
         */
        if (!IS_ALIGNED(start, PMD_SIZE))
                memset((void *)start, PAGE_UNUSED,
                        start - ALIGN_DOWN(start, PMD_SIZE));

        /*
         * We want to avoid memset(PAGE_UNUSED) when populating the vmemmap of
         * consecutive sections. Remember for the last added PMD where the
         * unused range begins.
         */
        if (!IS_ALIGNED(end, PMD_SIZE))
                unused_pmd_start = end;
}
#endif

/*
 * Memory hotplug specific functions
 */
#ifdef CONFIG_MEMORY_HOTPLUG
/*
 * After memory hotplug the variables max_pfn, max_low_pfn and high_memory need
 * updating.
 */
static void update_end_of_memory_vars(u64 start, u64 size)
{
        unsigned long end_pfn = PFN_UP(start + size);

        if (end_pfn > max_pfn) {
                max_pfn = end_pfn;
                max_low_pfn = end_pfn;
                high_memory = (void *)__va(max_pfn * PAGE_SIZE - 1) + 1;
        }
}

int add_pages(int nid, unsigned long start_pfn, unsigned long nr_pages,
              struct mhp_params *params)
{
        int ret;

        ret = __add_pages(nid, start_pfn, nr_pages, params);
        WARN_ON_ONCE(ret);

        /* update max_pfn, max_low_pfn and high_memory */
        update_end_of_memory_vars(start_pfn << PAGE_SHIFT,
                                  nr_pages << PAGE_SHIFT);

        return ret;
}

int arch_add_memory(int nid, u64 start, u64 size,
                    struct mhp_params *params)
{
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;

        init_memory_mapping(start, start + size, params->pgprot);

        return add_pages(nid, start_pfn, nr_pages, params);
}

static void __meminit free_pagetable(struct page *page, int order)
{
        unsigned long magic;
        unsigned int nr_pages = 1 << order;

        /* bootmem page has reserved flag */
        if (PageReserved(page)) {
                __ClearPageReserved(page);

                magic = (unsigned long)page->freelist;
                if (magic == SECTION_INFO || magic == MIX_SECTION_INFO) {
                        while (nr_pages--)
                                put_page_bootmem(page++);
                } else
                        while (nr_pages--)
                                free_reserved_page(page++);
        } else
                free_pages((unsigned long)page_address(page), order);
}

static void __meminit free_hugepage_table(struct page *page,
                struct vmem_altmap *altmap)
{
        if (altmap)
                vmem_altmap_free(altmap, PMD_SIZE / PAGE_SIZE);
        else
                free_pagetable(page, get_order(PMD_SIZE));
}

static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd)
{
        pte_t *pte;
        int i;

        for (i = 0; i < PTRS_PER_PTE; i++) {
                pte = pte_start + i;
                if (!pte_none(*pte))
                        return;
        }

        /* free a pte talbe */
        free_pagetable(pmd_page(*pmd), 0);
        spin_lock(&init_mm.page_table_lock);
        pmd_clear(pmd);
        spin_unlock(&init_mm.page_table_lock);
}

static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud)
{
        pmd_t *pmd;
        int i;

        for (i = 0; i < PTRS_PER_PMD; i++) {
                pmd = pmd_start + i;
                if (!pmd_none(*pmd))
                        return;
        }

        /* free a pmd talbe */
        free_pagetable(pud_page(*pud), 0);
        spin_lock(&init_mm.page_table_lock);
        pud_clear(pud);
        spin_unlock(&init_mm.page_table_lock);
}

static void __meminit free_pud_table(pud_t *pud_start, p4d_t *p4d)
{
        pud_t *pud;
        int i;

        for (i = 0; i < PTRS_PER_PUD; i++) {
                pud = pud_start + i;
                if (!pud_none(*pud))
                        return;
        }

        /* free a pud talbe */
        free_pagetable(p4d_page(*p4d), 0);
        spin_lock(&init_mm.page_table_lock);
        p4d_clear(p4d);
        spin_unlock(&init_mm.page_table_lock);
}

static void __meminit
remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end,
                 bool direct)
{
        unsigned long next, pages = 0;
        pte_t *pte;
        phys_addr_t phys_addr;

        pte = pte_start + pte_index(addr);
        for (; addr < end; addr = next, pte++) {
                next = (addr + PAGE_SIZE) & PAGE_MASK;
                if (next > end)
                        next = end;

                if (!pte_present(*pte))
                        continue;

                /*
                 * We mapped [0,1G) memory as identity mapping when
                 * initializing, in arch/x86/kernel/head_64.S. These
                 * pagetables cannot be removed.
                 */
                phys_addr = pte_val(*pte) + (addr & PAGE_MASK);
                if (phys_addr < (phys_addr_t)0x40000000)
                        return;

                if (!direct)
                        free_pagetable(pte_page(*pte), 0);

                spin_lock(&init_mm.page_table_lock);
                pte_clear(&init_mm, addr, pte);
                spin_unlock(&init_mm.page_table_lock);

                /* For non-direct mapping, pages means nothing. */
                pages++;
        }

        /* Call free_pte_table() in remove_pmd_table(). */
        flush_tlb_all();
        if (direct)
                update_page_count(PG_LEVEL_4K, -pages);
}

static void __meminit
remove_pmd_table(pmd_t *pmd_start, unsigned long addr, unsigned long end,
                 bool direct, struct vmem_altmap *altmap)
{
        unsigned long next, pages = 0;
        pte_t *pte_base;
        pmd_t *pmd;

        pmd = pmd_start + pmd_index(addr);
        for (; addr < end; addr = next, pmd++) {
                next = pmd_addr_end(addr, end);

                if (!pmd_present(*pmd))
                        continue;

                if (pmd_large(*pmd)) {
                        if (IS_ALIGNED(addr, PMD_SIZE) &&
                            IS_ALIGNED(next, PMD_SIZE)) {
                                if (!direct)
                                        free_hugepage_table(pmd_page(*pmd),
                                                            altmap);

                                spin_lock(&init_mm.page_table_lock);
                                pmd_clear(pmd);
                                spin_unlock(&init_mm.page_table_lock);
                                pages++;
                        }
#ifdef CONFIG_SPARSEMEM_VMEMMAP
                        else if (vmemmap_pmd_is_unused(addr, next)) {
                                        free_hugepage_table(pmd_page(*pmd),
                                                            altmap);
                                        spin_lock(&init_mm.page_table_lock);
                                        pmd_clear(pmd);
                                        spin_unlock(&init_mm.page_table_lock);
                        }
#endif
                        continue;
                }

                pte_base = (pte_t *)pmd_page_vaddr(*pmd);
                remove_pte_table(pte_base, addr, next, direct);
                free_pte_table(pte_base, pmd);
        }

        /* Call free_pmd_table() in remove_pud_table(). */
        if (direct)
                update_page_count(PG_LEVEL_2M, -pages);
}

static void __meminit
remove_pud_table(pud_t *pud_start, unsigned long addr, unsigned long end,
                 struct vmem_altmap *altmap, bool direct)
{
        unsigned long next, pages = 0;
        pmd_t *pmd_base;
        pud_t *pud;

        pud = pud_start + pud_index(addr);
        for (; addr < end; addr = next, pud++) {
                next = pud_addr_end(addr, end);

                if (!pud_present(*pud))
                        continue;

                if (pud_large(*pud) &&
                    IS_ALIGNED(addr, PUD_SIZE) &&
                    IS_ALIGNED(next, PUD_SIZE)) {
                        spin_lock(&init_mm.page_table_lock);
                        pud_clear(pud);
                        spin_unlock(&init_mm.page_table_lock);
                        pages++;
                        continue;
                }

                pmd_base = pmd_offset(pud, 0);
                remove_pmd_table(pmd_base, addr, next, direct, altmap);
                free_pmd_table(pmd_base, pud);
        }

        if (direct)
                update_page_count(PG_LEVEL_1G, -pages);
}

static void __meminit
remove_p4d_table(p4d_t *p4d_start, unsigned long addr, unsigned long end,
                 struct vmem_altmap *altmap, bool direct)
{
        unsigned long next, pages = 0;
        pud_t *pud_base;
        p4d_t *p4d;

        p4d = p4d_start + p4d_index(addr);
        for (; addr < end; addr = next, p4d++) {
                next = p4d_addr_end(addr, end);

                if (!p4d_present(*p4d))
                        continue;

                BUILD_BUG_ON(p4d_large(*p4d));

                pud_base = pud_offset(p4d, 0);
                remove_pud_table(pud_base, addr, next, altmap, direct);
                /*
                 * For 4-level page tables we do not want to free PUDs, but in the
                 * 5-level case we should free them. This code will have to change
                 * to adapt for boot-time switching between 4 and 5 level page tables.
                 */
                if (pgtable_l5_enabled())
                        free_pud_table(pud_base, p4d);
        }

        if (direct)
                update_page_count(PG_LEVEL_512G, -pages);
}

/* start and end are both virtual address. */
static void __meminit
remove_pagetable(unsigned long start, unsigned long end, bool direct,
                struct vmem_altmap *altmap)
{
        unsigned long next;
        unsigned long addr;
        pgd_t *pgd;
        p4d_t *p4d;

        for (addr = start; addr < end; addr = next) {
                next = pgd_addr_end(addr, end);

                pgd = pgd_offset_k(addr);
                if (!pgd_present(*pgd))
                        continue;

                p4d = p4d_offset(pgd, 0);
                remove_p4d_table(p4d, addr, next, altmap, direct);
        }

        flush_tlb_all();
}

void __ref vmemmap_free(unsigned long start, unsigned long end,
                struct vmem_altmap *altmap)
{
        VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE));
        VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE));

        remove_pagetable(start, end, false, altmap);
}

static void __meminit
kernel_physical_mapping_remove(unsigned long start, unsigned long end)
{
        start = (unsigned long)__va(start);
        end = (unsigned long)__va(end);

        remove_pagetable(start, end, true, NULL);
}

void __ref arch_remove_memory(int nid, 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);
        kernel_physical_mapping_remove(start, start + size);
}
#endif /* CONFIG_MEMORY_HOTPLUG */

static struct kcore_list kcore_vsyscall;

static void __init register_page_bootmem_info(void)
{
#if defined(CONFIG_NUMA) || defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP)
        int i;

        for_each_online_node(i)
                register_page_bootmem_info_node(NODE_DATA(i));
#endif
}

/*
 * Pre-allocates page-table pages for the vmalloc area in the kernel page-table.
 * Only the level which needs to be synchronized between all page-tables is
 * allocated because the synchronization can be expensive.
 */
static void __init preallocate_vmalloc_pages(void)
{
        unsigned long addr;
        const char *lvl;

        for (addr = VMALLOC_START; addr <= VMALLOC_END; addr = ALIGN(addr + 1, PGDIR_SIZE)) {
                pgd_t *pgd = pgd_offset_k(addr);
                p4d_t *p4d;
                pud_t *pud;

                lvl = "p4d";
                p4d = p4d_alloc(&init_mm, pgd, addr);
                if (!p4d)
                        goto failed;

                if (pgtable_l5_enabled())
                        continue;

                /*
                 * The goal here is to allocate all possibly required
                 * hardware page tables pointed to by the top hardware
                 * level.
                 *
                 * On 4-level systems, the P4D layer is folded away and
                 * the above code does no preallocation.  Below, go down
                 * to the pud _software_ level to ensure the second
                 * hardware level is allocated on 4-level systems too.
                 */
                lvl = "pud";
                pud = pud_alloc(&init_mm, p4d, addr);
                if (!pud)
                        goto failed;
        }

        return;

failed:

        /*
         * The pages have to be there now or they will be missing in
         * process page-tables later.
         */
        panic("Failed to pre-allocate %s pages for vmalloc area\n", lvl);
}

void __init mem_init(void)
{
        pci_iommu_alloc();

        /* clear_bss() already clear the empty_zero_page */

        /* this will put all memory onto the freelists */
        memblock_free_all();
        after_bootmem = 1;
        x86_init.hyper.init_after_bootmem();

        /*
         * Must be done after boot memory is put on freelist, because here we
         * might set fields in deferred struct pages that have not yet been
         * initialized, and memblock_free_all() initializes all the reserved
         * deferred pages for us.
         */
        register_page_bootmem_info();

        /* Register memory areas for /proc/kcore */
        if (get_gate_vma(&init_mm))
                kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR, PAGE_SIZE, KCORE_USER);

        preallocate_vmalloc_pages();
}

#ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
int __init deferred_page_init_max_threads(const struct cpumask *node_cpumask)
{
        /*
         * More CPUs always led to greater speedups on tested systems, up to
         * all the nodes' CPUs.  Use all since the system is otherwise idle
         * now.
         */
        return max_t(int, cpumask_weight(node_cpumask), 1);
}
#endif

int kernel_set_to_readonly;

void mark_rodata_ro(void)
{
        unsigned long start = PFN_ALIGN(_text);
        unsigned long rodata_start = PFN_ALIGN(__start_rodata);
        unsigned long end = (unsigned long)__end_rodata_hpage_align;
        unsigned long text_end = PFN_ALIGN(_etext);
        unsigned long rodata_end = PFN_ALIGN(__end_rodata);
        unsigned long all_end;

        printk(KERN_INFO "Write protecting the kernel read-only data: %luk\n",
               (end - start) >> 10);
        set_memory_ro(start, (end - start) >> PAGE_SHIFT);

        kernel_set_to_readonly = 1;

        /*
         * The rodata/data/bss/brk section (but not the kernel text!)
         * should also be not-executable.
         *
         * We align all_end to PMD_SIZE because the existing mapping
         * is a full PMD. If we would align _brk_end to PAGE_SIZE we
         * split the PMD and the reminder between _brk_end and the end
         * of the PMD will remain mapped executable.
         *
         * Any PMD which was setup after the one which covers _brk_end
         * has been zapped already via cleanup_highmem().
         */
        all_end = roundup((unsigned long)_brk_end, PMD_SIZE);
        set_memory_nx(text_end, (all_end - text_end) >> PAGE_SHIFT);

        set_ftrace_ops_ro();

#ifdef CONFIG_CPA_DEBUG
        printk(KERN_INFO "Testing CPA: undo %lx-%lx\n", start, end);
        set_memory_rw(start, (end-start) >> PAGE_SHIFT);

        printk(KERN_INFO "Testing CPA: again\n");
        set_memory_ro(start, (end-start) >> PAGE_SHIFT);
#endif

        free_kernel_image_pages("unused kernel image (text/rodata gap)",
                                (void *)text_end, (void *)rodata_start);
        free_kernel_image_pages("unused kernel image (rodata/data gap)",
                                (void *)rodata_end, (void *)_sdata);

        debug_checkwx();
}

int kern_addr_valid(unsigned long addr)
{
        unsigned long above = ((long)addr) >> __VIRTUAL_MASK_SHIFT;
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        if (above != 0 && above != -1UL)
                return 0;

        pgd = pgd_offset_k(addr);
        if (pgd_none(*pgd))
                return 0;

        p4d = p4d_offset(pgd, addr);
        if (p4d_none(*p4d))
                return 0;

        pud = pud_offset(p4d, addr);
        if (pud_none(*pud))
                return 0;

        if (pud_large(*pud))
                return pfn_valid(pud_pfn(*pud));

        pmd = pmd_offset(pud, addr);
        if (pmd_none(*pmd))
                return 0;

        if (pmd_large(*pmd))
                return pfn_valid(pmd_pfn(*pmd));

        pte = pte_offset_kernel(pmd, addr);
        if (pte_none(*pte))
                return 0;

        return pfn_valid(pte_pfn(*pte));
}

/*
 * Block size is the minimum amount of memory which can be hotplugged or
 * hotremoved. It must be power of two and must be equal or larger than
 * MIN_MEMORY_BLOCK_SIZE.
 */
#define MAX_BLOCK_SIZE (2UL << 30)

/* Amount of ram needed to start using large blocks */
#define MEM_SIZE_FOR_LARGE_BLOCK (64UL << 30)

/* Adjustable memory block size */
static unsigned long set_memory_block_size;
int __init set_memory_block_size_order(unsigned int order)
{
        unsigned long size = 1UL << order;

        if (size > MEM_SIZE_FOR_LARGE_BLOCK || size < MIN_MEMORY_BLOCK_SIZE)
                return -EINVAL;

        set_memory_block_size = size;
        return 0;
}

static unsigned long probe_memory_block_size(void)
{
        unsigned long boot_mem_end = max_pfn << PAGE_SHIFT;
        unsigned long bz;

        /* If memory block size has been set, then use it */
        bz = set_memory_block_size;
        if (bz)
                goto done;

        /* Use regular block if RAM is smaller than MEM_SIZE_FOR_LARGE_BLOCK */
        if (boot_mem_end < MEM_SIZE_FOR_LARGE_BLOCK) {
                bz = MIN_MEMORY_BLOCK_SIZE;
                goto done;
        }

        /*
         * Use max block size to minimize overhead on bare metal, where
         * alignment for memory hotplug isn't a concern.
         */
        if (!boot_cpu_has(X86_FEATURE_HYPERVISOR)) {
                bz = MAX_BLOCK_SIZE;
                goto done;
        }

        /* Find the largest allowed block size that aligns to memory end */
        for (bz = MAX_BLOCK_SIZE; bz > MIN_MEMORY_BLOCK_SIZE; bz >>= 1) {
                if (IS_ALIGNED(boot_mem_end, bz))
                        break;
        }
done:
        pr_info("x86/mm: Memory block size: %ldMB\n", bz >> 20);

        return bz;
}

static unsigned long memory_block_size_probed;
unsigned long memory_block_size_bytes(void)
{
        if (!memory_block_size_probed)
                memory_block_size_probed = probe_memory_block_size();

        return memory_block_size_probed;
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
/*
 * Initialise the sparsemem vmemmap using huge-pages at the PMD level.
 */
static long __meminitdata addr_start, addr_end;
static void __meminitdata *p_start, *p_end;
static int __meminitdata node_start;

static int __meminit vmemmap_populate_hugepages(unsigned long start,
                unsigned long end, int node, struct vmem_altmap *altmap)
{
        unsigned long addr;
        unsigned long next;
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;

        for (addr = start; addr < end; addr = next) {
                next = pmd_addr_end(addr, end);

                pgd = vmemmap_pgd_populate(addr, node);
                if (!pgd)
                        return -ENOMEM;

                p4d = vmemmap_p4d_populate(pgd, addr, node);
                if (!p4d)
                        return -ENOMEM;

                pud = vmemmap_pud_populate(p4d, addr, node);
                if (!pud)
                        return -ENOMEM;

                pmd = pmd_offset(pud, addr);
                if (pmd_none(*pmd)) {
                        void *p;

                        p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
                        if (p) {
                                pte_t entry;

                                entry = pfn_pte(__pa(p) >> PAGE_SHIFT,
                                                PAGE_KERNEL_LARGE);
                                set_pmd(pmd, __pmd(pte_val(entry)));

                                /* check to see if we have contiguous blocks */
                                if (p_end != p || node_start != node) {
                                        if (p_start)
                                                pr_debug(" [%lx-%lx] PMD -> [%p-%p] on node %d\n",
                                                       addr_start, addr_end-1, p_start, p_end-1, node_start);
                                        addr_start = addr;
                                        node_start = node;
                                        p_start = p;
                                }

                                addr_end = addr + PMD_SIZE;
                                p_end = p + PMD_SIZE;

                                if (!IS_ALIGNED(addr, PMD_SIZE) ||
                                    !IS_ALIGNED(next, PMD_SIZE))
                                        vmemmap_use_new_sub_pmd(addr, next);

                                continue;
                        } else if (altmap)
                                return -ENOMEM; /* no fallback */
                } else if (pmd_large(*pmd)) {
                        vmemmap_verify((pte_t *)pmd, node, addr, next);
                        vmemmap_use_sub_pmd(addr, next);
                        continue;
                }
                if (vmemmap_populate_basepages(addr, next, node, NULL))
                        return -ENOMEM;
        }
        return 0;
}

int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
                struct vmem_altmap *altmap)
{
        int err;

        VM_BUG_ON(!IS_ALIGNED(start, PAGE_SIZE));
        VM_BUG_ON(!IS_ALIGNED(end, PAGE_SIZE));

        if ((is_hugetlb_free_vmemmap_enabled()  && !altmap) ||
            end - start < PAGES_PER_SECTION * sizeof(struct page))
                err = vmemmap_populate_basepages(start, end, node, NULL);
        else if (boot_cpu_has(X86_FEATURE_PSE))
                err = vmemmap_populate_hugepages(start, end, node, altmap);
        else if (altmap) {
                pr_err_once("%s: no cpu support for altmap allocations\n",
                                __func__);
                err = -ENOMEM;
        } else
                err = vmemmap_populate_basepages(start, end, node, NULL);
        if (!err)
                sync_global_pgds(start, end - 1);
        return err;
}

#ifdef CONFIG_HAVE_BOOTMEM_INFO_NODE
void register_page_bootmem_memmap(unsigned long section_nr,
                                  struct page *start_page, unsigned long nr_pages)
{
        unsigned long addr = (unsigned long)start_page;
        unsigned long end = (unsigned long)(start_page + nr_pages);
        unsigned long next;
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        unsigned int nr_pmd_pages;
        struct page *page;
        bool base_mapping = !boot_cpu_has(X86_FEATURE_PSE) ||
                            is_hugetlb_free_vmemmap_enabled();

        for (; addr < end; addr = next) {
                pte_t *pte = NULL;

                pgd = pgd_offset_k(addr);
                if (pgd_none(*pgd)) {
                        next = (addr + PAGE_SIZE) & PAGE_MASK;
                        continue;
                }
                get_page_bootmem(section_nr, pgd_page(*pgd), MIX_SECTION_INFO);

                p4d = p4d_offset(pgd, addr);
                if (p4d_none(*p4d)) {
                        next = (addr + PAGE_SIZE) & PAGE_MASK;
                        continue;
                }
                get_page_bootmem(section_nr, p4d_page(*p4d), MIX_SECTION_INFO);

                pud = pud_offset(p4d, addr);
                if (pud_none(*pud)) {
                        next = (addr + PAGE_SIZE) & PAGE_MASK;
                        continue;
                }
                get_page_bootmem(section_nr, pud_page(*pud), MIX_SECTION_INFO);

                if (base_mapping) {
                        next = (addr + PAGE_SIZE) & PAGE_MASK;
                        pmd = pmd_offset(pud, addr);
                        if (pmd_none(*pmd))
                                continue;
                        get_page_bootmem(section_nr, pmd_page(*pmd),
                                         MIX_SECTION_INFO);

                        pte = pte_offset_kernel(pmd, addr);
                        if (pte_none(*pte))
                                continue;
                        get_page_bootmem(section_nr, pte_page(*pte),
                                         SECTION_INFO);
                } else {
                        next = pmd_addr_end(addr, end);

                        pmd = pmd_offset(pud, addr);
                        if (pmd_none(*pmd))
                                continue;

                        nr_pmd_pages = 1 << get_order(PMD_SIZE);
                        page = pmd_page(*pmd);
                        while (nr_pmd_pages--)
                                get_page_bootmem(section_nr, page++,
                                                 SECTION_INFO);
                }
        }
}
#endif

void __meminit vmemmap_populate_print_last(void)
{
        if (p_start) {
                pr_debug(" [%lx-%lx] PMD -> [%p-%p] on node %d\n",
                        addr_start, addr_end-1, p_start, p_end-1, node_start);
                p_start = NULL;
                p_end = NULL;
                node_start = 0;
        }
}
#endif