Add support for Allo Piano DAC 2.1 plus add-on board for Raspberry Pi.

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

/*
 *  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/bootmem.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 <asm/processor.h>
#include <asm/bios_ebda.h>
#include <linux/uaccess.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/dma.h>
#include <asm/fixmap.h>
#include <asm/e820.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/cacheflush.h>
#include <asm/init.h>
#include <asm/uv/uv.h>
#include <asm/setup.h>

#include "mm_internal.h"

#include "ident_map.c"

/*
 * 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.
 */

pteval_t __supported_pte_mask __read_mostly = ~0;
EXPORT_SYMBOL_GPL(__supported_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);

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

        for (address = start; address <= end; address += PGDIR_SIZE) {
                const pgd_t *pgd_ref = pgd_offset_k(address);
                struct page *page;

                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(address);
                        /* 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);
        }
}

/*
 * 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 | __GFP_NOTRACK);
        else
                ptr = alloc_bootmem_pages(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 pud_t *fill_pud(pgd_t *pgd, unsigned long vaddr)
{
        if (pgd_none(*pgd)) {
                pud_t *pud = (pud_t *)spp_getpage();
                pgd_populate(&init_mm, pgd, pud);
                if (pud != pud_offset(pgd, 0))
                        printk(KERN_ERR "PAGETABLE BUG #00! %p <-> %p\n",
                               pud, pud_offset(pgd, 0));
        }
        return pud_offset(pgd, 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 #01! %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 #02!\n");
        }
        return pte_offset_kernel(pmd, vaddr);
}

void set_pte_vaddr_pud(pud_t *pud_page, unsigned long vaddr, pte_t new_pte)
{
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        pud = pud_page + pud_index(vaddr);
        pmd = fill_pmd(pud, vaddr);
        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(vaddr);
}

void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
{
        pgd_t *pgd;
        pud_t *pud_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;
        }
        pud_page = (pud_t*)pgd_page_vaddr(*pgd);
        set_pte_vaddr_pud(pud_page, vaddr, pteval);
}

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

        pgd = pgd_offset_k(vaddr);
        pud = fill_pud(pgd, 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;
        pud_t *pud;
        pmd_t *pmd;
        pgprot_t prot;

        pgprot_val(prot) = pgprot_val(PAGE_KERNEL_LARGE) |
                pgprot_val(pgprot_4k_2_large(cachemode2pgprot(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)) {
                        pud = (pud_t *) spp_getpage();
                        set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE |
                                                _PAGE_USER));
                }
                pud = pud_offset(pgd, (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)
{
        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_any_mapped(paddr & PAGE_MASK, paddr_next,
                                             E820_RAM) &&
                            !e820_any_mapped(paddr & PAGE_MASK, paddr_next,
                                             E820_RESERVED_KERN))
                                set_pte(pte, __pte(0));
                        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(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
                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)
{
        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_any_mapped(paddr & PMD_MASK, paddr_next,
                                             E820_RAM) &&
                            !e820_any_mapped(paddr & PMD_MASK, paddr_next,
                                             E820_RESERVED_KERN))
                                set_pmd(pmd, __pmd(0));
                        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);
                                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((pte_t *)pmd,
                                pfn_pte((paddr & PMD_MASK) >> PAGE_SHIFT,
                                        __pgprot(pgprot_val(prot) | _PAGE_PSE)));
                        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);

                spin_lock(&init_mm.page_table_lock);
                pmd_populate_kernel(&init_mm, pmd, pte);
                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)
{
        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 = PAGE_KERNEL;

                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_any_mapped(paddr & PUD_MASK, paddr_next,
                                             E820_RAM) &&
                            !e820_any_mapped(paddr & PUD_MASK, paddr_next,
                                             E820_RESERVED_KERN))
                                set_pud(pud, __pud(0));
                        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);
                                __flush_tlb_all();
                                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);
                        set_pte((pte_t *)pud,
                                pfn_pte((paddr & PUD_MASK) >> PAGE_SHIFT,
                                        PAGE_KERNEL_LARGE));
                        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);

                spin_lock(&init_mm.page_table_lock);
                pud_populate(&init_mm, pud, pmd);
                spin_unlock(&init_mm.page_table_lock);
        }
        __flush_tlb_all();

        update_page_count(PG_LEVEL_1G, pages);

        return paddr_last;
}

/*
 * Create page table mapping for the physical memory for specific physical
 * addresses. 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)
{
        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);
                pud_t *pud;

                vaddr_next = (vaddr & PGDIR_MASK) + PGDIR_SIZE;

                if (pgd_val(*pgd)) {
                        pud = (pud_t *)pgd_page_vaddr(*pgd);
                        paddr_last = phys_pud_init(pud, __pa(vaddr),
                                                   __pa(vaddr_end),
                                                   page_size_mask);
                        continue;
                }

                pud = alloc_low_page();
                paddr_last = phys_pud_init(pud, __pa(vaddr), __pa(vaddr_end),
                                           page_size_mask);

                spin_lock(&init_mm.page_table_lock);
                pgd_populate(&init_mm, pgd, pud);
                spin_unlock(&init_mm.page_table_lock);
                pgd_changed = true;
        }

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

        __flush_tlb_all();

        return paddr_last;
}

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

void __init paging_init(void)
{
        sparse_memory_present_with_active_regions(MAX_NUMNODES);
        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);
        if (N_MEMORY != N_NORMAL_MEMORY)
                node_clear_state(0, N_NORMAL_MEMORY);

        zone_sizes_init();
}

/*
 * 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;
        }
}

/*
 * Memory is added always to NORMAL zone. This means you will never get
 * additional DMA/DMA32 memory.
 */
int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
{
        struct pglist_data *pgdat = NODE_DATA(nid);
        struct zone *zone = pgdat->node_zones +
                zone_for_memory(nid, start, size, ZONE_NORMAL, for_device);
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
        int ret;

        init_memory_mapping(start, start + size);

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

        /* update max_pfn, max_low_pfn and high_memory */
        update_end_of_memory_vars(start, size);

        return ret;
}
EXPORT_SYMBOL_GPL(arch_add_memory);

#define PAGE_INUSE 0xFD

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

        if (altmap) {
                vmem_altmap_free(altmap, nr_pages);
                return;
        }

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

                magic = (unsigned long)page->lru.next;
                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_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
remove_pte_table(pte_t *pte_start, unsigned long addr, unsigned long end,
                 bool direct)
{
        unsigned long next, pages = 0;
        pte_t *pte;
        void *page_addr;
        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 (PAGE_ALIGNED(addr) && PAGE_ALIGNED(next)) {
                        /*
                         * Do not free direct mapping pages since they were
                         * freed when offlining, or simplely not in use.
                         */
                        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++;
                } else {
                        /*
                         * If we are here, we are freeing vmemmap pages since
                         * direct mapped memory ranges to be freed are aligned.
                         *
                         * If we are not removing the whole page, it means
                         * other page structs in this page are being used and
                         * we canot remove them. So fill the unused page_structs
                         * with 0xFD, and remove the page when it is wholly
                         * filled with 0xFD.
                         */
                        memset((void *)addr, PAGE_INUSE, next - addr);

                        page_addr = page_address(pte_page(*pte));
                        if (!memchr_inv(page_addr, PAGE_INUSE, PAGE_SIZE)) {
                                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);
                        }
                }
        }

        /* 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)
{
        unsigned long next, pages = 0;
        pte_t *pte_base;
        pmd_t *pmd;
        void *page_addr;

        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_pagetable(pmd_page(*pmd),
                                                       get_order(PMD_SIZE));

                                spin_lock(&init_mm.page_table_lock);
                                pmd_clear(pmd);
                                spin_unlock(&init_mm.page_table_lock);
                                pages++;
                        } else {
                                /* If here, we are freeing vmemmap pages. */
                                memset((void *)addr, PAGE_INUSE, next - addr);

                                page_addr = page_address(pmd_page(*pmd));
                                if (!memchr_inv(page_addr, PAGE_INUSE,
                                                PMD_SIZE)) {
                                        free_pagetable(pmd_page(*pmd),
                                                       get_order(PMD_SIZE));

                                        spin_lock(&init_mm.page_table_lock);
                                        pmd_clear(pmd);
                                        spin_unlock(&init_mm.page_table_lock);
                                }
                        }

                        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,
                 bool direct)
{
        unsigned long next, pages = 0;
        pmd_t *pmd_base;
        pud_t *pud;
        void *page_addr;

        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)) {
                        if (IS_ALIGNED(addr, PUD_SIZE) &&
                            IS_ALIGNED(next, PUD_SIZE)) {
                                if (!direct)
                                        free_pagetable(pud_page(*pud),
                                                       get_order(PUD_SIZE));

                                spin_lock(&init_mm.page_table_lock);
                                pud_clear(pud);
                                spin_unlock(&init_mm.page_table_lock);
                                pages++;
                        } else {
                                /* If here, we are freeing vmemmap pages. */
                                memset((void *)addr, PAGE_INUSE, next - addr);

                                page_addr = page_address(pud_page(*pud));
                                if (!memchr_inv(page_addr, PAGE_INUSE,
                                                PUD_SIZE)) {
                                        free_pagetable(pud_page(*pud),
                                                       get_order(PUD_SIZE));

                                        spin_lock(&init_mm.page_table_lock);
                                        pud_clear(pud);
                                        spin_unlock(&init_mm.page_table_lock);
                                }
                        }

                        continue;
                }

                pmd_base = (pmd_t *)pud_page_vaddr(*pud);
                remove_pmd_table(pmd_base, addr, next, direct);
                free_pmd_table(pmd_base, pud);
        }

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

/* start and end are both virtual address. */
static void __meminit
remove_pagetable(unsigned long start, unsigned long end, bool direct)
{
        unsigned long next;
        unsigned long addr;
        pgd_t *pgd;
        pud_t *pud;

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

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

                pud = (pud_t *)pgd_page_vaddr(*pgd);
                remove_pud_table(pud, addr, next, direct);
        }

        flush_tlb_all();
}

void __ref vmemmap_free(unsigned long start, unsigned long end)
{
        remove_pagetable(start, end, false);
}

#ifdef CONFIG_MEMORY_HOTREMOVE
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);
}

int __ref arch_remove_memory(u64 start, u64 size)
{
        unsigned long start_pfn = start >> PAGE_SHIFT;
        unsigned long nr_pages = size >> PAGE_SHIFT;
        struct page *page = pfn_to_page(start_pfn);
        struct vmem_altmap *altmap;
        struct zone *zone;
        int ret;

        /* With altmap the first mapped page is offset from @start */
        altmap = to_vmem_altmap((unsigned long) page);
        if (altmap)
                page += vmem_altmap_offset(altmap);
        zone = page_zone(page);
        ret = __remove_pages(zone, start_pfn, nr_pages);
        WARN_ON_ONCE(ret);
        kernel_physical_mapping_remove(start, start + size);

        return ret;
}
#endif
#endif /* CONFIG_MEMORY_HOTPLUG */

static struct kcore_list kcore_vsyscall;

static void __init register_page_bootmem_info(void)
{
#ifdef CONFIG_NUMA
        int i;

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

void __init mem_init(void)
{
        pci_iommu_alloc();

        /* clear_bss() already clear the empty_zero_page */

        register_page_bootmem_info();

        /* this will put all memory onto the freelists */
        free_all_bootmem();
        after_bootmem = 1;

        /* Register memory areas for /proc/kcore */
        kclist_add(&kcore_vsyscall, (void *)VSYSCALL_ADDR,
                         PAGE_SIZE, KCORE_OTHER);

        mem_init_print_info(NULL);
}

const int rodata_test_data = 0xC3;
EXPORT_SYMBOL_GPL(rodata_test_data);

int kernel_set_to_readonly;

void set_kernel_text_rw(void)
{
        unsigned long start = PFN_ALIGN(_text);
        unsigned long end = PFN_ALIGN(__stop___ex_table);

        if (!kernel_set_to_readonly)
                return;

        pr_debug("Set kernel text: %lx - %lx for read write\n",
                 start, end);

        /*
         * Make the kernel identity mapping for text RW. Kernel text
         * mapping will always be RO. Refer to the comment in
         * static_protections() in pageattr.c
         */
        set_memory_rw(start, (end - start) >> PAGE_SHIFT);
}

void set_kernel_text_ro(void)
{
        unsigned long start = PFN_ALIGN(_text);
        unsigned long end = PFN_ALIGN(__stop___ex_table);

        if (!kernel_set_to_readonly)
                return;

        pr_debug("Set kernel text: %lx - %lx for read only\n",
                 start, end);

        /*
         * Set the kernel identity mapping for text RO.
         */
        set_memory_ro(start, (end - start) >> PAGE_SHIFT);
}

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(&__stop___ex_table);
        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);

        rodata_test();

#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_init_pages("unused kernel",
                        (unsigned long) __va(__pa_symbol(text_end)),
                        (unsigned long) __va(__pa_symbol(rodata_start)));
        free_init_pages("unused kernel",
                        (unsigned long) __va(__pa_symbol(rodata_end)),
                        (unsigned long) __va(__pa_symbol(_sdata)));

        debug_checkwx();
}

int kern_addr_valid(unsigned long addr)
{
        unsigned long above = ((long)addr) >> __VIRTUAL_MASK_SHIFT;
        pgd_t *pgd;
        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;

        pud = pud_offset(pgd, 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));
}

static unsigned long probe_memory_block_size(void)
{
        unsigned long bz = MIN_MEMORY_BLOCK_SIZE;

        /* if system is UV or has 64GB of RAM or more, use large blocks */
        if (is_uv_system() || ((max_pfn << PAGE_SHIFT) >= (64UL << 30)))
                bz = 2UL << 30; /* 2GB */

        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;
        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;

                pud = vmemmap_pud_populate(pgd, 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;
                                continue;
                        } else if (altmap)
                                return -ENOMEM; /* no fallback */
                } else if (pmd_large(*pmd)) {
                        vmemmap_verify((pte_t *)pmd, node, addr, next);
                        continue;
                }
                pr_warn_once("vmemmap: falling back to regular page backing\n");
                if (vmemmap_populate_basepages(addr, next, node))
                        return -ENOMEM;
        }
        return 0;
}

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

        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);
        if (!err)
                sync_global_pgds(start, end - 1);
        return err;
}

#if defined(CONFIG_MEMORY_HOTPLUG_SPARSE) && defined(CONFIG_HAVE_BOOTMEM_INFO_NODE)
void register_page_bootmem_memmap(unsigned long section_nr,
                                  struct page *start_page, unsigned long size)
{
        unsigned long addr = (unsigned long)start_page;
        unsigned long end = (unsigned long)(start_page + size);
        unsigned long next;
        pgd_t *pgd;
        pud_t *pud;
        pmd_t *pmd;
        unsigned int nr_pages;
        struct page *page;

        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);

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

                if (!boot_cpu_has(X86_FEATURE_PSE)) {
                        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_pages = 1 << (get_order(PMD_SIZE));
                        page = pmd_page(*pmd);
                        while (nr_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