// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Page table handling routines for radix page table.
 *
 * Copyright 2015-2016, Aneesh Kumar K.V, IBM Corporation.
 */

#define pr_fmt(fmt) "radix-mmu: " fmt

#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/sched/mm.h>
#include <linux/memblock.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/mm.h>
#include <linux/page_table_check.h>
#include <linux/hugetlb.h>
#include <linux/string_helpers.h>
#include <linux/memory.h>
#include <linux/kfence.h>

#include <asm/pgalloc.h>
#include <asm/mmu_context.h>
#include <asm/dma.h>
#include <asm/machdep.h>
#include <asm/mmu.h>
#include <asm/firmware.h>
#include <asm/powernv.h>
#include <asm/sections.h>
#include <asm/smp.h>
#include <asm/trace.h>
#include <asm/uaccess.h>
#include <asm/ultravisor.h>
#include <asm/set_memory.h>
#include <asm/kfence.h>

#include <trace/events/thp.h>

#include <mm/mmu_decl.h>

unsigned int mmu_base_pid;

static __ref void *early_alloc_pgtable(unsigned long size, int nid,
                        unsigned long region_start, unsigned long region_end)
{
        phys_addr_t min_addr = MEMBLOCK_LOW_LIMIT;
        phys_addr_t max_addr = MEMBLOCK_ALLOC_ANYWHERE;
        void *ptr;

        if (region_start)
                min_addr = region_start;
        if (region_end)
                max_addr = region_end;

        ptr = memblock_alloc_try_nid(size, size, min_addr, max_addr, nid);

        if (!ptr)
                panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa max_addr=%pa\n",
                      __func__, size, size, nid, &min_addr, &max_addr);

        return ptr;
}

/*
 * When allocating pud or pmd pointers, we allocate a complete page
 * of PAGE_SIZE rather than PUD_TABLE_SIZE or PMD_TABLE_SIZE. This
 * is to ensure that the page obtained from the memblock allocator
 * can be completely used as page table page and can be freed
 * correctly when the page table entries are removed.
 */
static int early_map_kernel_page(unsigned long ea, unsigned long pa,
                          pgprot_t flags,
                          unsigned int map_page_size,
                          int nid,
                          unsigned long region_start, unsigned long region_end)
{
        unsigned long pfn = pa >> PAGE_SHIFT;
        pgd_t *pgdp;
        p4d_t *p4dp;
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;

        pgdp = pgd_offset_k(ea);
        p4dp = p4d_offset(pgdp, ea);
        if (p4d_none(*p4dp)) {
                pudp = early_alloc_pgtable(PAGE_SIZE, nid,
                                           region_start, region_end);
                p4d_populate(&init_mm, p4dp, pudp);
        }
        pudp = pud_offset(p4dp, ea);
        if (map_page_size == PUD_SIZE) {
                ptep = (pte_t *)pudp;
                goto set_the_pte;
        }
        if (pud_none(*pudp)) {
                pmdp = early_alloc_pgtable(PAGE_SIZE, nid, region_start,
                                           region_end);
                pud_populate(&init_mm, pudp, pmdp);
        }
        pmdp = pmd_offset(pudp, ea);
        if (map_page_size == PMD_SIZE) {
                ptep = pmdp_ptep(pmdp);
                goto set_the_pte;
        }
        if (!pmd_present(*pmdp)) {
                ptep = early_alloc_pgtable(PAGE_SIZE, nid,
                                                region_start, region_end);
                pmd_populate_kernel(&init_mm, pmdp, ptep);
        }
        ptep = pte_offset_kernel(pmdp, ea);

set_the_pte:
        set_pte_at(&init_mm, ea, ptep, pfn_pte(pfn, flags));
        asm volatile("ptesync": : :"memory");
        return 0;
}

/*
 * nid, region_start, and region_end are hints to try to place the page
 * table memory in the same node or region.
 */
static int __map_kernel_page(unsigned long ea, unsigned long pa,
                          pgprot_t flags,
                          unsigned int map_page_size,
                          int nid,
                          unsigned long region_start, unsigned long region_end)
{
        unsigned long pfn = pa >> PAGE_SHIFT;
        pgd_t *pgdp;
        p4d_t *p4dp;
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;
        /*
         * Make sure task size is correct as per the max adddr
         */
        BUILD_BUG_ON(TASK_SIZE_USER64 > RADIX_PGTABLE_RANGE);

#ifdef CONFIG_PPC_64K_PAGES
        BUILD_BUG_ON(RADIX_KERN_MAP_SIZE != (1UL << MAX_EA_BITS_PER_CONTEXT));
#endif

        if (unlikely(!slab_is_available()))
                return early_map_kernel_page(ea, pa, flags, map_page_size,
                                                nid, region_start, region_end);

        /*
         * Should make page table allocation functions be able to take a
         * node, so we can place kernel page tables on the right nodes after
         * boot.
         */
        pgdp = pgd_offset_k(ea);
        p4dp = p4d_offset(pgdp, ea);
        pudp = pud_alloc(&init_mm, p4dp, ea);
        if (!pudp)
                return -ENOMEM;
        if (map_page_size == PUD_SIZE) {
                ptep = (pte_t *)pudp;
                goto set_the_pte;
        }
        pmdp = pmd_alloc(&init_mm, pudp, ea);
        if (!pmdp)
                return -ENOMEM;
        if (map_page_size == PMD_SIZE) {
                ptep = pmdp_ptep(pmdp);
                goto set_the_pte;
        }
        ptep = pte_alloc_kernel(pmdp, ea);
        if (!ptep)
                return -ENOMEM;

set_the_pte:
        set_pte_at(&init_mm, ea, ptep, pfn_pte(pfn, flags));
        asm volatile("ptesync": : :"memory");
        return 0;
}

int radix__map_kernel_page(unsigned long ea, unsigned long pa,
                          pgprot_t flags,
                          unsigned int map_page_size)
{
        return __map_kernel_page(ea, pa, flags, map_page_size, -1, 0, 0);
}

#ifdef CONFIG_STRICT_KERNEL_RWX
static void radix__change_memory_range(unsigned long start, unsigned long end,
                                       unsigned long clear)
{
        unsigned long idx;
        pgd_t *pgdp;
        p4d_t *p4dp;
        pud_t *pudp;
        pmd_t *pmdp;
        pte_t *ptep;

        start = ALIGN_DOWN(start, PAGE_SIZE);
        end = PAGE_ALIGN(end); // aligns up

        pr_debug("Changing flags on range %lx-%lx removing 0x%lx\n",
                 start, end, clear);

        for (idx = start; idx < end; idx += PAGE_SIZE) {
                pgdp = pgd_offset_k(idx);
                p4dp = p4d_offset(pgdp, idx);
                pudp = pud_alloc(&init_mm, p4dp, idx);
                if (!pudp)
                        continue;
                if (pud_leaf(*pudp)) {
                        ptep = (pte_t *)pudp;
                        goto update_the_pte;
                }
                pmdp = pmd_alloc(&init_mm, pudp, idx);
                if (!pmdp)
                        continue;
                if (pmd_leaf(*pmdp)) {
                        ptep = pmdp_ptep(pmdp);
                        goto update_the_pte;
                }
                ptep = pte_alloc_kernel(pmdp, idx);
                if (!ptep)
                        continue;
update_the_pte:
                radix__pte_update(&init_mm, idx, ptep, clear, 0, 0);
        }

        radix__flush_tlb_kernel_range(start, end);
}

void radix__mark_rodata_ro(void)
{
        unsigned long start, end;

        start = (unsigned long)_stext;
        end = (unsigned long)__end_rodata;

        radix__change_memory_range(start, end, _PAGE_WRITE);

        for (start = PAGE_OFFSET; start < (unsigned long)_stext; start += PAGE_SIZE) {
                end = start + PAGE_SIZE;
                if (overlaps_interrupt_vector_text(start, end))
                        radix__change_memory_range(start, end, _PAGE_WRITE);
                else
                        break;
        }
}

void radix__mark_initmem_nx(void)
{
        unsigned long start = (unsigned long)__init_begin;
        unsigned long end = (unsigned long)__init_end;

        radix__change_memory_range(start, end, _PAGE_EXEC);
}
#endif /* CONFIG_STRICT_KERNEL_RWX */

static inline void __meminit
print_mapping(unsigned long start, unsigned long end, unsigned long size, bool exec)
{
        char buf[10];

        if (end <= start)
                return;

        string_get_size(size, 1, STRING_UNITS_2, buf, sizeof(buf));

        pr_info("Mapped 0x%016lx-0x%016lx with %s pages%s\n", start, end, buf,
                exec ? " (exec)" : "");
}

static unsigned long next_boundary(unsigned long addr, unsigned long end)
{
#ifdef CONFIG_STRICT_KERNEL_RWX
        unsigned long stext_phys;

        stext_phys = __pa_symbol(_stext);

        // Relocatable kernel running at non-zero real address
        if (stext_phys != 0) {
                // The end of interrupts code at zero is a rodata boundary
                unsigned long end_intr = __pa_symbol(__end_interrupts) - stext_phys;
                if (addr < end_intr)
                        return end_intr;

                // Start of relocated kernel text is a rodata boundary
                if (addr < stext_phys)
                        return stext_phys;
        }

        if (addr < __pa_symbol(__srwx_boundary))
                return __pa_symbol(__srwx_boundary);
#endif
        return end;
}

static int __meminit create_physical_mapping(unsigned long start,
                                             unsigned long end,
                                             int nid, pgprot_t _prot,
                                             unsigned long mapping_sz_limit)
{
        unsigned long vaddr, addr, mapping_size = 0;
        bool prev_exec, exec = false;
        pgprot_t prot;
        int psize;
        unsigned long max_mapping_size = memory_block_size;

        if (mapping_sz_limit < max_mapping_size)
                max_mapping_size = mapping_sz_limit;

        if (debug_pagealloc_enabled())
                max_mapping_size = PAGE_SIZE;

        start = ALIGN(start, PAGE_SIZE);
        end   = ALIGN_DOWN(end, PAGE_SIZE);
        for (addr = start; addr < end; addr += mapping_size) {
                unsigned long gap, previous_size;
                int rc;

                gap = next_boundary(addr, end) - addr;
                if (gap > max_mapping_size)
                        gap = max_mapping_size;
                previous_size = mapping_size;
                prev_exec = exec;

                if (IS_ALIGNED(addr, PUD_SIZE) && gap >= PUD_SIZE &&
                    mmu_psize_defs[MMU_PAGE_1G].shift) {
                        mapping_size = PUD_SIZE;
                        psize = MMU_PAGE_1G;
                } else if (IS_ALIGNED(addr, PMD_SIZE) && gap >= PMD_SIZE &&
                           mmu_psize_defs[MMU_PAGE_2M].shift) {
                        mapping_size = PMD_SIZE;
                        psize = MMU_PAGE_2M;
                } else {
                        mapping_size = PAGE_SIZE;
                        psize = mmu_virtual_psize;
                }

                vaddr = (unsigned long)__va(addr);

                if (overlaps_kernel_text(vaddr, vaddr + mapping_size) ||
                    overlaps_interrupt_vector_text(vaddr, vaddr + mapping_size)) {
                        prot = PAGE_KERNEL_X;
                        exec = true;
                } else {
                        prot = _prot;
                        exec = false;
                }

                if (mapping_size != previous_size || exec != prev_exec) {
                        print_mapping(start, addr, previous_size, prev_exec);
                        start = addr;
                }

                rc = __map_kernel_page(vaddr, addr, prot, mapping_size, nid, start, end);
                if (rc)
                        return rc;

                update_page_count(psize, 1);
        }

        print_mapping(start, addr, mapping_size, exec);
        return 0;
}

#ifdef CONFIG_KFENCE
static __init phys_addr_t alloc_kfence_pool(void)
{
        phys_addr_t kfence_pool;

        /*
         * TODO: Support to enable KFENCE after bootup depends on the ability to
         *       split page table mappings. As such support is not currently
         *       implemented for radix pagetables, support enabling KFENCE
         *       only at system startup for now.
         *
         *       After support for splitting mappings is available on radix,
         *       alloc_kfence_pool() & map_kfence_pool() can be dropped and
         *       mapping for __kfence_pool memory can be
         *       split during arch_kfence_init_pool().
         */
        if (!kfence_early_init)
                goto no_kfence;

        kfence_pool = memblock_phys_alloc(KFENCE_POOL_SIZE, PAGE_SIZE);
        if (!kfence_pool)
                goto no_kfence;

        memblock_mark_nomap(kfence_pool, KFENCE_POOL_SIZE);
        return kfence_pool;

no_kfence:
        disable_kfence();
        return 0;
}

static __init void map_kfence_pool(phys_addr_t kfence_pool)
{
        if (!kfence_pool)
                return;

        if (create_physical_mapping(kfence_pool, kfence_pool + KFENCE_POOL_SIZE,
                                    -1, PAGE_KERNEL, PAGE_SIZE))
                goto err;

        memblock_clear_nomap(kfence_pool, KFENCE_POOL_SIZE);
        __kfence_pool = __va(kfence_pool);
        return;

err:
        memblock_phys_free(kfence_pool, KFENCE_POOL_SIZE);
        disable_kfence();
}
#else
static inline phys_addr_t alloc_kfence_pool(void) { return 0; }
static inline void map_kfence_pool(phys_addr_t kfence_pool) { }
#endif

static void __init radix_init_pgtable(void)
{
        phys_addr_t kfence_pool;
        unsigned long rts_field;
        phys_addr_t start, end;
        u64 i;

        /* We don't support slb for radix */
        slb_set_size(0);

        kfence_pool = alloc_kfence_pool();

        /*
         * Create the linear mapping
         */
        for_each_mem_range(i, &start, &end) {
                /*
                 * The memblock allocator  is up at this point, so the
                 * page tables will be allocated within the range. No
                 * need or a node (which we don't have yet).
                 */

                if (end >= RADIX_VMALLOC_START) {
                        pr_warn("Outside the supported range\n");
                        continue;
                }

                WARN_ON(create_physical_mapping(start, end,
                                                -1, PAGE_KERNEL, ~0UL));
        }

        map_kfence_pool(kfence_pool);

        if (!cpu_has_feature(CPU_FTR_HVMODE) &&
                        cpu_has_feature(CPU_FTR_P9_RADIX_PREFETCH_BUG)) {
                /*
                 * Older versions of KVM on these machines prefer if the
                 * guest only uses the low 19 PID bits.
                 */
                mmu_pid_bits = 19;
        }
        mmu_base_pid = 1;

        /*
         * Allocate Partition table and process table for the
         * host.
         */
        BUG_ON(PRTB_SIZE_SHIFT > 36);
        process_tb = early_alloc_pgtable(1UL << PRTB_SIZE_SHIFT, -1, 0, 0);
        /*
         * Fill in the process table.
         */
        rts_field = radix__get_tree_size();
        process_tb->prtb0 = cpu_to_be64(rts_field | __pa(init_mm.pgd) | RADIX_PGD_INDEX_SIZE);

        /*
         * The init_mm context is given the first available (non-zero) PID,
         * which is the "guard PID" and contains no page table. PIDR should
         * never be set to zero because that duplicates the kernel address
         * space at the 0x0... offset (quadrant 0)!
         *
         * An arbitrary PID that may later be allocated by the PID allocator
         * for userspace processes must not be used either, because that
         * would cause stale user mappings for that PID on CPUs outside of
         * the TLB invalidation scheme (because it won't be in mm_cpumask).
         *
         * So permanently carve out one PID for the purpose of a guard PID.
         */
        init_mm.context.id = mmu_base_pid;
        mmu_base_pid++;
}

static void __init radix_init_partition_table(void)
{
        unsigned long rts_field, dw0, dw1;

        mmu_partition_table_init();
        rts_field = radix__get_tree_size();
        dw0 = rts_field | __pa(init_mm.pgd) | RADIX_PGD_INDEX_SIZE | PATB_HR;
        dw1 = __pa(process_tb) | (PRTB_SIZE_SHIFT - 12) | PATB_GR;
        mmu_partition_table_set_entry(0, dw0, dw1, false);

        pr_info("Initializing Radix MMU\n");
}

static int __init get_idx_from_shift(unsigned int shift)
{
        int idx = -1;

        switch (shift) {
        case 0xc:
                idx = MMU_PAGE_4K;
                break;
        case 0x10:
                idx = MMU_PAGE_64K;
                break;
        case 0x15:
                idx = MMU_PAGE_2M;
                break;
        case 0x1e:
                idx = MMU_PAGE_1G;
                break;
        }
        return idx;
}

static int __init radix_dt_scan_page_sizes(unsigned long node,
                                           const char *uname, int depth,
                                           void *data)
{
        int size = 0;
        int shift, idx;
        unsigned int ap;
        const __be32 *prop;
        const char *type = of_get_flat_dt_prop(node, "device_type", NULL);

        /* We are scanning "cpu" nodes only */
        if (type == NULL || strcmp(type, "cpu") != 0)
                return 0;

        /* Grab page size encodings */
        prop = of_get_flat_dt_prop(node, "ibm,processor-radix-AP-encodings", &size);
        if (!prop)
                return 0;

        pr_info("Page sizes from device-tree:\n");
        for (; size >= 4; size -= 4, ++prop) {

                struct mmu_psize_def *def;

                /* top 3 bit is AP encoding */
                shift = be32_to_cpu(prop[0]) & ~(0xe << 28);
                ap = be32_to_cpu(prop[0]) >> 29;
                pr_info("Page size shift = %d AP=0x%x\n", shift, ap);

                idx = get_idx_from_shift(shift);
                if (idx < 0)
                        continue;

                def = &mmu_psize_defs[idx];
                def->shift = shift;
                def->ap  = ap;
                def->h_rpt_pgsize = psize_to_rpti_pgsize(idx);
        }

        /* needed ? */
        cur_cpu_spec->mmu_features &= ~MMU_FTR_NO_SLBIE_B;
        return 1;
}

void __init radix__early_init_devtree(void)
{
        int rc;

        /*
         * Try to find the available page sizes in the device-tree
         */
        rc = of_scan_flat_dt(radix_dt_scan_page_sizes, NULL);
        if (!rc) {
                /*
                 * No page size details found in device tree.
                 * Let's assume we have page 4k and 64k support
                 */
                mmu_psize_defs[MMU_PAGE_4K].shift = 12;
                mmu_psize_defs[MMU_PAGE_4K].ap = 0x0;
                mmu_psize_defs[MMU_PAGE_4K].h_rpt_pgsize =
                        psize_to_rpti_pgsize(MMU_PAGE_4K);

                mmu_psize_defs[MMU_PAGE_64K].shift = 16;
                mmu_psize_defs[MMU_PAGE_64K].ap = 0x5;
                mmu_psize_defs[MMU_PAGE_64K].h_rpt_pgsize =
                        psize_to_rpti_pgsize(MMU_PAGE_64K);
        }
        return;
}

void __init radix__early_init_mmu(void)
{
        unsigned long lpcr;

#ifdef CONFIG_PPC_64S_HASH_MMU
#ifdef CONFIG_PPC_64K_PAGES
        /* PAGE_SIZE mappings */
        mmu_virtual_psize = MMU_PAGE_64K;
#else
        mmu_virtual_psize = MMU_PAGE_4K;
#endif
#endif
        /*
         * initialize page table size
         */
        __pte_index_size = RADIX_PTE_INDEX_SIZE;
        __pmd_index_size = RADIX_PMD_INDEX_SIZE;
        __pud_index_size = RADIX_PUD_INDEX_SIZE;
        __pgd_index_size = RADIX_PGD_INDEX_SIZE;
        __pud_cache_index = RADIX_PUD_INDEX_SIZE;
        __pte_table_size = RADIX_PTE_TABLE_SIZE;
        __pmd_table_size = RADIX_PMD_TABLE_SIZE;
        __pud_table_size = RADIX_PUD_TABLE_SIZE;
        __pgd_table_size = RADIX_PGD_TABLE_SIZE;

        __pmd_val_bits = RADIX_PMD_VAL_BITS;
        __pud_val_bits = RADIX_PUD_VAL_BITS;
        __pgd_val_bits = RADIX_PGD_VAL_BITS;

        __kernel_virt_start = RADIX_KERN_VIRT_START;
        __vmalloc_start = RADIX_VMALLOC_START;
        __vmalloc_end = RADIX_VMALLOC_END;
        __kernel_io_start = RADIX_KERN_IO_START;
        __kernel_io_end = RADIX_KERN_IO_END;
        vmemmap = (struct page *)RADIX_VMEMMAP_START;
        ioremap_bot = IOREMAP_BASE;

#ifdef CONFIG_PCI
        pci_io_base = ISA_IO_BASE;
#endif
        __pte_frag_nr = RADIX_PTE_FRAG_NR;
        __pte_frag_size_shift = RADIX_PTE_FRAG_SIZE_SHIFT;
        __pmd_frag_nr = RADIX_PMD_FRAG_NR;
        __pmd_frag_size_shift = RADIX_PMD_FRAG_SIZE_SHIFT;

        radix_init_pgtable();

        if (!firmware_has_feature(FW_FEATURE_LPAR)) {
                lpcr = mfspr(SPRN_LPCR);
                mtspr(SPRN_LPCR, lpcr | LPCR_UPRT | LPCR_HR);
                radix_init_partition_table();
        } else {
                radix_init_pseries();
        }

        memblock_set_current_limit(MEMBLOCK_ALLOC_ANYWHERE);

        /* Switch to the guard PID before turning on MMU */
        radix__switch_mmu_context(NULL, &init_mm);
        tlbiel_all();
}

void radix__early_init_mmu_secondary(void)
{
        unsigned long lpcr;
        /*
         * update partition table control register and UPRT
         */
        if (!firmware_has_feature(FW_FEATURE_LPAR)) {
                lpcr = mfspr(SPRN_LPCR);
                mtspr(SPRN_LPCR, lpcr | LPCR_UPRT | LPCR_HR);

                set_ptcr_when_no_uv(__pa(partition_tb) |
                                    (PATB_SIZE_SHIFT - 12));
        }

        radix__switch_mmu_context(NULL, &init_mm);
        tlbiel_all();

        /* Make sure userspace can't change the AMR */
        mtspr(SPRN_UAMOR, 0);
}

/* Called during kexec sequence with MMU off */
notrace void radix__mmu_cleanup_all(void)
{
        unsigned long lpcr;

        if (!firmware_has_feature(FW_FEATURE_LPAR)) {
                lpcr = mfspr(SPRN_LPCR);
                mtspr(SPRN_LPCR, lpcr & ~LPCR_UPRT);
                set_ptcr_when_no_uv(0);
                powernv_set_nmmu_ptcr(0);
                radix__flush_tlb_all();
        }
}

#ifdef CONFIG_MEMORY_HOTPLUG
static void 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;
        }

        pte_free_kernel(&init_mm, pte_start);
        pmd_clear(pmd);
}

static void 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;
        }

        pmd_free(&init_mm, pmd_start);
        pud_clear(pud);
}

static void 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;
        }

        pud_free(&init_mm, pud_start);
        p4d_clear(p4d);
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
static bool __meminit vmemmap_pmd_is_unused(unsigned long addr, unsigned long end)
{
        unsigned long start = ALIGN_DOWN(addr, PMD_SIZE);

        return !vmemmap_populated(start, PMD_SIZE);
}

static bool __meminit vmemmap_page_is_unused(unsigned long addr, unsigned long end)
{
        unsigned long start = ALIGN_DOWN(addr, PAGE_SIZE);

        return !vmemmap_populated(start, PAGE_SIZE);

}
#endif

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

        if (altmap) {
                unsigned long alt_start, alt_end;
                unsigned long base_pfn = page_to_pfn(page);

                /*
                 * with 2M vmemmap mmaping we can have things setup
                 * such that even though atlmap is specified we never
                 * used altmap.
                 */
                alt_start = altmap->base_pfn;
                alt_end = altmap->base_pfn + altmap->reserve + altmap->free;

                if (base_pfn >= alt_start && base_pfn < alt_end) {
                        vmem_altmap_free(altmap, nr_pages);
                        return;
                }
        }

        if (PageReserved(page)) {
                /* allocated from memblock */
                while (nr_pages--)
                        free_reserved_page(page++);
        } else
                __free_pages(page, order);
}

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

        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;

                if (PAGE_ALIGNED(addr) && PAGE_ALIGNED(next)) {
                        if (!direct)
                                free_vmemmap_pages(pte_page(*pte), altmap, 0);
                        pte_clear(&init_mm, addr, pte);
                        pages++;
                }
#ifdef CONFIG_SPARSEMEM_VMEMMAP
                else if (!direct && vmemmap_page_is_unused(addr, next)) {
                        free_vmemmap_pages(pte_page(*pte), altmap, 0);
                        pte_clear(&init_mm, addr, pte);
                }
#endif
        }
        if (direct)
                update_page_count(mmu_virtual_psize, -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_leaf(*pmd)) {
                        if (IS_ALIGNED(addr, PMD_SIZE) &&
                            IS_ALIGNED(next, PMD_SIZE)) {
                                if (!direct)
                                        free_vmemmap_pages(pmd_page(*pmd), altmap, get_order(PMD_SIZE));
                                pte_clear(&init_mm, addr, (pte_t *)pmd);
                                pages++;
                        }
#ifdef CONFIG_SPARSEMEM_VMEMMAP
                        else if (!direct && vmemmap_pmd_is_unused(addr, next)) {
                                free_vmemmap_pages(pmd_page(*pmd), altmap, get_order(PMD_SIZE));
                                pte_clear(&init_mm, addr, (pte_t *)pmd);
                        }
#endif
                        continue;
                }

                pte_base = (pte_t *)pmd_page_vaddr(*pmd);
                remove_pte_table(pte_base, addr, next, direct, altmap);
                free_pte_table(pte_base, pmd);
        }
        if (direct)
                update_page_count(MMU_PAGE_2M, -pages);
}

static void __meminit remove_pud_table(pud_t *pud_start, unsigned long addr,
                                       unsigned long end, bool direct,
                                       struct vmem_altmap *altmap)
{
        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_leaf(*pud)) {
                        if (!IS_ALIGNED(addr, PUD_SIZE) ||
                            !IS_ALIGNED(next, PUD_SIZE)) {
                                WARN_ONCE(1, "%s: unaligned range\n", __func__);
                                continue;
                        }
                        pte_clear(&init_mm, addr, (pte_t *)pud);
                        pages++;
                        continue;
                }

                pmd_base = pud_pgtable(*pud);
                remove_pmd_table(pmd_base, addr, next, direct, altmap);
                free_pmd_table(pmd_base, pud);
        }
        if (direct)
                update_page_count(MMU_PAGE_1G, -pages);
}

static void __meminit
remove_pagetable(unsigned long start, unsigned long end, bool direct,
                 struct vmem_altmap *altmap)
{
        unsigned long addr, next;
        pud_t *pud_base;
        pgd_t *pgd;
        p4d_t *p4d;

        spin_lock(&init_mm.page_table_lock);

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

                pgd = pgd_offset_k(addr);
                p4d = p4d_offset(pgd, addr);
                if (!p4d_present(*p4d))
                        continue;

                if (p4d_leaf(*p4d)) {
                        if (!IS_ALIGNED(addr, P4D_SIZE) ||
                            !IS_ALIGNED(next, P4D_SIZE)) {
                                WARN_ONCE(1, "%s: unaligned range\n", __func__);
                                continue;
                        }

                        pte_clear(&init_mm, addr, (pte_t *)pgd);
                        continue;
                }

                pud_base = p4d_pgtable(*p4d);
                remove_pud_table(pud_base, addr, next, direct, altmap);
                free_pud_table(pud_base, p4d);
        }

        spin_unlock(&init_mm.page_table_lock);
        radix__flush_tlb_kernel_range(start, end);
}

int __meminit radix__create_section_mapping(unsigned long start,
                                            unsigned long end, int nid,
                                            pgprot_t prot)
{
        if (end >= RADIX_VMALLOC_START) {
                pr_warn("Outside the supported range\n");
                return -1;
        }

        return create_physical_mapping(__pa(start), __pa(end),
                                       nid, prot, ~0UL);
}

int __meminit radix__remove_section_mapping(unsigned long start, unsigned long end)
{
        remove_pagetable(start, end, true, NULL);
        return 0;
}
#endif /* CONFIG_MEMORY_HOTPLUG */

#ifdef CONFIG_SPARSEMEM_VMEMMAP
static int __map_kernel_page_nid(unsigned long ea, unsigned long pa,
                                 pgprot_t flags, unsigned int map_page_size,
                                 int nid)
{
        return __map_kernel_page(ea, pa, flags, map_page_size, nid, 0, 0);
}

int __meminit radix__vmemmap_create_mapping(unsigned long start,
                                      unsigned long page_size,
                                      unsigned long phys)
{
        /* Create a PTE encoding */
        int nid = early_pfn_to_nid(phys >> PAGE_SHIFT);
        int ret;

        if ((start + page_size) >= RADIX_VMEMMAP_END) {
                pr_warn("Outside the supported range\n");
                return -1;
        }

        ret = __map_kernel_page_nid(start, phys, PAGE_KERNEL, page_size, nid);
        BUG_ON(ret);

        return 0;
}

#ifdef CONFIG_ARCH_WANT_OPTIMIZE_DAX_VMEMMAP
bool vmemmap_can_optimize(struct vmem_altmap *altmap, struct dev_pagemap *pgmap)
{
        if (radix_enabled())
                return __vmemmap_can_optimize(altmap, pgmap);

        return false;
}
#endif

int __meminit vmemmap_check_pmd(pmd_t *pmdp, int node,
                                unsigned long addr, unsigned long next)
{
        int large = pmd_leaf(*pmdp);

        if (large)
                vmemmap_verify(pmdp_ptep(pmdp), node, addr, next);

        return large;
}

void __meminit vmemmap_set_pmd(pmd_t *pmdp, void *p, int node,
                               unsigned long addr, unsigned long next)
{
        pte_t entry;
        pte_t *ptep = pmdp_ptep(pmdp);

        VM_BUG_ON(!IS_ALIGNED(addr, PMD_SIZE));
        entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
        set_pte_at(&init_mm, addr, ptep, entry);
        asm volatile("ptesync": : :"memory");

        vmemmap_verify(ptep, node, addr, next);
}

static pte_t * __meminit radix__vmemmap_pte_populate(pmd_t *pmdp, unsigned long addr,
                                                     int node,
                                                     struct vmem_altmap *altmap,
                                                     struct page *reuse)
{
        pte_t *pte = pte_offset_kernel(pmdp, addr);

        if (pte_none(*pte)) {
                pte_t entry;
                void *p;

                if (!reuse) {
                        /*
                         * make sure we don't create altmap mappings
                         * covering things outside the device.
                         */
                        if (altmap && altmap_cross_boundary(altmap, addr, PAGE_SIZE))
                                altmap = NULL;

                        p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
                        if (!p && altmap)
                                p = vmemmap_alloc_block_buf(PAGE_SIZE, node, NULL);
                        if (!p)
                                return NULL;
                        pr_debug("PAGE_SIZE vmemmap mapping\n");
                } else {
                        /*
                         * When a PTE/PMD entry is freed from the init_mm
                         * there's a free_pages() call to this page allocated
                         * above. Thus this get_page() is paired with the
                         * put_page_testzero() on the freeing path.
                         * This can only called by certain ZONE_DEVICE path,
                         * and through vmemmap_populate_compound_pages() when
                         * slab is available.
                         */
                        get_page(reuse);
                        p = page_to_virt(reuse);
                        pr_debug("Tail page reuse vmemmap mapping\n");
                }

                VM_BUG_ON(!PAGE_ALIGNED(addr));
                entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
                set_pte_at(&init_mm, addr, pte, entry);
                asm volatile("ptesync": : :"memory");
        }
        return pte;
}

static inline pud_t *vmemmap_pud_alloc(p4d_t *p4dp, int node,
                                       unsigned long address)
{
        pud_t *pud;

        /* All early vmemmap mapping to keep simple do it at PAGE_SIZE */
        if (unlikely(p4d_none(*p4dp))) {
                if (unlikely(!slab_is_available())) {
                        pud = early_alloc_pgtable(PAGE_SIZE, node, 0, 0);
                        p4d_populate(&init_mm, p4dp, pud);
                        /* go to the pud_offset */
                } else
                        return pud_alloc(&init_mm, p4dp, address);
        }
        return pud_offset(p4dp, address);
}

static inline pmd_t *vmemmap_pmd_alloc(pud_t *pudp, int node,
                                       unsigned long address)
{
        pmd_t *pmd;

        /* All early vmemmap mapping to keep simple do it at PAGE_SIZE */
        if (unlikely(pud_none(*pudp))) {
                if (unlikely(!slab_is_available())) {
                        pmd = early_alloc_pgtable(PAGE_SIZE, node, 0, 0);
                        pud_populate(&init_mm, pudp, pmd);
                } else
                        return pmd_alloc(&init_mm, pudp, address);
        }
        return pmd_offset(pudp, address);
}

static inline pte_t *vmemmap_pte_alloc(pmd_t *pmdp, int node,
                                       unsigned long address)
{
        pte_t *pte;

        /* All early vmemmap mapping to keep simple do it at PAGE_SIZE */
        if (unlikely(pmd_none(*pmdp))) {
                if (unlikely(!slab_is_available())) {
                        pte = early_alloc_pgtable(PAGE_SIZE, node, 0, 0);
                        pmd_populate(&init_mm, pmdp, pte);
                } else
                        return pte_alloc_kernel(pmdp, address);
        }
        return pte_offset_kernel(pmdp, address);
}



int __meminit radix__vmemmap_populate(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;
        pte_t *pte;

        /*
         * If altmap is present, Make sure we align the start vmemmap addr
         * to PAGE_SIZE so that we calculate the correct start_pfn in
         * altmap boundary check to decide whether we should use altmap or
         * RAM based backing memory allocation. Also the address need to be
         * aligned for set_pte operation. If the start addr is already
         * PMD_SIZE aligned and with in the altmap boundary then we will
         * try to use a pmd size altmap mapping else we go for page size
         * mapping.
         *
         * If altmap is not present, align the vmemmap addr to PMD_SIZE and
         * always allocate a PMD size page for vmemmap backing.
         *
         */

        if (altmap)
                start = ALIGN_DOWN(start, PAGE_SIZE);
        else
                start = ALIGN_DOWN(start, PMD_SIZE);

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

                pgd = pgd_offset_k(addr);
                p4d = p4d_offset(pgd, addr);
                pud = vmemmap_pud_alloc(p4d, node, addr);
                if (!pud)
                        return -ENOMEM;
                pmd = vmemmap_pmd_alloc(pud, node, addr);
                if (!pmd)
                        return -ENOMEM;

                if (pmd_none(READ_ONCE(*pmd))) {
                        void *p;

                        /*
                         * keep it simple by checking addr PMD_SIZE alignment
                         * and verifying the device boundary condition.
                         * For us to use a pmd mapping, both addr and pfn should
                         * be aligned. We skip if addr is not aligned and for
                         * pfn we hope we have extra area in the altmap that
                         * can help to find an aligned block. This can result
                         * in altmap block allocation failures, in which case
                         * we fallback to RAM for vmemmap allocation.
                         */
                        if (altmap && (!IS_ALIGNED(addr, PMD_SIZE) ||
                            altmap_cross_boundary(altmap, addr, PMD_SIZE))) {
                                /*
                                 * make sure we don't create altmap mappings
                                 * covering things outside the device.
                                 */
                                goto base_mapping;
                        }

                        p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
                        if (p) {
                                vmemmap_set_pmd(pmd, p, node, addr, next);
                                pr_debug("PMD_SIZE vmemmap mapping\n");
                                continue;
                        } else {
                                /*
                                 * A vmemmap block allocation can fail due to
                                 * alignment requirements and we trying to align
                                 * things aggressively there by running out of
                                 * space. Try base mapping on failure.
                                 */
                                goto base_mapping;
                        }
                } else if (vmemmap_check_pmd(pmd, node, addr, next)) {
                        /*
                         * If a huge mapping exist due to early call to
                         * vmemmap_populate, let's try to use that.
                         */
                        continue;
                }
base_mapping:
                /*
                 * Not able allocate higher order memory to back memmap
                 * or we found a pointer to pte page. Allocate base page
                 * size vmemmap
                 */
                pte = vmemmap_pte_alloc(pmd, node, addr);
                if (!pte)
                        return -ENOMEM;

                pte = radix__vmemmap_pte_populate(pmd, addr, node, altmap, NULL);
                if (!pte)
                        return -ENOMEM;

                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
                next = addr + PAGE_SIZE;
        }
        return 0;
}

static pte_t * __meminit radix__vmemmap_populate_address(unsigned long addr, int node,
                                                         struct vmem_altmap *altmap,
                                                         struct page *reuse)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        pgd = pgd_offset_k(addr);
        p4d = p4d_offset(pgd, addr);
        pud = vmemmap_pud_alloc(p4d, node, addr);
        if (!pud)
                return NULL;
        pmd = vmemmap_pmd_alloc(pud, node, addr);
        if (!pmd)
                return NULL;
        if (pmd_leaf(*pmd))
                /*
                 * The second page is mapped as a hugepage due to a nearby request.
                 * Force our mapping to page size without deduplication
                 */
                return NULL;
        pte = vmemmap_pte_alloc(pmd, node, addr);
        if (!pte)
                return NULL;
        radix__vmemmap_pte_populate(pmd, addr, node, NULL, NULL);
        vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);

        return pte;
}

static pte_t * __meminit vmemmap_compound_tail_page(unsigned long addr,
                                                    unsigned long pfn_offset, int node)
{
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;
        unsigned long map_addr;

        /* the second vmemmap page which we use for duplication */
        map_addr = addr - pfn_offset * sizeof(struct page) + PAGE_SIZE;
        pgd = pgd_offset_k(map_addr);
        p4d = p4d_offset(pgd, map_addr);
        pud = vmemmap_pud_alloc(p4d, node, map_addr);
        if (!pud)
                return NULL;
        pmd = vmemmap_pmd_alloc(pud, node, map_addr);
        if (!pmd)
                return NULL;
        if (pmd_leaf(*pmd))
                /*
                 * The second page is mapped as a hugepage due to a nearby request.
                 * Force our mapping to page size without deduplication
                 */
                return NULL;
        pte = vmemmap_pte_alloc(pmd, node, map_addr);
        if (!pte)
                return NULL;
        /*
         * Check if there exist a mapping to the left
         */
        if (pte_none(*pte)) {
                /*
                 * Populate the head page vmemmap page.
                 * It can fall in different pmd, hence
                 * vmemmap_populate_address()
                 */
                pte = radix__vmemmap_populate_address(map_addr - PAGE_SIZE, node, NULL, NULL);
                if (!pte)
                        return NULL;
                /*
                 * Populate the tail pages vmemmap page
                 */
                pte = radix__vmemmap_pte_populate(pmd, map_addr, node, NULL, NULL);
                if (!pte)
                        return NULL;
                vmemmap_verify(pte, node, map_addr, map_addr + PAGE_SIZE);
                return pte;
        }
        return pte;
}

int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
                                              unsigned long start,
                                              unsigned long end, int node,
                                              struct dev_pagemap *pgmap)
{
        /*
         * we want to map things as base page size mapping so that
         * we can save space in vmemmap. We could have huge mapping
         * covering out both edges.
         */
        unsigned long addr;
        unsigned long addr_pfn = start_pfn;
        unsigned long next;
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

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

                pgd = pgd_offset_k(addr);
                p4d = p4d_offset(pgd, addr);
                pud = vmemmap_pud_alloc(p4d, node, addr);
                if (!pud)
                        return -ENOMEM;
                pmd = vmemmap_pmd_alloc(pud, node, addr);
                if (!pmd)
                        return -ENOMEM;

                if (pmd_leaf(READ_ONCE(*pmd))) {
                        /* existing huge mapping. Skip the range */
                        addr_pfn += (PMD_SIZE >> PAGE_SHIFT);
                        next = pmd_addr_end(addr, end);
                        continue;
                }
                pte = vmemmap_pte_alloc(pmd, node, addr);
                if (!pte)
                        return -ENOMEM;
                if (!pte_none(*pte)) {
                        /*
                         * This could be because we already have a compound
                         * page whose VMEMMAP_RESERVE_NR pages were mapped and
                         * this request fall in those pages.
                         */
                        addr_pfn += 1;
                        next = addr + PAGE_SIZE;
                        continue;
                } else {
                        unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
                        unsigned long pfn_offset = addr_pfn - ALIGN_DOWN(addr_pfn, nr_pages);
                        pte_t *tail_page_pte;

                        /*
                         * if the address is aligned to huge page size it is the
                         * head mapping.
                         */
                        if (pfn_offset == 0) {
                                /* Populate the head page vmemmap page */
                                pte = radix__vmemmap_pte_populate(pmd, addr, node, NULL, NULL);
                                if (!pte)
                                        return -ENOMEM;
                                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);

                                /*
                                 * Populate the tail pages vmemmap page
                                 * It can fall in different pmd, hence
                                 * vmemmap_populate_address()
                                 */
                                pte = radix__vmemmap_populate_address(addr + PAGE_SIZE, node, NULL, NULL);
                                if (!pte)
                                        return -ENOMEM;

                                addr_pfn += 2;
                                next = addr + 2 * PAGE_SIZE;
                                continue;
                        }
                        /*
                         * get the 2nd mapping details
                         * Also create it if that doesn't exist
                         */
                        tail_page_pte = vmemmap_compound_tail_page(addr, pfn_offset, node);
                        if (!tail_page_pte) {

                                pte = radix__vmemmap_pte_populate(pmd, addr, node, NULL, NULL);
                                if (!pte)
                                        return -ENOMEM;
                                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);

                                addr_pfn += 1;
                                next = addr + PAGE_SIZE;
                                continue;
                        }

                        pte = radix__vmemmap_pte_populate(pmd, addr, node, NULL, pte_page(*tail_page_pte));
                        if (!pte)
                                return -ENOMEM;
                        vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);

                        addr_pfn += 1;
                        next = addr + PAGE_SIZE;
                        continue;
                }
        }
        return 0;
}


#ifdef CONFIG_MEMORY_HOTPLUG
void __meminit radix__vmemmap_remove_mapping(unsigned long start, unsigned long page_size)
{
        remove_pagetable(start, start + page_size, true, NULL);
}

void __ref radix__vmemmap_free(unsigned long start, unsigned long end,
                               struct vmem_altmap *altmap)
{
        remove_pagetable(start, end, false, altmap);
}
#endif
#endif

#ifdef CONFIG_TRANSPARENT_HUGEPAGE

unsigned long radix__pmd_hugepage_update(struct mm_struct *mm, unsigned long addr,
                                  pmd_t *pmdp, unsigned long clr,
                                  unsigned long set)
{
        unsigned long old;

#ifdef CONFIG_DEBUG_VM
        WARN_ON(!radix__pmd_trans_huge(*pmdp));
        assert_spin_locked(pmd_lockptr(mm, pmdp));
#endif

        old = radix__pte_update(mm, addr, pmdp_ptep(pmdp), clr, set, 1);
        trace_hugepage_update_pmd(addr, old, clr, set);

        return old;
}

unsigned long radix__pud_hugepage_update(struct mm_struct *mm, unsigned long addr,
                                         pud_t *pudp, unsigned long clr,
                                         unsigned long set)
{
        unsigned long old;

#ifdef CONFIG_DEBUG_VM
        WARN_ON(!pud_trans_huge(*pudp));
        assert_spin_locked(pud_lockptr(mm, pudp));
#endif

        old = radix__pte_update(mm, addr, pudp_ptep(pudp), clr, set, 1);
        trace_hugepage_update_pud(addr, old, clr, set);

        return old;
}

pmd_t radix__pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address,
                        pmd_t *pmdp)

{
        pmd_t pmd;

        VM_BUG_ON(address & ~HPAGE_PMD_MASK);
        VM_BUG_ON(radix__pmd_trans_huge(*pmdp));
        /*
         * khugepaged calls this for normal pmd
         */
        pmd = *pmdp;
        pmd_clear(pmdp);

        page_table_check_pmd_clear(vma->vm_mm, address, pmd);

        radix__flush_tlb_collapsed_pmd(vma->vm_mm, address);

        return pmd;
}

/*
 * For us pgtable_t is pte_t *. Inorder to save the deposisted
 * page table, we consider the allocated page table as a list
 * head. On withdraw we need to make sure we zero out the used
 * list_head memory area.
 */
void radix__pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp,
                                 pgtable_t pgtable)
{
        struct list_head *lh = (struct list_head *) pgtable;

        assert_spin_locked(pmd_lockptr(mm, pmdp));

        /* FIFO */
        if (!pmd_huge_pte(mm, pmdp))
                INIT_LIST_HEAD(lh);
        else
                list_add(lh, (struct list_head *) pmd_huge_pte(mm, pmdp));
        pmd_huge_pte(mm, pmdp) = pgtable;
}

pgtable_t radix__pgtable_trans_huge_withdraw(struct mm_struct *mm, pmd_t *pmdp)
{
        pte_t *ptep;
        pgtable_t pgtable;
        struct list_head *lh;

        assert_spin_locked(pmd_lockptr(mm, pmdp));

        /* FIFO */
        pgtable = pmd_huge_pte(mm, pmdp);
        lh = (struct list_head *) pgtable;
        if (list_empty(lh))
                pmd_huge_pte(mm, pmdp) = NULL;
        else {
                pmd_huge_pte(mm, pmdp) = (pgtable_t) lh->next;
                list_del(lh);
        }
        ptep = (pte_t *) pgtable;
        *ptep = __pte(0);
        ptep++;
        *ptep = __pte(0);
        return pgtable;
}

pmd_t radix__pmdp_huge_get_and_clear(struct mm_struct *mm,
                                     unsigned long addr, pmd_t *pmdp)
{
        pmd_t old_pmd;
        unsigned long old;

        old = radix__pmd_hugepage_update(mm, addr, pmdp, ~0UL, 0);
        old_pmd = __pmd(old);
        return old_pmd;
}

pud_t radix__pudp_huge_get_and_clear(struct mm_struct *mm,
                                     unsigned long addr, pud_t *pudp)
{
        pud_t old_pud;
        unsigned long old;

        old = radix__pud_hugepage_update(mm, addr, pudp, ~0UL, 0);
        old_pud = __pud(old);
        return old_pud;
}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE */

void radix__ptep_set_access_flags(struct vm_area_struct *vma, pte_t *ptep,
                                  pte_t entry, unsigned long address, int psize)
{
        struct mm_struct *mm = vma->vm_mm;
        unsigned long set = pte_val(entry) & (_PAGE_DIRTY | _PAGE_SOFT_DIRTY |
                                              _PAGE_ACCESSED | _PAGE_RW | _PAGE_EXEC);

        unsigned long change = pte_val(entry) ^ pte_val(*ptep);
        /*
         * On POWER9, the NMMU is not able to relax PTE access permissions
         * for a translation with a TLB. The PTE must be invalidated, TLB
         * flushed before the new PTE is installed.
         *
         * This only needs to be done for radix, because hash translation does
         * flush when updating the linux pte (and we don't support NMMU
         * accelerators on HPT on POWER9 anyway XXX: do we?).
         *
         * POWER10 (and P9P) NMMU does behave as per ISA.
         */
        if (!cpu_has_feature(CPU_FTR_ARCH_31) && (change & _PAGE_RW) &&
            atomic_read(&mm->context.copros) > 0) {
                unsigned long old_pte, new_pte;

                old_pte = __radix_pte_update(ptep, _PAGE_PRESENT, _PAGE_INVALID);
                new_pte = old_pte | set;
                radix__flush_tlb_page_psize(mm, address, psize);
                __radix_pte_update(ptep, _PAGE_INVALID, new_pte);
        } else {
                __radix_pte_update(ptep, 0, set);
                /*
                 * Book3S does not require a TLB flush when relaxing access
                 * restrictions when the address space (modulo the POWER9 nest
                 * MMU issue above) because the MMU will reload the PTE after
                 * taking an access fault, as defined by the architecture. See
                 * "Setting a Reference or Change Bit or Upgrading Access
                 *  Authority (PTE Subject to Atomic Hardware Updates)" in
                 *  Power ISA Version 3.1B.
                 */
        }
        /* See ptesync comment in radix__set_pte_at */
}

void radix__ptep_modify_prot_commit(struct vm_area_struct *vma,
                                    unsigned long addr, pte_t *ptep,
                                    pte_t old_pte, pte_t pte)
{
        struct mm_struct *mm = vma->vm_mm;

        /*
         * POWER9 NMMU must flush the TLB after clearing the PTE before
         * installing a PTE with more relaxed access permissions, see
         * radix__ptep_set_access_flags.
         */
        if (!cpu_has_feature(CPU_FTR_ARCH_31) &&
            is_pte_rw_upgrade(pte_val(old_pte), pte_val(pte)) &&
            (atomic_read(&mm->context.copros) > 0))
                radix__flush_tlb_page(vma, addr);

        set_pte_at_unchecked(mm, addr, ptep, pte);
}

int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot)
{
        pte_t *ptep = (pte_t *)pud;
        pte_t new_pud = pfn_pte(__phys_to_pfn(addr), prot);

        if (!radix_enabled())
                return 0;

        set_pte_at_unchecked(&init_mm, 0 /* radix unused */, ptep, new_pud);

        return 1;
}

int pud_clear_huge(pud_t *pud)
{
        if (pud_leaf(*pud)) {
                pud_clear(pud);
                return 1;
        }

        return 0;
}

int pud_free_pmd_page(pud_t *pud, unsigned long addr)
{
        pmd_t *pmd;
        int i;

        pmd = pud_pgtable(*pud);
        pud_clear(pud);

        flush_tlb_kernel_range(addr, addr + PUD_SIZE);

        for (i = 0; i < PTRS_PER_PMD; i++) {
                if (!pmd_none(pmd[i])) {
                        pte_t *pte;
                        pte = (pte_t *)pmd_page_vaddr(pmd[i]);

                        pte_free_kernel(&init_mm, pte);
                }
        }

        pmd_free(&init_mm, pmd);

        return 1;
}

int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot)
{
        pte_t *ptep = (pte_t *)pmd;
        pte_t new_pmd = pfn_pte(__phys_to_pfn(addr), prot);

        if (!radix_enabled())
                return 0;

        set_pte_at_unchecked(&init_mm, 0 /* radix unused */, ptep, new_pmd);

        return 1;
}

int pmd_clear_huge(pmd_t *pmd)
{
        if (pmd_leaf(*pmd)) {
                pmd_clear(pmd);
                return 1;
        }

        return 0;
}

int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
{
        pte_t *pte;

        pte = (pte_t *)pmd_page_vaddr(*pmd);
        pmd_clear(pmd);

        flush_tlb_kernel_range(addr, addr + PMD_SIZE);

        pte_free_kernel(&init_mm, pte);

        return 1;
}