// SPDX-License-Identifier: GPL-2.0
/*
 * Virtual Memory Map support
 *
 * (C) 2007 sgi. Christoph Lameter.
 *
 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
 * virt_to_page, page_address() to be implemented as a base offset
 * calculation without memory access.
 *
 * However, virtual mappings need a page table and TLBs. Many Linux
 * architectures already map their physical space using 1-1 mappings
 * via TLBs. For those arches the virtual memory map is essentially
 * for free if we use the same page size as the 1-1 mappings. In that
 * case the overhead consists of a few additional pages that are
 * allocated to create a view of memory for vmemmap.
 *
 * The architecture is expected to provide a vmemmap_populate() function
 * to instantiate the mapping.
 */
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/memblock.h>
#include <linux/memremap.h>
#include <linux/highmem.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/vmalloc.h>
#include <linux/sched.h>
#include <linux/pgalloc.h>

#include <asm/dma.h>
#include <asm/tlbflush.h>

#include "hugetlb_vmemmap.h"

/*
 * Flags for vmemmap_populate_range and friends.
 */
/* Get a ref on the head page struct page, for ZONE_DEVICE compound pages */
#define VMEMMAP_POPULATE_PAGEREF        0x0001

#include "internal.h"

/*
 * Allocate a block of memory to be used to back the virtual memory map
 * or to back the page tables that are used to create the mapping.
 * Uses the main allocators if they are available, else bootmem.
 */

static void * __ref __earlyonly_bootmem_alloc(int node,
                                unsigned long size,
                                unsigned long align,
                                unsigned long goal)
{
        return memmap_alloc(size, align, goal, node, false);
}

void * __meminit vmemmap_alloc_block(unsigned long size, int node)
{
        /* If the main allocator is up use that, fallback to bootmem. */
        if (slab_is_available()) {
                gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
                int order = get_order(size);
                static bool warned;
                struct page *page;

                page = alloc_pages_node(node, gfp_mask, order);
                if (page)
                        return page_address(page);

                if (!warned) {
                        warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
                                   "vmemmap alloc failure: order:%u", order);
                        warned = true;
                }
                return NULL;
        } else
                return __earlyonly_bootmem_alloc(node, size, size,
                                __pa(MAX_DMA_ADDRESS));
}

static void * __meminit altmap_alloc_block_buf(unsigned long size,
                                               struct vmem_altmap *altmap);

/* need to make sure size is all the same during early stage */
void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node,
                                         struct vmem_altmap *altmap)
{
        void *ptr;

        if (altmap)
                return altmap_alloc_block_buf(size, altmap);

        ptr = sparse_buffer_alloc(size);
        if (!ptr)
                ptr = vmemmap_alloc_block(size, node);
        return ptr;
}

static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
{
        return altmap->base_pfn + altmap->reserve + altmap->alloc
                + altmap->align;
}

static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
{
        unsigned long allocated = altmap->alloc + altmap->align;

        if (altmap->free > allocated)
                return altmap->free - allocated;
        return 0;
}

static void * __meminit altmap_alloc_block_buf(unsigned long size,
                                               struct vmem_altmap *altmap)
{
        unsigned long pfn, nr_pfns, nr_align;

        if (size & ~PAGE_MASK) {
                pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
                                __func__, size);
                return NULL;
        }

        pfn = vmem_altmap_next_pfn(altmap);
        nr_pfns = size >> PAGE_SHIFT;
        nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
        nr_align = ALIGN(pfn, nr_align) - pfn;
        if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
                return NULL;

        altmap->alloc += nr_pfns;
        altmap->align += nr_align;
        pfn += nr_align;

        pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
                        __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
        return __va(__pfn_to_phys(pfn));
}

void __meminit vmemmap_verify(pte_t *pte, int node,
                                unsigned long start, unsigned long end)
{
        unsigned long pfn = pte_pfn(ptep_get(pte));
        int actual_node = early_pfn_to_nid(pfn);

        if (node_distance(actual_node, node) > LOCAL_DISTANCE)
                pr_warn_once("[%lx-%lx] potential offnode page_structs\n",
                        start, end - 1);
}

pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
                                       struct vmem_altmap *altmap,
                                       unsigned long ptpfn, unsigned long flags)
{
        pte_t *pte = pte_offset_kernel(pmd, addr);
        if (pte_none(ptep_get(pte))) {
                pte_t entry;
                void *p;

                if (ptpfn == (unsigned long)-1) {
                        p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);
                        if (!p)
                                return NULL;
                        ptpfn = PHYS_PFN(__pa(p));
                } 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.
                         */
                        if (flags & VMEMMAP_POPULATE_PAGEREF)
                                get_page(pfn_to_page(ptpfn));
                }
                entry = pfn_pte(ptpfn, PAGE_KERNEL);
                set_pte_at(&init_mm, addr, pte, entry);
        }
        return pte;
}

static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
{
        void *p = vmemmap_alloc_block(size, node);

        if (!p)
                return NULL;
        memset(p, 0, size);

        return p;
}

pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
{
        pmd_t *pmd = pmd_offset(pud, addr);
        if (pmd_none(*pmd)) {
                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
                if (!p)
                        return NULL;
                kernel_pte_init(p);
                pmd_populate_kernel(&init_mm, pmd, p);
        }
        return pmd;
}

pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
{
        pud_t *pud = pud_offset(p4d, addr);
        if (pud_none(*pud)) {
                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
                if (!p)
                        return NULL;
                pmd_init(p);
                pud_populate(&init_mm, pud, p);
        }
        return pud;
}

p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
{
        p4d_t *p4d = p4d_offset(pgd, addr);
        if (p4d_none(*p4d)) {
                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
                if (!p)
                        return NULL;
                pud_init(p);
                p4d_populate_kernel(addr, p4d, p);
        }
        return p4d;
}

pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
{
        pgd_t *pgd = pgd_offset_k(addr);
        if (pgd_none(*pgd)) {
                void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
                if (!p)
                        return NULL;
                pgd_populate_kernel(addr, pgd, p);
        }
        return pgd;
}

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

        pgd = vmemmap_pgd_populate(addr, node);
        if (!pgd)
                return NULL;
        p4d = vmemmap_p4d_populate(pgd, addr, node);
        if (!p4d)
                return NULL;
        pud = vmemmap_pud_populate(p4d, addr, node);
        if (!pud)
                return NULL;
        pmd = vmemmap_pmd_populate(pud, addr, node);
        if (!pmd)
                return NULL;
        pte = vmemmap_pte_populate(pmd, addr, node, altmap, ptpfn, flags);
        if (!pte)
                return NULL;
        vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);

        return pte;
}

static int __meminit vmemmap_populate_range(unsigned long start,
                                            unsigned long end, int node,
                                            struct vmem_altmap *altmap,
                                            unsigned long ptpfn,
                                            unsigned long flags)
{
        unsigned long addr = start;
        pte_t *pte;

        for (; addr < end; addr += PAGE_SIZE) {
                pte = vmemmap_populate_address(addr, node, altmap,
                                               ptpfn, flags);
                if (!pte)
                        return -ENOMEM;
        }

        return 0;
}

int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end,
                                         int node, struct vmem_altmap *altmap)
{
        return vmemmap_populate_range(start, end, node, altmap, -1, 0);
}

/*
 * Undo populate_hvo, and replace it with a normal base page mapping.
 * Used in memory init in case a HVO mapping needs to be undone.
 *
 * This can happen when it is discovered that a memblock allocated
 * hugetlb page spans multiple zones, which can only be verified
 * after zones have been initialized.
 *
 * We know that:
 * 1) The first @headsize / PAGE_SIZE vmemmap pages were individually
 *    allocated through memblock, and mapped.
 *
 * 2) The rest of the vmemmap pages are mirrors of the last head page.
 */
int __meminit vmemmap_undo_hvo(unsigned long addr, unsigned long end,
                                      int node, unsigned long headsize)
{
        unsigned long maddr, pfn;
        pte_t *pte;
        int headpages;

        /*
         * Should only be called early in boot, so nothing will
         * be accessing these page structures.
         */
        WARN_ON(!early_boot_irqs_disabled);

        headpages = headsize >> PAGE_SHIFT;

        /*
         * Clear mirrored mappings for tail page structs.
         */
        for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) {
                pte = virt_to_kpte(maddr);
                pte_clear(&init_mm, maddr, pte);
        }

        /*
         * Clear and free mappings for head page and first tail page
         * structs.
         */
        for (maddr = addr; headpages-- > 0; maddr += PAGE_SIZE) {
                pte = virt_to_kpte(maddr);
                pfn = pte_pfn(ptep_get(pte));
                pte_clear(&init_mm, maddr, pte);
                memblock_phys_free(PFN_PHYS(pfn), PAGE_SIZE);
        }

        flush_tlb_kernel_range(addr, end);

        return vmemmap_populate(addr, end, node, NULL);
}

/*
 * Write protect the mirrored tail page structs for HVO. This will be
 * called from the hugetlb code when gathering and initializing the
 * memblock allocated gigantic pages. The write protect can't be
 * done earlier, since it can't be guaranteed that the reserved
 * page structures will not be written to during initialization,
 * even if CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled.
 *
 * The PTEs are known to exist, and nothing else should be touching
 * these pages. The caller is responsible for any TLB flushing.
 */
void vmemmap_wrprotect_hvo(unsigned long addr, unsigned long end,
                                    int node, unsigned long headsize)
{
        unsigned long maddr;
        pte_t *pte;

        for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) {
                pte = virt_to_kpte(maddr);
                ptep_set_wrprotect(&init_mm, maddr, pte);
        }
}

/*
 * Populate vmemmap pages HVO-style. The first page contains the head
 * page and needed tail pages, the other ones are mirrors of the first
 * page.
 */
int __meminit vmemmap_populate_hvo(unsigned long addr, unsigned long end,
                                       int node, unsigned long headsize)
{
        pte_t *pte;
        unsigned long maddr;

        for (maddr = addr; maddr < addr + headsize; maddr += PAGE_SIZE) {
                pte = vmemmap_populate_address(maddr, node, NULL, -1, 0);
                if (!pte)
                        return -ENOMEM;
        }

        /*
         * Reuse the last page struct page mapped above for the rest.
         */
        return vmemmap_populate_range(maddr, end, node, NULL,
                                        pte_pfn(ptep_get(pte)), 0);
}

void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node,
                                      unsigned long addr, unsigned long next)
{
}

int __weak __meminit vmemmap_check_pmd(pmd_t *pmd, int node,
                                       unsigned long addr, unsigned long next)
{
        return 0;
}

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

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

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

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

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

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

                        p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
                        if (p) {
                                vmemmap_set_pmd(pmd, p, node, addr, next);
                                continue;
                        } else if (altmap) {
                                /*
                                 * No fallback: In any case we care about, the
                                 * altmap should be reasonably sized and aligned
                                 * such that vmemmap_alloc_block_buf() will always
                                 * succeed. For consistency with the PTE case,
                                 * return an error here as failure could indicate
                                 * a configuration issue with the size of the altmap.
                                 */
                                return -ENOMEM;
                        }
                } else if (vmemmap_check_pmd(pmd, node, addr, next))
                        continue;
                if (vmemmap_populate_basepages(addr, next, node, altmap))
                        return -ENOMEM;
        }
        return 0;
}

#ifndef vmemmap_populate_compound_pages
/*
 * For compound pages bigger than section size (e.g. x86 1G compound
 * pages with 2M subsection size) fill the rest of sections as tail
 * pages.
 *
 * Note that memremap_pages() resets @nr_range value and will increment
 * it after each range successful onlining. Thus the value or @nr_range
 * at section memmap populate corresponds to the in-progress range
 * being onlined here.
 */
static bool __meminit reuse_compound_section(unsigned long start_pfn,
                                             struct dev_pagemap *pgmap)
{
        unsigned long nr_pages = pgmap_vmemmap_nr(pgmap);
        unsigned long offset = start_pfn -
                PHYS_PFN(pgmap->ranges[pgmap->nr_range].start);

        return !IS_ALIGNED(offset, nr_pages) && nr_pages > PAGES_PER_SUBSECTION;
}

static pte_t * __meminit compound_section_tail_page(unsigned long addr)
{
        pte_t *pte;

        addr -= PAGE_SIZE;

        /*
         * Assuming sections are populated sequentially, the previous section's
         * page data can be reused.
         */
        pte = pte_offset_kernel(pmd_off_k(addr), addr);
        if (!pte)
                return NULL;

        return pte;
}

static int __meminit vmemmap_populate_compound_pages(unsigned long start_pfn,
                                                     unsigned long start,
                                                     unsigned long end, int node,
                                                     struct dev_pagemap *pgmap)
{
        unsigned long size, addr;
        pte_t *pte;
        int rc;

        if (reuse_compound_section(start_pfn, pgmap)) {
                pte = compound_section_tail_page(start);
                if (!pte)
                        return -ENOMEM;

                /*
                 * Reuse the page that was populated in the prior iteration
                 * with just tail struct pages.
                 */
                return vmemmap_populate_range(start, end, node, NULL,
                                              pte_pfn(ptep_get(pte)),
                                              VMEMMAP_POPULATE_PAGEREF);
        }

        size = min(end - start, pgmap_vmemmap_nr(pgmap) * sizeof(struct page));
        for (addr = start; addr < end; addr += size) {
                unsigned long next, last = addr + size;

                /* Populate the head page vmemmap page */
                pte = vmemmap_populate_address(addr, node, NULL, -1, 0);
                if (!pte)
                        return -ENOMEM;

                /* Populate the tail pages vmemmap page */
                next = addr + PAGE_SIZE;
                pte = vmemmap_populate_address(next, node, NULL, -1, 0);
                if (!pte)
                        return -ENOMEM;

                /*
                 * Reuse the previous page for the rest of tail pages
                 * See layout diagram in Documentation/mm/vmemmap_dedup.rst
                 */
                next += PAGE_SIZE;
                rc = vmemmap_populate_range(next, last, node, NULL,
                                            pte_pfn(ptep_get(pte)),
                                            VMEMMAP_POPULATE_PAGEREF);
                if (rc)
                        return -ENOMEM;
        }

        return 0;
}

#endif

struct page * __meminit __populate_section_memmap(unsigned long pfn,
                unsigned long nr_pages, int nid, struct vmem_altmap *altmap,
                struct dev_pagemap *pgmap)
{
        unsigned long start = (unsigned long) pfn_to_page(pfn);
        unsigned long end = start + nr_pages * sizeof(struct page);
        int r;

        if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
                !IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
                return NULL;

        if (vmemmap_can_optimize(altmap, pgmap))
                r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
        else
                r = vmemmap_populate(start, end, nid, altmap);

        if (r < 0)
                return NULL;

        return pfn_to_page(pfn);
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP_PREINIT
/*
 * This is called just before initializing sections for a NUMA node.
 * Any special initialization that needs to be done before the
 * generic initialization can be done from here. Sections that
 * are initialized in hooks called from here will be skipped by
 * the generic initialization.
 */
void __init sparse_vmemmap_init_nid_early(int nid)
{
        hugetlb_vmemmap_init_early(nid);
}

/*
 * This is called just before the initialization of page structures
 * through memmap_init. Zones are now initialized, so any work that
 * needs to be done that needs zone information can be done from
 * here.
 */
void __init sparse_vmemmap_init_nid_late(int nid)
{
        hugetlb_vmemmap_init_late(nid);
}
#endif