// 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 <asm/dma.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.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 memblock_alloc_try_nid_raw(size, align, goal,
                                               MEMBLOCK_ALLOC_ACCESSIBLE, node);
}

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));
}

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

/**
 * altmap_alloc_block_buf - allocate pages from the device page map
 * @altmap:     device page map
 * @size:       size (in bytes) of the allocation
 *
 * Allocations are aligned to the size of the request.
 */
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(*pte);
        int actual_node = early_pfn_to_nid(pfn);

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

pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
{
        pte_t *pte = pte_offset_kernel(pmd, addr);
        if (pte_none(*pte)) {
                pte_t entry;
                void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
                if (!p)
                        return NULL;
                entry = pfn_pte(__pa(p) >> PAGE_SHIFT, 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;
                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;
                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;
                p4d_populate(&init_mm, 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(&init_mm, pgd, p);
        }
        return pgd;
}

int __meminit vmemmap_populate_basepages(unsigned long start,
                                         unsigned long end, int node)
{
        unsigned long addr = start;
        pgd_t *pgd;
        p4d_t *p4d;
        pud_t *pud;
        pmd_t *pmd;
        pte_t *pte;

        for (; addr < end; addr += PAGE_SIZE) {
                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 = vmemmap_pmd_populate(pud, addr, node);
                if (!pmd)
                        return -ENOMEM;
                pte = vmemmap_pte_populate(pmd, addr, node);
                if (!pte)
                        return -ENOMEM;
                vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
        }

        return 0;
}

struct page * __meminit __populate_section_memmap(unsigned long pfn,
                unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
{
        unsigned long start;
        unsigned long end;

        /*
         * The minimum granularity of memmap extensions is
         * PAGES_PER_SUBSECTION as allocations are tracked in the
         * 'subsection_map' bitmap of the section.
         */
        end = ALIGN(pfn + nr_pages, PAGES_PER_SUBSECTION);
        pfn &= PAGE_SUBSECTION_MASK;
        nr_pages = end - pfn;

        start = (unsigned long) pfn_to_page(pfn);
        end = start + nr_pages * sizeof(struct page);

        if (vmemmap_populate(start, end, nid, altmap))
                return NULL;

        return pfn_to_page(pfn);
}