// 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/bootmem.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_virt_alloc_try_nid(size, align, goal,
  					    BOOTMEM_ALLOC_ACCESSIBLE, node);

  }

  static void *vmemmap_buf;
  static void *vmemmap_buf_end;

  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()) {

  		struct page *page;

  		page = alloc_pages_node(node,
  			GFP_KERNEL | __GFP_ZERO | __GFP_RETRY_MAYFAIL,
  			get_order(size));

  		if (page)
  			return page_address(page);
  		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 */

  static void * __meminit alloc_block_buf(unsigned long size, int node)

  {
  	void *ptr;
  
  	if (!vmemmap_buf)
  		return vmemmap_alloc_block(size, node);
  
  	/* take the from buf */
  	ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
  	if (ptr + size > vmemmap_buf_end)
  		return vmemmap_alloc_block(size, node);
  
  	vmemmap_buf = ptr + size;
  
  	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;
  }
  
  /**
   * vmem_altmap_alloc - allocate pages from the vmem_altmap reservation
   * @altmap - reserved page pool for the allocation
   * @nr_pfns - size (in pages) of the allocation
   *
   * Allocations are aligned to the size of the request
   */
  static unsigned long __meminit vmem_altmap_alloc(struct vmem_altmap *altmap,
  		unsigned long nr_pfns)
  {
  	unsigned long pfn = vmem_altmap_next_pfn(altmap);
  	unsigned long nr_align;
  
  	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 ULONG_MAX;
  	altmap->alloc += nr_pfns;
  	altmap->align += nr_align;
  	return pfn + nr_align;
  }
  
  static void * __meminit altmap_alloc_block_buf(unsigned long size,
  		struct vmem_altmap *altmap)
  {
  	unsigned long pfn, nr_pfns;
  	void *ptr;
  
  	if (size & ~PAGE_MASK) {
  		pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)
  ",
  				__func__, size);
  		return NULL;
  	}
  
  	nr_pfns = size >> PAGE_SHIFT;
  	pfn = vmem_altmap_alloc(altmap, nr_pfns);
  	if (pfn < ULONG_MAX)
  		ptr = __va(__pfn_to_phys(pfn));
  	else
  		ptr = NULL;
  	pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx
  ",
  			__func__, pfn, altmap->alloc, altmap->align, nr_pfns);
  
  	return ptr;
  }
  
  /* 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)
  {
  	if (altmap)
  		return altmap_alloc_block_buf(size, altmap);
  	return alloc_block_buf(size, node);
  }

  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
  ",
  			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 = 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;

  }

  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(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(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(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(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 sparse_mem_map_populate(unsigned long pnum, int nid)

  {

  	unsigned long start;
  	unsigned long end;
  	struct page *map;
  
  	map = pfn_to_page(pnum * PAGES_PER_SECTION);
  	start = (unsigned long)map;
  	end = (unsigned long)(map + PAGES_PER_SECTION);
  
  	if (vmemmap_populate(start, end, nid))

  		return NULL;
  
  	return map;
  }

  
  void __init sparse_mem_maps_populate_node(struct page **map_map,
  					  unsigned long pnum_begin,
  					  unsigned long pnum_end,
  					  unsigned long map_count, int nodeid)
  {
  	unsigned long pnum;
  	unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
  	void *vmemmap_buf_start;
  
  	size = ALIGN(size, PMD_SIZE);
  	vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
  			 PMD_SIZE, __pa(MAX_DMA_ADDRESS));
  
  	if (vmemmap_buf_start) {
  		vmemmap_buf = vmemmap_buf_start;
  		vmemmap_buf_end = vmemmap_buf_start + size * map_count;
  	}
  
  	for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
  		struct mem_section *ms;
  
  		if (!present_section_nr(pnum))
  			continue;
  
  		map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
  		if (map_map[pnum])
  			continue;
  		ms = __nr_to_section(pnum);

  		pr_err("%s: sparsemem memory map backing failed some memory will not be available
  ",

  		       __func__);

  		ms->section_mem_map = 0;
  	}
  
  	if (vmemmap_buf_start) {
  		/* need to free left buf */

  		memblock_free_early(__pa(vmemmap_buf),
  				    vmemmap_buf_end - vmemmap_buf);

  		vmemmap_buf = NULL;
  		vmemmap_buf_end = NULL;
  	}
  }