// 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>

  
  /*
   * 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));
  }

  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)
  ",
  				__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
  ",
  			__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
  ",
  			start, end - 1);

  }

  pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node,
  				       struct vmem_altmap *altmap)

  {

  	pte_t *pte = pte_offset_kernel(pmd, addr);
  	if (pte_none(*pte)) {
  		pte_t entry;

  		void *p;

  		p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);

  		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, struct vmem_altmap *altmap)

  {

  	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, altmap);

  		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) pfn_to_page(pfn);
  	unsigned long end = start + nr_pages * sizeof(struct page);
  
  	if (WARN_ON_ONCE(!IS_ALIGNED(pfn, PAGES_PER_SUBSECTION) ||
  		!IS_ALIGNED(nr_pages, PAGES_PER_SUBSECTION)))
  		return NULL;

  	if (vmemmap_populate(start, end, nid, altmap))

  		return NULL;

  	return pfn_to_page(pfn);

  }