// 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)\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,				       struct page *reuse){	pte_t *pte = pte_offset_kernel(pmd, addr);	if (pte_none(ptep_get(pte))) {		pte_t entry;		void *p; 		if (!reuse) {			p = vmemmap_alloc_block_buf(PAGE_SIZE, node, altmap);			if (!p)				return NULL;		} 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);		}		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;		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(&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;} static pte_t * __meminit 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 = 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, reuse);	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,					    struct page *reuse){	unsigned long addr = start;	pte_t *pte; 	for (; addr < end; addr += PAGE_SIZE) {		pte = vmemmap_populate_address(addr, node, altmap, reuse);		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, NULL);} 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(READ_ONCE(*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_page(ptep_get(pte)));	} 	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, NULL);		if (!pte)			return -ENOMEM; 		/* Populate the tail pages vmemmap page */		next = addr + PAGE_SIZE;		pte = vmemmap_populate_address(next, node, NULL, NULL);		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_page(ptep_get(pte)));		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; 	if (system_state == SYSTEM_BOOTING)		memmap_boot_pages_add(DIV_ROUND_UP(end - start, PAGE_SIZE));	else		memmap_pages_add(DIV_ROUND_UP(end - start, PAGE_SIZE)); 	return pfn_to_page(pfn);}