// 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(*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(*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; pmd_populate_kernel(&init_mm, pmd, p); } return pmd; } void __weak __meminit pmd_init(void *addr) { } 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; } void __weak __meminit pud_init(void *addr) { } 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; } /* * 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(*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(*pte)); if (rc) return -ENOMEM; } return 0; } 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 (is_power_of_2(sizeof(struct page)) && pgmap && pgmap_vmemmap_nr(pgmap) > 1 && !altmap) 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); }