1 // SPDX-License-Identifier: GPL-2.0
3 * Virtual Memory Map support
5 * (C) 2007 sgi. Christoph Lameter.
7 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn,
8 * virt_to_page, page_address() to be implemented as a base offset
9 * calculation without memory access.
11 * However, virtual mappings need a page table and TLBs. Many Linux
12 * architectures already map their physical space using 1-1 mappings
13 * via TLBs. For those arches the virtual memory map is essentially
14 * for free if we use the same page size as the 1-1 mappings. In that
15 * case the overhead consists of a few additional pages that are
16 * allocated to create a view of memory for vmemmap.
18 * The architecture is expected to provide a vmemmap_populate() function
19 * to instantiate the mapping.
22 #include <linux/mmzone.h>
23 #include <linux/memblock.h>
24 #include <linux/memremap.h>
25 #include <linux/highmem.h>
26 #include <linux/slab.h>
27 #include <linux/spinlock.h>
28 #include <linux/vmalloc.h>
29 #include <linux/sched.h>
31 #include <asm/pgalloc.h>
34 * Allocate a block of memory to be used to back the virtual memory map
35 * or to back the page tables that are used to create the mapping.
36 * Uses the main allocators if they are available, else bootmem.
39 static void * __ref __earlyonly_bootmem_alloc(int node,
44 return memblock_alloc_try_nid_raw(size, align, goal,
45 MEMBLOCK_ALLOC_ACCESSIBLE, node);
48 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
50 /* If the main allocator is up use that, fallback to bootmem. */
51 if (slab_is_available()) {
52 gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN;
53 int order = get_order(size);
57 page = alloc_pages_node(node, gfp_mask, order);
59 return page_address(page);
62 warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL,
63 "vmemmap alloc failure: order:%u", order);
68 return __earlyonly_bootmem_alloc(node, size, size,
69 __pa(MAX_DMA_ADDRESS));
72 /* need to make sure size is all the same during early stage */
73 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node)
75 void *ptr = sparse_buffer_alloc(size);
78 ptr = vmemmap_alloc_block(size, node);
82 static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
84 return altmap->base_pfn + altmap->reserve + altmap->alloc
88 static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
90 unsigned long allocated = altmap->alloc + altmap->align;
92 if (altmap->free > allocated)
93 return altmap->free - allocated;
98 * altmap_alloc_block_buf - allocate pages from the device page map
99 * @altmap: device page map
100 * @size: size (in bytes) of the allocation
102 * Allocations are aligned to the size of the request.
104 void * __meminit altmap_alloc_block_buf(unsigned long size,
105 struct vmem_altmap *altmap)
107 unsigned long pfn, nr_pfns, nr_align;
109 if (size & ~PAGE_MASK) {
110 pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
115 pfn = vmem_altmap_next_pfn(altmap);
116 nr_pfns = size >> PAGE_SHIFT;
117 nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
118 nr_align = ALIGN(pfn, nr_align) - pfn;
119 if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
122 altmap->alloc += nr_pfns;
123 altmap->align += nr_align;
126 pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
127 __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
128 return __va(__pfn_to_phys(pfn));
131 void __meminit vmemmap_verify(pte_t *pte, int node,
132 unsigned long start, unsigned long end)
134 unsigned long pfn = pte_pfn(*pte);
135 int actual_node = early_pfn_to_nid(pfn);
137 if (node_distance(actual_node, node) > LOCAL_DISTANCE)
138 pr_warn("[%lx-%lx] potential offnode page_structs\n",
142 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
144 pte_t *pte = pte_offset_kernel(pmd, addr);
145 if (pte_none(*pte)) {
147 void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node);
150 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
151 set_pte_at(&init_mm, addr, pte, entry);
156 static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node)
158 void *p = vmemmap_alloc_block(size, node);
167 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
169 pmd_t *pmd = pmd_offset(pud, addr);
170 if (pmd_none(*pmd)) {
171 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
174 pmd_populate_kernel(&init_mm, pmd, p);
179 pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node)
181 pud_t *pud = pud_offset(p4d, addr);
182 if (pud_none(*pud)) {
183 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
186 pud_populate(&init_mm, pud, p);
191 p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node)
193 p4d_t *p4d = p4d_offset(pgd, addr);
194 if (p4d_none(*p4d)) {
195 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
198 p4d_populate(&init_mm, p4d, p);
203 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
205 pgd_t *pgd = pgd_offset_k(addr);
206 if (pgd_none(*pgd)) {
207 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node);
210 pgd_populate(&init_mm, pgd, p);
215 int __meminit vmemmap_populate_basepages(unsigned long start,
216 unsigned long end, int node)
218 unsigned long addr = start;
225 for (; addr < end; addr += PAGE_SIZE) {
226 pgd = vmemmap_pgd_populate(addr, node);
229 p4d = vmemmap_p4d_populate(pgd, addr, node);
232 pud = vmemmap_pud_populate(p4d, addr, node);
235 pmd = vmemmap_pmd_populate(pud, addr, node);
238 pte = vmemmap_pte_populate(pmd, addr, node);
241 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
247 struct page * __meminit __populate_section_memmap(unsigned long pfn,
248 unsigned long nr_pages, int nid, struct vmem_altmap *altmap)
254 * The minimum granularity of memmap extensions is
255 * PAGES_PER_SUBSECTION as allocations are tracked in the
256 * 'subsection_map' bitmap of the section.
258 end = ALIGN(pfn + nr_pages, PAGES_PER_SUBSECTION);
259 pfn &= PAGE_SUBSECTION_MASK;
260 nr_pages = end - pfn;
262 start = (unsigned long) pfn_to_page(pfn);
263 end = start + nr_pages * sizeof(struct page);
265 if (vmemmap_populate(start, end, nid, altmap))
268 return pfn_to_page(pfn);