1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Virtual Memory Map support 4 * 5 * (C) 2007 sgi. Christoph Lameter. 6 * 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. 10 * 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. 17 * 18 * The architecture is expected to provide a vmemmap_populate() function 19 * to instantiate the mapping. 20 */ 21 #include <linux/mm.h> 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> 30 #include <asm/dma.h> 31 #include <asm/pgalloc.h> 32 #include <asm/pgtable.h> 33 34 /* 35 * Allocate a block of memory to be used to back the virtual memory map 36 * or to back the page tables that are used to create the mapping. 37 * Uses the main allocators if they are available, else bootmem. 38 */ 39 40 static void * __ref __earlyonly_bootmem_alloc(int node, 41 unsigned long size, 42 unsigned long align, 43 unsigned long goal) 44 { 45 return memblock_alloc_try_nid_raw(size, align, goal, 46 MEMBLOCK_ALLOC_ACCESSIBLE, node); 47 } 48 49 void * __meminit vmemmap_alloc_block(unsigned long size, int node) 50 { 51 /* If the main allocator is up use that, fallback to bootmem. */ 52 if (slab_is_available()) { 53 gfp_t gfp_mask = GFP_KERNEL|__GFP_RETRY_MAYFAIL|__GFP_NOWARN; 54 int order = get_order(size); 55 static bool warned; 56 struct page *page; 57 58 page = alloc_pages_node(node, gfp_mask, order); 59 if (page) 60 return page_address(page); 61 62 if (!warned) { 63 warn_alloc(gfp_mask & ~__GFP_NOWARN, NULL, 64 "vmemmap alloc failure: order:%u", order); 65 warned = true; 66 } 67 return NULL; 68 } else 69 return __earlyonly_bootmem_alloc(node, size, size, 70 __pa(MAX_DMA_ADDRESS)); 71 } 72 73 /* need to make sure size is all the same during early stage */ 74 void * __meminit vmemmap_alloc_block_buf(unsigned long size, int node) 75 { 76 void *ptr = sparse_buffer_alloc(size); 77 78 if (!ptr) 79 ptr = vmemmap_alloc_block(size, node); 80 return ptr; 81 } 82 83 static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap) 84 { 85 return altmap->base_pfn + altmap->reserve + altmap->alloc 86 + altmap->align; 87 } 88 89 static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap) 90 { 91 unsigned long allocated = altmap->alloc + altmap->align; 92 93 if (altmap->free > allocated) 94 return altmap->free - allocated; 95 return 0; 96 } 97 98 /** 99 * altmap_alloc_block_buf - allocate pages from the device page map 100 * @altmap: device page map 101 * @size: size (in bytes) of the allocation 102 * 103 * Allocations are aligned to the size of the request. 104 */ 105 void * __meminit altmap_alloc_block_buf(unsigned long size, 106 struct vmem_altmap *altmap) 107 { 108 unsigned long pfn, nr_pfns, nr_align; 109 110 if (size & ~PAGE_MASK) { 111 pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n", 112 __func__, size); 113 return NULL; 114 } 115 116 pfn = vmem_altmap_next_pfn(altmap); 117 nr_pfns = size >> PAGE_SHIFT; 118 nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG); 119 nr_align = ALIGN(pfn, nr_align) - pfn; 120 if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap)) 121 return NULL; 122 123 altmap->alloc += nr_pfns; 124 altmap->align += nr_align; 125 pfn += nr_align; 126 127 pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n", 128 __func__, pfn, altmap->alloc, altmap->align, nr_pfns); 129 return __va(__pfn_to_phys(pfn)); 130 } 131 132 void __meminit vmemmap_verify(pte_t *pte, int node, 133 unsigned long start, unsigned long end) 134 { 135 unsigned long pfn = pte_pfn(*pte); 136 int actual_node = early_pfn_to_nid(pfn); 137 138 if (node_distance(actual_node, node) > LOCAL_DISTANCE) 139 pr_warn("[%lx-%lx] potential offnode page_structs\n", 140 start, end - 1); 141 } 142 143 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node) 144 { 145 pte_t *pte = pte_offset_kernel(pmd, addr); 146 if (pte_none(*pte)) { 147 pte_t entry; 148 void *p = vmemmap_alloc_block_buf(PAGE_SIZE, node); 149 if (!p) 150 return NULL; 151 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL); 152 set_pte_at(&init_mm, addr, pte, entry); 153 } 154 return pte; 155 } 156 157 static void * __meminit vmemmap_alloc_block_zero(unsigned long size, int node) 158 { 159 void *p = vmemmap_alloc_block(size, node); 160 161 if (!p) 162 return NULL; 163 memset(p, 0, size); 164 165 return p; 166 } 167 168 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) 169 { 170 pmd_t *pmd = pmd_offset(pud, addr); 171 if (pmd_none(*pmd)) { 172 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 173 if (!p) 174 return NULL; 175 pmd_populate_kernel(&init_mm, pmd, p); 176 } 177 return pmd; 178 } 179 180 pud_t * __meminit vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node) 181 { 182 pud_t *pud = pud_offset(p4d, addr); 183 if (pud_none(*pud)) { 184 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 185 if (!p) 186 return NULL; 187 pud_populate(&init_mm, pud, p); 188 } 189 return pud; 190 } 191 192 p4d_t * __meminit vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node) 193 { 194 p4d_t *p4d = p4d_offset(pgd, addr); 195 if (p4d_none(*p4d)) { 196 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 197 if (!p) 198 return NULL; 199 p4d_populate(&init_mm, p4d, p); 200 } 201 return p4d; 202 } 203 204 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) 205 { 206 pgd_t *pgd = pgd_offset_k(addr); 207 if (pgd_none(*pgd)) { 208 void *p = vmemmap_alloc_block_zero(PAGE_SIZE, node); 209 if (!p) 210 return NULL; 211 pgd_populate(&init_mm, pgd, p); 212 } 213 return pgd; 214 } 215 216 int __meminit vmemmap_populate_basepages(unsigned long start, 217 unsigned long end, int node) 218 { 219 unsigned long addr = start; 220 pgd_t *pgd; 221 p4d_t *p4d; 222 pud_t *pud; 223 pmd_t *pmd; 224 pte_t *pte; 225 226 for (; addr < end; addr += PAGE_SIZE) { 227 pgd = vmemmap_pgd_populate(addr, node); 228 if (!pgd) 229 return -ENOMEM; 230 p4d = vmemmap_p4d_populate(pgd, addr, node); 231 if (!p4d) 232 return -ENOMEM; 233 pud = vmemmap_pud_populate(p4d, addr, node); 234 if (!pud) 235 return -ENOMEM; 236 pmd = vmemmap_pmd_populate(pud, addr, node); 237 if (!pmd) 238 return -ENOMEM; 239 pte = vmemmap_pte_populate(pmd, addr, node); 240 if (!pte) 241 return -ENOMEM; 242 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); 243 } 244 245 return 0; 246 } 247 248 struct page * __meminit __populate_section_memmap(unsigned long pfn, 249 unsigned long nr_pages, int nid, struct vmem_altmap *altmap) 250 { 251 unsigned long start; 252 unsigned long end; 253 254 /* 255 * The minimum granularity of memmap extensions is 256 * PAGES_PER_SUBSECTION as allocations are tracked in the 257 * 'subsection_map' bitmap of the section. 258 */ 259 end = ALIGN(pfn + nr_pages, PAGES_PER_SUBSECTION); 260 pfn &= PAGE_SUBSECTION_MASK; 261 nr_pages = end - pfn; 262 263 start = (unsigned long) pfn_to_page(pfn); 264 end = start + nr_pages * sizeof(struct page); 265 266 if (vmemmap_populate(start, end, nid, altmap)) 267 return NULL; 268 269 return pfn_to_page(pfn); 270 } 271