1 /* 2 * Virtual Memory Map support 3 * 4 * (C) 2007 sgi. Christoph Lameter <clameter@sgi.com>. 5 * 6 * Virtual memory maps allow VM primitives pfn_to_page, page_to_pfn, 7 * virt_to_page, page_address() to be implemented as a base offset 8 * calculation without memory access. 9 * 10 * However, virtual mappings need a page table and TLBs. Many Linux 11 * architectures already map their physical space using 1-1 mappings 12 * via TLBs. For those arches the virtual memmory map is essentially 13 * for free if we use the same page size as the 1-1 mappings. In that 14 * case the overhead consists of a few additional pages that are 15 * allocated to create a view of memory for vmemmap. 16 * 17 * The architecture is expected to provide a vmemmap_populate() function 18 * to instantiate the mapping. 19 */ 20 #include <linux/mm.h> 21 #include <linux/mmzone.h> 22 #include <linux/bootmem.h> 23 #include <linux/highmem.h> 24 #include <linux/module.h> 25 #include <linux/spinlock.h> 26 #include <linux/vmalloc.h> 27 #include <asm/dma.h> 28 #include <asm/pgalloc.h> 29 #include <asm/pgtable.h> 30 31 /* 32 * Allocate a block of memory to be used to back the virtual memory map 33 * or to back the page tables that are used to create the mapping. 34 * Uses the main allocators if they are available, else bootmem. 35 */ 36 void * __meminit vmemmap_alloc_block(unsigned long size, int node) 37 { 38 /* If the main allocator is up use that, fallback to bootmem. */ 39 if (slab_is_available()) { 40 struct page *page = alloc_pages_node(node, 41 GFP_KERNEL | __GFP_ZERO, get_order(size)); 42 if (page) 43 return page_address(page); 44 return NULL; 45 } else 46 return __alloc_bootmem_node(NODE_DATA(node), size, size, 47 __pa(MAX_DMA_ADDRESS)); 48 } 49 50 void __meminit vmemmap_verify(pte_t *pte, int node, 51 unsigned long start, unsigned long end) 52 { 53 unsigned long pfn = pte_pfn(*pte); 54 int actual_node = early_pfn_to_nid(pfn); 55 56 if (actual_node != node) 57 printk(KERN_WARNING "[%lx-%lx] potential offnode " 58 "page_structs\n", start, end - 1); 59 } 60 61 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node) 62 { 63 pte_t *pte = pte_offset_kernel(pmd, addr); 64 if (pte_none(*pte)) { 65 pte_t entry; 66 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 67 if (!p) 68 return 0; 69 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL); 70 set_pte_at(&init_mm, addr, pte, entry); 71 } 72 return pte; 73 } 74 75 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) 76 { 77 pmd_t *pmd = pmd_offset(pud, addr); 78 if (pmd_none(*pmd)) { 79 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 80 if (!p) 81 return 0; 82 pmd_populate_kernel(&init_mm, pmd, p); 83 } 84 return pmd; 85 } 86 87 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node) 88 { 89 pud_t *pud = pud_offset(pgd, addr); 90 if (pud_none(*pud)) { 91 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 92 if (!p) 93 return 0; 94 pud_populate(&init_mm, pud, p); 95 } 96 return pud; 97 } 98 99 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) 100 { 101 pgd_t *pgd = pgd_offset_k(addr); 102 if (pgd_none(*pgd)) { 103 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 104 if (!p) 105 return 0; 106 pgd_populate(&init_mm, pgd, p); 107 } 108 return pgd; 109 } 110 111 int __meminit vmemmap_populate_basepages(struct page *start_page, 112 unsigned long size, int node) 113 { 114 unsigned long addr = (unsigned long)start_page; 115 unsigned long end = (unsigned long)(start_page + size); 116 pgd_t *pgd; 117 pud_t *pud; 118 pmd_t *pmd; 119 pte_t *pte; 120 121 for (; addr < end; addr += PAGE_SIZE) { 122 pgd = vmemmap_pgd_populate(addr, node); 123 if (!pgd) 124 return -ENOMEM; 125 pud = vmemmap_pud_populate(pgd, addr, node); 126 if (!pud) 127 return -ENOMEM; 128 pmd = vmemmap_pmd_populate(pud, addr, node); 129 if (!pmd) 130 return -ENOMEM; 131 pte = vmemmap_pte_populate(pmd, addr, node); 132 if (!pte) 133 return -ENOMEM; 134 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); 135 } 136 137 return 0; 138 } 139 140 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid) 141 { 142 struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION); 143 int error = vmemmap_populate(map, PAGES_PER_SECTION, nid); 144 if (error) 145 return NULL; 146 147 return map; 148 } 149