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 <linux/sched.h> 28 #include <asm/dma.h> 29 #include <asm/pgalloc.h> 30 #include <asm/pgtable.h> 31 32 /* 33 * Allocate a block of memory to be used to back the virtual memory map 34 * or to back the page tables that are used to create the mapping. 35 * Uses the main allocators if they are available, else bootmem. 36 */ 37 void * __meminit vmemmap_alloc_block(unsigned long size, int node) 38 { 39 /* If the main allocator is up use that, fallback to bootmem. */ 40 if (slab_is_available()) { 41 struct page *page = alloc_pages_node(node, 42 GFP_KERNEL | __GFP_ZERO, get_order(size)); 43 if (page) 44 return page_address(page); 45 return NULL; 46 } else 47 return __alloc_bootmem_node(NODE_DATA(node), size, size, 48 __pa(MAX_DMA_ADDRESS)); 49 } 50 51 void __meminit vmemmap_verify(pte_t *pte, int node, 52 unsigned long start, unsigned long end) 53 { 54 unsigned long pfn = pte_pfn(*pte); 55 int actual_node = early_pfn_to_nid(pfn); 56 57 if (actual_node != node) 58 printk(KERN_WARNING "[%lx-%lx] potential offnode " 59 "page_structs\n", start, end - 1); 60 } 61 62 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node) 63 { 64 pte_t *pte = pte_offset_kernel(pmd, addr); 65 if (pte_none(*pte)) { 66 pte_t entry; 67 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 68 if (!p) 69 return 0; 70 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL); 71 set_pte_at(&init_mm, addr, pte, entry); 72 } 73 return pte; 74 } 75 76 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node) 77 { 78 pmd_t *pmd = pmd_offset(pud, addr); 79 if (pmd_none(*pmd)) { 80 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 81 if (!p) 82 return 0; 83 pmd_populate_kernel(&init_mm, pmd, p); 84 } 85 return pmd; 86 } 87 88 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node) 89 { 90 pud_t *pud = pud_offset(pgd, addr); 91 if (pud_none(*pud)) { 92 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 93 if (!p) 94 return 0; 95 pud_populate(&init_mm, pud, p); 96 } 97 return pud; 98 } 99 100 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node) 101 { 102 pgd_t *pgd = pgd_offset_k(addr); 103 if (pgd_none(*pgd)) { 104 void *p = vmemmap_alloc_block(PAGE_SIZE, node); 105 if (!p) 106 return 0; 107 pgd_populate(&init_mm, pgd, p); 108 } 109 return pgd; 110 } 111 112 int __meminit vmemmap_populate_basepages(struct page *start_page, 113 unsigned long size, int node) 114 { 115 unsigned long addr = (unsigned long)start_page; 116 unsigned long end = (unsigned long)(start_page + size); 117 pgd_t *pgd; 118 pud_t *pud; 119 pmd_t *pmd; 120 pte_t *pte; 121 122 for (; addr < end; addr += PAGE_SIZE) { 123 pgd = vmemmap_pgd_populate(addr, node); 124 if (!pgd) 125 return -ENOMEM; 126 pud = vmemmap_pud_populate(pgd, addr, node); 127 if (!pud) 128 return -ENOMEM; 129 pmd = vmemmap_pmd_populate(pud, addr, node); 130 if (!pmd) 131 return -ENOMEM; 132 pte = vmemmap_pte_populate(pmd, addr, node); 133 if (!pte) 134 return -ENOMEM; 135 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE); 136 } 137 138 return 0; 139 } 140 141 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid) 142 { 143 struct page *map = pfn_to_page(pnum * PAGES_PER_SECTION); 144 int error = vmemmap_populate(map, PAGES_PER_SECTION, nid); 145 if (error) 146 return NULL; 147 148 return map; 149 } 150