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Linux/mm/sparse-vmemmap.c

  1 /*
  2  * Virtual Memory Map support
  3  *
  4  * (C) 2007 sgi. Christoph Lameter.
  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 memory 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/memremap.h>
 24 #include <linux/highmem.h>
 25 #include <linux/slab.h>
 26 #include <linux/spinlock.h>
 27 #include <linux/vmalloc.h>
 28 #include <linux/sched.h>
 29 #include <asm/dma.h>
 30 #include <asm/pgalloc.h>
 31 #include <asm/pgtable.h>
 32 
 33 /*
 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.
 37  */
 38 
 39 static void * __ref __earlyonly_bootmem_alloc(int node,
 40                                 unsigned long size,
 41                                 unsigned long align,
 42                                 unsigned long goal)
 43 {
 44         return memblock_virt_alloc_try_nid(size, align, goal,
 45                                             BOOTMEM_ALLOC_ACCESSIBLE, node);
 46 }
 47 
 48 static void *vmemmap_buf;
 49 static void *vmemmap_buf_end;
 50 
 51 void * __meminit vmemmap_alloc_block(unsigned long size, int node)
 52 {
 53         /* If the main allocator is up use that, fallback to bootmem. */
 54         if (slab_is_available()) {
 55                 struct page *page;
 56 
 57                 if (node_state(node, N_HIGH_MEMORY))
 58                         page = alloc_pages_node(
 59                                 node, GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
 60                                 get_order(size));
 61                 else
 62                         page = alloc_pages(
 63                                 GFP_KERNEL | __GFP_ZERO | __GFP_REPEAT,
 64                                 get_order(size));
 65                 if (page)
 66                         return page_address(page);
 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 static void * __meminit alloc_block_buf(unsigned long size, int node)
 75 {
 76         void *ptr;
 77 
 78         if (!vmemmap_buf)
 79                 return vmemmap_alloc_block(size, node);
 80 
 81         /* take the from buf */
 82         ptr = (void *)ALIGN((unsigned long)vmemmap_buf, size);
 83         if (ptr + size > vmemmap_buf_end)
 84                 return vmemmap_alloc_block(size, node);
 85 
 86         vmemmap_buf = ptr + size;
 87 
 88         return ptr;
 89 }
 90 
 91 static unsigned long __meminit vmem_altmap_next_pfn(struct vmem_altmap *altmap)
 92 {
 93         return altmap->base_pfn + altmap->reserve + altmap->alloc
 94                 + altmap->align;
 95 }
 96 
 97 static unsigned long __meminit vmem_altmap_nr_free(struct vmem_altmap *altmap)
 98 {
 99         unsigned long allocated = altmap->alloc + altmap->align;
100 
101         if (altmap->free > allocated)
102                 return altmap->free - allocated;
103         return 0;
104 }
105 
106 /**
107  * vmem_altmap_alloc - allocate pages from the vmem_altmap reservation
108  * @altmap - reserved page pool for the allocation
109  * @nr_pfns - size (in pages) of the allocation
110  *
111  * Allocations are aligned to the size of the request
112  */
113 static unsigned long __meminit vmem_altmap_alloc(struct vmem_altmap *altmap,
114                 unsigned long nr_pfns)
115 {
116         unsigned long pfn = vmem_altmap_next_pfn(altmap);
117         unsigned long nr_align;
118 
119         nr_align = 1UL << find_first_bit(&nr_pfns, BITS_PER_LONG);
120         nr_align = ALIGN(pfn, nr_align) - pfn;
121 
122         if (nr_pfns + nr_align > vmem_altmap_nr_free(altmap))
123                 return ULONG_MAX;
124         altmap->alloc += nr_pfns;
125         altmap->align += nr_align;
126         return pfn + nr_align;
127 }
128 
129 static void * __meminit altmap_alloc_block_buf(unsigned long size,
130                 struct vmem_altmap *altmap)
131 {
132         unsigned long pfn, nr_pfns;
133         void *ptr;
134 
135         if (size & ~PAGE_MASK) {
136                 pr_warn_once("%s: allocations must be multiple of PAGE_SIZE (%ld)\n",
137                                 __func__, size);
138                 return NULL;
139         }
140 
141         nr_pfns = size >> PAGE_SHIFT;
142         pfn = vmem_altmap_alloc(altmap, nr_pfns);
143         if (pfn < ULONG_MAX)
144                 ptr = __va(__pfn_to_phys(pfn));
145         else
146                 ptr = NULL;
147         pr_debug("%s: pfn: %#lx alloc: %ld align: %ld nr: %#lx\n",
148                         __func__, pfn, altmap->alloc, altmap->align, nr_pfns);
149 
150         return ptr;
151 }
152 
153 /* need to make sure size is all the same during early stage */
154 void * __meminit __vmemmap_alloc_block_buf(unsigned long size, int node,
155                 struct vmem_altmap *altmap)
156 {
157         if (altmap)
158                 return altmap_alloc_block_buf(size, altmap);
159         return alloc_block_buf(size, node);
160 }
161 
162 void __meminit vmemmap_verify(pte_t *pte, int node,
163                                 unsigned long start, unsigned long end)
164 {
165         unsigned long pfn = pte_pfn(*pte);
166         int actual_node = early_pfn_to_nid(pfn);
167 
168         if (node_distance(actual_node, node) > LOCAL_DISTANCE)
169                 pr_warn("[%lx-%lx] potential offnode page_structs\n",
170                         start, end - 1);
171 }
172 
173 pte_t * __meminit vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node)
174 {
175         pte_t *pte = pte_offset_kernel(pmd, addr);
176         if (pte_none(*pte)) {
177                 pte_t entry;
178                 void *p = alloc_block_buf(PAGE_SIZE, node);
179                 if (!p)
180                         return NULL;
181                 entry = pfn_pte(__pa(p) >> PAGE_SHIFT, PAGE_KERNEL);
182                 set_pte_at(&init_mm, addr, pte, entry);
183         }
184         return pte;
185 }
186 
187 pmd_t * __meminit vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node)
188 {
189         pmd_t *pmd = pmd_offset(pud, addr);
190         if (pmd_none(*pmd)) {
191                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
192                 if (!p)
193                         return NULL;
194                 pmd_populate_kernel(&init_mm, pmd, p);
195         }
196         return pmd;
197 }
198 
199 pud_t * __meminit vmemmap_pud_populate(pgd_t *pgd, unsigned long addr, int node)
200 {
201         pud_t *pud = pud_offset(pgd, addr);
202         if (pud_none(*pud)) {
203                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
204                 if (!p)
205                         return NULL;
206                 pud_populate(&init_mm, pud, p);
207         }
208         return pud;
209 }
210 
211 pgd_t * __meminit vmemmap_pgd_populate(unsigned long addr, int node)
212 {
213         pgd_t *pgd = pgd_offset_k(addr);
214         if (pgd_none(*pgd)) {
215                 void *p = vmemmap_alloc_block(PAGE_SIZE, node);
216                 if (!p)
217                         return NULL;
218                 pgd_populate(&init_mm, pgd, p);
219         }
220         return pgd;
221 }
222 
223 int __meminit vmemmap_populate_basepages(unsigned long start,
224                                          unsigned long end, int node)
225 {
226         unsigned long addr = start;
227         pgd_t *pgd;
228         pud_t *pud;
229         pmd_t *pmd;
230         pte_t *pte;
231 
232         for (; addr < end; addr += PAGE_SIZE) {
233                 pgd = vmemmap_pgd_populate(addr, node);
234                 if (!pgd)
235                         return -ENOMEM;
236                 pud = vmemmap_pud_populate(pgd, addr, node);
237                 if (!pud)
238                         return -ENOMEM;
239                 pmd = vmemmap_pmd_populate(pud, addr, node);
240                 if (!pmd)
241                         return -ENOMEM;
242                 pte = vmemmap_pte_populate(pmd, addr, node);
243                 if (!pte)
244                         return -ENOMEM;
245                 vmemmap_verify(pte, node, addr, addr + PAGE_SIZE);
246         }
247 
248         return 0;
249 }
250 
251 struct page * __meminit sparse_mem_map_populate(unsigned long pnum, int nid)
252 {
253         unsigned long start;
254         unsigned long end;
255         struct page *map;
256 
257         map = pfn_to_page(pnum * PAGES_PER_SECTION);
258         start = (unsigned long)map;
259         end = (unsigned long)(map + PAGES_PER_SECTION);
260 
261         if (vmemmap_populate(start, end, nid))
262                 return NULL;
263 
264         return map;
265 }
266 
267 void __init sparse_mem_maps_populate_node(struct page **map_map,
268                                           unsigned long pnum_begin,
269                                           unsigned long pnum_end,
270                                           unsigned long map_count, int nodeid)
271 {
272         unsigned long pnum;
273         unsigned long size = sizeof(struct page) * PAGES_PER_SECTION;
274         void *vmemmap_buf_start;
275 
276         size = ALIGN(size, PMD_SIZE);
277         vmemmap_buf_start = __earlyonly_bootmem_alloc(nodeid, size * map_count,
278                          PMD_SIZE, __pa(MAX_DMA_ADDRESS));
279 
280         if (vmemmap_buf_start) {
281                 vmemmap_buf = vmemmap_buf_start;
282                 vmemmap_buf_end = vmemmap_buf_start + size * map_count;
283         }
284 
285         for (pnum = pnum_begin; pnum < pnum_end; pnum++) {
286                 struct mem_section *ms;
287 
288                 if (!present_section_nr(pnum))
289                         continue;
290 
291                 map_map[pnum] = sparse_mem_map_populate(pnum, nodeid);
292                 if (map_map[pnum])
293                         continue;
294                 ms = __nr_to_section(pnum);
295                 pr_err("%s: sparsemem memory map backing failed some memory will not be available\n",
296                        __func__);
297                 ms->section_mem_map = 0;
298         }
299 
300         if (vmemmap_buf_start) {
301                 /* need to free left buf */
302                 memblock_free_early(__pa(vmemmap_buf),
303                                     vmemmap_buf_end - vmemmap_buf);
304                 vmemmap_buf = NULL;
305                 vmemmap_buf_end = NULL;
306         }
307 }
308 

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