1 /* 2 * IA-32 Huge TLB Page Support for Kernel. 3 * 4 * Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com> 5 */ 6 7 #include <linux/init.h> 8 #include <linux/fs.h> 9 #include <linux/mm.h> 10 #include <linux/hugetlb.h> 11 #include <linux/pagemap.h> 12 #include <linux/slab.h> 13 #include <linux/err.h> 14 #include <linux/sysctl.h> 15 #include <asm/mman.h> 16 #include <asm/tlb.h> 17 #include <asm/tlbflush.h> 18 #include <asm/pgalloc.h> 19 20 static unsigned long page_table_shareable(struct vm_area_struct *svma, 21 struct vm_area_struct *vma, 22 unsigned long addr, pgoff_t idx) 23 { 24 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) + 25 svma->vm_start; 26 unsigned long sbase = saddr & PUD_MASK; 27 unsigned long s_end = sbase + PUD_SIZE; 28 29 /* 30 * match the virtual addresses, permission and the alignment of the 31 * page table page. 32 */ 33 if (pmd_index(addr) != pmd_index(saddr) || 34 vma->vm_flags != svma->vm_flags || 35 sbase < svma->vm_start || svma->vm_end < s_end) 36 return 0; 37 38 return saddr; 39 } 40 41 static int vma_shareable(struct vm_area_struct *vma, unsigned long addr) 42 { 43 unsigned long base = addr & PUD_MASK; 44 unsigned long end = base + PUD_SIZE; 45 46 /* 47 * check on proper vm_flags and page table alignment 48 */ 49 if (vma->vm_flags & VM_MAYSHARE && 50 vma->vm_start <= base && end <= vma->vm_end) 51 return 1; 52 return 0; 53 } 54 55 /* 56 * search for a shareable pmd page for hugetlb. 57 */ 58 static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) 59 { 60 struct vm_area_struct *vma = find_vma(mm, addr); 61 struct address_space *mapping = vma->vm_file->f_mapping; 62 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + 63 vma->vm_pgoff; 64 struct prio_tree_iter iter; 65 struct vm_area_struct *svma; 66 unsigned long saddr; 67 pte_t *spte = NULL; 68 69 if (!vma_shareable(vma, addr)) 70 return; 71 72 spin_lock(&mapping->i_mmap_lock); 73 vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) { 74 if (svma == vma) 75 continue; 76 77 saddr = page_table_shareable(svma, vma, addr, idx); 78 if (saddr) { 79 spte = huge_pte_offset(svma->vm_mm, saddr); 80 if (spte) { 81 get_page(virt_to_page(spte)); 82 break; 83 } 84 } 85 } 86 87 if (!spte) 88 goto out; 89 90 spin_lock(&mm->page_table_lock); 91 if (pud_none(*pud)) 92 pud_populate(mm, pud, (pmd_t *)((unsigned long)spte & PAGE_MASK)); 93 else 94 put_page(virt_to_page(spte)); 95 spin_unlock(&mm->page_table_lock); 96 out: 97 spin_unlock(&mapping->i_mmap_lock); 98 } 99 100 /* 101 * unmap huge page backed by shared pte. 102 * 103 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared 104 * indicated by page_count > 1, unmap is achieved by clearing pud and 105 * decrementing the ref count. If count == 1, the pte page is not shared. 106 * 107 * called with vma->vm_mm->page_table_lock held. 108 * 109 * returns: 1 successfully unmapped a shared pte page 110 * 0 the underlying pte page is not shared, or it is the last user 111 */ 112 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) 113 { 114 pgd_t *pgd = pgd_offset(mm, *addr); 115 pud_t *pud = pud_offset(pgd, *addr); 116 117 BUG_ON(page_count(virt_to_page(ptep)) == 0); 118 if (page_count(virt_to_page(ptep)) == 1) 119 return 0; 120 121 pud_clear(pud); 122 put_page(virt_to_page(ptep)); 123 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE; 124 return 1; 125 } 126 127 pte_t *huge_pte_alloc(struct mm_struct *mm, 128 unsigned long addr, unsigned long sz) 129 { 130 pgd_t *pgd; 131 pud_t *pud; 132 pte_t *pte = NULL; 133 134 pgd = pgd_offset(mm, addr); 135 pud = pud_alloc(mm, pgd, addr); 136 if (pud) { 137 if (sz == PUD_SIZE) { 138 pte = (pte_t *)pud; 139 } else { 140 BUG_ON(sz != PMD_SIZE); 141 if (pud_none(*pud)) 142 huge_pmd_share(mm, addr, pud); 143 pte = (pte_t *) pmd_alloc(mm, pud, addr); 144 } 145 } 146 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); 147 148 return pte; 149 } 150 151 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) 152 { 153 pgd_t *pgd; 154 pud_t *pud; 155 pmd_t *pmd = NULL; 156 157 pgd = pgd_offset(mm, addr); 158 if (pgd_present(*pgd)) { 159 pud = pud_offset(pgd, addr); 160 if (pud_present(*pud)) { 161 if (pud_large(*pud)) 162 return (pte_t *)pud; 163 pmd = pmd_offset(pud, addr); 164 } 165 } 166 return (pte_t *) pmd; 167 } 168 169 #if 0 /* This is just for testing */ 170 struct page * 171 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) 172 { 173 unsigned long start = address; 174 int length = 1; 175 int nr; 176 struct page *page; 177 struct vm_area_struct *vma; 178 179 vma = find_vma(mm, addr); 180 if (!vma || !is_vm_hugetlb_page(vma)) 181 return ERR_PTR(-EINVAL); 182 183 pte = huge_pte_offset(mm, address); 184 185 /* hugetlb should be locked, and hence, prefaulted */ 186 WARN_ON(!pte || pte_none(*pte)); 187 188 page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)]; 189 190 WARN_ON(!PageHead(page)); 191 192 return page; 193 } 194 195 int pmd_huge(pmd_t pmd) 196 { 197 return 0; 198 } 199 200 int pud_huge(pud_t pud) 201 { 202 return 0; 203 } 204 205 struct page * 206 follow_huge_pmd(struct mm_struct *mm, unsigned long address, 207 pmd_t *pmd, int write) 208 { 209 return NULL; 210 } 211 212 #else 213 214 struct page * 215 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) 216 { 217 return ERR_PTR(-EINVAL); 218 } 219 220 int pmd_huge(pmd_t pmd) 221 { 222 return !!(pmd_val(pmd) & _PAGE_PSE); 223 } 224 225 int pud_huge(pud_t pud) 226 { 227 return !!(pud_val(pud) & _PAGE_PSE); 228 } 229 230 struct page * 231 follow_huge_pmd(struct mm_struct *mm, unsigned long address, 232 pmd_t *pmd, int write) 233 { 234 struct page *page; 235 236 page = pte_page(*(pte_t *)pmd); 237 if (page) 238 page += ((address & ~PMD_MASK) >> PAGE_SHIFT); 239 return page; 240 } 241 242 struct page * 243 follow_huge_pud(struct mm_struct *mm, unsigned long address, 244 pud_t *pud, int write) 245 { 246 struct page *page; 247 248 page = pte_page(*(pte_t *)pud); 249 if (page) 250 page += ((address & ~PUD_MASK) >> PAGE_SHIFT); 251 return page; 252 } 253 254 #endif 255 256 /* x86_64 also uses this file */ 257 258 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA 259 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file, 260 unsigned long addr, unsigned long len, 261 unsigned long pgoff, unsigned long flags) 262 { 263 struct hstate *h = hstate_file(file); 264 struct mm_struct *mm = current->mm; 265 struct vm_area_struct *vma; 266 unsigned long start_addr; 267 268 if (len > mm->cached_hole_size) { 269 start_addr = mm->free_area_cache; 270 } else { 271 start_addr = TASK_UNMAPPED_BASE; 272 mm->cached_hole_size = 0; 273 } 274 275 full_search: 276 addr = ALIGN(start_addr, huge_page_size(h)); 277 278 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 279 /* At this point: (!vma || addr < vma->vm_end). */ 280 if (TASK_SIZE - len < addr) { 281 /* 282 * Start a new search - just in case we missed 283 * some holes. 284 */ 285 if (start_addr != TASK_UNMAPPED_BASE) { 286 start_addr = TASK_UNMAPPED_BASE; 287 mm->cached_hole_size = 0; 288 goto full_search; 289 } 290 return -ENOMEM; 291 } 292 if (!vma || addr + len <= vma->vm_start) { 293 mm->free_area_cache = addr + len; 294 return addr; 295 } 296 if (addr + mm->cached_hole_size < vma->vm_start) 297 mm->cached_hole_size = vma->vm_start - addr; 298 addr = ALIGN(vma->vm_end, huge_page_size(h)); 299 } 300 } 301 302 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file, 303 unsigned long addr0, unsigned long len, 304 unsigned long pgoff, unsigned long flags) 305 { 306 struct hstate *h = hstate_file(file); 307 struct mm_struct *mm = current->mm; 308 struct vm_area_struct *vma, *prev_vma; 309 unsigned long base = mm->mmap_base, addr = addr0; 310 unsigned long largest_hole = mm->cached_hole_size; 311 int first_time = 1; 312 313 /* don't allow allocations above current base */ 314 if (mm->free_area_cache > base) 315 mm->free_area_cache = base; 316 317 if (len <= largest_hole) { 318 largest_hole = 0; 319 mm->free_area_cache = base; 320 } 321 try_again: 322 /* make sure it can fit in the remaining address space */ 323 if (mm->free_area_cache < len) 324 goto fail; 325 326 /* either no address requested or cant fit in requested address hole */ 327 addr = (mm->free_area_cache - len) & huge_page_mask(h); 328 do { 329 /* 330 * Lookup failure means no vma is above this address, 331 * i.e. return with success: 332 */ 333 if (!(vma = find_vma_prev(mm, addr, &prev_vma))) 334 return addr; 335 336 /* 337 * new region fits between prev_vma->vm_end and 338 * vma->vm_start, use it: 339 */ 340 if (addr + len <= vma->vm_start && 341 (!prev_vma || (addr >= prev_vma->vm_end))) { 342 /* remember the address as a hint for next time */ 343 mm->cached_hole_size = largest_hole; 344 return (mm->free_area_cache = addr); 345 } else { 346 /* pull free_area_cache down to the first hole */ 347 if (mm->free_area_cache == vma->vm_end) { 348 mm->free_area_cache = vma->vm_start; 349 mm->cached_hole_size = largest_hole; 350 } 351 } 352 353 /* remember the largest hole we saw so far */ 354 if (addr + largest_hole < vma->vm_start) 355 largest_hole = vma->vm_start - addr; 356 357 /* try just below the current vma->vm_start */ 358 addr = (vma->vm_start - len) & huge_page_mask(h); 359 } while (len <= vma->vm_start); 360 361 fail: 362 /* 363 * if hint left us with no space for the requested 364 * mapping then try again: 365 */ 366 if (first_time) { 367 mm->free_area_cache = base; 368 largest_hole = 0; 369 first_time = 0; 370 goto try_again; 371 } 372 /* 373 * A failed mmap() very likely causes application failure, 374 * so fall back to the bottom-up function here. This scenario 375 * can happen with large stack limits and large mmap() 376 * allocations. 377 */ 378 mm->free_area_cache = TASK_UNMAPPED_BASE; 379 mm->cached_hole_size = ~0UL; 380 addr = hugetlb_get_unmapped_area_bottomup(file, addr0, 381 len, pgoff, flags); 382 383 /* 384 * Restore the topdown base: 385 */ 386 mm->free_area_cache = base; 387 mm->cached_hole_size = ~0UL; 388 389 return addr; 390 } 391 392 unsigned long 393 hugetlb_get_unmapped_area(struct file *file, unsigned long addr, 394 unsigned long len, unsigned long pgoff, unsigned long flags) 395 { 396 struct hstate *h = hstate_file(file); 397 struct mm_struct *mm = current->mm; 398 struct vm_area_struct *vma; 399 400 if (len & ~huge_page_mask(h)) 401 return -EINVAL; 402 if (len > TASK_SIZE) 403 return -ENOMEM; 404 405 if (flags & MAP_FIXED) { 406 if (prepare_hugepage_range(file, addr, len)) 407 return -EINVAL; 408 return addr; 409 } 410 411 if (addr) { 412 addr = ALIGN(addr, huge_page_size(h)); 413 vma = find_vma(mm, addr); 414 if (TASK_SIZE - len >= addr && 415 (!vma || addr + len <= vma->vm_start)) 416 return addr; 417 } 418 if (mm->get_unmapped_area == arch_get_unmapped_area) 419 return hugetlb_get_unmapped_area_bottomup(file, addr, len, 420 pgoff, flags); 421 else 422 return hugetlb_get_unmapped_area_topdown(file, addr, len, 423 pgoff, flags); 424 } 425 426 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/ 427 428 #ifdef CONFIG_X86_64 429 static __init int setup_hugepagesz(char *opt) 430 { 431 unsigned long ps = memparse(opt, &opt); 432 if (ps == PMD_SIZE) { 433 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT); 434 } else if (ps == PUD_SIZE && cpu_has_gbpages) { 435 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT); 436 } else { 437 printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n", 438 ps >> 20); 439 return 0; 440 } 441 return 1; 442 } 443 __setup("hugepagesz=", setup_hugepagesz); 444 #endif 445