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/err.h> 13 #include <linux/sysctl.h> 14 #include <asm/mman.h> 15 #include <asm/tlb.h> 16 #include <asm/tlbflush.h> 17 #include <asm/pgalloc.h> 18 19 static unsigned long page_table_shareable(struct vm_area_struct *svma, 20 struct vm_area_struct *vma, 21 unsigned long addr, pgoff_t idx) 22 { 23 unsigned long saddr = ((idx - svma->vm_pgoff) << PAGE_SHIFT) + 24 svma->vm_start; 25 unsigned long sbase = saddr & PUD_MASK; 26 unsigned long s_end = sbase + PUD_SIZE; 27 28 /* Allow segments to share if only one is marked locked */ 29 unsigned long vm_flags = vma->vm_flags & ~VM_LOCKED; 30 unsigned long svm_flags = svma->vm_flags & ~VM_LOCKED; 31 32 /* 33 * match the virtual addresses, permission and the alignment of the 34 * page table page. 35 */ 36 if (pmd_index(addr) != pmd_index(saddr) || 37 vm_flags != svm_flags || 38 sbase < svma->vm_start || svma->vm_end < s_end) 39 return 0; 40 41 return saddr; 42 } 43 44 static int vma_shareable(struct vm_area_struct *vma, unsigned long addr) 45 { 46 unsigned long base = addr & PUD_MASK; 47 unsigned long end = base + PUD_SIZE; 48 49 /* 50 * check on proper vm_flags and page table alignment 51 */ 52 if (vma->vm_flags & VM_MAYSHARE && 53 vma->vm_start <= base && end <= vma->vm_end) 54 return 1; 55 return 0; 56 } 57 58 /* 59 * search for a shareable pmd page for hugetlb. 60 */ 61 static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud) 62 { 63 struct vm_area_struct *vma = find_vma(mm, addr); 64 struct address_space *mapping = vma->vm_file->f_mapping; 65 pgoff_t idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + 66 vma->vm_pgoff; 67 struct prio_tree_iter iter; 68 struct vm_area_struct *svma; 69 unsigned long saddr; 70 pte_t *spte = NULL; 71 72 if (!vma_shareable(vma, addr)) 73 return; 74 75 mutex_lock(&mapping->i_mmap_mutex); 76 vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) { 77 if (svma == vma) 78 continue; 79 80 saddr = page_table_shareable(svma, vma, addr, idx); 81 if (saddr) { 82 spte = huge_pte_offset(svma->vm_mm, saddr); 83 if (spte) { 84 get_page(virt_to_page(spte)); 85 break; 86 } 87 } 88 } 89 90 if (!spte) 91 goto out; 92 93 spin_lock(&mm->page_table_lock); 94 if (pud_none(*pud)) 95 pud_populate(mm, pud, (pmd_t *)((unsigned long)spte & PAGE_MASK)); 96 else 97 put_page(virt_to_page(spte)); 98 spin_unlock(&mm->page_table_lock); 99 out: 100 mutex_unlock(&mapping->i_mmap_mutex); 101 } 102 103 /* 104 * unmap huge page backed by shared pte. 105 * 106 * Hugetlb pte page is ref counted at the time of mapping. If pte is shared 107 * indicated by page_count > 1, unmap is achieved by clearing pud and 108 * decrementing the ref count. If count == 1, the pte page is not shared. 109 * 110 * called with vma->vm_mm->page_table_lock held. 111 * 112 * returns: 1 successfully unmapped a shared pte page 113 * 0 the underlying pte page is not shared, or it is the last user 114 */ 115 int huge_pmd_unshare(struct mm_struct *mm, unsigned long *addr, pte_t *ptep) 116 { 117 pgd_t *pgd = pgd_offset(mm, *addr); 118 pud_t *pud = pud_offset(pgd, *addr); 119 120 BUG_ON(page_count(virt_to_page(ptep)) == 0); 121 if (page_count(virt_to_page(ptep)) == 1) 122 return 0; 123 124 pud_clear(pud); 125 put_page(virt_to_page(ptep)); 126 *addr = ALIGN(*addr, HPAGE_SIZE * PTRS_PER_PTE) - HPAGE_SIZE; 127 return 1; 128 } 129 130 pte_t *huge_pte_alloc(struct mm_struct *mm, 131 unsigned long addr, unsigned long sz) 132 { 133 pgd_t *pgd; 134 pud_t *pud; 135 pte_t *pte = NULL; 136 137 pgd = pgd_offset(mm, addr); 138 pud = pud_alloc(mm, pgd, addr); 139 if (pud) { 140 if (sz == PUD_SIZE) { 141 pte = (pte_t *)pud; 142 } else { 143 BUG_ON(sz != PMD_SIZE); 144 if (pud_none(*pud)) 145 huge_pmd_share(mm, addr, pud); 146 pte = (pte_t *) pmd_alloc(mm, pud, addr); 147 } 148 } 149 BUG_ON(pte && !pte_none(*pte) && !pte_huge(*pte)); 150 151 return pte; 152 } 153 154 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) 155 { 156 pgd_t *pgd; 157 pud_t *pud; 158 pmd_t *pmd = NULL; 159 160 pgd = pgd_offset(mm, addr); 161 if (pgd_present(*pgd)) { 162 pud = pud_offset(pgd, addr); 163 if (pud_present(*pud)) { 164 if (pud_large(*pud)) 165 return (pte_t *)pud; 166 pmd = pmd_offset(pud, addr); 167 } 168 } 169 return (pte_t *) pmd; 170 } 171 172 #if 0 /* This is just for testing */ 173 struct page * 174 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) 175 { 176 unsigned long start = address; 177 int length = 1; 178 int nr; 179 struct page *page; 180 struct vm_area_struct *vma; 181 182 vma = find_vma(mm, addr); 183 if (!vma || !is_vm_hugetlb_page(vma)) 184 return ERR_PTR(-EINVAL); 185 186 pte = huge_pte_offset(mm, address); 187 188 /* hugetlb should be locked, and hence, prefaulted */ 189 WARN_ON(!pte || pte_none(*pte)); 190 191 page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)]; 192 193 WARN_ON(!PageHead(page)); 194 195 return page; 196 } 197 198 int pmd_huge(pmd_t pmd) 199 { 200 return 0; 201 } 202 203 int pud_huge(pud_t pud) 204 { 205 return 0; 206 } 207 208 struct page * 209 follow_huge_pmd(struct mm_struct *mm, unsigned long address, 210 pmd_t *pmd, int write) 211 { 212 return NULL; 213 } 214 215 #else 216 217 struct page * 218 follow_huge_addr(struct mm_struct *mm, unsigned long address, int write) 219 { 220 return ERR_PTR(-EINVAL); 221 } 222 223 int pmd_huge(pmd_t pmd) 224 { 225 return !!(pmd_val(pmd) & _PAGE_PSE); 226 } 227 228 int pud_huge(pud_t pud) 229 { 230 return !!(pud_val(pud) & _PAGE_PSE); 231 } 232 233 struct page * 234 follow_huge_pmd(struct mm_struct *mm, unsigned long address, 235 pmd_t *pmd, int write) 236 { 237 struct page *page; 238 239 page = pte_page(*(pte_t *)pmd); 240 if (page) 241 page += ((address & ~PMD_MASK) >> PAGE_SHIFT); 242 return page; 243 } 244 245 struct page * 246 follow_huge_pud(struct mm_struct *mm, unsigned long address, 247 pud_t *pud, int write) 248 { 249 struct page *page; 250 251 page = pte_page(*(pte_t *)pud); 252 if (page) 253 page += ((address & ~PUD_MASK) >> PAGE_SHIFT); 254 return page; 255 } 256 257 #endif 258 259 /* x86_64 also uses this file */ 260 261 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA 262 static unsigned long hugetlb_get_unmapped_area_bottomup(struct file *file, 263 unsigned long addr, unsigned long len, 264 unsigned long pgoff, unsigned long flags) 265 { 266 struct hstate *h = hstate_file(file); 267 struct mm_struct *mm = current->mm; 268 struct vm_area_struct *vma; 269 unsigned long start_addr; 270 271 if (len > mm->cached_hole_size) { 272 start_addr = mm->free_area_cache; 273 } else { 274 start_addr = TASK_UNMAPPED_BASE; 275 mm->cached_hole_size = 0; 276 } 277 278 full_search: 279 addr = ALIGN(start_addr, huge_page_size(h)); 280 281 for (vma = find_vma(mm, addr); ; vma = vma->vm_next) { 282 /* At this point: (!vma || addr < vma->vm_end). */ 283 if (TASK_SIZE - len < addr) { 284 /* 285 * Start a new search - just in case we missed 286 * some holes. 287 */ 288 if (start_addr != TASK_UNMAPPED_BASE) { 289 start_addr = TASK_UNMAPPED_BASE; 290 mm->cached_hole_size = 0; 291 goto full_search; 292 } 293 return -ENOMEM; 294 } 295 if (!vma || addr + len <= vma->vm_start) { 296 mm->free_area_cache = addr + len; 297 return addr; 298 } 299 if (addr + mm->cached_hole_size < vma->vm_start) 300 mm->cached_hole_size = vma->vm_start - addr; 301 addr = ALIGN(vma->vm_end, huge_page_size(h)); 302 } 303 } 304 305 static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file, 306 unsigned long addr0, unsigned long len, 307 unsigned long pgoff, unsigned long flags) 308 { 309 struct hstate *h = hstate_file(file); 310 struct mm_struct *mm = current->mm; 311 struct vm_area_struct *vma, *prev_vma; 312 unsigned long base = mm->mmap_base, addr = addr0; 313 unsigned long largest_hole = mm->cached_hole_size; 314 int first_time = 1; 315 316 /* don't allow allocations above current base */ 317 if (mm->free_area_cache > base) 318 mm->free_area_cache = base; 319 320 if (len <= largest_hole) { 321 largest_hole = 0; 322 mm->free_area_cache = base; 323 } 324 try_again: 325 /* make sure it can fit in the remaining address space */ 326 if (mm->free_area_cache < len) 327 goto fail; 328 329 /* either no address requested or can't fit in requested address hole */ 330 addr = (mm->free_area_cache - len) & huge_page_mask(h); 331 do { 332 /* 333 * Lookup failure means no vma is above this address, 334 * i.e. return with success: 335 */ 336 if (!(vma = find_vma_prev(mm, addr, &prev_vma))) 337 return addr; 338 339 /* 340 * new region fits between prev_vma->vm_end and 341 * vma->vm_start, use it: 342 */ 343 if (addr + len <= vma->vm_start && 344 (!prev_vma || (addr >= prev_vma->vm_end))) { 345 /* remember the address as a hint for next time */ 346 mm->cached_hole_size = largest_hole; 347 return (mm->free_area_cache = addr); 348 } else { 349 /* pull free_area_cache down to the first hole */ 350 if (mm->free_area_cache == vma->vm_end) { 351 mm->free_area_cache = vma->vm_start; 352 mm->cached_hole_size = largest_hole; 353 } 354 } 355 356 /* remember the largest hole we saw so far */ 357 if (addr + largest_hole < vma->vm_start) 358 largest_hole = vma->vm_start - addr; 359 360 /* try just below the current vma->vm_start */ 361 addr = (vma->vm_start - len) & huge_page_mask(h); 362 } while (len <= vma->vm_start); 363 364 fail: 365 /* 366 * if hint left us with no space for the requested 367 * mapping then try again: 368 */ 369 if (first_time) { 370 mm->free_area_cache = base; 371 largest_hole = 0; 372 first_time = 0; 373 goto try_again; 374 } 375 /* 376 * A failed mmap() very likely causes application failure, 377 * so fall back to the bottom-up function here. This scenario 378 * can happen with large stack limits and large mmap() 379 * allocations. 380 */ 381 mm->free_area_cache = TASK_UNMAPPED_BASE; 382 mm->cached_hole_size = ~0UL; 383 addr = hugetlb_get_unmapped_area_bottomup(file, addr0, 384 len, pgoff, flags); 385 386 /* 387 * Restore the topdown base: 388 */ 389 mm->free_area_cache = base; 390 mm->cached_hole_size = ~0UL; 391 392 return addr; 393 } 394 395 unsigned long 396 hugetlb_get_unmapped_area(struct file *file, unsigned long addr, 397 unsigned long len, unsigned long pgoff, unsigned long flags) 398 { 399 struct hstate *h = hstate_file(file); 400 struct mm_struct *mm = current->mm; 401 struct vm_area_struct *vma; 402 403 if (len & ~huge_page_mask(h)) 404 return -EINVAL; 405 if (len > TASK_SIZE) 406 return -ENOMEM; 407 408 if (flags & MAP_FIXED) { 409 if (prepare_hugepage_range(file, addr, len)) 410 return -EINVAL; 411 return addr; 412 } 413 414 if (addr) { 415 addr = ALIGN(addr, huge_page_size(h)); 416 vma = find_vma(mm, addr); 417 if (TASK_SIZE - len >= addr && 418 (!vma || addr + len <= vma->vm_start)) 419 return addr; 420 } 421 if (mm->get_unmapped_area == arch_get_unmapped_area) 422 return hugetlb_get_unmapped_area_bottomup(file, addr, len, 423 pgoff, flags); 424 else 425 return hugetlb_get_unmapped_area_topdown(file, addr, len, 426 pgoff, flags); 427 } 428 429 #endif /*HAVE_ARCH_HUGETLB_UNMAPPED_AREA*/ 430 431 #ifdef CONFIG_X86_64 432 static __init int setup_hugepagesz(char *opt) 433 { 434 unsigned long ps = memparse(opt, &opt); 435 if (ps == PMD_SIZE) { 436 hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT); 437 } else if (ps == PUD_SIZE && cpu_has_gbpages) { 438 hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT); 439 } else { 440 printk(KERN_ERR "hugepagesz: Unsupported page size %lu M\n", 441 ps >> 20); 442 return 0; 443 } 444 return 1; 445 } 446 __setup("hugepagesz=", setup_hugepagesz); 447 #endif 448