1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Page table allocation functions 4 * 5 * Copyright IBM Corp. 2016 6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com> 7 */ 8 9 #include <linux/sysctl.h> 10 #include <linux/slab.h> 11 #include <linux/mm.h> 12 #include <asm/mmu_context.h> 13 #include <asm/pgalloc.h> 14 #include <asm/gmap.h> 15 #include <asm/tlb.h> 16 #include <asm/tlbflush.h> 17 18 #ifdef CONFIG_PGSTE 19 20 int page_table_allocate_pgste = 0; 21 EXPORT_SYMBOL(page_table_allocate_pgste); 22 23 static struct ctl_table page_table_sysctl[] = { 24 { 25 .procname = "allocate_pgste", 26 .data = &page_table_allocate_pgste, 27 .maxlen = sizeof(int), 28 .mode = S_IRUGO | S_IWUSR, 29 .proc_handler = proc_dointvec_minmax, 30 .extra1 = SYSCTL_ZERO, 31 .extra2 = SYSCTL_ONE, 32 }, 33 { } 34 }; 35 36 static struct ctl_table page_table_sysctl_dir[] = { 37 { 38 .procname = "vm", 39 .maxlen = 0, 40 .mode = 0555, 41 .child = page_table_sysctl, 42 }, 43 { } 44 }; 45 46 static int __init page_table_register_sysctl(void) 47 { 48 return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM; 49 } 50 __initcall(page_table_register_sysctl); 51 52 #endif /* CONFIG_PGSTE */ 53 54 unsigned long *crst_table_alloc(struct mm_struct *mm) 55 { 56 struct page *page = alloc_pages(GFP_KERNEL, 2); 57 58 if (!page) 59 return NULL; 60 arch_set_page_dat(page, 2); 61 return (unsigned long *) page_to_phys(page); 62 } 63 64 void crst_table_free(struct mm_struct *mm, unsigned long *table) 65 { 66 free_pages((unsigned long) table, 2); 67 } 68 69 static void __crst_table_upgrade(void *arg) 70 { 71 struct mm_struct *mm = arg; 72 73 if (current->active_mm == mm) 74 set_user_asce(mm); 75 __tlb_flush_local(); 76 } 77 78 int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 79 { 80 unsigned long *table, *pgd; 81 int rc, notify; 82 83 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ 84 VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE); 85 rc = 0; 86 notify = 0; 87 while (mm->context.asce_limit < end) { 88 table = crst_table_alloc(mm); 89 if (!table) { 90 rc = -ENOMEM; 91 break; 92 } 93 spin_lock_bh(&mm->page_table_lock); 94 pgd = (unsigned long *) mm->pgd; 95 if (mm->context.asce_limit == _REGION2_SIZE) { 96 crst_table_init(table, _REGION2_ENTRY_EMPTY); 97 p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd); 98 mm->pgd = (pgd_t *) table; 99 mm->context.asce_limit = _REGION1_SIZE; 100 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 101 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 102 mm_inc_nr_puds(mm); 103 } else { 104 crst_table_init(table, _REGION1_ENTRY_EMPTY); 105 pgd_populate(mm, (pgd_t *) table, (p4d_t *) pgd); 106 mm->pgd = (pgd_t *) table; 107 mm->context.asce_limit = -PAGE_SIZE; 108 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 109 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 110 } 111 notify = 1; 112 spin_unlock_bh(&mm->page_table_lock); 113 } 114 if (notify) 115 on_each_cpu(__crst_table_upgrade, mm, 0); 116 return rc; 117 } 118 119 void crst_table_downgrade(struct mm_struct *mm) 120 { 121 pgd_t *pgd; 122 123 /* downgrade should only happen from 3 to 2 levels (compat only) */ 124 VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE); 125 126 if (current->active_mm == mm) { 127 clear_user_asce(); 128 __tlb_flush_mm(mm); 129 } 130 131 pgd = mm->pgd; 132 mm_dec_nr_pmds(mm); 133 mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN); 134 mm->context.asce_limit = _REGION3_SIZE; 135 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 136 _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT; 137 crst_table_free(mm, (unsigned long *) pgd); 138 139 if (current->active_mm == mm) 140 set_user_asce(mm); 141 } 142 143 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits) 144 { 145 unsigned int old, new; 146 147 do { 148 old = atomic_read(v); 149 new = old ^ bits; 150 } while (atomic_cmpxchg(v, old, new) != old); 151 return new; 152 } 153 154 #ifdef CONFIG_PGSTE 155 156 struct page *page_table_alloc_pgste(struct mm_struct *mm) 157 { 158 struct page *page; 159 u64 *table; 160 161 page = alloc_page(GFP_KERNEL); 162 if (page) { 163 table = (u64 *)page_to_phys(page); 164 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 165 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 166 } 167 return page; 168 } 169 170 void page_table_free_pgste(struct page *page) 171 { 172 __free_page(page); 173 } 174 175 #endif /* CONFIG_PGSTE */ 176 177 /* 178 * page table entry allocation/free routines. 179 */ 180 unsigned long *page_table_alloc(struct mm_struct *mm) 181 { 182 unsigned long *table; 183 struct page *page; 184 unsigned int mask, bit; 185 186 /* Try to get a fragment of a 4K page as a 2K page table */ 187 if (!mm_alloc_pgste(mm)) { 188 table = NULL; 189 spin_lock_bh(&mm->context.lock); 190 if (!list_empty(&mm->context.pgtable_list)) { 191 page = list_first_entry(&mm->context.pgtable_list, 192 struct page, lru); 193 mask = atomic_read(&page->_refcount) >> 24; 194 mask = (mask | (mask >> 4)) & 3; 195 if (mask != 3) { 196 table = (unsigned long *) page_to_phys(page); 197 bit = mask & 1; /* =1 -> second 2K */ 198 if (bit) 199 table += PTRS_PER_PTE; 200 atomic_xor_bits(&page->_refcount, 201 1U << (bit + 24)); 202 list_del(&page->lru); 203 } 204 } 205 spin_unlock_bh(&mm->context.lock); 206 if (table) 207 return table; 208 } 209 /* Allocate a fresh page */ 210 page = alloc_page(GFP_KERNEL); 211 if (!page) 212 return NULL; 213 if (!pgtable_page_ctor(page)) { 214 __free_page(page); 215 return NULL; 216 } 217 arch_set_page_dat(page, 0); 218 /* Initialize page table */ 219 table = (unsigned long *) page_to_phys(page); 220 if (mm_alloc_pgste(mm)) { 221 /* Return 4K page table with PGSTEs */ 222 atomic_xor_bits(&page->_refcount, 3 << 24); 223 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 224 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 225 } else { 226 /* Return the first 2K fragment of the page */ 227 atomic_xor_bits(&page->_refcount, 1 << 24); 228 memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE); 229 spin_lock_bh(&mm->context.lock); 230 list_add(&page->lru, &mm->context.pgtable_list); 231 spin_unlock_bh(&mm->context.lock); 232 } 233 return table; 234 } 235 236 void page_table_free(struct mm_struct *mm, unsigned long *table) 237 { 238 struct page *page; 239 unsigned int bit, mask; 240 241 page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 242 if (!mm_alloc_pgste(mm)) { 243 /* Free 2K page table fragment of a 4K page */ 244 bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); 245 spin_lock_bh(&mm->context.lock); 246 mask = atomic_xor_bits(&page->_refcount, 1U << (bit + 24)); 247 mask >>= 24; 248 if (mask & 3) 249 list_add(&page->lru, &mm->context.pgtable_list); 250 else 251 list_del(&page->lru); 252 spin_unlock_bh(&mm->context.lock); 253 if (mask != 0) 254 return; 255 } else { 256 atomic_xor_bits(&page->_refcount, 3U << 24); 257 } 258 259 pgtable_page_dtor(page); 260 __free_page(page); 261 } 262 263 void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, 264 unsigned long vmaddr) 265 { 266 struct mm_struct *mm; 267 struct page *page; 268 unsigned int bit, mask; 269 270 mm = tlb->mm; 271 page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 272 if (mm_alloc_pgste(mm)) { 273 gmap_unlink(mm, table, vmaddr); 274 table = (unsigned long *) (__pa(table) | 3); 275 tlb_remove_table(tlb, table); 276 return; 277 } 278 bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); 279 spin_lock_bh(&mm->context.lock); 280 mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24)); 281 mask >>= 24; 282 if (mask & 3) 283 list_add_tail(&page->lru, &mm->context.pgtable_list); 284 else 285 list_del(&page->lru); 286 spin_unlock_bh(&mm->context.lock); 287 table = (unsigned long *) (__pa(table) | (1U << bit)); 288 tlb_remove_table(tlb, table); 289 } 290 291 void __tlb_remove_table(void *_table) 292 { 293 unsigned int mask = (unsigned long) _table & 3; 294 void *table = (void *)((unsigned long) _table ^ mask); 295 struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 296 297 switch (mask) { 298 case 0: /* pmd, pud, or p4d */ 299 free_pages((unsigned long) table, 2); 300 break; 301 case 1: /* lower 2K of a 4K page table */ 302 case 2: /* higher 2K of a 4K page table */ 303 mask = atomic_xor_bits(&page->_refcount, mask << (4 + 24)); 304 mask >>= 24; 305 if (mask != 0) 306 break; 307 /* fallthrough */ 308 case 3: /* 4K page table with pgstes */ 309 if (mask & 3) 310 atomic_xor_bits(&page->_refcount, 3 << 24); 311 pgtable_page_dtor(page); 312 __free_page(page); 313 break; 314 } 315 } 316 317 /* 318 * Base infrastructure required to generate basic asces, region, segment, 319 * and page tables that do not make use of enhanced features like EDAT1. 320 */ 321 322 static struct kmem_cache *base_pgt_cache; 323 324 static unsigned long base_pgt_alloc(void) 325 { 326 u64 *table; 327 328 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 329 if (table) 330 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 331 return (unsigned long) table; 332 } 333 334 static void base_pgt_free(unsigned long table) 335 { 336 kmem_cache_free(base_pgt_cache, (void *) table); 337 } 338 339 static unsigned long base_crst_alloc(unsigned long val) 340 { 341 unsigned long table; 342 343 table = __get_free_pages(GFP_KERNEL, CRST_ALLOC_ORDER); 344 if (table) 345 crst_table_init((unsigned long *)table, val); 346 return table; 347 } 348 349 static void base_crst_free(unsigned long table) 350 { 351 free_pages(table, CRST_ALLOC_ORDER); 352 } 353 354 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 355 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 356 unsigned long end) \ 357 { \ 358 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 359 \ 360 return (next - 1) < (end - 1) ? next : end; \ 361 } 362 363 BASE_ADDR_END_FUNC(page, _PAGE_SIZE) 364 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 365 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 366 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 367 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 368 369 static inline unsigned long base_lra(unsigned long address) 370 { 371 unsigned long real; 372 373 asm volatile( 374 " lra %0,0(%1)\n" 375 : "=d" (real) : "a" (address) : "cc"); 376 return real; 377 } 378 379 static int base_page_walk(unsigned long origin, unsigned long addr, 380 unsigned long end, int alloc) 381 { 382 unsigned long *pte, next; 383 384 if (!alloc) 385 return 0; 386 pte = (unsigned long *) origin; 387 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT; 388 do { 389 next = base_page_addr_end(addr, end); 390 *pte = base_lra(addr); 391 } while (pte++, addr = next, addr < end); 392 return 0; 393 } 394 395 static int base_segment_walk(unsigned long origin, unsigned long addr, 396 unsigned long end, int alloc) 397 { 398 unsigned long *ste, next, table; 399 int rc; 400 401 ste = (unsigned long *) origin; 402 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 403 do { 404 next = base_segment_addr_end(addr, end); 405 if (*ste & _SEGMENT_ENTRY_INVALID) { 406 if (!alloc) 407 continue; 408 table = base_pgt_alloc(); 409 if (!table) 410 return -ENOMEM; 411 *ste = table | _SEGMENT_ENTRY; 412 } 413 table = *ste & _SEGMENT_ENTRY_ORIGIN; 414 rc = base_page_walk(table, addr, next, alloc); 415 if (rc) 416 return rc; 417 if (!alloc) 418 base_pgt_free(table); 419 cond_resched(); 420 } while (ste++, addr = next, addr < end); 421 return 0; 422 } 423 424 static int base_region3_walk(unsigned long origin, unsigned long addr, 425 unsigned long end, int alloc) 426 { 427 unsigned long *rtte, next, table; 428 int rc; 429 430 rtte = (unsigned long *) origin; 431 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 432 do { 433 next = base_region3_addr_end(addr, end); 434 if (*rtte & _REGION_ENTRY_INVALID) { 435 if (!alloc) 436 continue; 437 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 438 if (!table) 439 return -ENOMEM; 440 *rtte = table | _REGION3_ENTRY; 441 } 442 table = *rtte & _REGION_ENTRY_ORIGIN; 443 rc = base_segment_walk(table, addr, next, alloc); 444 if (rc) 445 return rc; 446 if (!alloc) 447 base_crst_free(table); 448 } while (rtte++, addr = next, addr < end); 449 return 0; 450 } 451 452 static int base_region2_walk(unsigned long origin, unsigned long addr, 453 unsigned long end, int alloc) 454 { 455 unsigned long *rste, next, table; 456 int rc; 457 458 rste = (unsigned long *) origin; 459 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 460 do { 461 next = base_region2_addr_end(addr, end); 462 if (*rste & _REGION_ENTRY_INVALID) { 463 if (!alloc) 464 continue; 465 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 466 if (!table) 467 return -ENOMEM; 468 *rste = table | _REGION2_ENTRY; 469 } 470 table = *rste & _REGION_ENTRY_ORIGIN; 471 rc = base_region3_walk(table, addr, next, alloc); 472 if (rc) 473 return rc; 474 if (!alloc) 475 base_crst_free(table); 476 } while (rste++, addr = next, addr < end); 477 return 0; 478 } 479 480 static int base_region1_walk(unsigned long origin, unsigned long addr, 481 unsigned long end, int alloc) 482 { 483 unsigned long *rfte, next, table; 484 int rc; 485 486 rfte = (unsigned long *) origin; 487 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 488 do { 489 next = base_region1_addr_end(addr, end); 490 if (*rfte & _REGION_ENTRY_INVALID) { 491 if (!alloc) 492 continue; 493 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 494 if (!table) 495 return -ENOMEM; 496 *rfte = table | _REGION1_ENTRY; 497 } 498 table = *rfte & _REGION_ENTRY_ORIGIN; 499 rc = base_region2_walk(table, addr, next, alloc); 500 if (rc) 501 return rc; 502 if (!alloc) 503 base_crst_free(table); 504 } while (rfte++, addr = next, addr < end); 505 return 0; 506 } 507 508 /** 509 * base_asce_free - free asce and tables returned from base_asce_alloc() 510 * @asce: asce to be freed 511 * 512 * Frees all region, segment, and page tables that were allocated with a 513 * corresponding base_asce_alloc() call. 514 */ 515 void base_asce_free(unsigned long asce) 516 { 517 unsigned long table = asce & _ASCE_ORIGIN; 518 519 if (!asce) 520 return; 521 switch (asce & _ASCE_TYPE_MASK) { 522 case _ASCE_TYPE_SEGMENT: 523 base_segment_walk(table, 0, _REGION3_SIZE, 0); 524 break; 525 case _ASCE_TYPE_REGION3: 526 base_region3_walk(table, 0, _REGION2_SIZE, 0); 527 break; 528 case _ASCE_TYPE_REGION2: 529 base_region2_walk(table, 0, _REGION1_SIZE, 0); 530 break; 531 case _ASCE_TYPE_REGION1: 532 base_region1_walk(table, 0, -_PAGE_SIZE, 0); 533 break; 534 } 535 base_crst_free(table); 536 } 537 538 static int base_pgt_cache_init(void) 539 { 540 static DEFINE_MUTEX(base_pgt_cache_mutex); 541 unsigned long sz = _PAGE_TABLE_SIZE; 542 543 if (base_pgt_cache) 544 return 0; 545 mutex_lock(&base_pgt_cache_mutex); 546 if (!base_pgt_cache) 547 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 548 mutex_unlock(&base_pgt_cache_mutex); 549 return base_pgt_cache ? 0 : -ENOMEM; 550 } 551 552 /** 553 * base_asce_alloc - create kernel mapping without enhanced DAT features 554 * @addr: virtual start address of kernel mapping 555 * @num_pages: number of consecutive pages 556 * 557 * Generate an asce, including all required region, segment and page tables, 558 * that can be used to access the virtual kernel mapping. The difference is 559 * that the returned asce does not make use of any enhanced DAT features like 560 * e.g. large pages. This is required for some I/O functions that pass an 561 * asce, like e.g. some service call requests. 562 * 563 * Note: the returned asce may NEVER be attached to any cpu. It may only be 564 * used for I/O requests. tlb entries that might result because the 565 * asce was attached to a cpu won't be cleared. 566 */ 567 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 568 { 569 unsigned long asce, table, end; 570 int rc; 571 572 if (base_pgt_cache_init()) 573 return 0; 574 end = addr + num_pages * PAGE_SIZE; 575 if (end <= _REGION3_SIZE) { 576 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 577 if (!table) 578 return 0; 579 rc = base_segment_walk(table, addr, end, 1); 580 asce = table | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 581 } else if (end <= _REGION2_SIZE) { 582 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 583 if (!table) 584 return 0; 585 rc = base_region3_walk(table, addr, end, 1); 586 asce = table | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 587 } else if (end <= _REGION1_SIZE) { 588 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 589 if (!table) 590 return 0; 591 rc = base_region2_walk(table, addr, end, 1); 592 asce = table | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 593 } else { 594 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 595 if (!table) 596 return 0; 597 rc = base_region1_walk(table, addr, end, 1); 598 asce = table | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 599 } 600 if (rc) { 601 base_asce_free(asce); 602 asce = 0; 603 } 604 return asce; 605 } 606