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 static int page_table_allocate_pgste_min = 0; 21 static int page_table_allocate_pgste_max = 1; 22 int page_table_allocate_pgste = 0; 23 EXPORT_SYMBOL(page_table_allocate_pgste); 24 25 static struct ctl_table page_table_sysctl[] = { 26 { 27 .procname = "allocate_pgste", 28 .data = &page_table_allocate_pgste, 29 .maxlen = sizeof(int), 30 .mode = S_IRUGO | S_IWUSR, 31 .proc_handler = proc_dointvec_minmax, 32 .extra1 = &page_table_allocate_pgste_min, 33 .extra2 = &page_table_allocate_pgste_max, 34 }, 35 { } 36 }; 37 38 static struct ctl_table page_table_sysctl_dir[] = { 39 { 40 .procname = "vm", 41 .maxlen = 0, 42 .mode = 0555, 43 .child = page_table_sysctl, 44 }, 45 { } 46 }; 47 48 static int __init page_table_register_sysctl(void) 49 { 50 return register_sysctl_table(page_table_sysctl_dir) ? 0 : -ENOMEM; 51 } 52 __initcall(page_table_register_sysctl); 53 54 #endif /* CONFIG_PGSTE */ 55 56 unsigned long *crst_table_alloc(struct mm_struct *mm) 57 { 58 struct page *page = alloc_pages(GFP_KERNEL, 2); 59 60 if (!page) 61 return NULL; 62 arch_set_page_dat(page, 2); 63 return (unsigned long *) page_to_phys(page); 64 } 65 66 void crst_table_free(struct mm_struct *mm, unsigned long *table) 67 { 68 free_pages((unsigned long) table, 2); 69 } 70 71 static void __crst_table_upgrade(void *arg) 72 { 73 struct mm_struct *mm = arg; 74 75 if (current->active_mm == mm) 76 set_user_asce(mm); 77 __tlb_flush_local(); 78 } 79 80 int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 81 { 82 unsigned long *table, *pgd; 83 int rc, notify; 84 85 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ 86 VM_BUG_ON(mm->context.asce_limit < _REGION2_SIZE); 87 rc = 0; 88 notify = 0; 89 while (mm->context.asce_limit < end) { 90 table = crst_table_alloc(mm); 91 if (!table) { 92 rc = -ENOMEM; 93 break; 94 } 95 spin_lock_bh(&mm->page_table_lock); 96 pgd = (unsigned long *) mm->pgd; 97 if (mm->context.asce_limit == _REGION2_SIZE) { 98 crst_table_init(table, _REGION2_ENTRY_EMPTY); 99 p4d_populate(mm, (p4d_t *) table, (pud_t *) pgd); 100 mm->pgd = (pgd_t *) table; 101 mm->context.asce_limit = _REGION1_SIZE; 102 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 103 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 104 mm_inc_nr_puds(mm); 105 } else { 106 crst_table_init(table, _REGION1_ENTRY_EMPTY); 107 pgd_populate(mm, (pgd_t *) table, (p4d_t *) pgd); 108 mm->pgd = (pgd_t *) table; 109 mm->context.asce_limit = -PAGE_SIZE; 110 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 111 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 112 } 113 notify = 1; 114 spin_unlock_bh(&mm->page_table_lock); 115 } 116 if (notify) 117 on_each_cpu(__crst_table_upgrade, mm, 0); 118 return rc; 119 } 120 121 void crst_table_downgrade(struct mm_struct *mm) 122 { 123 pgd_t *pgd; 124 125 /* downgrade should only happen from 3 to 2 levels (compat only) */ 126 VM_BUG_ON(mm->context.asce_limit != _REGION2_SIZE); 127 128 if (current->active_mm == mm) { 129 clear_user_asce(); 130 __tlb_flush_mm(mm); 131 } 132 133 pgd = mm->pgd; 134 mm_dec_nr_pmds(mm); 135 mm->pgd = (pgd_t *) (pgd_val(*pgd) & _REGION_ENTRY_ORIGIN); 136 mm->context.asce_limit = _REGION3_SIZE; 137 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 138 _ASCE_USER_BITS | _ASCE_TYPE_SEGMENT; 139 crst_table_free(mm, (unsigned long *) pgd); 140 141 if (current->active_mm == mm) 142 set_user_asce(mm); 143 } 144 145 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits) 146 { 147 unsigned int old, new; 148 149 do { 150 old = atomic_read(v); 151 new = old ^ bits; 152 } while (atomic_cmpxchg(v, old, new) != old); 153 return new; 154 } 155 156 #ifdef CONFIG_PGSTE 157 158 struct page *page_table_alloc_pgste(struct mm_struct *mm) 159 { 160 struct page *page; 161 u64 *table; 162 163 page = alloc_page(GFP_KERNEL); 164 if (page) { 165 table = (u64 *)page_to_phys(page); 166 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 167 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 168 } 169 return page; 170 } 171 172 void page_table_free_pgste(struct page *page) 173 { 174 __free_page(page); 175 } 176 177 #endif /* CONFIG_PGSTE */ 178 179 /* 180 * page table entry allocation/free routines. 181 */ 182 unsigned long *page_table_alloc(struct mm_struct *mm) 183 { 184 unsigned long *table; 185 struct page *page; 186 unsigned int mask, bit; 187 188 /* Try to get a fragment of a 4K page as a 2K page table */ 189 if (!mm_alloc_pgste(mm)) { 190 table = NULL; 191 spin_lock_bh(&mm->context.lock); 192 if (!list_empty(&mm->context.pgtable_list)) { 193 page = list_first_entry(&mm->context.pgtable_list, 194 struct page, lru); 195 mask = atomic_read(&page->_refcount) >> 24; 196 mask = (mask | (mask >> 4)) & 3; 197 if (mask != 3) { 198 table = (unsigned long *) page_to_phys(page); 199 bit = mask & 1; /* =1 -> second 2K */ 200 if (bit) 201 table += PTRS_PER_PTE; 202 atomic_xor_bits(&page->_refcount, 203 1U << (bit + 24)); 204 list_del(&page->lru); 205 } 206 } 207 spin_unlock_bh(&mm->context.lock); 208 if (table) 209 return table; 210 } 211 /* Allocate a fresh page */ 212 page = alloc_page(GFP_KERNEL); 213 if (!page) 214 return NULL; 215 if (!pgtable_page_ctor(page)) { 216 __free_page(page); 217 return NULL; 218 } 219 arch_set_page_dat(page, 0); 220 /* Initialize page table */ 221 table = (unsigned long *) page_to_phys(page); 222 if (mm_alloc_pgste(mm)) { 223 /* Return 4K page table with PGSTEs */ 224 atomic_xor_bits(&page->_refcount, 3 << 24); 225 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 226 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 227 } else { 228 /* Return the first 2K fragment of the page */ 229 atomic_xor_bits(&page->_refcount, 1 << 24); 230 memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE); 231 spin_lock_bh(&mm->context.lock); 232 list_add(&page->lru, &mm->context.pgtable_list); 233 spin_unlock_bh(&mm->context.lock); 234 } 235 return table; 236 } 237 238 void page_table_free(struct mm_struct *mm, unsigned long *table) 239 { 240 struct page *page; 241 unsigned int bit, mask; 242 243 page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 244 if (!mm_alloc_pgste(mm)) { 245 /* Free 2K page table fragment of a 4K page */ 246 bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); 247 spin_lock_bh(&mm->context.lock); 248 mask = atomic_xor_bits(&page->_refcount, 1U << (bit + 24)); 249 mask >>= 24; 250 if (mask & 3) 251 list_add(&page->lru, &mm->context.pgtable_list); 252 else 253 list_del(&page->lru); 254 spin_unlock_bh(&mm->context.lock); 255 if (mask != 0) 256 return; 257 } else { 258 atomic_xor_bits(&page->_refcount, 3U << 24); 259 } 260 261 pgtable_page_dtor(page); 262 __free_page(page); 263 } 264 265 void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, 266 unsigned long vmaddr) 267 { 268 struct mm_struct *mm; 269 struct page *page; 270 unsigned int bit, mask; 271 272 mm = tlb->mm; 273 page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 274 if (mm_alloc_pgste(mm)) { 275 gmap_unlink(mm, table, vmaddr); 276 table = (unsigned long *) (__pa(table) | 3); 277 tlb_remove_table(tlb, table); 278 return; 279 } 280 bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); 281 spin_lock_bh(&mm->context.lock); 282 mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24)); 283 mask >>= 24; 284 if (mask & 3) 285 list_add_tail(&page->lru, &mm->context.pgtable_list); 286 else 287 list_del(&page->lru); 288 spin_unlock_bh(&mm->context.lock); 289 table = (unsigned long *) (__pa(table) | (1U << bit)); 290 tlb_remove_table(tlb, table); 291 } 292 293 void __tlb_remove_table(void *_table) 294 { 295 unsigned int mask = (unsigned long) _table & 3; 296 void *table = (void *)((unsigned long) _table ^ mask); 297 struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 298 299 switch (mask) { 300 case 0: /* pmd, pud, or p4d */ 301 free_pages((unsigned long) table, 2); 302 break; 303 case 1: /* lower 2K of a 4K page table */ 304 case 2: /* higher 2K of a 4K page table */ 305 mask = atomic_xor_bits(&page->_refcount, mask << (4 + 24)); 306 mask >>= 24; 307 if (mask != 0) 308 break; 309 /* fallthrough */ 310 case 3: /* 4K page table with pgstes */ 311 if (mask & 3) 312 atomic_xor_bits(&page->_refcount, 3 << 24); 313 pgtable_page_dtor(page); 314 __free_page(page); 315 break; 316 } 317 } 318 319 /* 320 * Base infrastructure required to generate basic asces, region, segment, 321 * and page tables that do not make use of enhanced features like EDAT1. 322 */ 323 324 static struct kmem_cache *base_pgt_cache; 325 326 static unsigned long base_pgt_alloc(void) 327 { 328 u64 *table; 329 330 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 331 if (table) 332 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 333 return (unsigned long) table; 334 } 335 336 static void base_pgt_free(unsigned long table) 337 { 338 kmem_cache_free(base_pgt_cache, (void *) table); 339 } 340 341 static unsigned long base_crst_alloc(unsigned long val) 342 { 343 unsigned long table; 344 345 table = __get_free_pages(GFP_KERNEL, CRST_ALLOC_ORDER); 346 if (table) 347 crst_table_init((unsigned long *)table, val); 348 return table; 349 } 350 351 static void base_crst_free(unsigned long table) 352 { 353 free_pages(table, CRST_ALLOC_ORDER); 354 } 355 356 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 357 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 358 unsigned long end) \ 359 { \ 360 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 361 \ 362 return (next - 1) < (end - 1) ? next : end; \ 363 } 364 365 BASE_ADDR_END_FUNC(page, _PAGE_SIZE) 366 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 367 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 368 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 369 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 370 371 static inline unsigned long base_lra(unsigned long address) 372 { 373 unsigned long real; 374 375 asm volatile( 376 " lra %0,0(%1)\n" 377 : "=d" (real) : "a" (address) : "cc"); 378 return real; 379 } 380 381 static int base_page_walk(unsigned long origin, unsigned long addr, 382 unsigned long end, int alloc) 383 { 384 unsigned long *pte, next; 385 386 if (!alloc) 387 return 0; 388 pte = (unsigned long *) origin; 389 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT; 390 do { 391 next = base_page_addr_end(addr, end); 392 *pte = base_lra(addr); 393 } while (pte++, addr = next, addr < end); 394 return 0; 395 } 396 397 static int base_segment_walk(unsigned long origin, unsigned long addr, 398 unsigned long end, int alloc) 399 { 400 unsigned long *ste, next, table; 401 int rc; 402 403 ste = (unsigned long *) origin; 404 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 405 do { 406 next = base_segment_addr_end(addr, end); 407 if (*ste & _SEGMENT_ENTRY_INVALID) { 408 if (!alloc) 409 continue; 410 table = base_pgt_alloc(); 411 if (!table) 412 return -ENOMEM; 413 *ste = table | _SEGMENT_ENTRY; 414 } 415 table = *ste & _SEGMENT_ENTRY_ORIGIN; 416 rc = base_page_walk(table, addr, next, alloc); 417 if (rc) 418 return rc; 419 if (!alloc) 420 base_pgt_free(table); 421 cond_resched(); 422 } while (ste++, addr = next, addr < end); 423 return 0; 424 } 425 426 static int base_region3_walk(unsigned long origin, unsigned long addr, 427 unsigned long end, int alloc) 428 { 429 unsigned long *rtte, next, table; 430 int rc; 431 432 rtte = (unsigned long *) origin; 433 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 434 do { 435 next = base_region3_addr_end(addr, end); 436 if (*rtte & _REGION_ENTRY_INVALID) { 437 if (!alloc) 438 continue; 439 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 440 if (!table) 441 return -ENOMEM; 442 *rtte = table | _REGION3_ENTRY; 443 } 444 table = *rtte & _REGION_ENTRY_ORIGIN; 445 rc = base_segment_walk(table, addr, next, alloc); 446 if (rc) 447 return rc; 448 if (!alloc) 449 base_crst_free(table); 450 } while (rtte++, addr = next, addr < end); 451 return 0; 452 } 453 454 static int base_region2_walk(unsigned long origin, unsigned long addr, 455 unsigned long end, int alloc) 456 { 457 unsigned long *rste, next, table; 458 int rc; 459 460 rste = (unsigned long *) origin; 461 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 462 do { 463 next = base_region2_addr_end(addr, end); 464 if (*rste & _REGION_ENTRY_INVALID) { 465 if (!alloc) 466 continue; 467 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 468 if (!table) 469 return -ENOMEM; 470 *rste = table | _REGION2_ENTRY; 471 } 472 table = *rste & _REGION_ENTRY_ORIGIN; 473 rc = base_region3_walk(table, addr, next, alloc); 474 if (rc) 475 return rc; 476 if (!alloc) 477 base_crst_free(table); 478 } while (rste++, addr = next, addr < end); 479 return 0; 480 } 481 482 static int base_region1_walk(unsigned long origin, unsigned long addr, 483 unsigned long end, int alloc) 484 { 485 unsigned long *rfte, next, table; 486 int rc; 487 488 rfte = (unsigned long *) origin; 489 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 490 do { 491 next = base_region1_addr_end(addr, end); 492 if (*rfte & _REGION_ENTRY_INVALID) { 493 if (!alloc) 494 continue; 495 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 496 if (!table) 497 return -ENOMEM; 498 *rfte = table | _REGION1_ENTRY; 499 } 500 table = *rfte & _REGION_ENTRY_ORIGIN; 501 rc = base_region2_walk(table, addr, next, alloc); 502 if (rc) 503 return rc; 504 if (!alloc) 505 base_crst_free(table); 506 } while (rfte++, addr = next, addr < end); 507 return 0; 508 } 509 510 /** 511 * base_asce_free - free asce and tables returned from base_asce_alloc() 512 * @asce: asce to be freed 513 * 514 * Frees all region, segment, and page tables that were allocated with a 515 * corresponding base_asce_alloc() call. 516 */ 517 void base_asce_free(unsigned long asce) 518 { 519 unsigned long table = asce & _ASCE_ORIGIN; 520 521 if (!asce) 522 return; 523 switch (asce & _ASCE_TYPE_MASK) { 524 case _ASCE_TYPE_SEGMENT: 525 base_segment_walk(table, 0, _REGION3_SIZE, 0); 526 break; 527 case _ASCE_TYPE_REGION3: 528 base_region3_walk(table, 0, _REGION2_SIZE, 0); 529 break; 530 case _ASCE_TYPE_REGION2: 531 base_region2_walk(table, 0, _REGION1_SIZE, 0); 532 break; 533 case _ASCE_TYPE_REGION1: 534 base_region1_walk(table, 0, -_PAGE_SIZE, 0); 535 break; 536 } 537 base_crst_free(table); 538 } 539 540 static int base_pgt_cache_init(void) 541 { 542 static DEFINE_MUTEX(base_pgt_cache_mutex); 543 unsigned long sz = _PAGE_TABLE_SIZE; 544 545 if (base_pgt_cache) 546 return 0; 547 mutex_lock(&base_pgt_cache_mutex); 548 if (!base_pgt_cache) 549 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 550 mutex_unlock(&base_pgt_cache_mutex); 551 return base_pgt_cache ? 0 : -ENOMEM; 552 } 553 554 /** 555 * base_asce_alloc - create kernel mapping without enhanced DAT features 556 * @addr: virtual start address of kernel mapping 557 * @num_pages: number of consecutive pages 558 * 559 * Generate an asce, including all required region, segment and page tables, 560 * that can be used to access the virtual kernel mapping. The difference is 561 * that the returned asce does not make use of any enhanced DAT features like 562 * e.g. large pages. This is required for some I/O functions that pass an 563 * asce, like e.g. some service call requests. 564 * 565 * Note: the returned asce may NEVER be attached to any cpu. It may only be 566 * used for I/O requests. tlb entries that might result because the 567 * asce was attached to a cpu won't be cleared. 568 */ 569 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 570 { 571 unsigned long asce, table, end; 572 int rc; 573 574 if (base_pgt_cache_init()) 575 return 0; 576 end = addr + num_pages * PAGE_SIZE; 577 if (end <= _REGION3_SIZE) { 578 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 579 if (!table) 580 return 0; 581 rc = base_segment_walk(table, addr, end, 1); 582 asce = table | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 583 } else if (end <= _REGION2_SIZE) { 584 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 585 if (!table) 586 return 0; 587 rc = base_region3_walk(table, addr, end, 1); 588 asce = table | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 589 } else if (end <= _REGION1_SIZE) { 590 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 591 if (!table) 592 return 0; 593 rc = base_region2_walk(table, addr, end, 1); 594 asce = table | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 595 } else { 596 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 597 if (!table) 598 return 0; 599 rc = base_region1_walk(table, addr, end, 1); 600 asce = table | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 601 } 602 if (rc) { 603 base_asce_free(asce); 604 asce = 0; 605 } 606 return asce; 607 } 608