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 /* we must change all active ASCEs to avoid the creation of new TLBs */ 74 if (current->active_mm == mm) { 75 S390_lowcore.user_asce = mm->context.asce; 76 if (current->thread.mm_segment == USER_DS) { 77 __ctl_load(S390_lowcore.user_asce, 1, 1); 78 /* Mark user-ASCE present in CR1 */ 79 clear_cpu_flag(CIF_ASCE_PRIMARY); 80 } 81 if (current->thread.mm_segment == USER_DS_SACF) { 82 __ctl_load(S390_lowcore.user_asce, 7, 7); 83 /* enable_sacf_uaccess does all or nothing */ 84 WARN_ON(!test_cpu_flag(CIF_ASCE_SECONDARY)); 85 } 86 } 87 __tlb_flush_local(); 88 } 89 90 int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 91 { 92 unsigned long *pgd = NULL, *p4d = NULL, *__pgd; 93 unsigned long asce_limit = mm->context.asce_limit; 94 95 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ 96 VM_BUG_ON(asce_limit < _REGION2_SIZE); 97 98 if (end <= asce_limit) 99 return 0; 100 101 if (asce_limit == _REGION2_SIZE) { 102 p4d = crst_table_alloc(mm); 103 if (unlikely(!p4d)) 104 goto err_p4d; 105 crst_table_init(p4d, _REGION2_ENTRY_EMPTY); 106 } 107 if (end > _REGION1_SIZE) { 108 pgd = crst_table_alloc(mm); 109 if (unlikely(!pgd)) 110 goto err_pgd; 111 crst_table_init(pgd, _REGION1_ENTRY_EMPTY); 112 } 113 114 spin_lock_bh(&mm->page_table_lock); 115 116 /* 117 * This routine gets called with mmap_lock lock held and there is 118 * no reason to optimize for the case of otherwise. However, if 119 * that would ever change, the below check will let us know. 120 */ 121 VM_BUG_ON(asce_limit != mm->context.asce_limit); 122 123 if (p4d) { 124 __pgd = (unsigned long *) mm->pgd; 125 p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd); 126 mm->pgd = (pgd_t *) p4d; 127 mm->context.asce_limit = _REGION1_SIZE; 128 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 129 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 130 mm_inc_nr_puds(mm); 131 } 132 if (pgd) { 133 __pgd = (unsigned long *) mm->pgd; 134 pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd); 135 mm->pgd = (pgd_t *) pgd; 136 mm->context.asce_limit = TASK_SIZE_MAX; 137 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 138 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 139 } 140 141 spin_unlock_bh(&mm->page_table_lock); 142 143 on_each_cpu(__crst_table_upgrade, mm, 0); 144 145 return 0; 146 147 err_pgd: 148 crst_table_free(mm, p4d); 149 err_p4d: 150 return -ENOMEM; 151 } 152 153 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits) 154 { 155 unsigned int old, new; 156 157 do { 158 old = atomic_read(v); 159 new = old ^ bits; 160 } while (atomic_cmpxchg(v, old, new) != old); 161 return new; 162 } 163 164 #ifdef CONFIG_PGSTE 165 166 struct page *page_table_alloc_pgste(struct mm_struct *mm) 167 { 168 struct page *page; 169 u64 *table; 170 171 page = alloc_page(GFP_KERNEL); 172 if (page) { 173 table = (u64 *)page_to_phys(page); 174 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 175 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 176 } 177 return page; 178 } 179 180 void page_table_free_pgste(struct page *page) 181 { 182 __free_page(page); 183 } 184 185 #endif /* CONFIG_PGSTE */ 186 187 /* 188 * page table entry allocation/free routines. 189 */ 190 unsigned long *page_table_alloc(struct mm_struct *mm) 191 { 192 unsigned long *table; 193 struct page *page; 194 unsigned int mask, bit; 195 196 /* Try to get a fragment of a 4K page as a 2K page table */ 197 if (!mm_alloc_pgste(mm)) { 198 table = NULL; 199 spin_lock_bh(&mm->context.lock); 200 if (!list_empty(&mm->context.pgtable_list)) { 201 page = list_first_entry(&mm->context.pgtable_list, 202 struct page, lru); 203 mask = atomic_read(&page->_refcount) >> 24; 204 mask = (mask | (mask >> 4)) & 3; 205 if (mask != 3) { 206 table = (unsigned long *) page_to_phys(page); 207 bit = mask & 1; /* =1 -> second 2K */ 208 if (bit) 209 table += PTRS_PER_PTE; 210 atomic_xor_bits(&page->_refcount, 211 1U << (bit + 24)); 212 list_del(&page->lru); 213 } 214 } 215 spin_unlock_bh(&mm->context.lock); 216 if (table) 217 return table; 218 } 219 /* Allocate a fresh page */ 220 page = alloc_page(GFP_KERNEL); 221 if (!page) 222 return NULL; 223 if (!pgtable_pte_page_ctor(page)) { 224 __free_page(page); 225 return NULL; 226 } 227 arch_set_page_dat(page, 0); 228 /* Initialize page table */ 229 table = (unsigned long *) page_to_phys(page); 230 if (mm_alloc_pgste(mm)) { 231 /* Return 4K page table with PGSTEs */ 232 atomic_xor_bits(&page->_refcount, 3 << 24); 233 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 234 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 235 } else { 236 /* Return the first 2K fragment of the page */ 237 atomic_xor_bits(&page->_refcount, 1 << 24); 238 memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE); 239 spin_lock_bh(&mm->context.lock); 240 list_add(&page->lru, &mm->context.pgtable_list); 241 spin_unlock_bh(&mm->context.lock); 242 } 243 return table; 244 } 245 246 void page_table_free(struct mm_struct *mm, unsigned long *table) 247 { 248 struct page *page; 249 unsigned int bit, mask; 250 251 page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 252 if (!mm_alloc_pgste(mm)) { 253 /* Free 2K page table fragment of a 4K page */ 254 bit = (__pa(table) & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); 255 spin_lock_bh(&mm->context.lock); 256 mask = atomic_xor_bits(&page->_refcount, 1U << (bit + 24)); 257 mask >>= 24; 258 if (mask & 3) 259 list_add(&page->lru, &mm->context.pgtable_list); 260 else 261 list_del(&page->lru); 262 spin_unlock_bh(&mm->context.lock); 263 if (mask != 0) 264 return; 265 } else { 266 atomic_xor_bits(&page->_refcount, 3U << 24); 267 } 268 269 pgtable_pte_page_dtor(page); 270 __free_page(page); 271 } 272 273 void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, 274 unsigned long vmaddr) 275 { 276 struct mm_struct *mm; 277 struct page *page; 278 unsigned int bit, mask; 279 280 mm = tlb->mm; 281 page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 282 if (mm_alloc_pgste(mm)) { 283 gmap_unlink(mm, table, vmaddr); 284 table = (unsigned long *) (__pa(table) | 3); 285 tlb_remove_table(tlb, table); 286 return; 287 } 288 bit = (__pa(table) & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); 289 spin_lock_bh(&mm->context.lock); 290 mask = atomic_xor_bits(&page->_refcount, 0x11U << (bit + 24)); 291 mask >>= 24; 292 if (mask & 3) 293 list_add_tail(&page->lru, &mm->context.pgtable_list); 294 else 295 list_del(&page->lru); 296 spin_unlock_bh(&mm->context.lock); 297 table = (unsigned long *) (__pa(table) | (1U << bit)); 298 tlb_remove_table(tlb, table); 299 } 300 301 void __tlb_remove_table(void *_table) 302 { 303 unsigned int mask = (unsigned long) _table & 3; 304 void *table = (void *)((unsigned long) _table ^ mask); 305 struct page *page = pfn_to_page(__pa(table) >> PAGE_SHIFT); 306 307 switch (mask) { 308 case 0: /* pmd, pud, or p4d */ 309 free_pages((unsigned long) table, 2); 310 break; 311 case 1: /* lower 2K of a 4K page table */ 312 case 2: /* higher 2K of a 4K page table */ 313 mask = atomic_xor_bits(&page->_refcount, mask << (4 + 24)); 314 mask >>= 24; 315 if (mask != 0) 316 break; 317 fallthrough; 318 case 3: /* 4K page table with pgstes */ 319 if (mask & 3) 320 atomic_xor_bits(&page->_refcount, 3 << 24); 321 pgtable_pte_page_dtor(page); 322 __free_page(page); 323 break; 324 } 325 } 326 327 /* 328 * Base infrastructure required to generate basic asces, region, segment, 329 * and page tables that do not make use of enhanced features like EDAT1. 330 */ 331 332 static struct kmem_cache *base_pgt_cache; 333 334 static unsigned long base_pgt_alloc(void) 335 { 336 u64 *table; 337 338 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 339 if (table) 340 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 341 return (unsigned long) table; 342 } 343 344 static void base_pgt_free(unsigned long table) 345 { 346 kmem_cache_free(base_pgt_cache, (void *) table); 347 } 348 349 static unsigned long base_crst_alloc(unsigned long val) 350 { 351 unsigned long table; 352 353 table = __get_free_pages(GFP_KERNEL, CRST_ALLOC_ORDER); 354 if (table) 355 crst_table_init((unsigned long *)table, val); 356 return table; 357 } 358 359 static void base_crst_free(unsigned long table) 360 { 361 free_pages(table, CRST_ALLOC_ORDER); 362 } 363 364 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 365 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 366 unsigned long end) \ 367 { \ 368 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 369 \ 370 return (next - 1) < (end - 1) ? next : end; \ 371 } 372 373 BASE_ADDR_END_FUNC(page, _PAGE_SIZE) 374 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 375 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 376 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 377 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 378 379 static inline unsigned long base_lra(unsigned long address) 380 { 381 unsigned long real; 382 383 asm volatile( 384 " lra %0,0(%1)\n" 385 : "=d" (real) : "a" (address) : "cc"); 386 return real; 387 } 388 389 static int base_page_walk(unsigned long origin, unsigned long addr, 390 unsigned long end, int alloc) 391 { 392 unsigned long *pte, next; 393 394 if (!alloc) 395 return 0; 396 pte = (unsigned long *) origin; 397 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT; 398 do { 399 next = base_page_addr_end(addr, end); 400 *pte = base_lra(addr); 401 } while (pte++, addr = next, addr < end); 402 return 0; 403 } 404 405 static int base_segment_walk(unsigned long origin, unsigned long addr, 406 unsigned long end, int alloc) 407 { 408 unsigned long *ste, next, table; 409 int rc; 410 411 ste = (unsigned long *) origin; 412 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 413 do { 414 next = base_segment_addr_end(addr, end); 415 if (*ste & _SEGMENT_ENTRY_INVALID) { 416 if (!alloc) 417 continue; 418 table = base_pgt_alloc(); 419 if (!table) 420 return -ENOMEM; 421 *ste = table | _SEGMENT_ENTRY; 422 } 423 table = *ste & _SEGMENT_ENTRY_ORIGIN; 424 rc = base_page_walk(table, addr, next, alloc); 425 if (rc) 426 return rc; 427 if (!alloc) 428 base_pgt_free(table); 429 cond_resched(); 430 } while (ste++, addr = next, addr < end); 431 return 0; 432 } 433 434 static int base_region3_walk(unsigned long origin, unsigned long addr, 435 unsigned long end, int alloc) 436 { 437 unsigned long *rtte, next, table; 438 int rc; 439 440 rtte = (unsigned long *) origin; 441 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 442 do { 443 next = base_region3_addr_end(addr, end); 444 if (*rtte & _REGION_ENTRY_INVALID) { 445 if (!alloc) 446 continue; 447 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 448 if (!table) 449 return -ENOMEM; 450 *rtte = table | _REGION3_ENTRY; 451 } 452 table = *rtte & _REGION_ENTRY_ORIGIN; 453 rc = base_segment_walk(table, addr, next, alloc); 454 if (rc) 455 return rc; 456 if (!alloc) 457 base_crst_free(table); 458 } while (rtte++, addr = next, addr < end); 459 return 0; 460 } 461 462 static int base_region2_walk(unsigned long origin, unsigned long addr, 463 unsigned long end, int alloc) 464 { 465 unsigned long *rste, next, table; 466 int rc; 467 468 rste = (unsigned long *) origin; 469 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 470 do { 471 next = base_region2_addr_end(addr, end); 472 if (*rste & _REGION_ENTRY_INVALID) { 473 if (!alloc) 474 continue; 475 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 476 if (!table) 477 return -ENOMEM; 478 *rste = table | _REGION2_ENTRY; 479 } 480 table = *rste & _REGION_ENTRY_ORIGIN; 481 rc = base_region3_walk(table, addr, next, alloc); 482 if (rc) 483 return rc; 484 if (!alloc) 485 base_crst_free(table); 486 } while (rste++, addr = next, addr < end); 487 return 0; 488 } 489 490 static int base_region1_walk(unsigned long origin, unsigned long addr, 491 unsigned long end, int alloc) 492 { 493 unsigned long *rfte, next, table; 494 int rc; 495 496 rfte = (unsigned long *) origin; 497 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 498 do { 499 next = base_region1_addr_end(addr, end); 500 if (*rfte & _REGION_ENTRY_INVALID) { 501 if (!alloc) 502 continue; 503 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 504 if (!table) 505 return -ENOMEM; 506 *rfte = table | _REGION1_ENTRY; 507 } 508 table = *rfte & _REGION_ENTRY_ORIGIN; 509 rc = base_region2_walk(table, addr, next, alloc); 510 if (rc) 511 return rc; 512 if (!alloc) 513 base_crst_free(table); 514 } while (rfte++, addr = next, addr < end); 515 return 0; 516 } 517 518 /** 519 * base_asce_free - free asce and tables returned from base_asce_alloc() 520 * @asce: asce to be freed 521 * 522 * Frees all region, segment, and page tables that were allocated with a 523 * corresponding base_asce_alloc() call. 524 */ 525 void base_asce_free(unsigned long asce) 526 { 527 unsigned long table = asce & _ASCE_ORIGIN; 528 529 if (!asce) 530 return; 531 switch (asce & _ASCE_TYPE_MASK) { 532 case _ASCE_TYPE_SEGMENT: 533 base_segment_walk(table, 0, _REGION3_SIZE, 0); 534 break; 535 case _ASCE_TYPE_REGION3: 536 base_region3_walk(table, 0, _REGION2_SIZE, 0); 537 break; 538 case _ASCE_TYPE_REGION2: 539 base_region2_walk(table, 0, _REGION1_SIZE, 0); 540 break; 541 case _ASCE_TYPE_REGION1: 542 base_region1_walk(table, 0, TASK_SIZE_MAX, 0); 543 break; 544 } 545 base_crst_free(table); 546 } 547 548 static int base_pgt_cache_init(void) 549 { 550 static DEFINE_MUTEX(base_pgt_cache_mutex); 551 unsigned long sz = _PAGE_TABLE_SIZE; 552 553 if (base_pgt_cache) 554 return 0; 555 mutex_lock(&base_pgt_cache_mutex); 556 if (!base_pgt_cache) 557 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 558 mutex_unlock(&base_pgt_cache_mutex); 559 return base_pgt_cache ? 0 : -ENOMEM; 560 } 561 562 /** 563 * base_asce_alloc - create kernel mapping without enhanced DAT features 564 * @addr: virtual start address of kernel mapping 565 * @num_pages: number of consecutive pages 566 * 567 * Generate an asce, including all required region, segment and page tables, 568 * that can be used to access the virtual kernel mapping. The difference is 569 * that the returned asce does not make use of any enhanced DAT features like 570 * e.g. large pages. This is required for some I/O functions that pass an 571 * asce, like e.g. some service call requests. 572 * 573 * Note: the returned asce may NEVER be attached to any cpu. It may only be 574 * used for I/O requests. tlb entries that might result because the 575 * asce was attached to a cpu won't be cleared. 576 */ 577 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 578 { 579 unsigned long asce, table, end; 580 int rc; 581 582 if (base_pgt_cache_init()) 583 return 0; 584 end = addr + num_pages * PAGE_SIZE; 585 if (end <= _REGION3_SIZE) { 586 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 587 if (!table) 588 return 0; 589 rc = base_segment_walk(table, addr, end, 1); 590 asce = table | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 591 } else if (end <= _REGION2_SIZE) { 592 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 593 if (!table) 594 return 0; 595 rc = base_region3_walk(table, addr, end, 1); 596 asce = table | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 597 } else if (end <= _REGION1_SIZE) { 598 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 599 if (!table) 600 return 0; 601 rc = base_region2_walk(table, addr, end, 1); 602 asce = table | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 603 } else { 604 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 605 if (!table) 606 return 0; 607 rc = base_region1_walk(table, addr, end, 1); 608 asce = table | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 609 } 610 if (rc) { 611 base_asce_free(asce); 612 asce = 0; 613 } 614 return asce; 615 } 616