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 static int __init page_table_register_sysctl(void) 36 { 37 return register_sysctl("vm", page_table_sysctl) ? 0 : -ENOMEM; 38 } 39 __initcall(page_table_register_sysctl); 40 41 #endif /* CONFIG_PGSTE */ 42 43 unsigned long *crst_table_alloc(struct mm_struct *mm) 44 { 45 struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER); 46 47 if (!ptdesc) 48 return NULL; 49 arch_set_page_dat(ptdesc_page(ptdesc), CRST_ALLOC_ORDER); 50 return (unsigned long *) ptdesc_to_virt(ptdesc); 51 } 52 53 void crst_table_free(struct mm_struct *mm, unsigned long *table) 54 { 55 pagetable_free(virt_to_ptdesc(table)); 56 } 57 58 static void __crst_table_upgrade(void *arg) 59 { 60 struct mm_struct *mm = arg; 61 62 /* change all active ASCEs to avoid the creation of new TLBs */ 63 if (current->active_mm == mm) { 64 S390_lowcore.user_asce = mm->context.asce; 65 __ctl_load(S390_lowcore.user_asce, 7, 7); 66 } 67 __tlb_flush_local(); 68 } 69 70 int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 71 { 72 unsigned long *pgd = NULL, *p4d = NULL, *__pgd; 73 unsigned long asce_limit = mm->context.asce_limit; 74 75 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ 76 VM_BUG_ON(asce_limit < _REGION2_SIZE); 77 78 if (end <= asce_limit) 79 return 0; 80 81 if (asce_limit == _REGION2_SIZE) { 82 p4d = crst_table_alloc(mm); 83 if (unlikely(!p4d)) 84 goto err_p4d; 85 crst_table_init(p4d, _REGION2_ENTRY_EMPTY); 86 } 87 if (end > _REGION1_SIZE) { 88 pgd = crst_table_alloc(mm); 89 if (unlikely(!pgd)) 90 goto err_pgd; 91 crst_table_init(pgd, _REGION1_ENTRY_EMPTY); 92 } 93 94 spin_lock_bh(&mm->page_table_lock); 95 96 /* 97 * This routine gets called with mmap_lock lock held and there is 98 * no reason to optimize for the case of otherwise. However, if 99 * that would ever change, the below check will let us know. 100 */ 101 VM_BUG_ON(asce_limit != mm->context.asce_limit); 102 103 if (p4d) { 104 __pgd = (unsigned long *) mm->pgd; 105 p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd); 106 mm->pgd = (pgd_t *) p4d; 107 mm->context.asce_limit = _REGION1_SIZE; 108 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 109 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 110 mm_inc_nr_puds(mm); 111 } 112 if (pgd) { 113 __pgd = (unsigned long *) mm->pgd; 114 pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd); 115 mm->pgd = (pgd_t *) pgd; 116 mm->context.asce_limit = TASK_SIZE_MAX; 117 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 118 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 119 } 120 121 spin_unlock_bh(&mm->page_table_lock); 122 123 on_each_cpu(__crst_table_upgrade, mm, 0); 124 125 return 0; 126 127 err_pgd: 128 crst_table_free(mm, p4d); 129 err_p4d: 130 return -ENOMEM; 131 } 132 133 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits) 134 { 135 return atomic_fetch_xor(bits, v) ^ bits; 136 } 137 138 #ifdef CONFIG_PGSTE 139 140 struct page *page_table_alloc_pgste(struct mm_struct *mm) 141 { 142 struct ptdesc *ptdesc; 143 u64 *table; 144 145 ptdesc = pagetable_alloc(GFP_KERNEL, 0); 146 if (ptdesc) { 147 table = (u64 *)ptdesc_to_virt(ptdesc); 148 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 149 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 150 } 151 return ptdesc_page(ptdesc); 152 } 153 154 void page_table_free_pgste(struct page *page) 155 { 156 pagetable_free(page_ptdesc(page)); 157 } 158 159 #endif /* CONFIG_PGSTE */ 160 161 /* 162 * A 2KB-pgtable is either upper or lower half of a normal page. 163 * The second half of the page may be unused or used as another 164 * 2KB-pgtable. 165 * 166 * Whenever possible the parent page for a new 2KB-pgtable is picked 167 * from the list of partially allocated pages mm_context_t::pgtable_list. 168 * In case the list is empty a new parent page is allocated and added to 169 * the list. 170 * 171 * When a parent page gets fully allocated it contains 2KB-pgtables in both 172 * upper and lower halves and is removed from mm_context_t::pgtable_list. 173 * 174 * When 2KB-pgtable is freed from to fully allocated parent page that 175 * page turns partially allocated and added to mm_context_t::pgtable_list. 176 * 177 * If 2KB-pgtable is freed from the partially allocated parent page that 178 * page turns unused and gets removed from mm_context_t::pgtable_list. 179 * Furthermore, the unused parent page is released. 180 * 181 * As follows from the above, no unallocated or fully allocated parent 182 * pages are contained in mm_context_t::pgtable_list. 183 * 184 * The upper byte (bits 24-31) of the parent page _refcount is used 185 * for tracking contained 2KB-pgtables and has the following format: 186 * 187 * PP AA 188 * 01234567 upper byte (bits 24-31) of struct page::_refcount 189 * || || 190 * || |+--- upper 2KB-pgtable is allocated 191 * || +---- lower 2KB-pgtable is allocated 192 * |+------- upper 2KB-pgtable is pending for removal 193 * +-------- lower 2KB-pgtable is pending for removal 194 * 195 * (See commit 620b4e903179 ("s390: use _refcount for pgtables") on why 196 * using _refcount is possible). 197 * 198 * When 2KB-pgtable is allocated the corresponding AA bit is set to 1. 199 * The parent page is either: 200 * - added to mm_context_t::pgtable_list in case the second half of the 201 * parent page is still unallocated; 202 * - removed from mm_context_t::pgtable_list in case both hales of the 203 * parent page are allocated; 204 * These operations are protected with mm_context_t::lock. 205 * 206 * When 2KB-pgtable is deallocated the corresponding AA bit is set to 0 207 * and the corresponding PP bit is set to 1 in a single atomic operation. 208 * Thus, PP and AA bits corresponding to the same 2KB-pgtable are mutually 209 * exclusive and may never be both set to 1! 210 * The parent page is either: 211 * - added to mm_context_t::pgtable_list in case the second half of the 212 * parent page is still allocated; 213 * - removed from mm_context_t::pgtable_list in case the second half of 214 * the parent page is unallocated; 215 * These operations are protected with mm_context_t::lock. 216 * 217 * It is important to understand that mm_context_t::lock only protects 218 * mm_context_t::pgtable_list and AA bits, but not the parent page itself 219 * and PP bits. 220 * 221 * Releasing the parent page happens whenever the PP bit turns from 1 to 0, 222 * while both AA bits and the second PP bit are already unset. Then the 223 * parent page does not contain any 2KB-pgtable fragment anymore, and it has 224 * also been removed from mm_context_t::pgtable_list. It is safe to release 225 * the page therefore. 226 * 227 * PGSTE memory spaces use full 4KB-pgtables and do not need most of the 228 * logic described above. Both AA bits are set to 1 to denote a 4KB-pgtable 229 * while the PP bits are never used, nor such a page is added to or removed 230 * from mm_context_t::pgtable_list. 231 * 232 * pte_free_defer() overrides those rules: it takes the page off pgtable_list, 233 * and prevents both 2K fragments from being reused. pte_free_defer() has to 234 * guarantee that its pgtable cannot be reused before the RCU grace period 235 * has elapsed (which page_table_free_rcu() does not actually guarantee). 236 * But for simplicity, because page->rcu_head overlays page->lru, and because 237 * the RCU callback might not be called before the mm_context_t has been freed, 238 * pte_free_defer() in this implementation prevents both fragments from being 239 * reused, and delays making the call to RCU until both fragments are freed. 240 */ 241 unsigned long *page_table_alloc(struct mm_struct *mm) 242 { 243 unsigned long *table; 244 struct ptdesc *ptdesc; 245 unsigned int mask, bit; 246 247 /* Try to get a fragment of a 4K page as a 2K page table */ 248 if (!mm_alloc_pgste(mm)) { 249 table = NULL; 250 spin_lock_bh(&mm->context.lock); 251 if (!list_empty(&mm->context.pgtable_list)) { 252 ptdesc = list_first_entry(&mm->context.pgtable_list, 253 struct ptdesc, pt_list); 254 mask = atomic_read(&ptdesc->_refcount) >> 24; 255 /* 256 * The pending removal bits must also be checked. 257 * Failure to do so might lead to an impossible 258 * value of (i.e 0x13 or 0x23) written to _refcount. 259 * Such values violate the assumption that pending and 260 * allocation bits are mutually exclusive, and the rest 261 * of the code unrails as result. That could lead to 262 * a whole bunch of races and corruptions. 263 */ 264 mask = (mask | (mask >> 4)) & 0x03U; 265 if (mask != 0x03U) { 266 table = (unsigned long *) ptdesc_to_virt(ptdesc); 267 bit = mask & 1; /* =1 -> second 2K */ 268 if (bit) 269 table += PTRS_PER_PTE; 270 atomic_xor_bits(&ptdesc->_refcount, 271 0x01U << (bit + 24)); 272 list_del_init(&ptdesc->pt_list); 273 } 274 } 275 spin_unlock_bh(&mm->context.lock); 276 if (table) 277 return table; 278 } 279 /* Allocate a fresh page */ 280 ptdesc = pagetable_alloc(GFP_KERNEL, 0); 281 if (!ptdesc) 282 return NULL; 283 if (!pagetable_pte_ctor(ptdesc)) { 284 pagetable_free(ptdesc); 285 return NULL; 286 } 287 arch_set_page_dat(ptdesc_page(ptdesc), 0); 288 /* Initialize page table */ 289 table = (unsigned long *) ptdesc_to_virt(ptdesc); 290 if (mm_alloc_pgste(mm)) { 291 /* Return 4K page table with PGSTEs */ 292 INIT_LIST_HEAD(&ptdesc->pt_list); 293 atomic_xor_bits(&ptdesc->_refcount, 0x03U << 24); 294 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 295 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 296 } else { 297 /* Return the first 2K fragment of the page */ 298 atomic_xor_bits(&ptdesc->_refcount, 0x01U << 24); 299 memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE); 300 spin_lock_bh(&mm->context.lock); 301 list_add(&ptdesc->pt_list, &mm->context.pgtable_list); 302 spin_unlock_bh(&mm->context.lock); 303 } 304 return table; 305 } 306 307 static void page_table_release_check(struct page *page, void *table, 308 unsigned int half, unsigned int mask) 309 { 310 char msg[128]; 311 312 if (!IS_ENABLED(CONFIG_DEBUG_VM)) 313 return; 314 if (!mask && list_empty(&page->lru)) 315 return; 316 snprintf(msg, sizeof(msg), 317 "Invalid pgtable %p release half 0x%02x mask 0x%02x", 318 table, half, mask); 319 dump_page(page, msg); 320 } 321 322 static void pte_free_now(struct rcu_head *head) 323 { 324 struct ptdesc *ptdesc; 325 326 ptdesc = container_of(head, struct ptdesc, pt_rcu_head); 327 pagetable_pte_dtor(ptdesc); 328 pagetable_free(ptdesc); 329 } 330 331 void page_table_free(struct mm_struct *mm, unsigned long *table) 332 { 333 unsigned int mask, bit, half; 334 struct ptdesc *ptdesc = virt_to_ptdesc(table); 335 336 if (!mm_alloc_pgste(mm)) { 337 /* Free 2K page table fragment of a 4K page */ 338 bit = ((unsigned long) table & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); 339 spin_lock_bh(&mm->context.lock); 340 /* 341 * Mark the page for delayed release. The actual release 342 * will happen outside of the critical section from this 343 * function or from __tlb_remove_table() 344 */ 345 mask = atomic_xor_bits(&ptdesc->_refcount, 0x11U << (bit + 24)); 346 mask >>= 24; 347 if ((mask & 0x03U) && !folio_test_active(ptdesc_folio(ptdesc))) { 348 /* 349 * Other half is allocated, and neither half has had 350 * its free deferred: add page to head of list, to make 351 * this freed half available for immediate reuse. 352 */ 353 list_add(&ptdesc->pt_list, &mm->context.pgtable_list); 354 } else { 355 /* If page is on list, now remove it. */ 356 list_del_init(&ptdesc->pt_list); 357 } 358 spin_unlock_bh(&mm->context.lock); 359 mask = atomic_xor_bits(&ptdesc->_refcount, 0x10U << (bit + 24)); 360 mask >>= 24; 361 if (mask != 0x00U) 362 return; 363 half = 0x01U << bit; 364 } else { 365 half = 0x03U; 366 mask = atomic_xor_bits(&ptdesc->_refcount, 0x03U << 24); 367 mask >>= 24; 368 } 369 370 page_table_release_check(ptdesc_page(ptdesc), table, half, mask); 371 if (folio_test_clear_active(ptdesc_folio(ptdesc))) 372 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 373 else 374 pte_free_now(&ptdesc->pt_rcu_head); 375 } 376 377 void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, 378 unsigned long vmaddr) 379 { 380 struct mm_struct *mm; 381 unsigned int bit, mask; 382 struct ptdesc *ptdesc = virt_to_ptdesc(table); 383 384 mm = tlb->mm; 385 if (mm_alloc_pgste(mm)) { 386 gmap_unlink(mm, table, vmaddr); 387 table = (unsigned long *) ((unsigned long)table | 0x03U); 388 tlb_remove_ptdesc(tlb, table); 389 return; 390 } 391 bit = ((unsigned long) table & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); 392 spin_lock_bh(&mm->context.lock); 393 /* 394 * Mark the page for delayed release. The actual release will happen 395 * outside of the critical section from __tlb_remove_table() or from 396 * page_table_free() 397 */ 398 mask = atomic_xor_bits(&ptdesc->_refcount, 0x11U << (bit + 24)); 399 mask >>= 24; 400 if ((mask & 0x03U) && !folio_test_active(ptdesc_folio(ptdesc))) { 401 /* 402 * Other half is allocated, and neither half has had 403 * its free deferred: add page to end of list, to make 404 * this freed half available for reuse once its pending 405 * bit has been cleared by __tlb_remove_table(). 406 */ 407 list_add_tail(&ptdesc->pt_list, &mm->context.pgtable_list); 408 } else { 409 /* If page is on list, now remove it. */ 410 list_del_init(&ptdesc->pt_list); 411 } 412 spin_unlock_bh(&mm->context.lock); 413 table = (unsigned long *) ((unsigned long) table | (0x01U << bit)); 414 tlb_remove_table(tlb, table); 415 } 416 417 void __tlb_remove_table(void *_table) 418 { 419 unsigned int mask = (unsigned long) _table & 0x03U, half = mask; 420 void *table = (void *)((unsigned long) _table ^ mask); 421 struct ptdesc *ptdesc = virt_to_ptdesc(table); 422 423 switch (half) { 424 case 0x00U: /* pmd, pud, or p4d */ 425 pagetable_free(ptdesc); 426 return; 427 case 0x01U: /* lower 2K of a 4K page table */ 428 case 0x02U: /* higher 2K of a 4K page table */ 429 mask = atomic_xor_bits(&ptdesc->_refcount, mask << (4 + 24)); 430 mask >>= 24; 431 if (mask != 0x00U) 432 return; 433 break; 434 case 0x03U: /* 4K page table with pgstes */ 435 mask = atomic_xor_bits(&ptdesc->_refcount, 0x03U << 24); 436 mask >>= 24; 437 break; 438 } 439 440 page_table_release_check(ptdesc_page(ptdesc), table, half, mask); 441 if (folio_test_clear_active(ptdesc_folio(ptdesc))) 442 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 443 else 444 pte_free_now(&ptdesc->pt_rcu_head); 445 } 446 447 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 448 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) 449 { 450 struct page *page; 451 452 page = virt_to_page(pgtable); 453 SetPageActive(page); 454 page_table_free(mm, (unsigned long *)pgtable); 455 /* 456 * page_table_free() does not do the pgste gmap_unlink() which 457 * page_table_free_rcu() does: warn us if pgste ever reaches here. 458 */ 459 WARN_ON_ONCE(mm_has_pgste(mm)); 460 } 461 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 462 463 /* 464 * Base infrastructure required to generate basic asces, region, segment, 465 * and page tables that do not make use of enhanced features like EDAT1. 466 */ 467 468 static struct kmem_cache *base_pgt_cache; 469 470 static unsigned long *base_pgt_alloc(void) 471 { 472 unsigned long *table; 473 474 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 475 if (table) 476 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 477 return table; 478 } 479 480 static void base_pgt_free(unsigned long *table) 481 { 482 kmem_cache_free(base_pgt_cache, table); 483 } 484 485 static unsigned long *base_crst_alloc(unsigned long val) 486 { 487 unsigned long *table; 488 struct ptdesc *ptdesc; 489 490 ptdesc = pagetable_alloc(GFP_KERNEL & ~__GFP_HIGHMEM, CRST_ALLOC_ORDER); 491 if (!ptdesc) 492 return NULL; 493 table = ptdesc_address(ptdesc); 494 495 crst_table_init(table, val); 496 return table; 497 } 498 499 static void base_crst_free(unsigned long *table) 500 { 501 pagetable_free(virt_to_ptdesc(table)); 502 } 503 504 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 505 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 506 unsigned long end) \ 507 { \ 508 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 509 \ 510 return (next - 1) < (end - 1) ? next : end; \ 511 } 512 513 BASE_ADDR_END_FUNC(page, _PAGE_SIZE) 514 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 515 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 516 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 517 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 518 519 static inline unsigned long base_lra(unsigned long address) 520 { 521 unsigned long real; 522 523 asm volatile( 524 " lra %0,0(%1)\n" 525 : "=d" (real) : "a" (address) : "cc"); 526 return real; 527 } 528 529 static int base_page_walk(unsigned long *origin, unsigned long addr, 530 unsigned long end, int alloc) 531 { 532 unsigned long *pte, next; 533 534 if (!alloc) 535 return 0; 536 pte = origin; 537 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT; 538 do { 539 next = base_page_addr_end(addr, end); 540 *pte = base_lra(addr); 541 } while (pte++, addr = next, addr < end); 542 return 0; 543 } 544 545 static int base_segment_walk(unsigned long *origin, unsigned long addr, 546 unsigned long end, int alloc) 547 { 548 unsigned long *ste, next, *table; 549 int rc; 550 551 ste = origin; 552 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 553 do { 554 next = base_segment_addr_end(addr, end); 555 if (*ste & _SEGMENT_ENTRY_INVALID) { 556 if (!alloc) 557 continue; 558 table = base_pgt_alloc(); 559 if (!table) 560 return -ENOMEM; 561 *ste = __pa(table) | _SEGMENT_ENTRY; 562 } 563 table = __va(*ste & _SEGMENT_ENTRY_ORIGIN); 564 rc = base_page_walk(table, addr, next, alloc); 565 if (rc) 566 return rc; 567 if (!alloc) 568 base_pgt_free(table); 569 cond_resched(); 570 } while (ste++, addr = next, addr < end); 571 return 0; 572 } 573 574 static int base_region3_walk(unsigned long *origin, unsigned long addr, 575 unsigned long end, int alloc) 576 { 577 unsigned long *rtte, next, *table; 578 int rc; 579 580 rtte = origin; 581 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 582 do { 583 next = base_region3_addr_end(addr, end); 584 if (*rtte & _REGION_ENTRY_INVALID) { 585 if (!alloc) 586 continue; 587 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 588 if (!table) 589 return -ENOMEM; 590 *rtte = __pa(table) | _REGION3_ENTRY; 591 } 592 table = __va(*rtte & _REGION_ENTRY_ORIGIN); 593 rc = base_segment_walk(table, addr, next, alloc); 594 if (rc) 595 return rc; 596 if (!alloc) 597 base_crst_free(table); 598 } while (rtte++, addr = next, addr < end); 599 return 0; 600 } 601 602 static int base_region2_walk(unsigned long *origin, unsigned long addr, 603 unsigned long end, int alloc) 604 { 605 unsigned long *rste, next, *table; 606 int rc; 607 608 rste = origin; 609 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 610 do { 611 next = base_region2_addr_end(addr, end); 612 if (*rste & _REGION_ENTRY_INVALID) { 613 if (!alloc) 614 continue; 615 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 616 if (!table) 617 return -ENOMEM; 618 *rste = __pa(table) | _REGION2_ENTRY; 619 } 620 table = __va(*rste & _REGION_ENTRY_ORIGIN); 621 rc = base_region3_walk(table, addr, next, alloc); 622 if (rc) 623 return rc; 624 if (!alloc) 625 base_crst_free(table); 626 } while (rste++, addr = next, addr < end); 627 return 0; 628 } 629 630 static int base_region1_walk(unsigned long *origin, unsigned long addr, 631 unsigned long end, int alloc) 632 { 633 unsigned long *rfte, next, *table; 634 int rc; 635 636 rfte = origin; 637 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 638 do { 639 next = base_region1_addr_end(addr, end); 640 if (*rfte & _REGION_ENTRY_INVALID) { 641 if (!alloc) 642 continue; 643 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 644 if (!table) 645 return -ENOMEM; 646 *rfte = __pa(table) | _REGION1_ENTRY; 647 } 648 table = __va(*rfte & _REGION_ENTRY_ORIGIN); 649 rc = base_region2_walk(table, addr, next, alloc); 650 if (rc) 651 return rc; 652 if (!alloc) 653 base_crst_free(table); 654 } while (rfte++, addr = next, addr < end); 655 return 0; 656 } 657 658 /** 659 * base_asce_free - free asce and tables returned from base_asce_alloc() 660 * @asce: asce to be freed 661 * 662 * Frees all region, segment, and page tables that were allocated with a 663 * corresponding base_asce_alloc() call. 664 */ 665 void base_asce_free(unsigned long asce) 666 { 667 unsigned long *table = __va(asce & _ASCE_ORIGIN); 668 669 if (!asce) 670 return; 671 switch (asce & _ASCE_TYPE_MASK) { 672 case _ASCE_TYPE_SEGMENT: 673 base_segment_walk(table, 0, _REGION3_SIZE, 0); 674 break; 675 case _ASCE_TYPE_REGION3: 676 base_region3_walk(table, 0, _REGION2_SIZE, 0); 677 break; 678 case _ASCE_TYPE_REGION2: 679 base_region2_walk(table, 0, _REGION1_SIZE, 0); 680 break; 681 case _ASCE_TYPE_REGION1: 682 base_region1_walk(table, 0, TASK_SIZE_MAX, 0); 683 break; 684 } 685 base_crst_free(table); 686 } 687 688 static int base_pgt_cache_init(void) 689 { 690 static DEFINE_MUTEX(base_pgt_cache_mutex); 691 unsigned long sz = _PAGE_TABLE_SIZE; 692 693 if (base_pgt_cache) 694 return 0; 695 mutex_lock(&base_pgt_cache_mutex); 696 if (!base_pgt_cache) 697 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 698 mutex_unlock(&base_pgt_cache_mutex); 699 return base_pgt_cache ? 0 : -ENOMEM; 700 } 701 702 /** 703 * base_asce_alloc - create kernel mapping without enhanced DAT features 704 * @addr: virtual start address of kernel mapping 705 * @num_pages: number of consecutive pages 706 * 707 * Generate an asce, including all required region, segment and page tables, 708 * that can be used to access the virtual kernel mapping. The difference is 709 * that the returned asce does not make use of any enhanced DAT features like 710 * e.g. large pages. This is required for some I/O functions that pass an 711 * asce, like e.g. some service call requests. 712 * 713 * Note: the returned asce may NEVER be attached to any cpu. It may only be 714 * used for I/O requests. tlb entries that might result because the 715 * asce was attached to a cpu won't be cleared. 716 */ 717 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 718 { 719 unsigned long asce, *table, end; 720 int rc; 721 722 if (base_pgt_cache_init()) 723 return 0; 724 end = addr + num_pages * PAGE_SIZE; 725 if (end <= _REGION3_SIZE) { 726 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 727 if (!table) 728 return 0; 729 rc = base_segment_walk(table, addr, end, 1); 730 asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 731 } else if (end <= _REGION2_SIZE) { 732 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 733 if (!table) 734 return 0; 735 rc = base_region3_walk(table, addr, end, 1); 736 asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 737 } else if (end <= _REGION1_SIZE) { 738 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 739 if (!table) 740 return 0; 741 rc = base_region2_walk(table, addr, end, 1); 742 asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 743 } else { 744 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 745 if (!table) 746 return 0; 747 rc = base_region1_walk(table, addr, end, 1); 748 asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 749 } 750 if (rc) { 751 base_asce_free(asce); 752 asce = 0; 753 } 754 return asce; 755 } 756