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 int __init page_table_register_sysctl(void) 37 { 38 return register_sysctl("vm", page_table_sysctl) ? 0 : -ENOMEM; 39 } 40 __initcall(page_table_register_sysctl); 41 42 #endif /* CONFIG_PGSTE */ 43 44 unsigned long *crst_table_alloc(struct mm_struct *mm) 45 { 46 struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER); 47 48 if (!ptdesc) 49 return NULL; 50 arch_set_page_dat(ptdesc_page(ptdesc), CRST_ALLOC_ORDER); 51 return (unsigned long *) ptdesc_to_virt(ptdesc); 52 } 53 54 void crst_table_free(struct mm_struct *mm, unsigned long *table) 55 { 56 pagetable_free(virt_to_ptdesc(table)); 57 } 58 59 static void __crst_table_upgrade(void *arg) 60 { 61 struct mm_struct *mm = arg; 62 63 /* change all active ASCEs to avoid the creation of new TLBs */ 64 if (current->active_mm == mm) { 65 S390_lowcore.user_asce = mm->context.asce; 66 __ctl_load(S390_lowcore.user_asce, 7, 7); 67 } 68 __tlb_flush_local(); 69 } 70 71 int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 72 { 73 unsigned long *pgd = NULL, *p4d = NULL, *__pgd; 74 unsigned long asce_limit = mm->context.asce_limit; 75 76 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ 77 VM_BUG_ON(asce_limit < _REGION2_SIZE); 78 79 if (end <= asce_limit) 80 return 0; 81 82 if (asce_limit == _REGION2_SIZE) { 83 p4d = crst_table_alloc(mm); 84 if (unlikely(!p4d)) 85 goto err_p4d; 86 crst_table_init(p4d, _REGION2_ENTRY_EMPTY); 87 } 88 if (end > _REGION1_SIZE) { 89 pgd = crst_table_alloc(mm); 90 if (unlikely(!pgd)) 91 goto err_pgd; 92 crst_table_init(pgd, _REGION1_ENTRY_EMPTY); 93 } 94 95 spin_lock_bh(&mm->page_table_lock); 96 97 /* 98 * This routine gets called with mmap_lock lock held and there is 99 * no reason to optimize for the case of otherwise. However, if 100 * that would ever change, the below check will let us know. 101 */ 102 VM_BUG_ON(asce_limit != mm->context.asce_limit); 103 104 if (p4d) { 105 __pgd = (unsigned long *) mm->pgd; 106 p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd); 107 mm->pgd = (pgd_t *) p4d; 108 mm->context.asce_limit = _REGION1_SIZE; 109 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 110 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 111 mm_inc_nr_puds(mm); 112 } 113 if (pgd) { 114 __pgd = (unsigned long *) mm->pgd; 115 pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd); 116 mm->pgd = (pgd_t *) pgd; 117 mm->context.asce_limit = TASK_SIZE_MAX; 118 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 119 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 120 } 121 122 spin_unlock_bh(&mm->page_table_lock); 123 124 on_each_cpu(__crst_table_upgrade, mm, 0); 125 126 return 0; 127 128 err_pgd: 129 crst_table_free(mm, p4d); 130 err_p4d: 131 return -ENOMEM; 132 } 133 134 static inline unsigned int atomic_xor_bits(atomic_t *v, unsigned int bits) 135 { 136 return atomic_fetch_xor(bits, v) ^ bits; 137 } 138 139 #ifdef CONFIG_PGSTE 140 141 struct page *page_table_alloc_pgste(struct mm_struct *mm) 142 { 143 struct ptdesc *ptdesc; 144 u64 *table; 145 146 ptdesc = pagetable_alloc(GFP_KERNEL, 0); 147 if (ptdesc) { 148 table = (u64 *)ptdesc_to_virt(ptdesc); 149 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 150 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 151 } 152 return ptdesc_page(ptdesc); 153 } 154 155 void page_table_free_pgste(struct page *page) 156 { 157 pagetable_free(page_ptdesc(page)); 158 } 159 160 #endif /* CONFIG_PGSTE */ 161 162 /* 163 * A 2KB-pgtable is either upper or lower half of a normal page. 164 * The second half of the page may be unused or used as another 165 * 2KB-pgtable. 166 * 167 * Whenever possible the parent page for a new 2KB-pgtable is picked 168 * from the list of partially allocated pages mm_context_t::pgtable_list. 169 * In case the list is empty a new parent page is allocated and added to 170 * the list. 171 * 172 * When a parent page gets fully allocated it contains 2KB-pgtables in both 173 * upper and lower halves and is removed from mm_context_t::pgtable_list. 174 * 175 * When 2KB-pgtable is freed from to fully allocated parent page that 176 * page turns partially allocated and added to mm_context_t::pgtable_list. 177 * 178 * If 2KB-pgtable is freed from the partially allocated parent page that 179 * page turns unused and gets removed from mm_context_t::pgtable_list. 180 * Furthermore, the unused parent page is released. 181 * 182 * As follows from the above, no unallocated or fully allocated parent 183 * pages are contained in mm_context_t::pgtable_list. 184 * 185 * The upper byte (bits 24-31) of the parent page _refcount is used 186 * for tracking contained 2KB-pgtables and has the following format: 187 * 188 * PP AA 189 * 01234567 upper byte (bits 24-31) of struct page::_refcount 190 * || || 191 * || |+--- upper 2KB-pgtable is allocated 192 * || +---- lower 2KB-pgtable is allocated 193 * |+------- upper 2KB-pgtable is pending for removal 194 * +-------- lower 2KB-pgtable is pending for removal 195 * 196 * (See commit 620b4e903179 ("s390: use _refcount for pgtables") on why 197 * using _refcount is possible). 198 * 199 * When 2KB-pgtable is allocated the corresponding AA bit is set to 1. 200 * The parent page is either: 201 * - added to mm_context_t::pgtable_list in case the second half of the 202 * parent page is still unallocated; 203 * - removed from mm_context_t::pgtable_list in case both hales of the 204 * parent page are allocated; 205 * These operations are protected with mm_context_t::lock. 206 * 207 * When 2KB-pgtable is deallocated the corresponding AA bit is set to 0 208 * and the corresponding PP bit is set to 1 in a single atomic operation. 209 * Thus, PP and AA bits corresponding to the same 2KB-pgtable are mutually 210 * exclusive and may never be both set to 1! 211 * The parent page is either: 212 * - added to mm_context_t::pgtable_list in case the second half of the 213 * parent page is still allocated; 214 * - removed from mm_context_t::pgtable_list in case the second half of 215 * the parent page is unallocated; 216 * These operations are protected with mm_context_t::lock. 217 * 218 * It is important to understand that mm_context_t::lock only protects 219 * mm_context_t::pgtable_list and AA bits, but not the parent page itself 220 * and PP bits. 221 * 222 * Releasing the parent page happens whenever the PP bit turns from 1 to 0, 223 * while both AA bits and the second PP bit are already unset. Then the 224 * parent page does not contain any 2KB-pgtable fragment anymore, and it has 225 * also been removed from mm_context_t::pgtable_list. It is safe to release 226 * the page therefore. 227 * 228 * PGSTE memory spaces use full 4KB-pgtables and do not need most of the 229 * logic described above. Both AA bits are set to 1 to denote a 4KB-pgtable 230 * while the PP bits are never used, nor such a page is added to or removed 231 * from mm_context_t::pgtable_list. 232 * 233 * pte_free_defer() overrides those rules: it takes the page off pgtable_list, 234 * and prevents both 2K fragments from being reused. pte_free_defer() has to 235 * guarantee that its pgtable cannot be reused before the RCU grace period 236 * has elapsed (which page_table_free_rcu() does not actually guarantee). 237 * But for simplicity, because page->rcu_head overlays page->lru, and because 238 * the RCU callback might not be called before the mm_context_t has been freed, 239 * pte_free_defer() in this implementation prevents both fragments from being 240 * reused, and delays making the call to RCU until both fragments are freed. 241 */ 242 unsigned long *page_table_alloc(struct mm_struct *mm) 243 { 244 unsigned long *table; 245 struct ptdesc *ptdesc; 246 unsigned int mask, bit; 247 248 /* Try to get a fragment of a 4K page as a 2K page table */ 249 if (!mm_alloc_pgste(mm)) { 250 table = NULL; 251 spin_lock_bh(&mm->context.lock); 252 if (!list_empty(&mm->context.pgtable_list)) { 253 ptdesc = list_first_entry(&mm->context.pgtable_list, 254 struct ptdesc, pt_list); 255 mask = atomic_read(&ptdesc->_refcount) >> 24; 256 /* 257 * The pending removal bits must also be checked. 258 * Failure to do so might lead to an impossible 259 * value of (i.e 0x13 or 0x23) written to _refcount. 260 * Such values violate the assumption that pending and 261 * allocation bits are mutually exclusive, and the rest 262 * of the code unrails as result. That could lead to 263 * a whole bunch of races and corruptions. 264 */ 265 mask = (mask | (mask >> 4)) & 0x03U; 266 if (mask != 0x03U) { 267 table = (unsigned long *) ptdesc_to_virt(ptdesc); 268 bit = mask & 1; /* =1 -> second 2K */ 269 if (bit) 270 table += PTRS_PER_PTE; 271 atomic_xor_bits(&ptdesc->_refcount, 272 0x01U << (bit + 24)); 273 list_del_init(&ptdesc->pt_list); 274 } 275 } 276 spin_unlock_bh(&mm->context.lock); 277 if (table) 278 return table; 279 } 280 /* Allocate a fresh page */ 281 ptdesc = pagetable_alloc(GFP_KERNEL, 0); 282 if (!ptdesc) 283 return NULL; 284 if (!pagetable_pte_ctor(ptdesc)) { 285 pagetable_free(ptdesc); 286 return NULL; 287 } 288 arch_set_page_dat(ptdesc_page(ptdesc), 0); 289 /* Initialize page table */ 290 table = (unsigned long *) ptdesc_to_virt(ptdesc); 291 if (mm_alloc_pgste(mm)) { 292 /* Return 4K page table with PGSTEs */ 293 INIT_LIST_HEAD(&ptdesc->pt_list); 294 atomic_xor_bits(&ptdesc->_refcount, 0x03U << 24); 295 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 296 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 297 } else { 298 /* Return the first 2K fragment of the page */ 299 atomic_xor_bits(&ptdesc->_refcount, 0x01U << 24); 300 memset64((u64 *)table, _PAGE_INVALID, 2 * PTRS_PER_PTE); 301 spin_lock_bh(&mm->context.lock); 302 list_add(&ptdesc->pt_list, &mm->context.pgtable_list); 303 spin_unlock_bh(&mm->context.lock); 304 } 305 return table; 306 } 307 308 static void page_table_release_check(struct page *page, void *table, 309 unsigned int half, unsigned int mask) 310 { 311 char msg[128]; 312 313 if (!IS_ENABLED(CONFIG_DEBUG_VM)) 314 return; 315 if (!mask && list_empty(&page->lru)) 316 return; 317 snprintf(msg, sizeof(msg), 318 "Invalid pgtable %p release half 0x%02x mask 0x%02x", 319 table, half, mask); 320 dump_page(page, msg); 321 } 322 323 static void pte_free_now(struct rcu_head *head) 324 { 325 struct ptdesc *ptdesc; 326 327 ptdesc = container_of(head, struct ptdesc, pt_rcu_head); 328 pagetable_pte_dtor(ptdesc); 329 pagetable_free(ptdesc); 330 } 331 332 void page_table_free(struct mm_struct *mm, unsigned long *table) 333 { 334 unsigned int mask, bit, half; 335 struct ptdesc *ptdesc = virt_to_ptdesc(table); 336 337 if (!mm_alloc_pgste(mm)) { 338 /* Free 2K page table fragment of a 4K page */ 339 bit = ((unsigned long) table & ~PAGE_MASK)/(PTRS_PER_PTE*sizeof(pte_t)); 340 spin_lock_bh(&mm->context.lock); 341 /* 342 * Mark the page for delayed release. The actual release 343 * will happen outside of the critical section from this 344 * function or from __tlb_remove_table() 345 */ 346 mask = atomic_xor_bits(&ptdesc->_refcount, 0x11U << (bit + 24)); 347 mask >>= 24; 348 if ((mask & 0x03U) && !folio_test_active(ptdesc_folio(ptdesc))) { 349 /* 350 * Other half is allocated, and neither half has had 351 * its free deferred: add page to head of list, to make 352 * this freed half available for immediate reuse. 353 */ 354 list_add(&ptdesc->pt_list, &mm->context.pgtable_list); 355 } else { 356 /* If page is on list, now remove it. */ 357 list_del_init(&ptdesc->pt_list); 358 } 359 spin_unlock_bh(&mm->context.lock); 360 mask = atomic_xor_bits(&ptdesc->_refcount, 0x10U << (bit + 24)); 361 mask >>= 24; 362 if (mask != 0x00U) 363 return; 364 half = 0x01U << bit; 365 } else { 366 half = 0x03U; 367 mask = atomic_xor_bits(&ptdesc->_refcount, 0x03U << 24); 368 mask >>= 24; 369 } 370 371 page_table_release_check(ptdesc_page(ptdesc), table, half, mask); 372 if (folio_test_clear_active(ptdesc_folio(ptdesc))) 373 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 374 else 375 pte_free_now(&ptdesc->pt_rcu_head); 376 } 377 378 void page_table_free_rcu(struct mmu_gather *tlb, unsigned long *table, 379 unsigned long vmaddr) 380 { 381 struct mm_struct *mm; 382 unsigned int bit, mask; 383 struct ptdesc *ptdesc = virt_to_ptdesc(table); 384 385 mm = tlb->mm; 386 if (mm_alloc_pgste(mm)) { 387 gmap_unlink(mm, table, vmaddr); 388 table = (unsigned long *) ((unsigned long)table | 0x03U); 389 tlb_remove_ptdesc(tlb, table); 390 return; 391 } 392 bit = ((unsigned long) table & ~PAGE_MASK) / (PTRS_PER_PTE*sizeof(pte_t)); 393 spin_lock_bh(&mm->context.lock); 394 /* 395 * Mark the page for delayed release. The actual release will happen 396 * outside of the critical section from __tlb_remove_table() or from 397 * page_table_free() 398 */ 399 mask = atomic_xor_bits(&ptdesc->_refcount, 0x11U << (bit + 24)); 400 mask >>= 24; 401 if ((mask & 0x03U) && !folio_test_active(ptdesc_folio(ptdesc))) { 402 /* 403 * Other half is allocated, and neither half has had 404 * its free deferred: add page to end of list, to make 405 * this freed half available for reuse once its pending 406 * bit has been cleared by __tlb_remove_table(). 407 */ 408 list_add_tail(&ptdesc->pt_list, &mm->context.pgtable_list); 409 } else { 410 /* If page is on list, now remove it. */ 411 list_del_init(&ptdesc->pt_list); 412 } 413 spin_unlock_bh(&mm->context.lock); 414 table = (unsigned long *) ((unsigned long) table | (0x01U << bit)); 415 tlb_remove_table(tlb, table); 416 } 417 418 void __tlb_remove_table(void *_table) 419 { 420 unsigned int mask = (unsigned long) _table & 0x03U, half = mask; 421 void *table = (void *)((unsigned long) _table ^ mask); 422 struct ptdesc *ptdesc = virt_to_ptdesc(table); 423 424 switch (half) { 425 case 0x00U: /* pmd, pud, or p4d */ 426 pagetable_free(ptdesc); 427 return; 428 case 0x01U: /* lower 2K of a 4K page table */ 429 case 0x02U: /* higher 2K of a 4K page table */ 430 mask = atomic_xor_bits(&ptdesc->_refcount, mask << (4 + 24)); 431 mask >>= 24; 432 if (mask != 0x00U) 433 return; 434 break; 435 case 0x03U: /* 4K page table with pgstes */ 436 mask = atomic_xor_bits(&ptdesc->_refcount, 0x03U << 24); 437 mask >>= 24; 438 break; 439 } 440 441 page_table_release_check(ptdesc_page(ptdesc), table, half, mask); 442 if (folio_test_clear_active(ptdesc_folio(ptdesc))) 443 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 444 else 445 pte_free_now(&ptdesc->pt_rcu_head); 446 } 447 448 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 449 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) 450 { 451 struct page *page; 452 453 page = virt_to_page(pgtable); 454 SetPageActive(page); 455 page_table_free(mm, (unsigned long *)pgtable); 456 /* 457 * page_table_free() does not do the pgste gmap_unlink() which 458 * page_table_free_rcu() does: warn us if pgste ever reaches here. 459 */ 460 WARN_ON_ONCE(mm_has_pgste(mm)); 461 } 462 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 463 464 /* 465 * Base infrastructure required to generate basic asces, region, segment, 466 * and page tables that do not make use of enhanced features like EDAT1. 467 */ 468 469 static struct kmem_cache *base_pgt_cache; 470 471 static unsigned long *base_pgt_alloc(void) 472 { 473 unsigned long *table; 474 475 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 476 if (table) 477 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 478 return table; 479 } 480 481 static void base_pgt_free(unsigned long *table) 482 { 483 kmem_cache_free(base_pgt_cache, table); 484 } 485 486 static unsigned long *base_crst_alloc(unsigned long val) 487 { 488 unsigned long *table; 489 struct ptdesc *ptdesc; 490 491 ptdesc = pagetable_alloc(GFP_KERNEL & ~__GFP_HIGHMEM, CRST_ALLOC_ORDER); 492 if (!ptdesc) 493 return NULL; 494 table = ptdesc_address(ptdesc); 495 496 crst_table_init(table, val); 497 return table; 498 } 499 500 static void base_crst_free(unsigned long *table) 501 { 502 pagetable_free(virt_to_ptdesc(table)); 503 } 504 505 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 506 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 507 unsigned long end) \ 508 { \ 509 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 510 \ 511 return (next - 1) < (end - 1) ? next : end; \ 512 } 513 514 BASE_ADDR_END_FUNC(page, _PAGE_SIZE) 515 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 516 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 517 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 518 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 519 520 static inline unsigned long base_lra(unsigned long address) 521 { 522 unsigned long real; 523 524 asm volatile( 525 " lra %0,0(%1)\n" 526 : "=d" (real) : "a" (address) : "cc"); 527 return real; 528 } 529 530 static int base_page_walk(unsigned long *origin, unsigned long addr, 531 unsigned long end, int alloc) 532 { 533 unsigned long *pte, next; 534 535 if (!alloc) 536 return 0; 537 pte = origin; 538 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT; 539 do { 540 next = base_page_addr_end(addr, end); 541 *pte = base_lra(addr); 542 } while (pte++, addr = next, addr < end); 543 return 0; 544 } 545 546 static int base_segment_walk(unsigned long *origin, unsigned long addr, 547 unsigned long end, int alloc) 548 { 549 unsigned long *ste, next, *table; 550 int rc; 551 552 ste = origin; 553 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 554 do { 555 next = base_segment_addr_end(addr, end); 556 if (*ste & _SEGMENT_ENTRY_INVALID) { 557 if (!alloc) 558 continue; 559 table = base_pgt_alloc(); 560 if (!table) 561 return -ENOMEM; 562 *ste = __pa(table) | _SEGMENT_ENTRY; 563 } 564 table = __va(*ste & _SEGMENT_ENTRY_ORIGIN); 565 rc = base_page_walk(table, addr, next, alloc); 566 if (rc) 567 return rc; 568 if (!alloc) 569 base_pgt_free(table); 570 cond_resched(); 571 } while (ste++, addr = next, addr < end); 572 return 0; 573 } 574 575 static int base_region3_walk(unsigned long *origin, unsigned long addr, 576 unsigned long end, int alloc) 577 { 578 unsigned long *rtte, next, *table; 579 int rc; 580 581 rtte = origin; 582 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 583 do { 584 next = base_region3_addr_end(addr, end); 585 if (*rtte & _REGION_ENTRY_INVALID) { 586 if (!alloc) 587 continue; 588 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 589 if (!table) 590 return -ENOMEM; 591 *rtte = __pa(table) | _REGION3_ENTRY; 592 } 593 table = __va(*rtte & _REGION_ENTRY_ORIGIN); 594 rc = base_segment_walk(table, addr, next, alloc); 595 if (rc) 596 return rc; 597 if (!alloc) 598 base_crst_free(table); 599 } while (rtte++, addr = next, addr < end); 600 return 0; 601 } 602 603 static int base_region2_walk(unsigned long *origin, unsigned long addr, 604 unsigned long end, int alloc) 605 { 606 unsigned long *rste, next, *table; 607 int rc; 608 609 rste = origin; 610 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 611 do { 612 next = base_region2_addr_end(addr, end); 613 if (*rste & _REGION_ENTRY_INVALID) { 614 if (!alloc) 615 continue; 616 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 617 if (!table) 618 return -ENOMEM; 619 *rste = __pa(table) | _REGION2_ENTRY; 620 } 621 table = __va(*rste & _REGION_ENTRY_ORIGIN); 622 rc = base_region3_walk(table, addr, next, alloc); 623 if (rc) 624 return rc; 625 if (!alloc) 626 base_crst_free(table); 627 } while (rste++, addr = next, addr < end); 628 return 0; 629 } 630 631 static int base_region1_walk(unsigned long *origin, unsigned long addr, 632 unsigned long end, int alloc) 633 { 634 unsigned long *rfte, next, *table; 635 int rc; 636 637 rfte = origin; 638 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 639 do { 640 next = base_region1_addr_end(addr, end); 641 if (*rfte & _REGION_ENTRY_INVALID) { 642 if (!alloc) 643 continue; 644 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 645 if (!table) 646 return -ENOMEM; 647 *rfte = __pa(table) | _REGION1_ENTRY; 648 } 649 table = __va(*rfte & _REGION_ENTRY_ORIGIN); 650 rc = base_region2_walk(table, addr, next, alloc); 651 if (rc) 652 return rc; 653 if (!alloc) 654 base_crst_free(table); 655 } while (rfte++, addr = next, addr < end); 656 return 0; 657 } 658 659 /** 660 * base_asce_free - free asce and tables returned from base_asce_alloc() 661 * @asce: asce to be freed 662 * 663 * Frees all region, segment, and page tables that were allocated with a 664 * corresponding base_asce_alloc() call. 665 */ 666 void base_asce_free(unsigned long asce) 667 { 668 unsigned long *table = __va(asce & _ASCE_ORIGIN); 669 670 if (!asce) 671 return; 672 switch (asce & _ASCE_TYPE_MASK) { 673 case _ASCE_TYPE_SEGMENT: 674 base_segment_walk(table, 0, _REGION3_SIZE, 0); 675 break; 676 case _ASCE_TYPE_REGION3: 677 base_region3_walk(table, 0, _REGION2_SIZE, 0); 678 break; 679 case _ASCE_TYPE_REGION2: 680 base_region2_walk(table, 0, _REGION1_SIZE, 0); 681 break; 682 case _ASCE_TYPE_REGION1: 683 base_region1_walk(table, 0, TASK_SIZE_MAX, 0); 684 break; 685 } 686 base_crst_free(table); 687 } 688 689 static int base_pgt_cache_init(void) 690 { 691 static DEFINE_MUTEX(base_pgt_cache_mutex); 692 unsigned long sz = _PAGE_TABLE_SIZE; 693 694 if (base_pgt_cache) 695 return 0; 696 mutex_lock(&base_pgt_cache_mutex); 697 if (!base_pgt_cache) 698 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 699 mutex_unlock(&base_pgt_cache_mutex); 700 return base_pgt_cache ? 0 : -ENOMEM; 701 } 702 703 /** 704 * base_asce_alloc - create kernel mapping without enhanced DAT features 705 * @addr: virtual start address of kernel mapping 706 * @num_pages: number of consecutive pages 707 * 708 * Generate an asce, including all required region, segment and page tables, 709 * that can be used to access the virtual kernel mapping. The difference is 710 * that the returned asce does not make use of any enhanced DAT features like 711 * e.g. large pages. This is required for some I/O functions that pass an 712 * asce, like e.g. some service call requests. 713 * 714 * Note: the returned asce may NEVER be attached to any cpu. It may only be 715 * used for I/O requests. tlb entries that might result because the 716 * asce was attached to a cpu won't be cleared. 717 */ 718 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 719 { 720 unsigned long asce, *table, end; 721 int rc; 722 723 if (base_pgt_cache_init()) 724 return 0; 725 end = addr + num_pages * PAGE_SIZE; 726 if (end <= _REGION3_SIZE) { 727 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 728 if (!table) 729 return 0; 730 rc = base_segment_walk(table, addr, end, 1); 731 asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 732 } else if (end <= _REGION2_SIZE) { 733 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 734 if (!table) 735 return 0; 736 rc = base_region3_walk(table, addr, end, 1); 737 asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 738 } else if (end <= _REGION1_SIZE) { 739 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 740 if (!table) 741 return 0; 742 rc = base_region2_walk(table, addr, end, 1); 743 asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 744 } else { 745 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 746 if (!table) 747 return 0; 748 rc = base_region1_walk(table, addr, end, 1); 749 asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 750 } 751 if (rc) { 752 base_asce_free(asce); 753 asce = 0; 754 } 755 return asce; 756 } 757