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/page-states.h> 14 #include <asm/pgalloc.h> 15 #include <asm/gmap.h> 16 #include <asm/tlb.h> 17 #include <asm/tlbflush.h> 18 19 #ifdef CONFIG_PGSTE 20 21 int page_table_allocate_pgste = 0; 22 EXPORT_SYMBOL(page_table_allocate_pgste); 23 24 static struct ctl_table page_table_sysctl[] = { 25 { 26 .procname = "allocate_pgste", 27 .data = &page_table_allocate_pgste, 28 .maxlen = sizeof(int), 29 .mode = S_IRUGO | S_IWUSR, 30 .proc_handler = proc_dointvec_minmax, 31 .extra1 = SYSCTL_ZERO, 32 .extra2 = SYSCTL_ONE, 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 unsigned long *table; 48 49 if (!ptdesc) 50 return NULL; 51 table = ptdesc_to_virt(ptdesc); 52 __arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER); 53 return table; 54 } 55 56 void crst_table_free(struct mm_struct *mm, unsigned long *table) 57 { 58 if (!table) 59 return; 60 pagetable_free(virt_to_ptdesc(table)); 61 } 62 63 static void __crst_table_upgrade(void *arg) 64 { 65 struct mm_struct *mm = arg; 66 67 /* change all active ASCEs to avoid the creation of new TLBs */ 68 if (current->active_mm == mm) { 69 get_lowcore()->user_asce.val = mm->context.asce; 70 local_ctl_load(7, &get_lowcore()->user_asce); 71 } 72 __tlb_flush_local(); 73 } 74 75 int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 76 { 77 unsigned long *pgd = NULL, *p4d = NULL, *__pgd; 78 unsigned long asce_limit = mm->context.asce_limit; 79 80 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ 81 VM_BUG_ON(asce_limit < _REGION2_SIZE); 82 83 if (end <= asce_limit) 84 return 0; 85 86 if (asce_limit == _REGION2_SIZE) { 87 p4d = crst_table_alloc(mm); 88 if (unlikely(!p4d)) 89 goto err_p4d; 90 crst_table_init(p4d, _REGION2_ENTRY_EMPTY); 91 } 92 if (end > _REGION1_SIZE) { 93 pgd = crst_table_alloc(mm); 94 if (unlikely(!pgd)) 95 goto err_pgd; 96 crst_table_init(pgd, _REGION1_ENTRY_EMPTY); 97 } 98 99 spin_lock_bh(&mm->page_table_lock); 100 101 /* 102 * This routine gets called with mmap_lock lock held and there is 103 * no reason to optimize for the case of otherwise. However, if 104 * that would ever change, the below check will let us know. 105 */ 106 VM_BUG_ON(asce_limit != mm->context.asce_limit); 107 108 if (p4d) { 109 __pgd = (unsigned long *) mm->pgd; 110 p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd); 111 mm->pgd = (pgd_t *) p4d; 112 mm->context.asce_limit = _REGION1_SIZE; 113 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 114 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 115 mm_inc_nr_puds(mm); 116 } 117 if (pgd) { 118 __pgd = (unsigned long *) mm->pgd; 119 pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd); 120 mm->pgd = (pgd_t *) pgd; 121 mm->context.asce_limit = TASK_SIZE_MAX; 122 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 123 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 124 } 125 126 spin_unlock_bh(&mm->page_table_lock); 127 128 on_each_cpu(__crst_table_upgrade, mm, 0); 129 130 return 0; 131 132 err_pgd: 133 crst_table_free(mm, p4d); 134 err_p4d: 135 return -ENOMEM; 136 } 137 138 #ifdef CONFIG_PGSTE 139 140 struct ptdesc *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 __arch_set_page_dat(table, 1); 149 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 150 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 151 } 152 return ptdesc; 153 } 154 155 void page_table_free_pgste(struct ptdesc *ptdesc) 156 { 157 pagetable_free(ptdesc); 158 } 159 160 #endif /* CONFIG_PGSTE */ 161 162 unsigned long *page_table_alloc(struct mm_struct *mm) 163 { 164 struct ptdesc *ptdesc; 165 unsigned long *table; 166 167 ptdesc = pagetable_alloc(GFP_KERNEL, 0); 168 if (!ptdesc) 169 return NULL; 170 if (!pagetable_pte_ctor(ptdesc)) { 171 pagetable_free(ptdesc); 172 return NULL; 173 } 174 table = ptdesc_to_virt(ptdesc); 175 __arch_set_page_dat(table, 1); 176 /* pt_list is used by gmap only */ 177 INIT_LIST_HEAD(&ptdesc->pt_list); 178 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 179 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 180 return table; 181 } 182 183 static void pagetable_pte_dtor_free(struct ptdesc *ptdesc) 184 { 185 pagetable_pte_dtor(ptdesc); 186 pagetable_free(ptdesc); 187 } 188 189 void page_table_free(struct mm_struct *mm, unsigned long *table) 190 { 191 struct ptdesc *ptdesc = virt_to_ptdesc(table); 192 193 pagetable_pte_dtor_free(ptdesc); 194 } 195 196 void __tlb_remove_table(void *table) 197 { 198 struct ptdesc *ptdesc = virt_to_ptdesc(table); 199 struct page *page = ptdesc_page(ptdesc); 200 201 if (compound_order(page) == CRST_ALLOC_ORDER) { 202 /* pmd, pud, or p4d */ 203 pagetable_free(ptdesc); 204 return; 205 } 206 pagetable_pte_dtor_free(ptdesc); 207 } 208 209 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 210 static void pte_free_now(struct rcu_head *head) 211 { 212 struct ptdesc *ptdesc = container_of(head, struct ptdesc, pt_rcu_head); 213 214 pagetable_pte_dtor_free(ptdesc); 215 } 216 217 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) 218 { 219 struct ptdesc *ptdesc = virt_to_ptdesc(pgtable); 220 221 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 222 /* 223 * THPs are not allowed for KVM guests. Warn if pgste ever reaches here. 224 * Turn to the generic pte_free_defer() version once gmap is removed. 225 */ 226 WARN_ON_ONCE(mm_has_pgste(mm)); 227 } 228 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 229 230 /* 231 * Base infrastructure required to generate basic asces, region, segment, 232 * and page tables that do not make use of enhanced features like EDAT1. 233 */ 234 235 static struct kmem_cache *base_pgt_cache; 236 237 static unsigned long *base_pgt_alloc(void) 238 { 239 unsigned long *table; 240 241 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 242 if (table) 243 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 244 return table; 245 } 246 247 static void base_pgt_free(unsigned long *table) 248 { 249 kmem_cache_free(base_pgt_cache, table); 250 } 251 252 static unsigned long *base_crst_alloc(unsigned long val) 253 { 254 unsigned long *table; 255 struct ptdesc *ptdesc; 256 257 ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER); 258 if (!ptdesc) 259 return NULL; 260 table = ptdesc_address(ptdesc); 261 crst_table_init(table, val); 262 return table; 263 } 264 265 static void base_crst_free(unsigned long *table) 266 { 267 if (!table) 268 return; 269 pagetable_free(virt_to_ptdesc(table)); 270 } 271 272 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 273 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 274 unsigned long end) \ 275 { \ 276 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 277 \ 278 return (next - 1) < (end - 1) ? next : end; \ 279 } 280 281 BASE_ADDR_END_FUNC(page, _PAGE_SIZE) 282 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 283 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 284 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 285 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 286 287 static inline unsigned long base_lra(unsigned long address) 288 { 289 unsigned long real; 290 291 asm volatile( 292 " lra %0,0(%1)\n" 293 : "=d" (real) : "a" (address) : "cc"); 294 return real; 295 } 296 297 static int base_page_walk(unsigned long *origin, unsigned long addr, 298 unsigned long end, int alloc) 299 { 300 unsigned long *pte, next; 301 302 if (!alloc) 303 return 0; 304 pte = origin; 305 pte += (addr & _PAGE_INDEX) >> _PAGE_SHIFT; 306 do { 307 next = base_page_addr_end(addr, end); 308 *pte = base_lra(addr); 309 } while (pte++, addr = next, addr < end); 310 return 0; 311 } 312 313 static int base_segment_walk(unsigned long *origin, unsigned long addr, 314 unsigned long end, int alloc) 315 { 316 unsigned long *ste, next, *table; 317 int rc; 318 319 ste = origin; 320 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 321 do { 322 next = base_segment_addr_end(addr, end); 323 if (*ste & _SEGMENT_ENTRY_INVALID) { 324 if (!alloc) 325 continue; 326 table = base_pgt_alloc(); 327 if (!table) 328 return -ENOMEM; 329 *ste = __pa(table) | _SEGMENT_ENTRY; 330 } 331 table = __va(*ste & _SEGMENT_ENTRY_ORIGIN); 332 rc = base_page_walk(table, addr, next, alloc); 333 if (rc) 334 return rc; 335 if (!alloc) 336 base_pgt_free(table); 337 cond_resched(); 338 } while (ste++, addr = next, addr < end); 339 return 0; 340 } 341 342 static int base_region3_walk(unsigned long *origin, unsigned long addr, 343 unsigned long end, int alloc) 344 { 345 unsigned long *rtte, next, *table; 346 int rc; 347 348 rtte = origin; 349 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 350 do { 351 next = base_region3_addr_end(addr, end); 352 if (*rtte & _REGION_ENTRY_INVALID) { 353 if (!alloc) 354 continue; 355 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 356 if (!table) 357 return -ENOMEM; 358 *rtte = __pa(table) | _REGION3_ENTRY; 359 } 360 table = __va(*rtte & _REGION_ENTRY_ORIGIN); 361 rc = base_segment_walk(table, addr, next, alloc); 362 if (rc) 363 return rc; 364 if (!alloc) 365 base_crst_free(table); 366 } while (rtte++, addr = next, addr < end); 367 return 0; 368 } 369 370 static int base_region2_walk(unsigned long *origin, unsigned long addr, 371 unsigned long end, int alloc) 372 { 373 unsigned long *rste, next, *table; 374 int rc; 375 376 rste = origin; 377 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 378 do { 379 next = base_region2_addr_end(addr, end); 380 if (*rste & _REGION_ENTRY_INVALID) { 381 if (!alloc) 382 continue; 383 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 384 if (!table) 385 return -ENOMEM; 386 *rste = __pa(table) | _REGION2_ENTRY; 387 } 388 table = __va(*rste & _REGION_ENTRY_ORIGIN); 389 rc = base_region3_walk(table, addr, next, alloc); 390 if (rc) 391 return rc; 392 if (!alloc) 393 base_crst_free(table); 394 } while (rste++, addr = next, addr < end); 395 return 0; 396 } 397 398 static int base_region1_walk(unsigned long *origin, unsigned long addr, 399 unsigned long end, int alloc) 400 { 401 unsigned long *rfte, next, *table; 402 int rc; 403 404 rfte = origin; 405 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 406 do { 407 next = base_region1_addr_end(addr, end); 408 if (*rfte & _REGION_ENTRY_INVALID) { 409 if (!alloc) 410 continue; 411 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 412 if (!table) 413 return -ENOMEM; 414 *rfte = __pa(table) | _REGION1_ENTRY; 415 } 416 table = __va(*rfte & _REGION_ENTRY_ORIGIN); 417 rc = base_region2_walk(table, addr, next, alloc); 418 if (rc) 419 return rc; 420 if (!alloc) 421 base_crst_free(table); 422 } while (rfte++, addr = next, addr < end); 423 return 0; 424 } 425 426 /** 427 * base_asce_free - free asce and tables returned from base_asce_alloc() 428 * @asce: asce to be freed 429 * 430 * Frees all region, segment, and page tables that were allocated with a 431 * corresponding base_asce_alloc() call. 432 */ 433 void base_asce_free(unsigned long asce) 434 { 435 unsigned long *table = __va(asce & _ASCE_ORIGIN); 436 437 if (!asce) 438 return; 439 switch (asce & _ASCE_TYPE_MASK) { 440 case _ASCE_TYPE_SEGMENT: 441 base_segment_walk(table, 0, _REGION3_SIZE, 0); 442 break; 443 case _ASCE_TYPE_REGION3: 444 base_region3_walk(table, 0, _REGION2_SIZE, 0); 445 break; 446 case _ASCE_TYPE_REGION2: 447 base_region2_walk(table, 0, _REGION1_SIZE, 0); 448 break; 449 case _ASCE_TYPE_REGION1: 450 base_region1_walk(table, 0, TASK_SIZE_MAX, 0); 451 break; 452 } 453 base_crst_free(table); 454 } 455 456 static int base_pgt_cache_init(void) 457 { 458 static DEFINE_MUTEX(base_pgt_cache_mutex); 459 unsigned long sz = _PAGE_TABLE_SIZE; 460 461 if (base_pgt_cache) 462 return 0; 463 mutex_lock(&base_pgt_cache_mutex); 464 if (!base_pgt_cache) 465 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 466 mutex_unlock(&base_pgt_cache_mutex); 467 return base_pgt_cache ? 0 : -ENOMEM; 468 } 469 470 /** 471 * base_asce_alloc - create kernel mapping without enhanced DAT features 472 * @addr: virtual start address of kernel mapping 473 * @num_pages: number of consecutive pages 474 * 475 * Generate an asce, including all required region, segment and page tables, 476 * that can be used to access the virtual kernel mapping. The difference is 477 * that the returned asce does not make use of any enhanced DAT features like 478 * e.g. large pages. This is required for some I/O functions that pass an 479 * asce, like e.g. some service call requests. 480 * 481 * Note: the returned asce may NEVER be attached to any cpu. It may only be 482 * used for I/O requests. tlb entries that might result because the 483 * asce was attached to a cpu won't be cleared. 484 */ 485 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 486 { 487 unsigned long asce, *table, end; 488 int rc; 489 490 if (base_pgt_cache_init()) 491 return 0; 492 end = addr + num_pages * PAGE_SIZE; 493 if (end <= _REGION3_SIZE) { 494 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 495 if (!table) 496 return 0; 497 rc = base_segment_walk(table, addr, end, 1); 498 asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 499 } else if (end <= _REGION2_SIZE) { 500 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 501 if (!table) 502 return 0; 503 rc = base_region3_walk(table, addr, end, 1); 504 asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 505 } else if (end <= _REGION1_SIZE) { 506 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 507 if (!table) 508 return 0; 509 rc = base_region2_walk(table, addr, end, 1); 510 asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 511 } else { 512 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 513 if (!table) 514 return 0; 515 rc = base_region1_walk(table, addr, end, 1); 516 asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 517 } 518 if (rc) { 519 base_asce_free(asce); 520 asce = 0; 521 } 522 return asce; 523 } 524