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 const 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 pagetable_p4d_ctor(virt_to_ptdesc(p4d)); 92 } 93 if (end > _REGION1_SIZE) { 94 pgd = crst_table_alloc(mm); 95 if (unlikely(!pgd)) 96 goto err_pgd; 97 crst_table_init(pgd, _REGION1_ENTRY_EMPTY); 98 pagetable_pgd_ctor(virt_to_ptdesc(pgd)); 99 } 100 101 spin_lock_bh(&mm->page_table_lock); 102 103 /* 104 * This routine gets called with mmap_lock lock held and there is 105 * no reason to optimize for the case of otherwise. However, if 106 * that would ever change, the below check will let us know. 107 */ 108 VM_BUG_ON(asce_limit != mm->context.asce_limit); 109 110 if (p4d) { 111 __pgd = (unsigned long *) mm->pgd; 112 p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd); 113 mm->pgd = (pgd_t *) p4d; 114 mm->context.asce_limit = _REGION1_SIZE; 115 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 116 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 117 mm_inc_nr_puds(mm); 118 } 119 if (pgd) { 120 __pgd = (unsigned long *) mm->pgd; 121 pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd); 122 mm->pgd = (pgd_t *) pgd; 123 mm->context.asce_limit = TASK_SIZE_MAX; 124 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 125 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 126 } 127 128 spin_unlock_bh(&mm->page_table_lock); 129 130 on_each_cpu(__crst_table_upgrade, mm, 0); 131 132 return 0; 133 134 err_pgd: 135 pagetable_dtor(virt_to_ptdesc(p4d)); 136 crst_table_free(mm, p4d); 137 err_p4d: 138 return -ENOMEM; 139 } 140 141 #ifdef CONFIG_PGSTE 142 143 struct ptdesc *page_table_alloc_pgste(struct mm_struct *mm) 144 { 145 struct ptdesc *ptdesc; 146 u64 *table; 147 148 ptdesc = pagetable_alloc(GFP_KERNEL, 0); 149 if (ptdesc) { 150 table = (u64 *)ptdesc_to_virt(ptdesc); 151 __arch_set_page_dat(table, 1); 152 memset64(table, _PAGE_INVALID, PTRS_PER_PTE); 153 memset64(table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 154 } 155 return ptdesc; 156 } 157 158 void page_table_free_pgste(struct ptdesc *ptdesc) 159 { 160 pagetable_free(ptdesc); 161 } 162 163 #endif /* CONFIG_PGSTE */ 164 165 unsigned long *page_table_alloc(struct mm_struct *mm) 166 { 167 struct ptdesc *ptdesc; 168 unsigned long *table; 169 170 ptdesc = pagetable_alloc(GFP_KERNEL, 0); 171 if (!ptdesc) 172 return NULL; 173 if (!pagetable_pte_ctor(ptdesc)) { 174 pagetable_free(ptdesc); 175 return NULL; 176 } 177 table = ptdesc_to_virt(ptdesc); 178 __arch_set_page_dat(table, 1); 179 /* pt_list is used by gmap only */ 180 INIT_LIST_HEAD(&ptdesc->pt_list); 181 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 182 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 183 return table; 184 } 185 186 void page_table_free(struct mm_struct *mm, unsigned long *table) 187 { 188 struct ptdesc *ptdesc = virt_to_ptdesc(table); 189 190 pagetable_dtor_free(ptdesc); 191 } 192 193 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 194 static void pte_free_now(struct rcu_head *head) 195 { 196 struct ptdesc *ptdesc = container_of(head, struct ptdesc, pt_rcu_head); 197 198 pagetable_dtor_free(ptdesc); 199 } 200 201 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) 202 { 203 struct ptdesc *ptdesc = virt_to_ptdesc(pgtable); 204 205 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 206 /* 207 * THPs are not allowed for KVM guests. Warn if pgste ever reaches here. 208 * Turn to the generic pte_free_defer() version once gmap is removed. 209 */ 210 WARN_ON_ONCE(mm_has_pgste(mm)); 211 } 212 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 213 214 /* 215 * Base infrastructure required to generate basic asces, region, segment, 216 * and page tables that do not make use of enhanced features like EDAT1. 217 */ 218 219 static struct kmem_cache *base_pgt_cache; 220 221 static unsigned long *base_pgt_alloc(void) 222 { 223 unsigned long *table; 224 225 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 226 if (table) 227 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 228 return table; 229 } 230 231 static void base_pgt_free(unsigned long *table) 232 { 233 kmem_cache_free(base_pgt_cache, table); 234 } 235 236 static unsigned long *base_crst_alloc(unsigned long val) 237 { 238 unsigned long *table; 239 struct ptdesc *ptdesc; 240 241 ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER); 242 if (!ptdesc) 243 return NULL; 244 table = ptdesc_address(ptdesc); 245 crst_table_init(table, val); 246 return table; 247 } 248 249 static void base_crst_free(unsigned long *table) 250 { 251 if (!table) 252 return; 253 pagetable_free(virt_to_ptdesc(table)); 254 } 255 256 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 257 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 258 unsigned long end) \ 259 { \ 260 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 261 \ 262 return (next - 1) < (end - 1) ? next : end; \ 263 } 264 265 BASE_ADDR_END_FUNC(page, PAGE_SIZE) 266 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 267 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 268 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 269 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 270 271 static inline unsigned long base_lra(unsigned long address) 272 { 273 unsigned long real; 274 275 asm volatile( 276 " lra %0,0(%1)\n" 277 : "=d" (real) : "a" (address) : "cc"); 278 return real; 279 } 280 281 static int base_page_walk(unsigned long *origin, unsigned long addr, 282 unsigned long end, int alloc) 283 { 284 unsigned long *pte, next; 285 286 if (!alloc) 287 return 0; 288 pte = origin; 289 pte += (addr & _PAGE_INDEX) >> PAGE_SHIFT; 290 do { 291 next = base_page_addr_end(addr, end); 292 *pte = base_lra(addr); 293 } while (pte++, addr = next, addr < end); 294 return 0; 295 } 296 297 static int base_segment_walk(unsigned long *origin, unsigned long addr, 298 unsigned long end, int alloc) 299 { 300 unsigned long *ste, next, *table; 301 int rc; 302 303 ste = origin; 304 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 305 do { 306 next = base_segment_addr_end(addr, end); 307 if (*ste & _SEGMENT_ENTRY_INVALID) { 308 if (!alloc) 309 continue; 310 table = base_pgt_alloc(); 311 if (!table) 312 return -ENOMEM; 313 *ste = __pa(table) | _SEGMENT_ENTRY; 314 } 315 table = __va(*ste & _SEGMENT_ENTRY_ORIGIN); 316 rc = base_page_walk(table, addr, next, alloc); 317 if (rc) 318 return rc; 319 if (!alloc) 320 base_pgt_free(table); 321 cond_resched(); 322 } while (ste++, addr = next, addr < end); 323 return 0; 324 } 325 326 static int base_region3_walk(unsigned long *origin, unsigned long addr, 327 unsigned long end, int alloc) 328 { 329 unsigned long *rtte, next, *table; 330 int rc; 331 332 rtte = origin; 333 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 334 do { 335 next = base_region3_addr_end(addr, end); 336 if (*rtte & _REGION_ENTRY_INVALID) { 337 if (!alloc) 338 continue; 339 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 340 if (!table) 341 return -ENOMEM; 342 *rtte = __pa(table) | _REGION3_ENTRY; 343 } 344 table = __va(*rtte & _REGION_ENTRY_ORIGIN); 345 rc = base_segment_walk(table, addr, next, alloc); 346 if (rc) 347 return rc; 348 if (!alloc) 349 base_crst_free(table); 350 } while (rtte++, addr = next, addr < end); 351 return 0; 352 } 353 354 static int base_region2_walk(unsigned long *origin, unsigned long addr, 355 unsigned long end, int alloc) 356 { 357 unsigned long *rste, next, *table; 358 int rc; 359 360 rste = origin; 361 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 362 do { 363 next = base_region2_addr_end(addr, end); 364 if (*rste & _REGION_ENTRY_INVALID) { 365 if (!alloc) 366 continue; 367 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 368 if (!table) 369 return -ENOMEM; 370 *rste = __pa(table) | _REGION2_ENTRY; 371 } 372 table = __va(*rste & _REGION_ENTRY_ORIGIN); 373 rc = base_region3_walk(table, addr, next, alloc); 374 if (rc) 375 return rc; 376 if (!alloc) 377 base_crst_free(table); 378 } while (rste++, addr = next, addr < end); 379 return 0; 380 } 381 382 static int base_region1_walk(unsigned long *origin, unsigned long addr, 383 unsigned long end, int alloc) 384 { 385 unsigned long *rfte, next, *table; 386 int rc; 387 388 rfte = origin; 389 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 390 do { 391 next = base_region1_addr_end(addr, end); 392 if (*rfte & _REGION_ENTRY_INVALID) { 393 if (!alloc) 394 continue; 395 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 396 if (!table) 397 return -ENOMEM; 398 *rfte = __pa(table) | _REGION1_ENTRY; 399 } 400 table = __va(*rfte & _REGION_ENTRY_ORIGIN); 401 rc = base_region2_walk(table, addr, next, alloc); 402 if (rc) 403 return rc; 404 if (!alloc) 405 base_crst_free(table); 406 } while (rfte++, addr = next, addr < end); 407 return 0; 408 } 409 410 /** 411 * base_asce_free - free asce and tables returned from base_asce_alloc() 412 * @asce: asce to be freed 413 * 414 * Frees all region, segment, and page tables that were allocated with a 415 * corresponding base_asce_alloc() call. 416 */ 417 void base_asce_free(unsigned long asce) 418 { 419 unsigned long *table = __va(asce & _ASCE_ORIGIN); 420 421 if (!asce) 422 return; 423 switch (asce & _ASCE_TYPE_MASK) { 424 case _ASCE_TYPE_SEGMENT: 425 base_segment_walk(table, 0, _REGION3_SIZE, 0); 426 break; 427 case _ASCE_TYPE_REGION3: 428 base_region3_walk(table, 0, _REGION2_SIZE, 0); 429 break; 430 case _ASCE_TYPE_REGION2: 431 base_region2_walk(table, 0, _REGION1_SIZE, 0); 432 break; 433 case _ASCE_TYPE_REGION1: 434 base_region1_walk(table, 0, TASK_SIZE_MAX, 0); 435 break; 436 } 437 base_crst_free(table); 438 } 439 440 static int base_pgt_cache_init(void) 441 { 442 static DEFINE_MUTEX(base_pgt_cache_mutex); 443 unsigned long sz = _PAGE_TABLE_SIZE; 444 445 if (base_pgt_cache) 446 return 0; 447 mutex_lock(&base_pgt_cache_mutex); 448 if (!base_pgt_cache) 449 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 450 mutex_unlock(&base_pgt_cache_mutex); 451 return base_pgt_cache ? 0 : -ENOMEM; 452 } 453 454 /** 455 * base_asce_alloc - create kernel mapping without enhanced DAT features 456 * @addr: virtual start address of kernel mapping 457 * @num_pages: number of consecutive pages 458 * 459 * Generate an asce, including all required region, segment and page tables, 460 * that can be used to access the virtual kernel mapping. The difference is 461 * that the returned asce does not make use of any enhanced DAT features like 462 * e.g. large pages. This is required for some I/O functions that pass an 463 * asce, like e.g. some service call requests. 464 * 465 * Note: the returned asce may NEVER be attached to any cpu. It may only be 466 * used for I/O requests. tlb entries that might result because the 467 * asce was attached to a cpu won't be cleared. 468 */ 469 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 470 { 471 unsigned long asce, *table, end; 472 int rc; 473 474 if (base_pgt_cache_init()) 475 return 0; 476 end = addr + num_pages * PAGE_SIZE; 477 if (end <= _REGION3_SIZE) { 478 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 479 if (!table) 480 return 0; 481 rc = base_segment_walk(table, addr, end, 1); 482 asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 483 } else if (end <= _REGION2_SIZE) { 484 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 485 if (!table) 486 return 0; 487 rc = base_region3_walk(table, addr, end, 1); 488 asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 489 } else if (end <= _REGION1_SIZE) { 490 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 491 if (!table) 492 return 0; 493 rc = base_region2_walk(table, addr, end, 1); 494 asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 495 } else { 496 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 497 if (!table) 498 return 0; 499 rc = base_region1_walk(table, addr, end, 1); 500 asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 501 } 502 if (rc) { 503 base_asce_free(asce); 504 asce = 0; 505 } 506 return asce; 507 } 508