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 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 180 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 181 return table; 182 } 183 184 void page_table_free(struct mm_struct *mm, unsigned long *table) 185 { 186 struct ptdesc *ptdesc = virt_to_ptdesc(table); 187 188 pagetable_dtor_free(ptdesc); 189 } 190 191 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 192 static void pte_free_now(struct rcu_head *head) 193 { 194 struct ptdesc *ptdesc = container_of(head, struct ptdesc, pt_rcu_head); 195 196 pagetable_dtor_free(ptdesc); 197 } 198 199 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) 200 { 201 struct ptdesc *ptdesc = virt_to_ptdesc(pgtable); 202 203 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 204 /* 205 * THPs are not allowed for KVM guests. Warn if pgste ever reaches here. 206 * Turn to the generic pte_free_defer() version once gmap is removed. 207 */ 208 WARN_ON_ONCE(mm_has_pgste(mm)); 209 } 210 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 211 212 /* 213 * Base infrastructure required to generate basic asces, region, segment, 214 * and page tables that do not make use of enhanced features like EDAT1. 215 */ 216 217 static struct kmem_cache *base_pgt_cache; 218 219 static unsigned long *base_pgt_alloc(void) 220 { 221 unsigned long *table; 222 223 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 224 if (table) 225 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 226 return table; 227 } 228 229 static void base_pgt_free(unsigned long *table) 230 { 231 kmem_cache_free(base_pgt_cache, table); 232 } 233 234 static unsigned long *base_crst_alloc(unsigned long val) 235 { 236 unsigned long *table; 237 struct ptdesc *ptdesc; 238 239 ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER); 240 if (!ptdesc) 241 return NULL; 242 table = ptdesc_address(ptdesc); 243 crst_table_init(table, val); 244 return table; 245 } 246 247 static void base_crst_free(unsigned long *table) 248 { 249 if (!table) 250 return; 251 pagetable_free(virt_to_ptdesc(table)); 252 } 253 254 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 255 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 256 unsigned long end) \ 257 { \ 258 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 259 \ 260 return (next - 1) < (end - 1) ? next : end; \ 261 } 262 263 BASE_ADDR_END_FUNC(page, PAGE_SIZE) 264 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 265 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 266 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 267 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 268 269 static inline unsigned long base_lra(unsigned long address) 270 { 271 unsigned long real; 272 273 asm volatile( 274 " lra %0,0(%1)\n" 275 : "=d" (real) : "a" (address) : "cc"); 276 return real; 277 } 278 279 static int base_page_walk(unsigned long *origin, unsigned long addr, 280 unsigned long end, int alloc) 281 { 282 unsigned long *pte, next; 283 284 if (!alloc) 285 return 0; 286 pte = origin; 287 pte += (addr & _PAGE_INDEX) >> PAGE_SHIFT; 288 do { 289 next = base_page_addr_end(addr, end); 290 *pte = base_lra(addr); 291 } while (pte++, addr = next, addr < end); 292 return 0; 293 } 294 295 static int base_segment_walk(unsigned long *origin, unsigned long addr, 296 unsigned long end, int alloc) 297 { 298 unsigned long *ste, next, *table; 299 int rc; 300 301 ste = origin; 302 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 303 do { 304 next = base_segment_addr_end(addr, end); 305 if (*ste & _SEGMENT_ENTRY_INVALID) { 306 if (!alloc) 307 continue; 308 table = base_pgt_alloc(); 309 if (!table) 310 return -ENOMEM; 311 *ste = __pa(table) | _SEGMENT_ENTRY; 312 } 313 table = __va(*ste & _SEGMENT_ENTRY_ORIGIN); 314 rc = base_page_walk(table, addr, next, alloc); 315 if (rc) 316 return rc; 317 if (!alloc) 318 base_pgt_free(table); 319 cond_resched(); 320 } while (ste++, addr = next, addr < end); 321 return 0; 322 } 323 324 static int base_region3_walk(unsigned long *origin, unsigned long addr, 325 unsigned long end, int alloc) 326 { 327 unsigned long *rtte, next, *table; 328 int rc; 329 330 rtte = origin; 331 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 332 do { 333 next = base_region3_addr_end(addr, end); 334 if (*rtte & _REGION_ENTRY_INVALID) { 335 if (!alloc) 336 continue; 337 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 338 if (!table) 339 return -ENOMEM; 340 *rtte = __pa(table) | _REGION3_ENTRY; 341 } 342 table = __va(*rtte & _REGION_ENTRY_ORIGIN); 343 rc = base_segment_walk(table, addr, next, alloc); 344 if (rc) 345 return rc; 346 if (!alloc) 347 base_crst_free(table); 348 } while (rtte++, addr = next, addr < end); 349 return 0; 350 } 351 352 static int base_region2_walk(unsigned long *origin, unsigned long addr, 353 unsigned long end, int alloc) 354 { 355 unsigned long *rste, next, *table; 356 int rc; 357 358 rste = origin; 359 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 360 do { 361 next = base_region2_addr_end(addr, end); 362 if (*rste & _REGION_ENTRY_INVALID) { 363 if (!alloc) 364 continue; 365 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 366 if (!table) 367 return -ENOMEM; 368 *rste = __pa(table) | _REGION2_ENTRY; 369 } 370 table = __va(*rste & _REGION_ENTRY_ORIGIN); 371 rc = base_region3_walk(table, addr, next, alloc); 372 if (rc) 373 return rc; 374 if (!alloc) 375 base_crst_free(table); 376 } while (rste++, addr = next, addr < end); 377 return 0; 378 } 379 380 static int base_region1_walk(unsigned long *origin, unsigned long addr, 381 unsigned long end, int alloc) 382 { 383 unsigned long *rfte, next, *table; 384 int rc; 385 386 rfte = origin; 387 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 388 do { 389 next = base_region1_addr_end(addr, end); 390 if (*rfte & _REGION_ENTRY_INVALID) { 391 if (!alloc) 392 continue; 393 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 394 if (!table) 395 return -ENOMEM; 396 *rfte = __pa(table) | _REGION1_ENTRY; 397 } 398 table = __va(*rfte & _REGION_ENTRY_ORIGIN); 399 rc = base_region2_walk(table, addr, next, alloc); 400 if (rc) 401 return rc; 402 if (!alloc) 403 base_crst_free(table); 404 } while (rfte++, addr = next, addr < end); 405 return 0; 406 } 407 408 /** 409 * base_asce_free - free asce and tables returned from base_asce_alloc() 410 * @asce: asce to be freed 411 * 412 * Frees all region, segment, and page tables that were allocated with a 413 * corresponding base_asce_alloc() call. 414 */ 415 void base_asce_free(unsigned long asce) 416 { 417 unsigned long *table = __va(asce & _ASCE_ORIGIN); 418 419 if (!asce) 420 return; 421 switch (asce & _ASCE_TYPE_MASK) { 422 case _ASCE_TYPE_SEGMENT: 423 base_segment_walk(table, 0, _REGION3_SIZE, 0); 424 break; 425 case _ASCE_TYPE_REGION3: 426 base_region3_walk(table, 0, _REGION2_SIZE, 0); 427 break; 428 case _ASCE_TYPE_REGION2: 429 base_region2_walk(table, 0, _REGION1_SIZE, 0); 430 break; 431 case _ASCE_TYPE_REGION1: 432 base_region1_walk(table, 0, TASK_SIZE_MAX, 0); 433 break; 434 } 435 base_crst_free(table); 436 } 437 438 static int base_pgt_cache_init(void) 439 { 440 static DEFINE_MUTEX(base_pgt_cache_mutex); 441 unsigned long sz = _PAGE_TABLE_SIZE; 442 443 if (base_pgt_cache) 444 return 0; 445 mutex_lock(&base_pgt_cache_mutex); 446 if (!base_pgt_cache) 447 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 448 mutex_unlock(&base_pgt_cache_mutex); 449 return base_pgt_cache ? 0 : -ENOMEM; 450 } 451 452 /** 453 * base_asce_alloc - create kernel mapping without enhanced DAT features 454 * @addr: virtual start address of kernel mapping 455 * @num_pages: number of consecutive pages 456 * 457 * Generate an asce, including all required region, segment and page tables, 458 * that can be used to access the virtual kernel mapping. The difference is 459 * that the returned asce does not make use of any enhanced DAT features like 460 * e.g. large pages. This is required for some I/O functions that pass an 461 * asce, like e.g. some service call requests. 462 * 463 * Note: the returned asce may NEVER be attached to any cpu. It may only be 464 * used for I/O requests. tlb entries that might result because the 465 * asce was attached to a cpu won't be cleared. 466 */ 467 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 468 { 469 unsigned long asce, *table, end; 470 int rc; 471 472 if (base_pgt_cache_init()) 473 return 0; 474 end = addr + num_pages * PAGE_SIZE; 475 if (end <= _REGION3_SIZE) { 476 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 477 if (!table) 478 return 0; 479 rc = base_segment_walk(table, addr, end, 1); 480 asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 481 } else if (end <= _REGION2_SIZE) { 482 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 483 if (!table) 484 return 0; 485 rc = base_region3_walk(table, addr, end, 1); 486 asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 487 } else if (end <= _REGION1_SIZE) { 488 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 489 if (!table) 490 return 0; 491 rc = base_region2_walk(table, addr, end, 1); 492 asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 493 } else { 494 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 495 if (!table) 496 return 0; 497 rc = base_region1_walk(table, addr, end, 1); 498 asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 499 } 500 if (rc) { 501 base_asce_free(asce); 502 asce = 0; 503 } 504 return asce; 505 } 506