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/tlbflush.h> 16 17 unsigned long *crst_table_alloc_noprof(struct mm_struct *mm) 18 { 19 gfp_t gfp = GFP_KERNEL_ACCOUNT; 20 struct ptdesc *ptdesc; 21 unsigned long *table; 22 23 if (mm == &init_mm) 24 gfp &= ~__GFP_ACCOUNT; 25 ptdesc = pagetable_alloc_noprof(gfp, CRST_ALLOC_ORDER); 26 if (!ptdesc) 27 return NULL; 28 table = ptdesc_address(ptdesc); 29 __arch_set_page_dat(table, 1UL << CRST_ALLOC_ORDER); 30 return table; 31 } 32 33 void crst_table_free(struct mm_struct *mm, unsigned long *table) 34 { 35 if (!table) 36 return; 37 pagetable_free(virt_to_ptdesc(table)); 38 } 39 40 static void __crst_table_upgrade(void *arg) 41 { 42 struct mm_struct *mm = arg; 43 struct ctlreg asce; 44 45 /* change all active ASCEs to avoid the creation of new TLBs */ 46 if (current->active_mm == mm) { 47 asce.val = mm->context.asce; 48 get_lowcore()->user_asce = asce; 49 local_ctl_load(7, &asce); 50 if (!test_thread_flag(TIF_ASCE_PRIMARY)) 51 local_ctl_load(1, &asce); 52 } 53 __tlb_flush_local(); 54 } 55 56 int crst_table_upgrade(struct mm_struct *mm, unsigned long end) 57 { 58 unsigned long *pgd = NULL, *p4d = NULL, *__pgd; 59 unsigned long asce_limit = mm->context.asce_limit; 60 61 mmap_assert_write_locked(mm); 62 63 /* upgrade should only happen from 3 to 4, 3 to 5, or 4 to 5 levels */ 64 VM_BUG_ON(asce_limit < _REGION2_SIZE); 65 66 if (end <= asce_limit) 67 return 0; 68 69 if (asce_limit == _REGION2_SIZE) { 70 p4d = crst_table_alloc(mm); 71 if (unlikely(!p4d)) 72 goto err_p4d; 73 crst_table_init(p4d, _REGION2_ENTRY_EMPTY); 74 pagetable_p4d_ctor(virt_to_ptdesc(p4d)); 75 } 76 if (end > _REGION1_SIZE) { 77 pgd = crst_table_alloc(mm); 78 if (unlikely(!pgd)) 79 goto err_pgd; 80 crst_table_init(pgd, _REGION1_ENTRY_EMPTY); 81 pagetable_pgd_ctor(virt_to_ptdesc(pgd)); 82 } 83 84 spin_lock_bh(&mm->page_table_lock); 85 86 if (p4d) { 87 __pgd = (unsigned long *) mm->pgd; 88 p4d_populate(mm, (p4d_t *) p4d, (pud_t *) __pgd); 89 mm->pgd = (pgd_t *) p4d; 90 mm->context.asce_limit = _REGION1_SIZE; 91 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 92 _ASCE_USER_BITS | _ASCE_TYPE_REGION2; 93 mm_inc_nr_puds(mm); 94 } 95 if (pgd) { 96 __pgd = (unsigned long *) mm->pgd; 97 pgd_populate(mm, (pgd_t *) pgd, (p4d_t *) __pgd); 98 mm->pgd = (pgd_t *) pgd; 99 mm->context.asce_limit = TASK_SIZE_MAX; 100 mm->context.asce = __pa(mm->pgd) | _ASCE_TABLE_LENGTH | 101 _ASCE_USER_BITS | _ASCE_TYPE_REGION1; 102 } 103 104 spin_unlock_bh(&mm->page_table_lock); 105 106 on_each_cpu(__crst_table_upgrade, mm, 0); 107 108 return 0; 109 110 err_pgd: 111 pagetable_dtor(virt_to_ptdesc(p4d)); 112 crst_table_free(mm, p4d); 113 err_p4d: 114 return -ENOMEM; 115 } 116 117 unsigned long *page_table_alloc_noprof(struct mm_struct *mm) 118 { 119 gfp_t gfp = GFP_KERNEL_ACCOUNT; 120 struct ptdesc *ptdesc; 121 unsigned long *table; 122 123 if (mm == &init_mm) 124 gfp &= ~__GFP_ACCOUNT; 125 ptdesc = pagetable_alloc_noprof(gfp, 0); 126 if (!ptdesc) 127 return NULL; 128 if (!pagetable_pte_ctor(mm, ptdesc)) { 129 pagetable_free(ptdesc); 130 return NULL; 131 } 132 table = ptdesc_address(ptdesc); 133 __arch_set_page_dat(table, 1); 134 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 135 memset64((u64 *)table + PTRS_PER_PTE, 0, PTRS_PER_PTE); 136 return table; 137 } 138 139 void page_table_free(struct mm_struct *mm, unsigned long *table) 140 { 141 struct ptdesc *ptdesc = virt_to_ptdesc(table); 142 143 if (pagetable_is_reserved(ptdesc)) 144 return free_reserved_ptdesc(ptdesc); 145 pagetable_dtor_free(ptdesc); 146 } 147 148 #ifdef CONFIG_TRANSPARENT_HUGEPAGE 149 static void pte_free_now(struct rcu_head *head) 150 { 151 struct ptdesc *ptdesc = container_of(head, struct ptdesc, pt_rcu_head); 152 153 pagetable_dtor_free(ptdesc); 154 } 155 156 void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable) 157 { 158 struct ptdesc *ptdesc = virt_to_ptdesc(pgtable); 159 160 call_rcu(&ptdesc->pt_rcu_head, pte_free_now); 161 } 162 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ 163 164 /* 165 * Base infrastructure required to generate basic asces, region, segment, 166 * and page tables that do not make use of enhanced features like EDAT1. 167 */ 168 169 static struct kmem_cache *base_pgt_cache; 170 171 static unsigned long *base_pgt_alloc(void) 172 { 173 unsigned long *table; 174 175 table = kmem_cache_alloc(base_pgt_cache, GFP_KERNEL); 176 if (table) 177 memset64((u64 *)table, _PAGE_INVALID, PTRS_PER_PTE); 178 return table; 179 } 180 181 static void base_pgt_free(unsigned long *table) 182 { 183 kmem_cache_free(base_pgt_cache, table); 184 } 185 186 static unsigned long *base_crst_alloc(unsigned long val) 187 { 188 unsigned long *table; 189 struct ptdesc *ptdesc; 190 191 ptdesc = pagetable_alloc(GFP_KERNEL, CRST_ALLOC_ORDER); 192 if (!ptdesc) 193 return NULL; 194 table = ptdesc_address(ptdesc); 195 crst_table_init(table, val); 196 return table; 197 } 198 199 static void base_crst_free(unsigned long *table) 200 { 201 if (!table) 202 return; 203 pagetable_free(virt_to_ptdesc(table)); 204 } 205 206 #define BASE_ADDR_END_FUNC(NAME, SIZE) \ 207 static inline unsigned long base_##NAME##_addr_end(unsigned long addr, \ 208 unsigned long end) \ 209 { \ 210 unsigned long next = (addr + (SIZE)) & ~((SIZE) - 1); \ 211 \ 212 return (next - 1) < (end - 1) ? next : end; \ 213 } 214 215 BASE_ADDR_END_FUNC(page, PAGE_SIZE) 216 BASE_ADDR_END_FUNC(segment, _SEGMENT_SIZE) 217 BASE_ADDR_END_FUNC(region3, _REGION3_SIZE) 218 BASE_ADDR_END_FUNC(region2, _REGION2_SIZE) 219 BASE_ADDR_END_FUNC(region1, _REGION1_SIZE) 220 221 static inline unsigned long base_lra(unsigned long address) 222 { 223 unsigned long real; 224 225 asm volatile( 226 " lra %0,0(%1)" 227 : "=d" (real) : "a" (address) : "cc"); 228 return real; 229 } 230 231 static int base_page_walk(unsigned long *origin, unsigned long addr, 232 unsigned long end, int alloc) 233 { 234 unsigned long *pte, next; 235 236 if (!alloc) 237 return 0; 238 pte = origin; 239 pte += (addr & _PAGE_INDEX) >> PAGE_SHIFT; 240 do { 241 next = base_page_addr_end(addr, end); 242 *pte = base_lra(addr); 243 } while (pte++, addr = next, addr < end); 244 return 0; 245 } 246 247 static int base_segment_walk(unsigned long *origin, unsigned long addr, 248 unsigned long end, int alloc) 249 { 250 unsigned long *ste, next, *table; 251 int rc; 252 253 ste = origin; 254 ste += (addr & _SEGMENT_INDEX) >> _SEGMENT_SHIFT; 255 do { 256 next = base_segment_addr_end(addr, end); 257 if (*ste & _SEGMENT_ENTRY_INVALID) { 258 if (!alloc) 259 continue; 260 table = base_pgt_alloc(); 261 if (!table) 262 return -ENOMEM; 263 *ste = __pa(table) | _SEGMENT_ENTRY; 264 } 265 table = __va(*ste & _SEGMENT_ENTRY_ORIGIN); 266 rc = base_page_walk(table, addr, next, alloc); 267 if (rc) 268 return rc; 269 if (!alloc) 270 base_pgt_free(table); 271 cond_resched(); 272 } while (ste++, addr = next, addr < end); 273 return 0; 274 } 275 276 static int base_region3_walk(unsigned long *origin, unsigned long addr, 277 unsigned long end, int alloc) 278 { 279 unsigned long *rtte, next, *table; 280 int rc; 281 282 rtte = origin; 283 rtte += (addr & _REGION3_INDEX) >> _REGION3_SHIFT; 284 do { 285 next = base_region3_addr_end(addr, end); 286 if (*rtte & _REGION_ENTRY_INVALID) { 287 if (!alloc) 288 continue; 289 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 290 if (!table) 291 return -ENOMEM; 292 *rtte = __pa(table) | _REGION3_ENTRY; 293 } 294 table = __va(*rtte & _REGION_ENTRY_ORIGIN); 295 rc = base_segment_walk(table, addr, next, alloc); 296 if (rc) 297 return rc; 298 if (!alloc) 299 base_crst_free(table); 300 } while (rtte++, addr = next, addr < end); 301 return 0; 302 } 303 304 static int base_region2_walk(unsigned long *origin, unsigned long addr, 305 unsigned long end, int alloc) 306 { 307 unsigned long *rste, next, *table; 308 int rc; 309 310 rste = origin; 311 rste += (addr & _REGION2_INDEX) >> _REGION2_SHIFT; 312 do { 313 next = base_region2_addr_end(addr, end); 314 if (*rste & _REGION_ENTRY_INVALID) { 315 if (!alloc) 316 continue; 317 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 318 if (!table) 319 return -ENOMEM; 320 *rste = __pa(table) | _REGION2_ENTRY; 321 } 322 table = __va(*rste & _REGION_ENTRY_ORIGIN); 323 rc = base_region3_walk(table, addr, next, alloc); 324 if (rc) 325 return rc; 326 if (!alloc) 327 base_crst_free(table); 328 } while (rste++, addr = next, addr < end); 329 return 0; 330 } 331 332 static int base_region1_walk(unsigned long *origin, unsigned long addr, 333 unsigned long end, int alloc) 334 { 335 unsigned long *rfte, next, *table; 336 int rc; 337 338 rfte = origin; 339 rfte += (addr & _REGION1_INDEX) >> _REGION1_SHIFT; 340 do { 341 next = base_region1_addr_end(addr, end); 342 if (*rfte & _REGION_ENTRY_INVALID) { 343 if (!alloc) 344 continue; 345 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 346 if (!table) 347 return -ENOMEM; 348 *rfte = __pa(table) | _REGION1_ENTRY; 349 } 350 table = __va(*rfte & _REGION_ENTRY_ORIGIN); 351 rc = base_region2_walk(table, addr, next, alloc); 352 if (rc) 353 return rc; 354 if (!alloc) 355 base_crst_free(table); 356 } while (rfte++, addr = next, addr < end); 357 return 0; 358 } 359 360 /** 361 * base_asce_free - free asce and tables returned from base_asce_alloc() 362 * @asce: asce to be freed 363 * 364 * Frees all region, segment, and page tables that were allocated with a 365 * corresponding base_asce_alloc() call. 366 */ 367 void base_asce_free(unsigned long asce) 368 { 369 unsigned long *table = __va(asce & _ASCE_ORIGIN); 370 371 if (!asce) 372 return; 373 switch (asce & _ASCE_TYPE_MASK) { 374 case _ASCE_TYPE_SEGMENT: 375 base_segment_walk(table, 0, _REGION3_SIZE, 0); 376 break; 377 case _ASCE_TYPE_REGION3: 378 base_region3_walk(table, 0, _REGION2_SIZE, 0); 379 break; 380 case _ASCE_TYPE_REGION2: 381 base_region2_walk(table, 0, _REGION1_SIZE, 0); 382 break; 383 case _ASCE_TYPE_REGION1: 384 base_region1_walk(table, 0, TASK_SIZE_MAX, 0); 385 break; 386 } 387 base_crst_free(table); 388 } 389 390 static int base_pgt_cache_init(void) 391 { 392 static DEFINE_MUTEX(base_pgt_cache_mutex); 393 unsigned long sz = _PAGE_TABLE_SIZE; 394 395 if (base_pgt_cache) 396 return 0; 397 mutex_lock(&base_pgt_cache_mutex); 398 if (!base_pgt_cache) 399 base_pgt_cache = kmem_cache_create("base_pgt", sz, sz, 0, NULL); 400 mutex_unlock(&base_pgt_cache_mutex); 401 return base_pgt_cache ? 0 : -ENOMEM; 402 } 403 404 /** 405 * base_asce_alloc - create kernel mapping without enhanced DAT features 406 * @addr: virtual start address of kernel mapping 407 * @num_pages: number of consecutive pages 408 * 409 * Generate an asce, including all required region, segment and page tables, 410 * that can be used to access the virtual kernel mapping. The difference is 411 * that the returned asce does not make use of any enhanced DAT features like 412 * e.g. large pages. This is required for some I/O functions that pass an 413 * asce, like e.g. some service call requests. 414 * 415 * Note: the returned asce may NEVER be attached to any cpu. It may only be 416 * used for I/O requests. tlb entries that might result because the 417 * asce was attached to a cpu won't be cleared. 418 */ 419 unsigned long base_asce_alloc(unsigned long addr, unsigned long num_pages) 420 { 421 unsigned long asce, *table, end; 422 int rc; 423 424 if (base_pgt_cache_init()) 425 return 0; 426 end = addr + num_pages * PAGE_SIZE; 427 if (end <= _REGION3_SIZE) { 428 table = base_crst_alloc(_SEGMENT_ENTRY_EMPTY); 429 if (!table) 430 return 0; 431 rc = base_segment_walk(table, addr, end, 1); 432 asce = __pa(table) | _ASCE_TYPE_SEGMENT | _ASCE_TABLE_LENGTH; 433 } else if (end <= _REGION2_SIZE) { 434 table = base_crst_alloc(_REGION3_ENTRY_EMPTY); 435 if (!table) 436 return 0; 437 rc = base_region3_walk(table, addr, end, 1); 438 asce = __pa(table) | _ASCE_TYPE_REGION3 | _ASCE_TABLE_LENGTH; 439 } else if (end <= _REGION1_SIZE) { 440 table = base_crst_alloc(_REGION2_ENTRY_EMPTY); 441 if (!table) 442 return 0; 443 rc = base_region2_walk(table, addr, end, 1); 444 asce = __pa(table) | _ASCE_TYPE_REGION2 | _ASCE_TABLE_LENGTH; 445 } else { 446 table = base_crst_alloc(_REGION1_ENTRY_EMPTY); 447 if (!table) 448 return 0; 449 rc = base_region1_walk(table, addr, end, 1); 450 asce = __pa(table) | _ASCE_TYPE_REGION1 | _ASCE_TABLE_LENGTH; 451 } 452 if (rc) { 453 base_asce_free(asce); 454 asce = 0; 455 } 456 return asce; 457 } 458