1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * This file contains the routines for handling the MMU on those 4 * PowerPC implementations where the MMU substantially follows the 5 * architecture specification. This includes the 6xx, 7xx, 7xxx, 6 * and 8260 implementations but excludes the 8xx and 4xx. 7 * -- paulus 8 * 9 * Derived from arch/ppc/mm/init.c: 10 * Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org) 11 * 12 * Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au) 13 * and Cort Dougan (PReP) (cort@cs.nmt.edu) 14 * Copyright (C) 1996 Paul Mackerras 15 * 16 * Derived from "arch/i386/mm/init.c" 17 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds 18 */ 19 20 #include <linux/kernel.h> 21 #include <linux/mm.h> 22 #include <linux/init.h> 23 #include <linux/highmem.h> 24 #include <linux/memblock.h> 25 26 #include <asm/prom.h> 27 #include <asm/mmu.h> 28 #include <asm/machdep.h> 29 #include <asm/code-patching.h> 30 #include <asm/sections.h> 31 32 #include <mm/mmu_decl.h> 33 34 u8 __initdata early_hash[SZ_256K] __aligned(SZ_256K) = {0}; 35 36 static struct hash_pte __initdata *Hash = (struct hash_pte *)early_hash; 37 static unsigned long __initdata Hash_size, Hash_mask; 38 static unsigned int __initdata hash_mb, hash_mb2; 39 unsigned long __initdata _SDR1; 40 41 struct ppc_bat BATS[8][2]; /* 8 pairs of IBAT, DBAT */ 42 43 static struct batrange { /* stores address ranges mapped by BATs */ 44 unsigned long start; 45 unsigned long limit; 46 phys_addr_t phys; 47 } bat_addrs[8]; 48 49 #ifdef CONFIG_SMP 50 unsigned long mmu_hash_lock; 51 #endif 52 53 /* 54 * Return PA for this VA if it is mapped by a BAT, or 0 55 */ 56 phys_addr_t v_block_mapped(unsigned long va) 57 { 58 int b; 59 for (b = 0; b < ARRAY_SIZE(bat_addrs); ++b) 60 if (va >= bat_addrs[b].start && va < bat_addrs[b].limit) 61 return bat_addrs[b].phys + (va - bat_addrs[b].start); 62 return 0; 63 } 64 65 /* 66 * Return VA for a given PA or 0 if not mapped 67 */ 68 unsigned long p_block_mapped(phys_addr_t pa) 69 { 70 int b; 71 for (b = 0; b < ARRAY_SIZE(bat_addrs); ++b) 72 if (pa >= bat_addrs[b].phys 73 && pa < (bat_addrs[b].limit-bat_addrs[b].start) 74 +bat_addrs[b].phys) 75 return bat_addrs[b].start+(pa-bat_addrs[b].phys); 76 return 0; 77 } 78 79 static int find_free_bat(void) 80 { 81 int b; 82 int n = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4; 83 84 for (b = 0; b < n; b++) { 85 struct ppc_bat *bat = BATS[b]; 86 87 if (!(bat[1].batu & 3)) 88 return b; 89 } 90 return -1; 91 } 92 93 /* 94 * This function calculates the size of the larger block usable to map the 95 * beginning of an area based on the start address and size of that area: 96 * - max block size is 256 on 6xx. 97 * - base address must be aligned to the block size. So the maximum block size 98 * is identified by the lowest bit set to 1 in the base address (for instance 99 * if base is 0x16000000, max size is 0x02000000). 100 * - block size has to be a power of two. This is calculated by finding the 101 * highest bit set to 1. 102 */ 103 static unsigned int block_size(unsigned long base, unsigned long top) 104 { 105 unsigned int max_size = SZ_256M; 106 unsigned int base_shift = (ffs(base) - 1) & 31; 107 unsigned int block_shift = (fls(top - base) - 1) & 31; 108 109 return min3(max_size, 1U << base_shift, 1U << block_shift); 110 } 111 112 /* 113 * Set up one of the IBAT (block address translation) register pairs. 114 * The parameters are not checked; in particular size must be a power 115 * of 2 between 128k and 256M. 116 */ 117 static void setibat(int index, unsigned long virt, phys_addr_t phys, 118 unsigned int size, pgprot_t prot) 119 { 120 unsigned int bl = (size >> 17) - 1; 121 int wimgxpp; 122 struct ppc_bat *bat = BATS[index]; 123 unsigned long flags = pgprot_val(prot); 124 125 if (!cpu_has_feature(CPU_FTR_NEED_COHERENT)) 126 flags &= ~_PAGE_COHERENT; 127 128 wimgxpp = (flags & _PAGE_COHERENT) | (_PAGE_EXEC ? BPP_RX : BPP_XX); 129 bat[0].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */ 130 bat[0].batl = BAT_PHYS_ADDR(phys) | wimgxpp; 131 if (flags & _PAGE_USER) 132 bat[0].batu |= 1; /* Vp = 1 */ 133 } 134 135 static void clearibat(int index) 136 { 137 struct ppc_bat *bat = BATS[index]; 138 139 bat[0].batu = 0; 140 bat[0].batl = 0; 141 } 142 143 static unsigned long __init __mmu_mapin_ram(unsigned long base, unsigned long top) 144 { 145 int idx; 146 147 while ((idx = find_free_bat()) != -1 && base != top) { 148 unsigned int size = block_size(base, top); 149 150 if (size < 128 << 10) 151 break; 152 setbat(idx, PAGE_OFFSET + base, base, size, PAGE_KERNEL_X); 153 base += size; 154 } 155 156 return base; 157 } 158 159 unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top) 160 { 161 unsigned long done; 162 unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET; 163 164 165 if (debug_pagealloc_enabled() || __map_without_bats) { 166 pr_debug_once("Read-Write memory mapped without BATs\n"); 167 if (base >= border) 168 return base; 169 if (top >= border) 170 top = border; 171 } 172 173 if (!strict_kernel_rwx_enabled() || base >= border || top <= border) 174 return __mmu_mapin_ram(base, top); 175 176 done = __mmu_mapin_ram(base, border); 177 if (done != border) 178 return done; 179 180 return __mmu_mapin_ram(border, top); 181 } 182 183 static bool is_module_segment(unsigned long addr) 184 { 185 if (!IS_ENABLED(CONFIG_MODULES)) 186 return false; 187 #ifdef MODULES_VADDR 188 if (addr < ALIGN_DOWN(MODULES_VADDR, SZ_256M)) 189 return false; 190 if (addr > ALIGN(MODULES_END, SZ_256M) - 1) 191 return false; 192 #else 193 if (addr < ALIGN_DOWN(VMALLOC_START, SZ_256M)) 194 return false; 195 if (addr > ALIGN(VMALLOC_END, SZ_256M) - 1) 196 return false; 197 #endif 198 return true; 199 } 200 201 void mmu_mark_initmem_nx(void) 202 { 203 int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4; 204 int i; 205 unsigned long base = (unsigned long)_stext - PAGE_OFFSET; 206 unsigned long top = (unsigned long)_etext - PAGE_OFFSET; 207 unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET; 208 unsigned long size; 209 210 for (i = 0; i < nb - 1 && base < top && top - base > (128 << 10);) { 211 size = block_size(base, top); 212 setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT); 213 base += size; 214 } 215 if (base < top) { 216 size = block_size(base, top); 217 size = max(size, 128UL << 10); 218 if ((top - base) > size) { 219 size <<= 1; 220 if (strict_kernel_rwx_enabled() && base + size > border) 221 pr_warn("Some RW data is getting mapped X. " 222 "Adjust CONFIG_DATA_SHIFT to avoid that.\n"); 223 } 224 setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT); 225 base += size; 226 } 227 for (; i < nb; i++) 228 clearibat(i); 229 230 update_bats(); 231 232 for (i = TASK_SIZE >> 28; i < 16; i++) { 233 /* Do not set NX on VM space for modules */ 234 if (is_module_segment(i << 28)) 235 continue; 236 237 mtsr(mfsr(i << 28) | 0x10000000, i << 28); 238 } 239 } 240 241 void mmu_mark_rodata_ro(void) 242 { 243 int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4; 244 int i; 245 246 for (i = 0; i < nb; i++) { 247 struct ppc_bat *bat = BATS[i]; 248 249 if (bat_addrs[i].start < (unsigned long)__init_begin) 250 bat[1].batl = (bat[1].batl & ~BPP_RW) | BPP_RX; 251 } 252 253 update_bats(); 254 } 255 256 /* 257 * Set up one of the I/D BAT (block address translation) register pairs. 258 * The parameters are not checked; in particular size must be a power 259 * of 2 between 128k and 256M. 260 * On 603+, only set IBAT when _PAGE_EXEC is set 261 */ 262 void __init setbat(int index, unsigned long virt, phys_addr_t phys, 263 unsigned int size, pgprot_t prot) 264 { 265 unsigned int bl; 266 int wimgxpp; 267 struct ppc_bat *bat; 268 unsigned long flags = pgprot_val(prot); 269 270 if (index == -1) 271 index = find_free_bat(); 272 if (index == -1) { 273 pr_err("%s: no BAT available for mapping 0x%llx\n", __func__, 274 (unsigned long long)phys); 275 return; 276 } 277 bat = BATS[index]; 278 279 if ((flags & _PAGE_NO_CACHE) || 280 (cpu_has_feature(CPU_FTR_NEED_COHERENT) == 0)) 281 flags &= ~_PAGE_COHERENT; 282 283 bl = (size >> 17) - 1; 284 /* Do DBAT first */ 285 wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE 286 | _PAGE_COHERENT | _PAGE_GUARDED); 287 wimgxpp |= (flags & _PAGE_RW)? BPP_RW: BPP_RX; 288 bat[1].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */ 289 bat[1].batl = BAT_PHYS_ADDR(phys) | wimgxpp; 290 if (flags & _PAGE_USER) 291 bat[1].batu |= 1; /* Vp = 1 */ 292 if (flags & _PAGE_GUARDED) { 293 /* G bit must be zero in IBATs */ 294 flags &= ~_PAGE_EXEC; 295 } 296 if (flags & _PAGE_EXEC) 297 bat[0] = bat[1]; 298 else 299 bat[0].batu = bat[0].batl = 0; 300 301 bat_addrs[index].start = virt; 302 bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1; 303 bat_addrs[index].phys = phys; 304 } 305 306 /* 307 * Preload a translation in the hash table 308 */ 309 static void hash_preload(struct mm_struct *mm, unsigned long ea) 310 { 311 pmd_t *pmd; 312 313 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE)) 314 return; 315 pmd = pmd_off(mm, ea); 316 if (!pmd_none(*pmd)) 317 add_hash_page(mm->context.id, ea, pmd_val(*pmd)); 318 } 319 320 /* 321 * This is called at the end of handling a user page fault, when the 322 * fault has been handled by updating a PTE in the linux page tables. 323 * We use it to preload an HPTE into the hash table corresponding to 324 * the updated linux PTE. 325 * 326 * This must always be called with the pte lock held. 327 */ 328 void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, 329 pte_t *ptep) 330 { 331 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE)) 332 return; 333 /* 334 * We don't need to worry about _PAGE_PRESENT here because we are 335 * called with either mm->page_table_lock held or ptl lock held 336 */ 337 338 /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */ 339 if (!pte_young(*ptep) || address >= TASK_SIZE) 340 return; 341 342 /* We have to test for regs NULL since init will get here first thing at boot */ 343 if (!current->thread.regs) 344 return; 345 346 /* We also avoid filling the hash if not coming from a fault */ 347 if (TRAP(current->thread.regs) != 0x300 && TRAP(current->thread.regs) != 0x400) 348 return; 349 350 hash_preload(vma->vm_mm, address); 351 } 352 353 /* 354 * Initialize the hash table and patch the instructions in hashtable.S. 355 */ 356 void __init MMU_init_hw(void) 357 { 358 unsigned int n_hpteg, lg_n_hpteg; 359 360 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE)) 361 return; 362 363 if ( ppc_md.progress ) ppc_md.progress("hash:enter", 0x105); 364 365 #define LG_HPTEG_SIZE 6 /* 64 bytes per HPTEG */ 366 #define SDR1_LOW_BITS ((n_hpteg - 1) >> 10) 367 #define MIN_N_HPTEG 1024 /* min 64kB hash table */ 368 369 /* 370 * Allow 1 HPTE (1/8 HPTEG) for each page of memory. 371 * This is less than the recommended amount, but then 372 * Linux ain't AIX. 373 */ 374 n_hpteg = total_memory / (PAGE_SIZE * 8); 375 if (n_hpteg < MIN_N_HPTEG) 376 n_hpteg = MIN_N_HPTEG; 377 lg_n_hpteg = __ilog2(n_hpteg); 378 if (n_hpteg & (n_hpteg - 1)) { 379 ++lg_n_hpteg; /* round up if not power of 2 */ 380 n_hpteg = 1 << lg_n_hpteg; 381 } 382 Hash_size = n_hpteg << LG_HPTEG_SIZE; 383 384 /* 385 * Find some memory for the hash table. 386 */ 387 if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322); 388 Hash = memblock_alloc(Hash_size, Hash_size); 389 if (!Hash) 390 panic("%s: Failed to allocate %lu bytes align=0x%lx\n", 391 __func__, Hash_size, Hash_size); 392 _SDR1 = __pa(Hash) | SDR1_LOW_BITS; 393 394 pr_info("Total memory = %lldMB; using %ldkB for hash table\n", 395 (unsigned long long)(total_memory >> 20), Hash_size >> 10); 396 397 398 Hash_mask = n_hpteg - 1; 399 hash_mb2 = hash_mb = 32 - LG_HPTEG_SIZE - lg_n_hpteg; 400 if (lg_n_hpteg > 16) 401 hash_mb2 = 16 - LG_HPTEG_SIZE; 402 } 403 404 void __init MMU_init_hw_patch(void) 405 { 406 unsigned int hmask = Hash_mask >> (16 - LG_HPTEG_SIZE); 407 unsigned int hash = (unsigned int)Hash - PAGE_OFFSET; 408 409 if (!mmu_has_feature(MMU_FTR_HPTE_TABLE)) 410 return; 411 412 if (ppc_md.progress) 413 ppc_md.progress("hash:patch", 0x345); 414 if (ppc_md.progress) 415 ppc_md.progress("hash:done", 0x205); 416 417 /* WARNING: Make sure nothing can trigger a KASAN check past this point */ 418 419 /* 420 * Patch up the instructions in hashtable.S:create_hpte 421 */ 422 modify_instruction_site(&patch__hash_page_A0, 0xffff, hash >> 16); 423 modify_instruction_site(&patch__hash_page_A1, 0x7c0, hash_mb << 6); 424 modify_instruction_site(&patch__hash_page_A2, 0x7c0, hash_mb2 << 6); 425 modify_instruction_site(&patch__hash_page_B, 0xffff, hmask); 426 modify_instruction_site(&patch__hash_page_C, 0xffff, hmask); 427 428 /* 429 * Patch up the instructions in hashtable.S:flush_hash_page 430 */ 431 modify_instruction_site(&patch__flush_hash_A0, 0xffff, hash >> 16); 432 modify_instruction_site(&patch__flush_hash_A1, 0x7c0, hash_mb << 6); 433 modify_instruction_site(&patch__flush_hash_A2, 0x7c0, hash_mb2 << 6); 434 modify_instruction_site(&patch__flush_hash_B, 0xffff, hmask); 435 } 436 437 void setup_initial_memory_limit(phys_addr_t first_memblock_base, 438 phys_addr_t first_memblock_size) 439 { 440 /* We don't currently support the first MEMBLOCK not mapping 0 441 * physical on those processors 442 */ 443 BUG_ON(first_memblock_base != 0); 444 445 memblock_set_current_limit(min_t(u64, first_memblock_size, SZ_256M)); 446 } 447 448 void __init print_system_hash_info(void) 449 { 450 pr_info("Hash_size = 0x%lx\n", Hash_size); 451 if (Hash_mask) 452 pr_info("Hash_mask = 0x%lx\n", Hash_mask); 453 } 454 455 #ifdef CONFIG_PPC_KUEP 456 void __init setup_kuep(bool disabled) 457 { 458 pr_info("Activating Kernel Userspace Execution Prevention\n"); 459 460 if (disabled) 461 pr_warn("KUEP cannot be disabled yet on 6xx when compiled in\n"); 462 } 463 #endif 464 465 #ifdef CONFIG_PPC_KUAP 466 void __init setup_kuap(bool disabled) 467 { 468 pr_info("Activating Kernel Userspace Access Protection\n"); 469 470 if (disabled) 471 pr_warn("KUAP cannot be disabled yet on 6xx when compiled in\n"); 472 } 473 #endif 474 475 void __init early_init_mmu(void) 476 { 477 } 478