1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Based on arch/arm/mm/init.c 4 * 5 * Copyright (C) 1995-2005 Russell King 6 * Copyright (C) 2012 ARM Ltd. 7 */ 8 9 #include <linux/kernel.h> 10 #include <linux/export.h> 11 #include <linux/errno.h> 12 #include <linux/swap.h> 13 #include <linux/init.h> 14 #include <linux/cache.h> 15 #include <linux/mman.h> 16 #include <linux/nodemask.h> 17 #include <linux/initrd.h> 18 #include <linux/gfp.h> 19 #include <linux/math.h> 20 #include <linux/memblock.h> 21 #include <linux/sort.h> 22 #include <linux/of.h> 23 #include <linux/of_fdt.h> 24 #include <linux/dma-direct.h> 25 #include <linux/dma-map-ops.h> 26 #include <linux/efi.h> 27 #include <linux/swiotlb.h> 28 #include <linux/vmalloc.h> 29 #include <linux/mm.h> 30 #include <linux/kexec.h> 31 #include <linux/crash_dump.h> 32 #include <linux/hugetlb.h> 33 #include <linux/acpi_iort.h> 34 #include <linux/kmemleak.h> 35 #include <linux/execmem.h> 36 37 #include <asm/boot.h> 38 #include <asm/fixmap.h> 39 #include <asm/kasan.h> 40 #include <asm/kernel-pgtable.h> 41 #include <asm/kvm_host.h> 42 #include <asm/memory.h> 43 #include <asm/numa.h> 44 #include <asm/sections.h> 45 #include <asm/setup.h> 46 #include <linux/sizes.h> 47 #include <asm/tlb.h> 48 #include <asm/alternative.h> 49 #include <asm/xen/swiotlb-xen.h> 50 51 /* 52 * We need to be able to catch inadvertent references to memstart_addr 53 * that occur (potentially in generic code) before arm64_memblock_init() 54 * executes, which assigns it its actual value. So use a default value 55 * that cannot be mistaken for a real physical address. 56 */ 57 s64 memstart_addr __ro_after_init = -1; 58 EXPORT_SYMBOL(memstart_addr); 59 60 /* 61 * If the corresponding config options are enabled, we create both ZONE_DMA 62 * and ZONE_DMA32. By default ZONE_DMA covers the 32-bit addressable memory 63 * unless restricted on specific platforms (e.g. 30-bit on Raspberry Pi 4). 64 * In such case, ZONE_DMA32 covers the rest of the 32-bit addressable memory, 65 * otherwise it is empty. 66 */ 67 phys_addr_t __ro_after_init arm64_dma_phys_limit; 68 69 /* 70 * To make optimal use of block mappings when laying out the linear 71 * mapping, round down the base of physical memory to a size that can 72 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE 73 * (64k granule), or a multiple that can be mapped using contiguous bits 74 * in the page tables: 32 * PMD_SIZE (16k granule) 75 */ 76 #if defined(CONFIG_ARM64_4K_PAGES) 77 #define ARM64_MEMSTART_SHIFT PUD_SHIFT 78 #elif defined(CONFIG_ARM64_16K_PAGES) 79 #define ARM64_MEMSTART_SHIFT CONT_PMD_SHIFT 80 #else 81 #define ARM64_MEMSTART_SHIFT PMD_SHIFT 82 #endif 83 84 /* 85 * sparsemem vmemmap imposes an additional requirement on the alignment of 86 * memstart_addr, due to the fact that the base of the vmemmap region 87 * has a direct correspondence, and needs to appear sufficiently aligned 88 * in the virtual address space. 89 */ 90 #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS 91 #define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS) 92 #else 93 #define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT) 94 #endif 95 96 static void __init arch_reserve_crashkernel(void) 97 { 98 unsigned long long low_size = 0; 99 unsigned long long crash_base, crash_size; 100 char *cmdline = boot_command_line; 101 bool high = false; 102 int ret; 103 104 if (!IS_ENABLED(CONFIG_CRASH_RESERVE)) 105 return; 106 107 ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), 108 &crash_size, &crash_base, 109 &low_size, &high); 110 if (ret) 111 return; 112 113 reserve_crashkernel_generic(cmdline, crash_size, crash_base, 114 low_size, high); 115 } 116 117 /* 118 * Return the maximum physical address for a zone accessible by the given bits 119 * limit. If DRAM starts above 32-bit, expand the zone to the maximum 120 * available memory, otherwise cap it at 32-bit. 121 */ 122 static phys_addr_t __init max_zone_phys(unsigned int zone_bits) 123 { 124 phys_addr_t zone_mask = DMA_BIT_MASK(zone_bits); 125 phys_addr_t phys_start = memblock_start_of_DRAM(); 126 127 if (phys_start > U32_MAX) 128 zone_mask = PHYS_ADDR_MAX; 129 else if (phys_start > zone_mask) 130 zone_mask = U32_MAX; 131 132 return min(zone_mask, memblock_end_of_DRAM() - 1) + 1; 133 } 134 135 static void __init zone_sizes_init(void) 136 { 137 unsigned long max_zone_pfns[MAX_NR_ZONES] = {0}; 138 unsigned int __maybe_unused acpi_zone_dma_bits; 139 unsigned int __maybe_unused dt_zone_dma_bits; 140 phys_addr_t __maybe_unused dma32_phys_limit = max_zone_phys(32); 141 142 #ifdef CONFIG_ZONE_DMA 143 acpi_zone_dma_bits = fls64(acpi_iort_dma_get_max_cpu_address()); 144 dt_zone_dma_bits = fls64(of_dma_get_max_cpu_address(NULL)); 145 zone_dma_bits = min3(32U, dt_zone_dma_bits, acpi_zone_dma_bits); 146 arm64_dma_phys_limit = max_zone_phys(zone_dma_bits); 147 max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit); 148 #endif 149 #ifdef CONFIG_ZONE_DMA32 150 max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit); 151 if (!arm64_dma_phys_limit) 152 arm64_dma_phys_limit = dma32_phys_limit; 153 #endif 154 if (!arm64_dma_phys_limit) 155 arm64_dma_phys_limit = PHYS_MASK + 1; 156 max_zone_pfns[ZONE_NORMAL] = max_pfn; 157 158 free_area_init(max_zone_pfns); 159 } 160 161 int pfn_is_map_memory(unsigned long pfn) 162 { 163 phys_addr_t addr = PFN_PHYS(pfn); 164 165 /* avoid false positives for bogus PFNs, see comment in pfn_valid() */ 166 if (PHYS_PFN(addr) != pfn) 167 return 0; 168 169 return memblock_is_map_memory(addr); 170 } 171 EXPORT_SYMBOL(pfn_is_map_memory); 172 173 static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX; 174 175 /* 176 * Limit the memory size that was specified via FDT. 177 */ 178 static int __init early_mem(char *p) 179 { 180 if (!p) 181 return 1; 182 183 memory_limit = memparse(p, &p) & PAGE_MASK; 184 pr_notice("Memory limited to %lldMB\n", memory_limit >> 20); 185 186 return 0; 187 } 188 early_param("mem", early_mem); 189 190 void __init arm64_memblock_init(void) 191 { 192 s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual); 193 194 /* 195 * Corner case: 52-bit VA capable systems running KVM in nVHE mode may 196 * be limited in their ability to support a linear map that exceeds 51 197 * bits of VA space, depending on the placement of the ID map. Given 198 * that the placement of the ID map may be randomized, let's simply 199 * limit the kernel's linear map to 51 bits as well if we detect this 200 * configuration. 201 */ 202 if (IS_ENABLED(CONFIG_KVM) && vabits_actual == 52 && 203 is_hyp_mode_available() && !is_kernel_in_hyp_mode()) { 204 pr_info("Capping linear region to 51 bits for KVM in nVHE mode on LVA capable hardware.\n"); 205 linear_region_size = min_t(u64, linear_region_size, BIT(51)); 206 } 207 208 /* Remove memory above our supported physical address size */ 209 memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX); 210 211 /* 212 * Select a suitable value for the base of physical memory. 213 */ 214 memstart_addr = round_down(memblock_start_of_DRAM(), 215 ARM64_MEMSTART_ALIGN); 216 217 if ((memblock_end_of_DRAM() - memstart_addr) > linear_region_size) 218 pr_warn("Memory doesn't fit in the linear mapping, VA_BITS too small\n"); 219 220 /* 221 * Remove the memory that we will not be able to cover with the 222 * linear mapping. Take care not to clip the kernel which may be 223 * high in memory. 224 */ 225 memblock_remove(max_t(u64, memstart_addr + linear_region_size, 226 __pa_symbol(_end)), ULLONG_MAX); 227 if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) { 228 /* ensure that memstart_addr remains sufficiently aligned */ 229 memstart_addr = round_up(memblock_end_of_DRAM() - linear_region_size, 230 ARM64_MEMSTART_ALIGN); 231 memblock_remove(0, memstart_addr); 232 } 233 234 /* 235 * If we are running with a 52-bit kernel VA config on a system that 236 * does not support it, we have to place the available physical 237 * memory in the 48-bit addressable part of the linear region, i.e., 238 * we have to move it upward. Since memstart_addr represents the 239 * physical address of PAGE_OFFSET, we have to *subtract* from it. 240 */ 241 if (IS_ENABLED(CONFIG_ARM64_VA_BITS_52) && (vabits_actual != 52)) 242 memstart_addr -= _PAGE_OFFSET(vabits_actual) - _PAGE_OFFSET(52); 243 244 /* 245 * Apply the memory limit if it was set. Since the kernel may be loaded 246 * high up in memory, add back the kernel region that must be accessible 247 * via the linear mapping. 248 */ 249 if (memory_limit != PHYS_ADDR_MAX) { 250 memblock_mem_limit_remove_map(memory_limit); 251 memblock_add(__pa_symbol(_text), (u64)(_end - _text)); 252 } 253 254 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) { 255 /* 256 * Add back the memory we just removed if it results in the 257 * initrd to become inaccessible via the linear mapping. 258 * Otherwise, this is a no-op 259 */ 260 u64 base = phys_initrd_start & PAGE_MASK; 261 u64 size = PAGE_ALIGN(phys_initrd_start + phys_initrd_size) - base; 262 263 /* 264 * We can only add back the initrd memory if we don't end up 265 * with more memory than we can address via the linear mapping. 266 * It is up to the bootloader to position the kernel and the 267 * initrd reasonably close to each other (i.e., within 32 GB of 268 * each other) so that all granule/#levels combinations can 269 * always access both. 270 */ 271 if (WARN(base < memblock_start_of_DRAM() || 272 base + size > memblock_start_of_DRAM() + 273 linear_region_size, 274 "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) { 275 phys_initrd_size = 0; 276 } else { 277 memblock_add(base, size); 278 memblock_clear_nomap(base, size); 279 memblock_reserve(base, size); 280 } 281 } 282 283 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 284 extern u16 memstart_offset_seed; 285 u64 mmfr0 = read_cpuid(ID_AA64MMFR0_EL1); 286 int parange = cpuid_feature_extract_unsigned_field( 287 mmfr0, ID_AA64MMFR0_EL1_PARANGE_SHIFT); 288 s64 range = linear_region_size - 289 BIT(id_aa64mmfr0_parange_to_phys_shift(parange)); 290 291 /* 292 * If the size of the linear region exceeds, by a sufficient 293 * margin, the size of the region that the physical memory can 294 * span, randomize the linear region as well. 295 */ 296 if (memstart_offset_seed > 0 && range >= (s64)ARM64_MEMSTART_ALIGN) { 297 range /= ARM64_MEMSTART_ALIGN; 298 memstart_addr -= ARM64_MEMSTART_ALIGN * 299 ((range * memstart_offset_seed) >> 16); 300 } 301 } 302 303 /* 304 * Register the kernel text, kernel data, initrd, and initial 305 * pagetables with memblock. 306 */ 307 memblock_reserve(__pa_symbol(_stext), _end - _stext); 308 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) { 309 /* the generic initrd code expects virtual addresses */ 310 initrd_start = __phys_to_virt(phys_initrd_start); 311 initrd_end = initrd_start + phys_initrd_size; 312 } 313 314 early_init_fdt_scan_reserved_mem(); 315 316 high_memory = __va(memblock_end_of_DRAM() - 1) + 1; 317 } 318 319 void __init bootmem_init(void) 320 { 321 unsigned long min, max; 322 323 min = PFN_UP(memblock_start_of_DRAM()); 324 max = PFN_DOWN(memblock_end_of_DRAM()); 325 326 early_memtest(min << PAGE_SHIFT, max << PAGE_SHIFT); 327 328 max_pfn = max_low_pfn = max; 329 min_low_pfn = min; 330 331 arch_numa_init(); 332 333 /* 334 * must be done after arch_numa_init() which calls numa_init() to 335 * initialize node_online_map that gets used in hugetlb_cma_reserve() 336 * while allocating required CMA size across online nodes. 337 */ 338 #if defined(CONFIG_HUGETLB_PAGE) && defined(CONFIG_CMA) 339 arm64_hugetlb_cma_reserve(); 340 #endif 341 342 kvm_hyp_reserve(); 343 344 /* 345 * sparse_init() tries to allocate memory from memblock, so must be 346 * done after the fixed reservations 347 */ 348 sparse_init(); 349 zone_sizes_init(); 350 351 /* 352 * Reserve the CMA area after arm64_dma_phys_limit was initialised. 353 */ 354 dma_contiguous_reserve(arm64_dma_phys_limit); 355 356 /* 357 * request_standard_resources() depends on crashkernel's memory being 358 * reserved, so do it here. 359 */ 360 arch_reserve_crashkernel(); 361 362 memblock_dump_all(); 363 } 364 365 /* 366 * mem_init() marks the free areas in the mem_map and tells us how much memory 367 * is free. This is done after various parts of the system have claimed their 368 * memory after the kernel image. 369 */ 370 void __init mem_init(void) 371 { 372 bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit); 373 374 if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) { 375 /* 376 * If no bouncing needed for ZONE_DMA, reduce the swiotlb 377 * buffer for kmalloc() bouncing to 1MB per 1GB of RAM. 378 */ 379 unsigned long size = 380 DIV_ROUND_UP(memblock_phys_mem_size(), 1024); 381 swiotlb_adjust_size(min(swiotlb_size_or_default(), size)); 382 swiotlb = true; 383 } 384 385 swiotlb_init(swiotlb, SWIOTLB_VERBOSE); 386 387 /* this will put all unused low memory onto the freelists */ 388 memblock_free_all(); 389 390 /* 391 * Check boundaries twice: Some fundamental inconsistencies can be 392 * detected at build time already. 393 */ 394 #ifdef CONFIG_COMPAT 395 BUILD_BUG_ON(TASK_SIZE_32 > DEFAULT_MAP_WINDOW_64); 396 #endif 397 398 /* 399 * Selected page table levels should match when derived from 400 * scratch using the virtual address range and page size. 401 */ 402 BUILD_BUG_ON(ARM64_HW_PGTABLE_LEVELS(CONFIG_ARM64_VA_BITS) != 403 CONFIG_PGTABLE_LEVELS); 404 405 if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) { 406 extern int sysctl_overcommit_memory; 407 /* 408 * On a machine this small we won't get anywhere without 409 * overcommit, so turn it on by default. 410 */ 411 sysctl_overcommit_memory = OVERCOMMIT_ALWAYS; 412 } 413 } 414 415 void free_initmem(void) 416 { 417 void *lm_init_begin = lm_alias(__init_begin); 418 void *lm_init_end = lm_alias(__init_end); 419 420 WARN_ON(!IS_ALIGNED((unsigned long)lm_init_begin, PAGE_SIZE)); 421 WARN_ON(!IS_ALIGNED((unsigned long)lm_init_end, PAGE_SIZE)); 422 423 /* Delete __init region from memblock.reserved. */ 424 memblock_free(lm_init_begin, lm_init_end - lm_init_begin); 425 426 free_reserved_area(lm_init_begin, lm_init_end, 427 POISON_FREE_INITMEM, "unused kernel"); 428 /* 429 * Unmap the __init region but leave the VM area in place. This 430 * prevents the region from being reused for kernel modules, which 431 * is not supported by kallsyms. 432 */ 433 vunmap_range((u64)__init_begin, (u64)__init_end); 434 } 435 436 void dump_mem_limit(void) 437 { 438 if (memory_limit != PHYS_ADDR_MAX) { 439 pr_emerg("Memory Limit: %llu MB\n", memory_limit >> 20); 440 } else { 441 pr_emerg("Memory Limit: none\n"); 442 } 443 } 444 445 #ifdef CONFIG_EXECMEM 446 static u64 module_direct_base __ro_after_init = 0; 447 static u64 module_plt_base __ro_after_init = 0; 448 449 /* 450 * Choose a random page-aligned base address for a window of 'size' bytes which 451 * entirely contains the interval [start, end - 1]. 452 */ 453 static u64 __init random_bounding_box(u64 size, u64 start, u64 end) 454 { 455 u64 max_pgoff, pgoff; 456 457 if ((end - start) >= size) 458 return 0; 459 460 max_pgoff = (size - (end - start)) / PAGE_SIZE; 461 pgoff = get_random_u32_inclusive(0, max_pgoff); 462 463 return start - pgoff * PAGE_SIZE; 464 } 465 466 /* 467 * Modules may directly reference data and text anywhere within the kernel 468 * image and other modules. References using PREL32 relocations have a +/-2G 469 * range, and so we need to ensure that the entire kernel image and all modules 470 * fall within a 2G window such that these are always within range. 471 * 472 * Modules may directly branch to functions and code within the kernel text, 473 * and to functions and code within other modules. These branches will use 474 * CALL26/JUMP26 relocations with a +/-128M range. Without PLTs, we must ensure 475 * that the entire kernel text and all module text falls within a 128M window 476 * such that these are always within range. With PLTs, we can expand this to a 477 * 2G window. 478 * 479 * We chose the 128M region to surround the entire kernel image (rather than 480 * just the text) as using the same bounds for the 128M and 2G regions ensures 481 * by construction that we never select a 128M region that is not a subset of 482 * the 2G region. For very large and unusual kernel configurations this means 483 * we may fall back to PLTs where they could have been avoided, but this keeps 484 * the logic significantly simpler. 485 */ 486 static int __init module_init_limits(void) 487 { 488 u64 kernel_end = (u64)_end; 489 u64 kernel_start = (u64)_text; 490 u64 kernel_size = kernel_end - kernel_start; 491 492 /* 493 * The default modules region is placed immediately below the kernel 494 * image, and is large enough to use the full 2G relocation range. 495 */ 496 BUILD_BUG_ON(KIMAGE_VADDR != MODULES_END); 497 BUILD_BUG_ON(MODULES_VSIZE < SZ_2G); 498 499 if (!kaslr_enabled()) { 500 if (kernel_size < SZ_128M) 501 module_direct_base = kernel_end - SZ_128M; 502 if (kernel_size < SZ_2G) 503 module_plt_base = kernel_end - SZ_2G; 504 } else { 505 u64 min = kernel_start; 506 u64 max = kernel_end; 507 508 if (IS_ENABLED(CONFIG_RANDOMIZE_MODULE_REGION_FULL)) { 509 pr_info("2G module region forced by RANDOMIZE_MODULE_REGION_FULL\n"); 510 } else { 511 module_direct_base = random_bounding_box(SZ_128M, min, max); 512 if (module_direct_base) { 513 min = module_direct_base; 514 max = module_direct_base + SZ_128M; 515 } 516 } 517 518 module_plt_base = random_bounding_box(SZ_2G, min, max); 519 } 520 521 pr_info("%llu pages in range for non-PLT usage", 522 module_direct_base ? (SZ_128M - kernel_size) / PAGE_SIZE : 0); 523 pr_info("%llu pages in range for PLT usage", 524 module_plt_base ? (SZ_2G - kernel_size) / PAGE_SIZE : 0); 525 526 return 0; 527 } 528 529 static struct execmem_info execmem_info __ro_after_init; 530 531 struct execmem_info __init *execmem_arch_setup(void) 532 { 533 unsigned long fallback_start = 0, fallback_end = 0; 534 unsigned long start = 0, end = 0; 535 536 module_init_limits(); 537 538 /* 539 * Where possible, prefer to allocate within direct branch range of the 540 * kernel such that no PLTs are necessary. 541 */ 542 if (module_direct_base) { 543 start = module_direct_base; 544 end = module_direct_base + SZ_128M; 545 546 if (module_plt_base) { 547 fallback_start = module_plt_base; 548 fallback_end = module_plt_base + SZ_2G; 549 } 550 } else if (module_plt_base) { 551 start = module_plt_base; 552 end = module_plt_base + SZ_2G; 553 } 554 555 execmem_info = (struct execmem_info){ 556 .ranges = { 557 [EXECMEM_DEFAULT] = { 558 .start = start, 559 .end = end, 560 .pgprot = PAGE_KERNEL, 561 .alignment = 1, 562 .fallback_start = fallback_start, 563 .fallback_end = fallback_end, 564 }, 565 [EXECMEM_KPROBES] = { 566 .start = VMALLOC_START, 567 .end = VMALLOC_END, 568 .pgprot = PAGE_KERNEL_ROX, 569 .alignment = 1, 570 }, 571 [EXECMEM_BPF] = { 572 .start = VMALLOC_START, 573 .end = VMALLOC_END, 574 .pgprot = PAGE_KERNEL, 575 .alignment = 1, 576 }, 577 }, 578 }; 579 580 return &execmem_info; 581 } 582 #endif /* CONFIG_EXECMEM */ 583