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/rsi.h> 45 #include <asm/sections.h> 46 #include <asm/setup.h> 47 #include <linux/sizes.h> 48 #include <asm/tlb.h> 49 #include <asm/alternative.h> 50 #include <asm/xen/swiotlb-xen.h> 51 52 /* 53 * We need to be able to catch inadvertent references to memstart_addr 54 * that occur (potentially in generic code) before arm64_memblock_init() 55 * executes, which assigns it its actual value. So use a default value 56 * that cannot be mistaken for a real physical address. 57 */ 58 s64 memstart_addr __ro_after_init = -1; 59 EXPORT_SYMBOL(memstart_addr); 60 61 /* 62 * If the corresponding config options are enabled, we create both ZONE_DMA 63 * and ZONE_DMA32. By default ZONE_DMA covers the 32-bit addressable memory 64 * unless restricted on specific platforms (e.g. 30-bit on Raspberry Pi 4). 65 * In such case, ZONE_DMA32 covers the rest of the 32-bit addressable memory, 66 * otherwise it is empty. 67 */ 68 phys_addr_t __ro_after_init arm64_dma_phys_limit; 69 70 /* 71 * To make optimal use of block mappings when laying out the linear 72 * mapping, round down the base of physical memory to a size that can 73 * be mapped efficiently, i.e., either PUD_SIZE (4k granule) or PMD_SIZE 74 * (64k granule), or a multiple that can be mapped using contiguous bits 75 * in the page tables: 32 * PMD_SIZE (16k granule) 76 */ 77 #if defined(CONFIG_ARM64_4K_PAGES) 78 #define ARM64_MEMSTART_SHIFT PUD_SHIFT 79 #elif defined(CONFIG_ARM64_16K_PAGES) 80 #define ARM64_MEMSTART_SHIFT CONT_PMD_SHIFT 81 #else 82 #define ARM64_MEMSTART_SHIFT PMD_SHIFT 83 #endif 84 85 /* 86 * sparsemem vmemmap imposes an additional requirement on the alignment of 87 * memstart_addr, due to the fact that the base of the vmemmap region 88 * has a direct correspondence, and needs to appear sufficiently aligned 89 * in the virtual address space. 90 */ 91 #if ARM64_MEMSTART_SHIFT < SECTION_SIZE_BITS 92 #define ARM64_MEMSTART_ALIGN (1UL << SECTION_SIZE_BITS) 93 #else 94 #define ARM64_MEMSTART_ALIGN (1UL << ARM64_MEMSTART_SHIFT) 95 #endif 96 97 static void __init arch_reserve_crashkernel(void) 98 { 99 unsigned long long low_size = 0; 100 unsigned long long crash_base, crash_size; 101 char *cmdline = boot_command_line; 102 bool high = false; 103 int ret; 104 105 if (!IS_ENABLED(CONFIG_CRASH_RESERVE)) 106 return; 107 108 ret = parse_crashkernel(cmdline, memblock_phys_mem_size(), 109 &crash_size, &crash_base, 110 &low_size, &high); 111 if (ret) 112 return; 113 114 reserve_crashkernel_generic(cmdline, crash_size, crash_base, 115 low_size, high); 116 } 117 118 static phys_addr_t __init max_zone_phys(phys_addr_t zone_limit) 119 { 120 return min(zone_limit, memblock_end_of_DRAM() - 1) + 1; 121 } 122 123 static void __init zone_sizes_init(void) 124 { 125 unsigned long max_zone_pfns[MAX_NR_ZONES] = {0}; 126 phys_addr_t __maybe_unused acpi_zone_dma_limit; 127 phys_addr_t __maybe_unused dt_zone_dma_limit; 128 phys_addr_t __maybe_unused dma32_phys_limit = 129 max_zone_phys(DMA_BIT_MASK(32)); 130 131 #ifdef CONFIG_ZONE_DMA 132 acpi_zone_dma_limit = acpi_iort_dma_get_max_cpu_address(); 133 dt_zone_dma_limit = of_dma_get_max_cpu_address(NULL); 134 zone_dma_limit = min(dt_zone_dma_limit, acpi_zone_dma_limit); 135 /* 136 * Information we get from firmware (e.g. DT dma-ranges) describe DMA 137 * bus constraints. Devices using DMA might have their own limitations. 138 * Some of them rely on DMA zone in low 32-bit memory. Keep low RAM 139 * DMA zone on platforms that have RAM there. 140 */ 141 if (memblock_start_of_DRAM() < U32_MAX) 142 zone_dma_limit = min(zone_dma_limit, U32_MAX); 143 arm64_dma_phys_limit = max_zone_phys(zone_dma_limit); 144 max_zone_pfns[ZONE_DMA] = PFN_DOWN(arm64_dma_phys_limit); 145 #endif 146 #ifdef CONFIG_ZONE_DMA32 147 max_zone_pfns[ZONE_DMA32] = PFN_DOWN(dma32_phys_limit); 148 if (!arm64_dma_phys_limit) 149 arm64_dma_phys_limit = dma32_phys_limit; 150 #endif 151 if (!arm64_dma_phys_limit) 152 arm64_dma_phys_limit = PHYS_MASK + 1; 153 max_zone_pfns[ZONE_NORMAL] = max_pfn; 154 155 free_area_init(max_zone_pfns); 156 } 157 158 int pfn_is_map_memory(unsigned long pfn) 159 { 160 phys_addr_t addr = PFN_PHYS(pfn); 161 162 /* avoid false positives for bogus PFNs, see comment in pfn_valid() */ 163 if (PHYS_PFN(addr) != pfn) 164 return 0; 165 166 return memblock_is_map_memory(addr); 167 } 168 EXPORT_SYMBOL(pfn_is_map_memory); 169 170 static phys_addr_t memory_limit __ro_after_init = PHYS_ADDR_MAX; 171 172 /* 173 * Limit the memory size that was specified via FDT. 174 */ 175 static int __init early_mem(char *p) 176 { 177 if (!p) 178 return 1; 179 180 memory_limit = memparse(p, &p) & PAGE_MASK; 181 pr_notice("Memory limited to %lldMB\n", memory_limit >> 20); 182 183 return 0; 184 } 185 early_param("mem", early_mem); 186 187 void __init arm64_memblock_init(void) 188 { 189 s64 linear_region_size = PAGE_END - _PAGE_OFFSET(vabits_actual); 190 191 /* 192 * Corner case: 52-bit VA capable systems running KVM in nVHE mode may 193 * be limited in their ability to support a linear map that exceeds 51 194 * bits of VA space, depending on the placement of the ID map. Given 195 * that the placement of the ID map may be randomized, let's simply 196 * limit the kernel's linear map to 51 bits as well if we detect this 197 * configuration. 198 */ 199 if (IS_ENABLED(CONFIG_KVM) && vabits_actual == 52 && 200 is_hyp_mode_available() && !is_kernel_in_hyp_mode()) { 201 pr_info("Capping linear region to 51 bits for KVM in nVHE mode on LVA capable hardware.\n"); 202 linear_region_size = min_t(u64, linear_region_size, BIT(51)); 203 } 204 205 /* Remove memory above our supported physical address size */ 206 memblock_remove(1ULL << PHYS_MASK_SHIFT, ULLONG_MAX); 207 208 /* 209 * Select a suitable value for the base of physical memory. 210 */ 211 memstart_addr = round_down(memblock_start_of_DRAM(), 212 ARM64_MEMSTART_ALIGN); 213 214 if ((memblock_end_of_DRAM() - memstart_addr) > linear_region_size) 215 pr_warn("Memory doesn't fit in the linear mapping, VA_BITS too small\n"); 216 217 /* 218 * Remove the memory that we will not be able to cover with the 219 * linear mapping. Take care not to clip the kernel which may be 220 * high in memory. 221 */ 222 memblock_remove(max_t(u64, memstart_addr + linear_region_size, 223 __pa_symbol(_end)), ULLONG_MAX); 224 if (memstart_addr + linear_region_size < memblock_end_of_DRAM()) { 225 /* ensure that memstart_addr remains sufficiently aligned */ 226 memstart_addr = round_up(memblock_end_of_DRAM() - linear_region_size, 227 ARM64_MEMSTART_ALIGN); 228 memblock_remove(0, memstart_addr); 229 } 230 231 /* 232 * If we are running with a 52-bit kernel VA config on a system that 233 * does not support it, we have to place the available physical 234 * memory in the 48-bit addressable part of the linear region, i.e., 235 * we have to move it upward. Since memstart_addr represents the 236 * physical address of PAGE_OFFSET, we have to *subtract* from it. 237 */ 238 if (IS_ENABLED(CONFIG_ARM64_VA_BITS_52) && (vabits_actual != 52)) 239 memstart_addr -= _PAGE_OFFSET(vabits_actual) - _PAGE_OFFSET(52); 240 241 /* 242 * Apply the memory limit if it was set. Since the kernel may be loaded 243 * high up in memory, add back the kernel region that must be accessible 244 * via the linear mapping. 245 */ 246 if (memory_limit != PHYS_ADDR_MAX) { 247 memblock_mem_limit_remove_map(memory_limit); 248 memblock_add(__pa_symbol(_text), (u64)(_end - _text)); 249 } 250 251 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) { 252 /* 253 * Add back the memory we just removed if it results in the 254 * initrd to become inaccessible via the linear mapping. 255 * Otherwise, this is a no-op 256 */ 257 u64 base = phys_initrd_start & PAGE_MASK; 258 u64 size = PAGE_ALIGN(phys_initrd_start + phys_initrd_size) - base; 259 260 /* 261 * We can only add back the initrd memory if we don't end up 262 * with more memory than we can address via the linear mapping. 263 * It is up to the bootloader to position the kernel and the 264 * initrd reasonably close to each other (i.e., within 32 GB of 265 * each other) so that all granule/#levels combinations can 266 * always access both. 267 */ 268 if (WARN(base < memblock_start_of_DRAM() || 269 base + size > memblock_start_of_DRAM() + 270 linear_region_size, 271 "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) { 272 phys_initrd_size = 0; 273 } else { 274 memblock_add(base, size); 275 memblock_clear_nomap(base, size); 276 memblock_reserve(base, size); 277 } 278 } 279 280 if (IS_ENABLED(CONFIG_RANDOMIZE_BASE)) { 281 extern u16 memstart_offset_seed; 282 u64 mmfr0 = read_cpuid(ID_AA64MMFR0_EL1); 283 int parange = cpuid_feature_extract_unsigned_field( 284 mmfr0, ID_AA64MMFR0_EL1_PARANGE_SHIFT); 285 s64 range = linear_region_size - 286 BIT(id_aa64mmfr0_parange_to_phys_shift(parange)); 287 288 /* 289 * If the size of the linear region exceeds, by a sufficient 290 * margin, the size of the region that the physical memory can 291 * span, randomize the linear region as well. 292 */ 293 if (memstart_offset_seed > 0 && range >= (s64)ARM64_MEMSTART_ALIGN) { 294 range /= ARM64_MEMSTART_ALIGN; 295 memstart_addr -= ARM64_MEMSTART_ALIGN * 296 ((range * memstart_offset_seed) >> 16); 297 } 298 } 299 300 /* 301 * Register the kernel text, kernel data, initrd, and initial 302 * pagetables with memblock. 303 */ 304 memblock_reserve(__pa_symbol(_stext), _end - _stext); 305 if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && phys_initrd_size) { 306 /* the generic initrd code expects virtual addresses */ 307 initrd_start = __phys_to_virt(phys_initrd_start); 308 initrd_end = initrd_start + phys_initrd_size; 309 } 310 311 early_init_fdt_scan_reserved_mem(); 312 313 high_memory = __va(memblock_end_of_DRAM() - 1) + 1; 314 } 315 316 void __init bootmem_init(void) 317 { 318 unsigned long min, max; 319 320 min = PFN_UP(memblock_start_of_DRAM()); 321 max = PFN_DOWN(memblock_end_of_DRAM()); 322 323 early_memtest(min << PAGE_SHIFT, max << PAGE_SHIFT); 324 325 max_pfn = max_low_pfn = max; 326 min_low_pfn = min; 327 328 arch_numa_init(); 329 330 /* 331 * must be done after arch_numa_init() which calls numa_init() to 332 * initialize node_online_map that gets used in hugetlb_cma_reserve() 333 * while allocating required CMA size across online nodes. 334 */ 335 #if defined(CONFIG_HUGETLB_PAGE) && defined(CONFIG_CMA) 336 arm64_hugetlb_cma_reserve(); 337 #endif 338 339 kvm_hyp_reserve(); 340 341 /* 342 * sparse_init() tries to allocate memory from memblock, so must be 343 * done after the fixed reservations 344 */ 345 sparse_init(); 346 zone_sizes_init(); 347 348 /* 349 * Reserve the CMA area after arm64_dma_phys_limit was initialised. 350 */ 351 dma_contiguous_reserve(arm64_dma_phys_limit); 352 353 /* 354 * request_standard_resources() depends on crashkernel's memory being 355 * reserved, so do it here. 356 */ 357 arch_reserve_crashkernel(); 358 359 memblock_dump_all(); 360 } 361 362 /* 363 * mem_init() marks the free areas in the mem_map and tells us how much memory 364 * is free. This is done after various parts of the system have claimed their 365 * memory after the kernel image. 366 */ 367 void __init mem_init(void) 368 { 369 unsigned int flags = SWIOTLB_VERBOSE; 370 bool swiotlb = max_pfn > PFN_DOWN(arm64_dma_phys_limit); 371 372 if (is_realm_world()) { 373 swiotlb = true; 374 flags |= SWIOTLB_FORCE; 375 } 376 377 if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && !swiotlb) { 378 /* 379 * If no bouncing needed for ZONE_DMA, reduce the swiotlb 380 * buffer for kmalloc() bouncing to 1MB per 1GB of RAM. 381 */ 382 unsigned long size = 383 DIV_ROUND_UP(memblock_phys_mem_size(), 1024); 384 swiotlb_adjust_size(min(swiotlb_size_or_default(), size)); 385 swiotlb = true; 386 } 387 388 swiotlb_init(swiotlb, flags); 389 swiotlb_update_mem_attributes(); 390 391 /* this will put all unused low memory onto the freelists */ 392 memblock_free_all(); 393 394 /* 395 * Check boundaries twice: Some fundamental inconsistencies can be 396 * detected at build time already. 397 */ 398 #ifdef CONFIG_COMPAT 399 BUILD_BUG_ON(TASK_SIZE_32 > DEFAULT_MAP_WINDOW_64); 400 #endif 401 402 /* 403 * Selected page table levels should match when derived from 404 * scratch using the virtual address range and page size. 405 */ 406 BUILD_BUG_ON(ARM64_HW_PGTABLE_LEVELS(CONFIG_ARM64_VA_BITS) != 407 CONFIG_PGTABLE_LEVELS); 408 409 if (PAGE_SIZE >= 16384 && get_num_physpages() <= 128) { 410 extern int sysctl_overcommit_memory; 411 /* 412 * On a machine this small we won't get anywhere without 413 * overcommit, so turn it on by default. 414 */ 415 sysctl_overcommit_memory = OVERCOMMIT_ALWAYS; 416 } 417 } 418 419 void free_initmem(void) 420 { 421 void *lm_init_begin = lm_alias(__init_begin); 422 void *lm_init_end = lm_alias(__init_end); 423 424 WARN_ON(!IS_ALIGNED((unsigned long)lm_init_begin, PAGE_SIZE)); 425 WARN_ON(!IS_ALIGNED((unsigned long)lm_init_end, PAGE_SIZE)); 426 427 /* Delete __init region from memblock.reserved. */ 428 memblock_free(lm_init_begin, lm_init_end - lm_init_begin); 429 430 free_reserved_area(lm_init_begin, lm_init_end, 431 POISON_FREE_INITMEM, "unused kernel"); 432 /* 433 * Unmap the __init region but leave the VM area in place. This 434 * prevents the region from being reused for kernel modules, which 435 * is not supported by kallsyms. 436 */ 437 vunmap_range((u64)__init_begin, (u64)__init_end); 438 } 439 440 void dump_mem_limit(void) 441 { 442 if (memory_limit != PHYS_ADDR_MAX) { 443 pr_emerg("Memory Limit: %llu MB\n", memory_limit >> 20); 444 } else { 445 pr_emerg("Memory Limit: none\n"); 446 } 447 } 448 449 #ifdef CONFIG_EXECMEM 450 static u64 module_direct_base __ro_after_init = 0; 451 static u64 module_plt_base __ro_after_init = 0; 452 453 /* 454 * Choose a random page-aligned base address for a window of 'size' bytes which 455 * entirely contains the interval [start, end - 1]. 456 */ 457 static u64 __init random_bounding_box(u64 size, u64 start, u64 end) 458 { 459 u64 max_pgoff, pgoff; 460 461 if ((end - start) >= size) 462 return 0; 463 464 max_pgoff = (size - (end - start)) / PAGE_SIZE; 465 pgoff = get_random_u32_inclusive(0, max_pgoff); 466 467 return start - pgoff * PAGE_SIZE; 468 } 469 470 /* 471 * Modules may directly reference data and text anywhere within the kernel 472 * image and other modules. References using PREL32 relocations have a +/-2G 473 * range, and so we need to ensure that the entire kernel image and all modules 474 * fall within a 2G window such that these are always within range. 475 * 476 * Modules may directly branch to functions and code within the kernel text, 477 * and to functions and code within other modules. These branches will use 478 * CALL26/JUMP26 relocations with a +/-128M range. Without PLTs, we must ensure 479 * that the entire kernel text and all module text falls within a 128M window 480 * such that these are always within range. With PLTs, we can expand this to a 481 * 2G window. 482 * 483 * We chose the 128M region to surround the entire kernel image (rather than 484 * just the text) as using the same bounds for the 128M and 2G regions ensures 485 * by construction that we never select a 128M region that is not a subset of 486 * the 2G region. For very large and unusual kernel configurations this means 487 * we may fall back to PLTs where they could have been avoided, but this keeps 488 * the logic significantly simpler. 489 */ 490 static int __init module_init_limits(void) 491 { 492 u64 kernel_end = (u64)_end; 493 u64 kernel_start = (u64)_text; 494 u64 kernel_size = kernel_end - kernel_start; 495 496 /* 497 * The default modules region is placed immediately below the kernel 498 * image, and is large enough to use the full 2G relocation range. 499 */ 500 BUILD_BUG_ON(KIMAGE_VADDR != MODULES_END); 501 BUILD_BUG_ON(MODULES_VSIZE < SZ_2G); 502 503 if (!kaslr_enabled()) { 504 if (kernel_size < SZ_128M) 505 module_direct_base = kernel_end - SZ_128M; 506 if (kernel_size < SZ_2G) 507 module_plt_base = kernel_end - SZ_2G; 508 } else { 509 u64 min = kernel_start; 510 u64 max = kernel_end; 511 512 if (IS_ENABLED(CONFIG_RANDOMIZE_MODULE_REGION_FULL)) { 513 pr_info("2G module region forced by RANDOMIZE_MODULE_REGION_FULL\n"); 514 } else { 515 module_direct_base = random_bounding_box(SZ_128M, min, max); 516 if (module_direct_base) { 517 min = module_direct_base; 518 max = module_direct_base + SZ_128M; 519 } 520 } 521 522 module_plt_base = random_bounding_box(SZ_2G, min, max); 523 } 524 525 pr_info("%llu pages in range for non-PLT usage", 526 module_direct_base ? (SZ_128M - kernel_size) / PAGE_SIZE : 0); 527 pr_info("%llu pages in range for PLT usage", 528 module_plt_base ? (SZ_2G - kernel_size) / PAGE_SIZE : 0); 529 530 return 0; 531 } 532 533 static struct execmem_info execmem_info __ro_after_init; 534 535 struct execmem_info __init *execmem_arch_setup(void) 536 { 537 unsigned long fallback_start = 0, fallback_end = 0; 538 unsigned long start = 0, end = 0; 539 540 module_init_limits(); 541 542 /* 543 * Where possible, prefer to allocate within direct branch range of the 544 * kernel such that no PLTs are necessary. 545 */ 546 if (module_direct_base) { 547 start = module_direct_base; 548 end = module_direct_base + SZ_128M; 549 550 if (module_plt_base) { 551 fallback_start = module_plt_base; 552 fallback_end = module_plt_base + SZ_2G; 553 } 554 } else if (module_plt_base) { 555 start = module_plt_base; 556 end = module_plt_base + SZ_2G; 557 } 558 559 execmem_info = (struct execmem_info){ 560 .ranges = { 561 [EXECMEM_DEFAULT] = { 562 .start = start, 563 .end = end, 564 .pgprot = PAGE_KERNEL, 565 .alignment = 1, 566 .fallback_start = fallback_start, 567 .fallback_end = fallback_end, 568 }, 569 [EXECMEM_KPROBES] = { 570 .start = VMALLOC_START, 571 .end = VMALLOC_END, 572 .pgprot = PAGE_KERNEL_ROX, 573 .alignment = 1, 574 }, 575 [EXECMEM_BPF] = { 576 .start = VMALLOC_START, 577 .end = VMALLOC_END, 578 .pgprot = PAGE_KERNEL, 579 .alignment = 1, 580 }, 581 }, 582 }; 583 584 return &execmem_info; 585 } 586 #endif /* CONFIG_EXECMEM */ 587