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