1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * prepare to run common code 4 * 5 * Copyright (C) 2000 Andrea Arcangeli <andrea@suse.de> SuSE 6 */ 7 8 #define DISABLE_BRANCH_PROFILING 9 10 /* cpu_feature_enabled() cannot be used this early */ 11 #define USE_EARLY_PGTABLE_L5 12 13 #include <linux/init.h> 14 #include <linux/linkage.h> 15 #include <linux/types.h> 16 #include <linux/kernel.h> 17 #include <linux/string.h> 18 #include <linux/percpu.h> 19 #include <linux/start_kernel.h> 20 #include <linux/io.h> 21 #include <linux/memblock.h> 22 #include <linux/cc_platform.h> 23 #include <linux/pgtable.h> 24 25 #include <asm/asm.h> 26 #include <asm/page_64.h> 27 #include <asm/processor.h> 28 #include <asm/proto.h> 29 #include <asm/smp.h> 30 #include <asm/setup.h> 31 #include <asm/desc.h> 32 #include <asm/tlbflush.h> 33 #include <asm/sections.h> 34 #include <asm/kdebug.h> 35 #include <asm/e820/api.h> 36 #include <asm/bios_ebda.h> 37 #include <asm/bootparam_utils.h> 38 #include <asm/microcode.h> 39 #include <asm/kasan.h> 40 #include <asm/fixmap.h> 41 #include <asm/realmode.h> 42 #include <asm/extable.h> 43 #include <asm/trapnr.h> 44 #include <asm/sev.h> 45 #include <asm/tdx.h> 46 #include <asm/init.h> 47 48 /* 49 * Manage page tables very early on. 50 */ 51 extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD]; 52 static unsigned int __initdata next_early_pgt; 53 pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX); 54 55 #ifdef CONFIG_X86_5LEVEL 56 unsigned int __pgtable_l5_enabled __ro_after_init; 57 unsigned int pgdir_shift __ro_after_init = 39; 58 EXPORT_SYMBOL(pgdir_shift); 59 unsigned int ptrs_per_p4d __ro_after_init = 1; 60 EXPORT_SYMBOL(ptrs_per_p4d); 61 #endif 62 63 #ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT 64 unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4; 65 EXPORT_SYMBOL(page_offset_base); 66 unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4; 67 EXPORT_SYMBOL(vmalloc_base); 68 unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4; 69 EXPORT_SYMBOL(vmemmap_base); 70 #endif 71 72 static inline bool check_la57_support(void) 73 { 74 if (!IS_ENABLED(CONFIG_X86_5LEVEL)) 75 return false; 76 77 /* 78 * 5-level paging is detected and enabled at kernel decompression 79 * stage. Only check if it has been enabled there. 80 */ 81 if (!(native_read_cr4() & X86_CR4_LA57)) 82 return false; 83 84 RIP_REL_REF(__pgtable_l5_enabled) = 1; 85 RIP_REL_REF(pgdir_shift) = 48; 86 RIP_REL_REF(ptrs_per_p4d) = 512; 87 RIP_REL_REF(page_offset_base) = __PAGE_OFFSET_BASE_L5; 88 RIP_REL_REF(vmalloc_base) = __VMALLOC_BASE_L5; 89 RIP_REL_REF(vmemmap_base) = __VMEMMAP_BASE_L5; 90 91 return true; 92 } 93 94 static unsigned long __head sme_postprocess_startup(struct boot_params *bp, pmdval_t *pmd) 95 { 96 unsigned long vaddr, vaddr_end; 97 int i; 98 99 /* Encrypt the kernel and related (if SME is active) */ 100 sme_encrypt_kernel(bp); 101 102 /* 103 * Clear the memory encryption mask from the .bss..decrypted section. 104 * The bss section will be memset to zero later in the initialization so 105 * there is no need to zero it after changing the memory encryption 106 * attribute. 107 */ 108 if (sme_get_me_mask()) { 109 vaddr = (unsigned long)__start_bss_decrypted; 110 vaddr_end = (unsigned long)__end_bss_decrypted; 111 112 for (; vaddr < vaddr_end; vaddr += PMD_SIZE) { 113 /* 114 * On SNP, transition the page to shared in the RMP table so that 115 * it is consistent with the page table attribute change. 116 * 117 * __start_bss_decrypted has a virtual address in the high range 118 * mapping (kernel .text). PVALIDATE, by way of 119 * early_snp_set_memory_shared(), requires a valid virtual 120 * address but the kernel is currently running off of the identity 121 * mapping so use __pa() to get a *currently* valid virtual address. 122 */ 123 early_snp_set_memory_shared(__pa(vaddr), __pa(vaddr), PTRS_PER_PMD); 124 125 i = pmd_index(vaddr); 126 pmd[i] -= sme_get_me_mask(); 127 } 128 } 129 130 /* 131 * Return the SME encryption mask (if SME is active) to be used as a 132 * modifier for the initial pgdir entry programmed into CR3. 133 */ 134 return sme_get_me_mask(); 135 } 136 137 /* Code in __startup_64() can be relocated during execution, but the compiler 138 * doesn't have to generate PC-relative relocations when accessing globals from 139 * that function. Clang actually does not generate them, which leads to 140 * boot-time crashes. To work around this problem, every global pointer must 141 * be accessed using RIP_REL_REF(). 142 */ 143 unsigned long __head __startup_64(unsigned long physaddr, 144 struct boot_params *bp) 145 { 146 pmd_t (*early_pgts)[PTRS_PER_PMD] = RIP_REL_REF(early_dynamic_pgts); 147 unsigned long pgtable_flags; 148 unsigned long load_delta; 149 pgdval_t *pgd; 150 p4dval_t *p4d; 151 pudval_t *pud; 152 pmdval_t *pmd, pmd_entry; 153 bool la57; 154 int i; 155 156 la57 = check_la57_support(); 157 158 /* Is the address too large? */ 159 if (physaddr >> MAX_PHYSMEM_BITS) 160 for (;;); 161 162 /* 163 * Compute the delta between the address I am compiled to run at 164 * and the address I am actually running at. 165 */ 166 load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map); 167 RIP_REL_REF(phys_base) = load_delta; 168 169 /* Is the address not 2M aligned? */ 170 if (load_delta & ~PMD_MASK) 171 for (;;); 172 173 /* Include the SME encryption mask in the fixup value */ 174 load_delta += sme_get_me_mask(); 175 176 /* Fixup the physical addresses in the page table */ 177 178 pgd = &RIP_REL_REF(early_top_pgt)->pgd; 179 pgd[pgd_index(__START_KERNEL_map)] += load_delta; 180 181 if (la57) { 182 p4d = (p4dval_t *)&RIP_REL_REF(level4_kernel_pgt); 183 p4d[MAX_PTRS_PER_P4D - 1] += load_delta; 184 185 pgd[pgd_index(__START_KERNEL_map)] = (pgdval_t)p4d | _PAGE_TABLE; 186 } 187 188 RIP_REL_REF(level3_kernel_pgt)[PTRS_PER_PUD - 2].pud += load_delta; 189 RIP_REL_REF(level3_kernel_pgt)[PTRS_PER_PUD - 1].pud += load_delta; 190 191 for (i = FIXMAP_PMD_TOP; i > FIXMAP_PMD_TOP - FIXMAP_PMD_NUM; i--) 192 RIP_REL_REF(level2_fixmap_pgt)[i].pmd += load_delta; 193 194 /* 195 * Set up the identity mapping for the switchover. These 196 * entries should *NOT* have the global bit set! This also 197 * creates a bunch of nonsense entries but that is fine -- 198 * it avoids problems around wraparound. 199 */ 200 201 pud = &early_pgts[0]->pmd; 202 pmd = &early_pgts[1]->pmd; 203 RIP_REL_REF(next_early_pgt) = 2; 204 205 pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask(); 206 207 if (la57) { 208 p4d = &early_pgts[RIP_REL_REF(next_early_pgt)++]->pmd; 209 210 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD; 211 pgd[i + 0] = (pgdval_t)p4d + pgtable_flags; 212 pgd[i + 1] = (pgdval_t)p4d + pgtable_flags; 213 214 i = physaddr >> P4D_SHIFT; 215 p4d[(i + 0) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags; 216 p4d[(i + 1) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags; 217 } else { 218 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD; 219 pgd[i + 0] = (pgdval_t)pud + pgtable_flags; 220 pgd[i + 1] = (pgdval_t)pud + pgtable_flags; 221 } 222 223 i = physaddr >> PUD_SHIFT; 224 pud[(i + 0) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags; 225 pud[(i + 1) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags; 226 227 pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL; 228 /* Filter out unsupported __PAGE_KERNEL_* bits: */ 229 pmd_entry &= RIP_REL_REF(__supported_pte_mask); 230 pmd_entry += sme_get_me_mask(); 231 pmd_entry += physaddr; 232 233 for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) { 234 int idx = i + (physaddr >> PMD_SHIFT); 235 236 pmd[idx % PTRS_PER_PMD] = pmd_entry + i * PMD_SIZE; 237 } 238 239 /* 240 * Fixup the kernel text+data virtual addresses. Note that 241 * we might write invalid pmds, when the kernel is relocated 242 * cleanup_highmap() fixes this up along with the mappings 243 * beyond _end. 244 * 245 * Only the region occupied by the kernel image has so far 246 * been checked against the table of usable memory regions 247 * provided by the firmware, so invalidate pages outside that 248 * region. A page table entry that maps to a reserved area of 249 * memory would allow processor speculation into that area, 250 * and on some hardware (particularly the UV platform) even 251 * speculative access to some reserved areas is caught as an 252 * error, causing the BIOS to halt the system. 253 */ 254 255 pmd = &RIP_REL_REF(level2_kernel_pgt)->pmd; 256 257 /* invalidate pages before the kernel image */ 258 for (i = 0; i < pmd_index((unsigned long)_text); i++) 259 pmd[i] &= ~_PAGE_PRESENT; 260 261 /* fixup pages that are part of the kernel image */ 262 for (; i <= pmd_index((unsigned long)_end); i++) 263 if (pmd[i] & _PAGE_PRESENT) 264 pmd[i] += load_delta; 265 266 /* invalidate pages after the kernel image */ 267 for (; i < PTRS_PER_PMD; i++) 268 pmd[i] &= ~_PAGE_PRESENT; 269 270 return sme_postprocess_startup(bp, pmd); 271 } 272 273 /* Wipe all early page tables except for the kernel symbol map */ 274 static void __init reset_early_page_tables(void) 275 { 276 memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1)); 277 next_early_pgt = 0; 278 write_cr3(__sme_pa_nodebug(early_top_pgt)); 279 } 280 281 /* Create a new PMD entry */ 282 bool __init __early_make_pgtable(unsigned long address, pmdval_t pmd) 283 { 284 unsigned long physaddr = address - __PAGE_OFFSET; 285 pgdval_t pgd, *pgd_p; 286 p4dval_t p4d, *p4d_p; 287 pudval_t pud, *pud_p; 288 pmdval_t *pmd_p; 289 290 /* Invalid address or early pgt is done ? */ 291 if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt)) 292 return false; 293 294 again: 295 pgd_p = &early_top_pgt[pgd_index(address)].pgd; 296 pgd = *pgd_p; 297 298 /* 299 * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is 300 * critical -- __PAGE_OFFSET would point us back into the dynamic 301 * range and we might end up looping forever... 302 */ 303 if (!pgtable_l5_enabled()) 304 p4d_p = pgd_p; 305 else if (pgd) 306 p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base); 307 else { 308 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) { 309 reset_early_page_tables(); 310 goto again; 311 } 312 313 p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++]; 314 memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D); 315 *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE; 316 } 317 p4d_p += p4d_index(address); 318 p4d = *p4d_p; 319 320 if (p4d) 321 pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base); 322 else { 323 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) { 324 reset_early_page_tables(); 325 goto again; 326 } 327 328 pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++]; 329 memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD); 330 *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE; 331 } 332 pud_p += pud_index(address); 333 pud = *pud_p; 334 335 if (pud) 336 pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base); 337 else { 338 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) { 339 reset_early_page_tables(); 340 goto again; 341 } 342 343 pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++]; 344 memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD); 345 *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE; 346 } 347 pmd_p[pmd_index(address)] = pmd; 348 349 return true; 350 } 351 352 static bool __init early_make_pgtable(unsigned long address) 353 { 354 unsigned long physaddr = address - __PAGE_OFFSET; 355 pmdval_t pmd; 356 357 pmd = (physaddr & PMD_MASK) + early_pmd_flags; 358 359 return __early_make_pgtable(address, pmd); 360 } 361 362 void __init do_early_exception(struct pt_regs *regs, int trapnr) 363 { 364 if (trapnr == X86_TRAP_PF && 365 early_make_pgtable(native_read_cr2())) 366 return; 367 368 if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT) && 369 trapnr == X86_TRAP_VC && handle_vc_boot_ghcb(regs)) 370 return; 371 372 if (trapnr == X86_TRAP_VE && tdx_early_handle_ve(regs)) 373 return; 374 375 early_fixup_exception(regs, trapnr); 376 } 377 378 /* Don't add a printk in there. printk relies on the PDA which is not initialized 379 yet. */ 380 void __init clear_bss(void) 381 { 382 memset(__bss_start, 0, 383 (unsigned long) __bss_stop - (unsigned long) __bss_start); 384 memset(__brk_base, 0, 385 (unsigned long) __brk_limit - (unsigned long) __brk_base); 386 } 387 388 static unsigned long get_cmd_line_ptr(void) 389 { 390 unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr; 391 392 cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32; 393 394 return cmd_line_ptr; 395 } 396 397 static void __init copy_bootdata(char *real_mode_data) 398 { 399 char * command_line; 400 unsigned long cmd_line_ptr; 401 402 /* 403 * If SME is active, this will create decrypted mappings of the 404 * boot data in advance of the copy operations. 405 */ 406 sme_map_bootdata(real_mode_data); 407 408 memcpy(&boot_params, real_mode_data, sizeof(boot_params)); 409 sanitize_boot_params(&boot_params); 410 cmd_line_ptr = get_cmd_line_ptr(); 411 if (cmd_line_ptr) { 412 command_line = __va(cmd_line_ptr); 413 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE); 414 } 415 416 /* 417 * The old boot data is no longer needed and won't be reserved, 418 * freeing up that memory for use by the system. If SME is active, 419 * we need to remove the mappings that were created so that the 420 * memory doesn't remain mapped as decrypted. 421 */ 422 sme_unmap_bootdata(real_mode_data); 423 } 424 425 asmlinkage __visible void __init __noreturn x86_64_start_kernel(char * real_mode_data) 426 { 427 /* 428 * Build-time sanity checks on the kernel image and module 429 * area mappings. (these are purely build-time and produce no code) 430 */ 431 BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map); 432 BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE); 433 BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE); 434 BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0); 435 BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0); 436 BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL)); 437 MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) == 438 (__START_KERNEL & PGDIR_MASK))); 439 BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END); 440 441 cr4_init_shadow(); 442 443 /* Kill off the identity-map trampoline */ 444 reset_early_page_tables(); 445 446 clear_bss(); 447 448 /* 449 * This needs to happen *before* kasan_early_init() because latter maps stuff 450 * into that page. 451 */ 452 clear_page(init_top_pgt); 453 454 /* 455 * SME support may update early_pmd_flags to include the memory 456 * encryption mask, so it needs to be called before anything 457 * that may generate a page fault. 458 */ 459 sme_early_init(); 460 461 kasan_early_init(); 462 463 /* 464 * Flush global TLB entries which could be left over from the trampoline page 465 * table. 466 * 467 * This needs to happen *after* kasan_early_init() as KASAN-enabled .configs 468 * instrument native_write_cr4() so KASAN must be initialized for that 469 * instrumentation to work. 470 */ 471 __native_tlb_flush_global(this_cpu_read(cpu_tlbstate.cr4)); 472 473 idt_setup_early_handler(); 474 475 /* Needed before cc_platform_has() can be used for TDX */ 476 tdx_early_init(); 477 478 copy_bootdata(__va(real_mode_data)); 479 480 /* 481 * Load microcode early on BSP. 482 */ 483 load_ucode_bsp(); 484 485 /* set init_top_pgt kernel high mapping*/ 486 init_top_pgt[511] = early_top_pgt[511]; 487 488 x86_64_start_reservations(real_mode_data); 489 } 490 491 void __init __noreturn x86_64_start_reservations(char *real_mode_data) 492 { 493 /* version is always not zero if it is copied */ 494 if (!boot_params.hdr.version) 495 copy_bootdata(__va(real_mode_data)); 496 497 x86_early_init_platform_quirks(); 498 499 switch (boot_params.hdr.hardware_subarch) { 500 case X86_SUBARCH_INTEL_MID: 501 x86_intel_mid_early_setup(); 502 break; 503 default: 504 break; 505 } 506 507 start_kernel(); 508 } 509 510 /* 511 * Data structures and code used for IDT setup in head_64.S. The bringup-IDT is 512 * used until the idt_table takes over. On the boot CPU this happens in 513 * x86_64_start_kernel(), on secondary CPUs in start_secondary(). In both cases 514 * this happens in the functions called from head_64.S. 515 * 516 * The idt_table can't be used that early because all the code modifying it is 517 * in idt.c and can be instrumented by tracing or KASAN, which both don't work 518 * during early CPU bringup. Also the idt_table has the runtime vectors 519 * configured which require certain CPU state to be setup already (like TSS), 520 * which also hasn't happened yet in early CPU bringup. 521 */ 522 static gate_desc bringup_idt_table[NUM_EXCEPTION_VECTORS] __page_aligned_data; 523 524 /* This may run while still in the direct mapping */ 525 static void __head startup_64_load_idt(void *vc_handler) 526 { 527 struct desc_ptr desc = { 528 .address = (unsigned long)&RIP_REL_REF(bringup_idt_table), 529 .size = sizeof(bringup_idt_table) - 1, 530 }; 531 struct idt_data data; 532 gate_desc idt_desc; 533 534 /* @vc_handler is set only for a VMM Communication Exception */ 535 if (vc_handler) { 536 init_idt_data(&data, X86_TRAP_VC, vc_handler); 537 idt_init_desc(&idt_desc, &data); 538 native_write_idt_entry((gate_desc *)desc.address, X86_TRAP_VC, &idt_desc); 539 } 540 541 native_load_idt(&desc); 542 } 543 544 /* This is used when running on kernel addresses */ 545 void early_setup_idt(void) 546 { 547 void *handler = NULL; 548 549 if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { 550 setup_ghcb(); 551 handler = vc_boot_ghcb; 552 } 553 554 startup_64_load_idt(handler); 555 } 556 557 /* 558 * Setup boot CPU state needed before kernel switches to virtual addresses. 559 */ 560 void __head startup_64_setup_gdt_idt(void) 561 { 562 struct desc_struct *gdt = (void *)(__force unsigned long)init_per_cpu_var(gdt_page.gdt); 563 void *handler = NULL; 564 565 struct desc_ptr startup_gdt_descr = { 566 .address = (unsigned long)&RIP_REL_REF(*gdt), 567 .size = GDT_SIZE - 1, 568 }; 569 570 /* Load GDT */ 571 native_load_gdt(&startup_gdt_descr); 572 573 /* New GDT is live - reload data segment registers */ 574 asm volatile("movl %%eax, %%ds\n" 575 "movl %%eax, %%ss\n" 576 "movl %%eax, %%es\n" : : "a"(__KERNEL_DS) : "memory"); 577 578 if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) 579 handler = &RIP_REL_REF(vc_no_ghcb); 580 581 startup_64_load_idt(handler); 582 } 583