arch/x86/kernel/head64.c

   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/mem_encrypt.h>
  23
  24 #include <asm/processor.h>
  25 #include <asm/proto.h>
  26 #include <asm/smp.h>
  27 #include <asm/setup.h>
  28 #include <asm/desc.h>
  29 #include <asm/pgtable.h>
  30 #include <asm/tlbflush.h>
  31 #include <asm/sections.h>
  32 #include <asm/kdebug.h>
  33 #include <asm/e820/api.h>
  34 #include <asm/bios_ebda.h>
  35 #include <asm/bootparam_utils.h>
  36 #include <asm/microcode.h>
  37 #include <asm/kasan.h>
  38 #include <asm/fixmap.h>
  39
  40 /*
  41  * Manage page tables very early on.
  42  */
  43 extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
  44 static unsigned int __initdata next_early_pgt;
  45 pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
  46
  47 #ifdef CONFIG_X86_5LEVEL
  48 unsigned int __pgtable_l5_enabled __ro_after_init;
  49 unsigned int pgdir_shift __ro_after_init = 39;
  50 EXPORT_SYMBOL(pgdir_shift);
  51 unsigned int ptrs_per_p4d __ro_after_init = 1;
  52 EXPORT_SYMBOL(ptrs_per_p4d);
  53 #endif
  54
  55 #ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
  56 unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4;
  57 EXPORT_SYMBOL(page_offset_base);
  58 unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;
  59 EXPORT_SYMBOL(vmalloc_base);
  60 unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
  61 EXPORT_SYMBOL(vmemmap_base);
  62 #endif
  63
  64 #define __head  __section(.head.text)
  65
  66 static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
  67 {
  68         return ptr - (void *)_text + (void *)physaddr;
  69 }
  70
  71 static unsigned long __head *fixup_long(void *ptr, unsigned long physaddr)
  72 {
  73         return fixup_pointer(ptr, physaddr);
  74 }
  75
  76 #ifdef CONFIG_X86_5LEVEL
  77 static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr)
  78 {
  79         return fixup_pointer(ptr, physaddr);
  80 }
  81
  82 static bool __head check_la57_support(unsigned long physaddr)
  83 {
  84         /*
  85          * 5-level paging is detected and enabled at kernel decomression
  86          * stage. Only check if it has been enabled there.
  87          */
  88         if (!(native_read_cr4() & X86_CR4_LA57))
  89                 return false;
  90
  91         *fixup_int(&__pgtable_l5_enabled, physaddr) = 1;
  92         *fixup_int(&pgdir_shift, physaddr) = 48;
  93         *fixup_int(&ptrs_per_p4d, physaddr) = 512;
  94         *fixup_long(&page_offset_base, physaddr) = __PAGE_OFFSET_BASE_L5;
  95         *fixup_long(&vmalloc_base, physaddr) = __VMALLOC_BASE_L5;
  96         *fixup_long(&vmemmap_base, physaddr) = __VMEMMAP_BASE_L5;
  97
  98         return true;
  99 }
 100 #else
 101 static bool __head check_la57_support(unsigned long physaddr)
 102 {
 103         return false;
 104 }
 105 #endif
 106
 107 /* Code in __startup_64() can be relocated during execution, but the compiler
 108  * doesn't have to generate PC-relative relocations when accessing globals from
 109  * that function. Clang actually does not generate them, which leads to
 110  * boot-time crashes. To work around this problem, every global pointer must
 111  * be adjusted using fixup_pointer().
 112  */
 113 unsigned long __head __startup_64(unsigned long physaddr,
 114                                   struct boot_params *bp)
 115 {
 116         unsigned long vaddr, vaddr_end;
 117         unsigned long load_delta, *p;
 118         unsigned long pgtable_flags;
 119         pgdval_t *pgd;
 120         p4dval_t *p4d;
 121         pudval_t *pud;
 122         pmdval_t *pmd, pmd_entry;
 123         pteval_t *mask_ptr;
 124         bool la57;
 125         int i;
 126         unsigned int *next_pgt_ptr;
 127
 128         la57 = check_la57_support(physaddr);
 129
 130         /* Is the address too large? */
 131         if (physaddr >> MAX_PHYSMEM_BITS)
 132                 for (;;);
 133
 134         /*
 135          * Compute the delta between the address I am compiled to run at
 136          * and the address I am actually running at.
 137          */
 138         load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);
 139
 140         /* Is the address not 2M aligned? */
 141         if (load_delta & ~PMD_PAGE_MASK)
 142                 for (;;);
 143
 144         /* Activate Secure Memory Encryption (SME) if supported and enabled */
 145         sme_enable(bp);
 146
 147         /* Include the SME encryption mask in the fixup value */
 148         load_delta += sme_get_me_mask();
 149
 150         /* Fixup the physical addresses in the page table */
 151
 152         pgd = fixup_pointer(&early_top_pgt, physaddr);
 153         p = pgd + pgd_index(__START_KERNEL_map);
 154         if (la57)
 155                 *p = (unsigned long)level4_kernel_pgt;
 156         else
 157                 *p = (unsigned long)level3_kernel_pgt;
 158         *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
 159
 160         if (la57) {
 161                 p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
 162                 p4d[511] += load_delta;
 163         }
 164
 165         pud = fixup_pointer(&level3_kernel_pgt, physaddr);
 166         pud[510] += load_delta;
 167         pud[511] += load_delta;
 168
 169         pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
 170         for (i = FIXMAP_PMD_TOP; i > FIXMAP_PMD_TOP - FIXMAP_PMD_NUM; i--)
 171                 pmd[i] += load_delta;
 172
 173         /*
 174          * Set up the identity mapping for the switchover.  These
 175          * entries should *NOT* have the global bit set!  This also
 176          * creates a bunch of nonsense entries but that is fine --
 177          * it avoids problems around wraparound.
 178          */
 179
 180         next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
 181         pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 182         pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 183
 184         pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
 185
 186         if (la57) {
 187                 p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
 188
 189                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 190                 pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
 191                 pgd[i + 1] = (pgdval_t)p4d + pgtable_flags;
 192
 193                 i = (physaddr >> P4D_SHIFT) % PTRS_PER_P4D;
 194                 p4d[i + 0] = (pgdval_t)pud + pgtable_flags;
 195                 p4d[i + 1] = (pgdval_t)pud + pgtable_flags;
 196         } else {
 197                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 198                 pgd[i + 0] = (pgdval_t)pud + pgtable_flags;
 199                 pgd[i + 1] = (pgdval_t)pud + pgtable_flags;
 200         }
 201
 202         i = (physaddr >> PUD_SHIFT) % PTRS_PER_PUD;
 203         pud[i + 0] = (pudval_t)pmd + pgtable_flags;
 204         pud[i + 1] = (pudval_t)pmd + pgtable_flags;
 205
 206         pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
 207         /* Filter out unsupported __PAGE_KERNEL_* bits: */
 208         mask_ptr = fixup_pointer(&__supported_pte_mask, physaddr);
 209         pmd_entry &= *mask_ptr;
 210         pmd_entry += sme_get_me_mask();
 211         pmd_entry +=  physaddr;
 212
 213         for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
 214                 int idx = i + (physaddr >> PMD_SHIFT) % PTRS_PER_PMD;
 215                 pmd[idx] = pmd_entry + i * PMD_SIZE;
 216         }
 217
 218         /*
 219          * Fixup the kernel text+data virtual addresses. Note that
 220          * we might write invalid pmds, when the kernel is relocated
 221          * cleanup_highmap() fixes this up along with the mappings
 222          * beyond _end.
 223          */
 224
 225         pmd = fixup_pointer(level2_kernel_pgt, physaddr);
 226         for (i = 0; i < PTRS_PER_PMD; i++) {
 227                 if (pmd[i] & _PAGE_PRESENT)
 228                         pmd[i] += load_delta;
 229         }
 230
 231         /*
 232          * Fixup phys_base - remove the memory encryption mask to obtain
 233          * the true physical address.
 234          */
 235         *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask();
 236
 237         /* Encrypt the kernel and related (if SME is active) */
 238         sme_encrypt_kernel(bp);
 239
 240         /*
 241          * Clear the memory encryption mask from the .bss..decrypted section.
 242          * The bss section will be memset to zero later in the initialization so
 243          * there is no need to zero it after changing the memory encryption
 244          * attribute.
 245          */
 246         if (mem_encrypt_active()) {
 247                 vaddr = (unsigned long)__start_bss_decrypted;
 248                 vaddr_end = (unsigned long)__end_bss_decrypted;
 249                 for (; vaddr < vaddr_end; vaddr += PMD_SIZE) {
 250                         i = pmd_index(vaddr);
 251                         pmd[i] -= sme_get_me_mask();
 252                 }
 253         }
 254
 255         /*
 256          * Return the SME encryption mask (if SME is active) to be used as a
 257          * modifier for the initial pgdir entry programmed into CR3.
 258          */
 259         return sme_get_me_mask();
 260 }
 261
 262 unsigned long __startup_secondary_64(void)
 263 {
 264         /*
 265          * Return the SME encryption mask (if SME is active) to be used as a
 266          * modifier for the initial pgdir entry programmed into CR3.
 267          */
 268         return sme_get_me_mask();
 269 }
 270
 271 /* Wipe all early page tables except for the kernel symbol map */
 272 static void __init reset_early_page_tables(void)
 273 {
 274         memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
 275         next_early_pgt = 0;
 276         write_cr3(__sme_pa_nodebug(early_top_pgt));
 277 }
 278
 279 /* Create a new PMD entry */
 280 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 281 {
 282         unsigned long physaddr = address - __PAGE_OFFSET;
 283         pgdval_t pgd, *pgd_p;
 284         p4dval_t p4d, *p4d_p;
 285         pudval_t pud, *pud_p;
 286         pmdval_t *pmd_p;
 287
 288         /* Invalid address or early pgt is done ?  */
 289         if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
 290                 return -1;
 291
 292 again:
 293         pgd_p = &early_top_pgt[pgd_index(address)].pgd;
 294         pgd = *pgd_p;
 295
 296         /*
 297          * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
 298          * critical -- __PAGE_OFFSET would point us back into the dynamic
 299          * range and we might end up looping forever...
 300          */
 301         if (!pgtable_l5_enabled())
 302                 p4d_p = pgd_p;
 303         else if (pgd)
 304                 p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 305         else {
 306                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 307                         reset_early_page_tables();
 308                         goto again;
 309                 }
 310
 311                 p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
 312                 memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
 313                 *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 314         }
 315         p4d_p += p4d_index(address);
 316         p4d = *p4d_p;
 317
 318         if (p4d)
 319                 pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 320         else {
 321                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 322                         reset_early_page_tables();
 323                         goto again;
 324                 }
 325
 326                 pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
 327                 memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
 328                 *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 329         }
 330         pud_p += pud_index(address);
 331         pud = *pud_p;
 332
 333         if (pud)
 334                 pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 335         else {
 336                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 337                         reset_early_page_tables();
 338                         goto again;
 339                 }
 340
 341                 pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
 342                 memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
 343                 *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 344         }
 345         pmd_p[pmd_index(address)] = pmd;
 346
 347         return 0;
 348 }
 349
 350 int __init early_make_pgtable(unsigned long address)
 351 {
 352         unsigned long physaddr = address - __PAGE_OFFSET;
 353         pmdval_t pmd;
 354
 355         pmd = (physaddr & PMD_MASK) + early_pmd_flags;
 356
 357         return __early_make_pgtable(address, pmd);
 358 }
 359
 360 /* Don't add a printk in there. printk relies on the PDA which is not initialized
 361    yet. */
 362 static void __init clear_bss(void)
 363 {
 364         memset(__bss_start, 0,
 365                (unsigned long) __bss_stop - (unsigned long) __bss_start);
 366 }
 367
 368 static unsigned long get_cmd_line_ptr(void)
 369 {
 370         unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
 371
 372         cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
 373
 374         return cmd_line_ptr;
 375 }
 376
 377 static void __init copy_bootdata(char *real_mode_data)
 378 {
 379         char * command_line;
 380         unsigned long cmd_line_ptr;
 381
 382         /*
 383          * If SME is active, this will create decrypted mappings of the
 384          * boot data in advance of the copy operations.
 385          */
 386         sme_map_bootdata(real_mode_data);
 387
 388         memcpy(&boot_params, real_mode_data, sizeof(boot_params));
 389         sanitize_boot_params(&boot_params);
 390         cmd_line_ptr = get_cmd_line_ptr();
 391         if (cmd_line_ptr) {
 392                 command_line = __va(cmd_line_ptr);
 393                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 394         }
 395
 396         /*
 397          * The old boot data is no longer needed and won't be reserved,
 398          * freeing up that memory for use by the system. If SME is active,
 399          * we need to remove the mappings that were created so that the
 400          * memory doesn't remain mapped as decrypted.
 401          */
 402         sme_unmap_bootdata(real_mode_data);
 403 }
 404
 405 asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 406 {
 407         /*
 408          * Build-time sanity checks on the kernel image and module
 409          * area mappings. (these are purely build-time and produce no code)
 410          */
 411         BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
 412         BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
 413         BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 414         BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
 415         BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 416         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
 417         MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 418                                 (__START_KERNEL & PGDIR_MASK)));
 419         BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
 420
 421         cr4_init_shadow();
 422
 423         /* Kill off the identity-map trampoline */
 424         reset_early_page_tables();
 425
 426         clear_bss();
 427
 428         clear_page(init_top_pgt);
 429
 430         /*
 431          * SME support may update early_pmd_flags to include the memory
 432          * encryption mask, so it needs to be called before anything
 433          * that may generate a page fault.
 434          */
 435         sme_early_init();
 436
 437         kasan_early_init();
 438
 439         idt_setup_early_handler();
 440
 441         copy_bootdata(__va(real_mode_data));
 442
 443         /*
 444          * Load microcode early on BSP.
 445          */
 446         load_ucode_bsp();
 447
 448         /* set init_top_pgt kernel high mapping*/
 449         init_top_pgt[511] = early_top_pgt[511];
 450
 451         x86_64_start_reservations(real_mode_data);
 452 }
 453
 454 void __init x86_64_start_reservations(char *real_mode_data)
 455 {
 456         /* version is always not zero if it is copied */
 457         if (!boot_params.hdr.version)
 458                 copy_bootdata(__va(real_mode_data));
 459
 460         x86_early_init_platform_quirks();
 461
 462         switch (boot_params.hdr.hardware_subarch) {
 463         case X86_SUBARCH_INTEL_MID:
 464                 x86_intel_mid_early_setup();
 465                 break;
 466         default:
 467                 break;
 468         }
 469
 470         start_kernel();
 471 }