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 <[email protected]> SuSE
   6  */
   7
   8 #define DISABLE_BRANCH_PROFILING
   9 #include <linux/init.h>
  10 #include <linux/linkage.h>
  11 #include <linux/types.h>
  12 #include <linux/kernel.h>
  13 #include <linux/string.h>
  14 #include <linux/percpu.h>
  15 #include <linux/start_kernel.h>
  16 #include <linux/io.h>
  17 #include <linux/memblock.h>
  18 #include <linux/mem_encrypt.h>
  19
  20 #include <asm/processor.h>
  21 #include <asm/proto.h>
  22 #include <asm/smp.h>
  23 #include <asm/setup.h>
  24 #include <asm/desc.h>
  25 #include <asm/pgtable.h>
  26 #include <asm/tlbflush.h>
  27 #include <asm/sections.h>
  28 #include <asm/kdebug.h>
  29 #include <asm/e820/api.h>
  30 #include <asm/bios_ebda.h>
  31 #include <asm/bootparam_utils.h>
  32 #include <asm/microcode.h>
  33 #include <asm/kasan.h>
  34
  35 #ifdef CONFIG_X86_5LEVEL
  36 #undef pgtable_l5_enabled
  37 #define pgtable_l5_enabled __pgtable_l5_enabled
  38 #endif
  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 EXPORT_SYMBOL(__pgtable_l5_enabled);
  50 unsigned int pgdir_shift __ro_after_init = 39;
  51 EXPORT_SYMBOL(pgdir_shift);
  52 unsigned int ptrs_per_p4d __ro_after_init = 1;
  53 EXPORT_SYMBOL(ptrs_per_p4d);
  54 #endif
  55
  56 #ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
  57 unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4;
  58 EXPORT_SYMBOL(page_offset_base);
  59 unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;
  60 EXPORT_SYMBOL(vmalloc_base);
  61 unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
  62 EXPORT_SYMBOL(vmemmap_base);
  63 #endif
  64
  65 #define __head  __section(.head.text)
  66
  67 static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
  68 {
  69         return ptr - (void *)_text + (void *)physaddr;
  70 }
  71
  72 static unsigned long __head *fixup_long(void *ptr, unsigned long physaddr)
  73 {
  74         return fixup_pointer(ptr, physaddr);
  75 }
  76
  77 #ifdef CONFIG_X86_5LEVEL
  78 static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr)
  79 {
  80         return fixup_pointer(ptr, physaddr);
  81 }
  82
  83 static bool __head check_la57_support(unsigned long physaddr)
  84 {
  85         if (native_cpuid_eax(0) < 7)
  86                 return false;
  87
  88         if (!(native_cpuid_ecx(7) & (1 << (X86_FEATURE_LA57 & 31))))
  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 load_delta, *p;
 117         unsigned long pgtable_flags;
 118         pgdval_t *pgd;
 119         p4dval_t *p4d;
 120         pudval_t *pud;
 121         pmdval_t *pmd, pmd_entry;
 122         pteval_t *mask_ptr;
 123         bool la57;
 124         int i;
 125         unsigned int *next_pgt_ptr;
 126
 127         la57 = check_la57_support(physaddr);
 128
 129         /* Is the address too large? */
 130         if (physaddr >> MAX_PHYSMEM_BITS)
 131                 for (;;);
 132
 133         /*
 134          * Compute the delta between the address I am compiled to run at
 135          * and the address I am actually running at.
 136          */
 137         load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);
 138
 139         /* Is the address not 2M aligned? */
 140         if (load_delta & ~PMD_PAGE_MASK)
 141                 for (;;);
 142
 143         /* Activate Secure Memory Encryption (SME) if supported and enabled */
 144         sme_enable(bp);
 145
 146         /* Include the SME encryption mask in the fixup value */
 147         load_delta += sme_get_me_mask();
 148
 149         /* Fixup the physical addresses in the page table */
 150
 151         pgd = fixup_pointer(&early_top_pgt, physaddr);
 152         p = pgd + pgd_index(__START_KERNEL_map);
 153         if (la57)
 154                 *p = (unsigned long)level4_kernel_pgt;
 155         else
 156                 *p = (unsigned long)level3_kernel_pgt;
 157         *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
 158
 159         if (la57) {
 160                 p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
 161                 p4d[511] += load_delta;
 162         }
 163
 164         pud = fixup_pointer(&level3_kernel_pgt, physaddr);
 165         pud[510] += load_delta;
 166         pud[511] += load_delta;
 167
 168         pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
 169         pmd[506] += load_delta;
 170
 171         /*
 172          * Set up the identity mapping for the switchover.  These
 173          * entries should *NOT* have the global bit set!  This also
 174          * creates a bunch of nonsense entries but that is fine --
 175          * it avoids problems around wraparound.
 176          */
 177
 178         next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
 179         pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 180         pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 181
 182         pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
 183
 184         if (la57) {
 185                 p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
 186
 187                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 188                 pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
 189                 pgd[i + 1] = (pgdval_t)p4d + pgtable_flags;
 190
 191                 i = (physaddr >> P4D_SHIFT) % PTRS_PER_P4D;
 192                 p4d[i + 0] = (pgdval_t)pud + pgtable_flags;
 193                 p4d[i + 1] = (pgdval_t)pud + pgtable_flags;
 194         } else {
 195                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 196                 pgd[i + 0] = (pgdval_t)pud + pgtable_flags;
 197                 pgd[i + 1] = (pgdval_t)pud + pgtable_flags;
 198         }
 199
 200         i = (physaddr >> PUD_SHIFT) % PTRS_PER_PUD;
 201         pud[i + 0] = (pudval_t)pmd + pgtable_flags;
 202         pud[i + 1] = (pudval_t)pmd + pgtable_flags;
 203
 204         pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
 205         /* Filter out unsupported __PAGE_KERNEL_* bits: */
 206         mask_ptr = fixup_pointer(&__supported_pte_mask, physaddr);
 207         pmd_entry &= *mask_ptr;
 208         pmd_entry += sme_get_me_mask();
 209         pmd_entry +=  physaddr;
 210
 211         for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
 212                 int idx = i + (physaddr >> PMD_SHIFT) % PTRS_PER_PMD;
 213                 pmd[idx] = pmd_entry + i * PMD_SIZE;
 214         }
 215
 216         /*
 217          * Fixup the kernel text+data virtual addresses. Note that
 218          * we might write invalid pmds, when the kernel is relocated
 219          * cleanup_highmap() fixes this up along with the mappings
 220          * beyond _end.
 221          */
 222
 223         pmd = fixup_pointer(level2_kernel_pgt, physaddr);
 224         for (i = 0; i < PTRS_PER_PMD; i++) {
 225                 if (pmd[i] & _PAGE_PRESENT)
 226                         pmd[i] += load_delta;
 227         }
 228
 229         /*
 230          * Fixup phys_base - remove the memory encryption mask to obtain
 231          * the true physical address.
 232          */
 233         *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask();
 234
 235         /* Encrypt the kernel and related (if SME is active) */
 236         sme_encrypt_kernel(bp);
 237
 238         /*
 239          * Return the SME encryption mask (if SME is active) to be used as a
 240          * modifier for the initial pgdir entry programmed into CR3.
 241          */
 242         return sme_get_me_mask();
 243 }
 244
 245 unsigned long __startup_secondary_64(void)
 246 {
 247         /*
 248          * Return the SME encryption mask (if SME is active) to be used as a
 249          * modifier for the initial pgdir entry programmed into CR3.
 250          */
 251         return sme_get_me_mask();
 252 }
 253
 254 /* Wipe all early page tables except for the kernel symbol map */
 255 static void __init reset_early_page_tables(void)
 256 {
 257         memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
 258         next_early_pgt = 0;
 259         write_cr3(__sme_pa_nodebug(early_top_pgt));
 260 }
 261
 262 /* Create a new PMD entry */
 263 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 264 {
 265         unsigned long physaddr = address - __PAGE_OFFSET;
 266         pgdval_t pgd, *pgd_p;
 267         p4dval_t p4d, *p4d_p;
 268         pudval_t pud, *pud_p;
 269         pmdval_t *pmd_p;
 270
 271         /* Invalid address or early pgt is done ?  */
 272         if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
 273                 return -1;
 274
 275 again:
 276         pgd_p = &early_top_pgt[pgd_index(address)].pgd;
 277         pgd = *pgd_p;
 278
 279         /*
 280          * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
 281          * critical -- __PAGE_OFFSET would point us back into the dynamic
 282          * range and we might end up looping forever...
 283          */
 284         if (!pgtable_l5_enabled)
 285                 p4d_p = pgd_p;
 286         else if (pgd)
 287                 p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 288         else {
 289                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 290                         reset_early_page_tables();
 291                         goto again;
 292                 }
 293
 294                 p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
 295                 memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
 296                 *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 297         }
 298         p4d_p += p4d_index(address);
 299         p4d = *p4d_p;
 300
 301         if (p4d)
 302                 pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 303         else {
 304                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 305                         reset_early_page_tables();
 306                         goto again;
 307                 }
 308
 309                 pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
 310                 memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
 311                 *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 312         }
 313         pud_p += pud_index(address);
 314         pud = *pud_p;
 315
 316         if (pud)
 317                 pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 318         else {
 319                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 320                         reset_early_page_tables();
 321                         goto again;
 322                 }
 323
 324                 pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
 325                 memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
 326                 *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 327         }
 328         pmd_p[pmd_index(address)] = pmd;
 329
 330         return 0;
 331 }
 332
 333 int __init early_make_pgtable(unsigned long address)
 334 {
 335         unsigned long physaddr = address - __PAGE_OFFSET;
 336         pmdval_t pmd;
 337
 338         pmd = (physaddr & PMD_MASK) + early_pmd_flags;
 339
 340         return __early_make_pgtable(address, pmd);
 341 }
 342
 343 /* Don't add a printk in there. printk relies on the PDA which is not initialized
 344    yet. */
 345 static void __init clear_bss(void)
 346 {
 347         memset(__bss_start, 0,
 348                (unsigned long) __bss_stop - (unsigned long) __bss_start);
 349 }
 350
 351 static unsigned long get_cmd_line_ptr(void)
 352 {
 353         unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
 354
 355         cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
 356
 357         return cmd_line_ptr;
 358 }
 359
 360 static void __init copy_bootdata(char *real_mode_data)
 361 {
 362         char * command_line;
 363         unsigned long cmd_line_ptr;
 364
 365         /*
 366          * If SME is active, this will create decrypted mappings of the
 367          * boot data in advance of the copy operations.
 368          */
 369         sme_map_bootdata(real_mode_data);
 370
 371         memcpy(&boot_params, real_mode_data, sizeof boot_params);
 372         sanitize_boot_params(&boot_params);
 373         cmd_line_ptr = get_cmd_line_ptr();
 374         if (cmd_line_ptr) {
 375                 command_line = __va(cmd_line_ptr);
 376                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 377         }
 378
 379         /*
 380          * The old boot data is no longer needed and won't be reserved,
 381          * freeing up that memory for use by the system. If SME is active,
 382          * we need to remove the mappings that were created so that the
 383          * memory doesn't remain mapped as decrypted.
 384          */
 385         sme_unmap_bootdata(real_mode_data);
 386 }
 387
 388 asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 389 {
 390         /*
 391          * Build-time sanity checks on the kernel image and module
 392          * area mappings. (these are purely build-time and produce no code)
 393          */
 394         BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
 395         BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
 396         BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 397         BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
 398         BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 399         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
 400         MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 401                                 (__START_KERNEL & PGDIR_MASK)));
 402         BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
 403
 404         cr4_init_shadow();
 405
 406         /* Kill off the identity-map trampoline */
 407         reset_early_page_tables();
 408
 409         clear_bss();
 410
 411         clear_page(init_top_pgt);
 412
 413         /*
 414          * SME support may update early_pmd_flags to include the memory
 415          * encryption mask, so it needs to be called before anything
 416          * that may generate a page fault.
 417          */
 418         sme_early_init();
 419
 420         kasan_early_init();
 421
 422         idt_setup_early_handler();
 423
 424         copy_bootdata(__va(real_mode_data));
 425
 426         /*
 427          * Load microcode early on BSP.
 428          */
 429         load_ucode_bsp();
 430
 431         /* set init_top_pgt kernel high mapping*/
 432         init_top_pgt[511] = early_top_pgt[511];
 433
 434         x86_64_start_reservations(real_mode_data);
 435 }
 436
 437 void __init x86_64_start_reservations(char *real_mode_data)
 438 {
 439         /* version is always not zero if it is copied */
 440         if (!boot_params.hdr.version)
 441                 copy_bootdata(__va(real_mode_data));
 442
 443         x86_early_init_platform_quirks();
 444
 445         switch (boot_params.hdr.hardware_subarch) {
 446         case X86_SUBARCH_INTEL_MID:
 447                 x86_intel_mid_early_setup();
 448                 break;
 449         default:
 450                 break;
 451         }
 452
 453         start_kernel();
 454 }