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_pgt_ptr)++],
 188                                     physaddr);
 189
 190                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 191                 pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
 192                 pgd[i + 1] = (pgdval_t)p4d + pgtable_flags;
 193
 194                 i = physaddr >> P4D_SHIFT;
 195                 p4d[(i + 0) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags;
 196                 p4d[(i + 1) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags;
 197         } else {
 198                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 199                 pgd[i + 0] = (pgdval_t)pud + pgtable_flags;
 200                 pgd[i + 1] = (pgdval_t)pud + pgtable_flags;
 201         }
 202
 203         i = physaddr >> PUD_SHIFT;
 204         pud[(i + 0) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags;
 205         pud[(i + 1) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags;
 206
 207         pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
 208         /* Filter out unsupported __PAGE_KERNEL_* bits: */
 209         mask_ptr = fixup_pointer(&__supported_pte_mask, physaddr);
 210         pmd_entry &= *mask_ptr;
 211         pmd_entry += sme_get_me_mask();
 212         pmd_entry +=  physaddr;
 213
 214         for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
 215                 int idx = i + (physaddr >> PMD_SHIFT);
 216
 217                 pmd[idx % PTRS_PER_PMD] = pmd_entry + i * PMD_SIZE;
 218         }
 219
 220         /*
 221          * Fixup the kernel text+data virtual addresses. Note that
 222          * we might write invalid pmds, when the kernel is relocated
 223          * cleanup_highmap() fixes this up along with the mappings
 224          * beyond _end.
 225          */
 226
 227         pmd = fixup_pointer(level2_kernel_pgt, physaddr);
 228         for (i = 0; i < PTRS_PER_PMD; i++) {
 229                 if (pmd[i] & _PAGE_PRESENT)
 230                         pmd[i] += load_delta;
 231         }
 232
 233         /*
 234          * Fixup phys_base - remove the memory encryption mask to obtain
 235          * the true physical address.
 236          */
 237         *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask();
 238
 239         /* Encrypt the kernel and related (if SME is active) */
 240         sme_encrypt_kernel(bp);
 241
 242         /*
 243          * Clear the memory encryption mask from the .bss..decrypted section.
 244          * The bss section will be memset to zero later in the initialization so
 245          * there is no need to zero it after changing the memory encryption
 246          * attribute.
 247          */
 248         if (mem_encrypt_active()) {
 249                 vaddr = (unsigned long)__start_bss_decrypted;
 250                 vaddr_end = (unsigned long)__end_bss_decrypted;
 251                 for (; vaddr < vaddr_end; vaddr += PMD_SIZE) {
 252                         i = pmd_index(vaddr);
 253                         pmd[i] -= sme_get_me_mask();
 254                 }
 255         }
 256
 257         /*
 258          * Return the SME encryption mask (if SME is active) to be used as a
 259          * modifier for the initial pgdir entry programmed into CR3.
 260          */
 261         return sme_get_me_mask();
 262 }
 263
 264 unsigned long __startup_secondary_64(void)
 265 {
 266         /*
 267          * Return the SME encryption mask (if SME is active) to be used as a
 268          * modifier for the initial pgdir entry programmed into CR3.
 269          */
 270         return sme_get_me_mask();
 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 int __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 -1;
 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 0;
 350 }
 351
 352 int __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 /* Don't add a printk in there. printk relies on the PDA which is not initialized
 363    yet. */
 364 static void __init clear_bss(void)
 365 {
 366         memset(__bss_start, 0,
 367                (unsigned long) __bss_stop - (unsigned long) __bss_start);
 368 }
 369
 370 static unsigned long get_cmd_line_ptr(void)
 371 {
 372         unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
 373
 374         cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
 375
 376         return cmd_line_ptr;
 377 }
 378
 379 static void __init copy_bootdata(char *real_mode_data)
 380 {
 381         char * command_line;
 382         unsigned long cmd_line_ptr;
 383
 384         /*
 385          * If SME is active, this will create decrypted mappings of the
 386          * boot data in advance of the copy operations.
 387          */
 388         sme_map_bootdata(real_mode_data);
 389
 390         memcpy(&boot_params, real_mode_data, sizeof(boot_params));
 391         sanitize_boot_params(&boot_params);
 392         cmd_line_ptr = get_cmd_line_ptr();
 393         if (cmd_line_ptr) {
 394                 command_line = __va(cmd_line_ptr);
 395                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 396         }
 397
 398         /*
 399          * The old boot data is no longer needed and won't be reserved,
 400          * freeing up that memory for use by the system. If SME is active,
 401          * we need to remove the mappings that were created so that the
 402          * memory doesn't remain mapped as decrypted.
 403          */
 404         sme_unmap_bootdata(real_mode_data);
 405 }
 406
 407 asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 408 {
 409         /*
 410          * Build-time sanity checks on the kernel image and module
 411          * area mappings. (these are purely build-time and produce no code)
 412          */
 413         BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
 414         BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
 415         BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 416         BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
 417         BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 418         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
 419         MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 420                                 (__START_KERNEL & PGDIR_MASK)));
 421         BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
 422
 423         cr4_init_shadow();
 424
 425         /* Kill off the identity-map trampoline */
 426         reset_early_page_tables();
 427
 428         clear_bss();
 429
 430         clear_page(init_top_pgt);
 431
 432         /*
 433          * SME support may update early_pmd_flags to include the memory
 434          * encryption mask, so it needs to be called before anything
 435          * that may generate a page fault.
 436          */
 437         sme_early_init();
 438
 439         kasan_early_init();
 440
 441         idt_setup_early_handler();
 442
 443         copy_bootdata(__va(real_mode_data));
 444
 445         /*
 446          * Load microcode early on BSP.
 447          */
 448         load_ucode_bsp();
 449
 450         /* set init_top_pgt kernel high mapping*/
 451         init_top_pgt[511] = early_top_pgt[511];
 452
 453         x86_64_start_reservations(real_mode_data);
 454 }
 455
 456 void __init x86_64_start_reservations(char *real_mode_data)
 457 {
 458         /* version is always not zero if it is copied */
 459         if (!boot_params.hdr.version)
 460                 copy_bootdata(__va(real_mode_data));
 461
 462         x86_early_init_platform_quirks();
 463
 464         switch (boot_params.hdr.hardware_subarch) {
 465         case X86_SUBARCH_INTEL_MID:
 466                 x86_intel_mid_early_setup();
 467                 break;
 468         default:
 469                 break;
 470         }
 471
 472         start_kernel();
 473 }