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
  39 /*
  40  * Manage page tables very early on.
  41  */
  42 extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
  43 static unsigned int __initdata next_early_pgt;
  44 pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
  45
  46 #ifdef CONFIG_X86_5LEVEL
  47 unsigned int __pgtable_l5_enabled __ro_after_init;
  48 unsigned int pgdir_shift __ro_after_init = 39;
  49 EXPORT_SYMBOL(pgdir_shift);
  50 unsigned int ptrs_per_p4d __ro_after_init = 1;
  51 EXPORT_SYMBOL(ptrs_per_p4d);
  52 #endif
  53
  54 #ifdef CONFIG_DYNAMIC_MEMORY_LAYOUT
  55 unsigned long page_offset_base __ro_after_init = __PAGE_OFFSET_BASE_L4;
  56 EXPORT_SYMBOL(page_offset_base);
  57 unsigned long vmalloc_base __ro_after_init = __VMALLOC_BASE_L4;
  58 EXPORT_SYMBOL(vmalloc_base);
  59 unsigned long vmemmap_base __ro_after_init = __VMEMMAP_BASE_L4;
  60 EXPORT_SYMBOL(vmemmap_base);
  61 #endif
  62
  63 #define __head  __section(.head.text)
  64
  65 static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
  66 {
  67         return ptr - (void *)_text + (void *)physaddr;
  68 }
  69
  70 static unsigned long __head *fixup_long(void *ptr, unsigned long physaddr)
  71 {
  72         return fixup_pointer(ptr, physaddr);
  73 }
  74
  75 #ifdef CONFIG_X86_5LEVEL
  76 static unsigned int __head *fixup_int(void *ptr, unsigned long physaddr)
  77 {
  78         return fixup_pointer(ptr, physaddr);
  79 }
  80
  81 static bool __head check_la57_support(unsigned long physaddr)
  82 {
  83         /*
  84          * 5-level paging is detected and enabled at kernel decomression
  85          * stage. Only check if it has been enabled there.
  86          */
  87         if (!(native_read_cr4() & X86_CR4_LA57))
  88                 return false;
  89
  90         *fixup_int(&__pgtable_l5_enabled, physaddr) = 1;
  91         *fixup_int(&pgdir_shift, physaddr) = 48;
  92         *fixup_int(&ptrs_per_p4d, physaddr) = 512;
  93         *fixup_long(&page_offset_base, physaddr) = __PAGE_OFFSET_BASE_L5;
  94         *fixup_long(&vmalloc_base, physaddr) = __VMALLOC_BASE_L5;
  95         *fixup_long(&vmemmap_base, physaddr) = __VMEMMAP_BASE_L5;
  96
  97         return true;
  98 }
  99 #else
 100 static bool __head check_la57_support(unsigned long physaddr)
 101 {
 102         return false;
 103 }
 104 #endif
 105
 106 /* Code in __startup_64() can be relocated during execution, but the compiler
 107  * doesn't have to generate PC-relative relocations when accessing globals from
 108  * that function. Clang actually does not generate them, which leads to
 109  * boot-time crashes. To work around this problem, every global pointer must
 110  * be adjusted using fixup_pointer().
 111  */
 112 unsigned long __head __startup_64(unsigned long physaddr,
 113                                   struct boot_params *bp)
 114 {
 115         unsigned long load_delta, *p;
 116         unsigned long pgtable_flags;
 117         pgdval_t *pgd;
 118         p4dval_t *p4d;
 119         pudval_t *pud;
 120         pmdval_t *pmd, pmd_entry;
 121         pteval_t *mask_ptr;
 122         bool la57;
 123         int i;
 124         unsigned int *next_pgt_ptr;
 125
 126         la57 = check_la57_support(physaddr);
 127
 128         /* Is the address too large? */
 129         if (physaddr >> MAX_PHYSMEM_BITS)
 130                 for (;;);
 131
 132         /*
 133          * Compute the delta between the address I am compiled to run at
 134          * and the address I am actually running at.
 135          */
 136         load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);
 137
 138         /* Is the address not 2M aligned? */
 139         if (load_delta & ~PMD_PAGE_MASK)
 140                 for (;;);
 141
 142         /* Activate Secure Memory Encryption (SME) if supported and enabled */
 143         sme_enable(bp);
 144
 145         /* Include the SME encryption mask in the fixup value */
 146         load_delta += sme_get_me_mask();
 147
 148         /* Fixup the physical addresses in the page table */
 149
 150         pgd = fixup_pointer(&early_top_pgt, physaddr);
 151         p = pgd + pgd_index(__START_KERNEL_map);
 152         if (la57)
 153                 *p = (unsigned long)level4_kernel_pgt;
 154         else
 155                 *p = (unsigned long)level3_kernel_pgt;
 156         *p += _PAGE_TABLE_NOENC - __START_KERNEL_map + load_delta;
 157
 158         if (la57) {
 159                 p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
 160                 p4d[511] += load_delta;
 161         }
 162
 163         pud = fixup_pointer(&level3_kernel_pgt, physaddr);
 164         pud[510] += load_delta;
 165         pud[511] += load_delta;
 166
 167         pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
 168         pmd[506] += load_delta;
 169
 170         /*
 171          * Set up the identity mapping for the switchover.  These
 172          * entries should *NOT* have the global bit set!  This also
 173          * creates a bunch of nonsense entries but that is fine --
 174          * it avoids problems around wraparound.
 175          */
 176
 177         next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
 178         pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 179         pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 180
 181         pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
 182
 183         if (la57) {
 184                 p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
 185
 186                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 187                 pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
 188                 pgd[i + 1] = (pgdval_t)p4d + pgtable_flags;
 189
 190                 i = (physaddr >> P4D_SHIFT) % PTRS_PER_P4D;
 191                 p4d[i + 0] = (pgdval_t)pud + pgtable_flags;
 192                 p4d[i + 1] = (pgdval_t)pud + pgtable_flags;
 193         } else {
 194                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 195                 pgd[i + 0] = (pgdval_t)pud + pgtable_flags;
 196                 pgd[i + 1] = (pgdval_t)pud + pgtable_flags;
 197         }
 198
 199         i = (physaddr >> PUD_SHIFT) % PTRS_PER_PUD;
 200         pud[i + 0] = (pudval_t)pmd + pgtable_flags;
 201         pud[i + 1] = (pudval_t)pmd + pgtable_flags;
 202
 203         pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
 204         /* Filter out unsupported __PAGE_KERNEL_* bits: */
 205         mask_ptr = fixup_pointer(&__supported_pte_mask, physaddr);
 206         pmd_entry &= *mask_ptr;
 207         pmd_entry += sme_get_me_mask();
 208         pmd_entry +=  physaddr;
 209
 210         for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
 211                 int idx = i + (physaddr >> PMD_SHIFT) % PTRS_PER_PMD;
 212                 pmd[idx] = pmd_entry + i * PMD_SIZE;
 213         }
 214
 215         /*
 216          * Fixup the kernel text+data virtual addresses. Note that
 217          * we might write invalid pmds, when the kernel is relocated
 218          * cleanup_highmap() fixes this up along with the mappings
 219          * beyond _end.
 220          */
 221
 222         pmd = fixup_pointer(level2_kernel_pgt, physaddr);
 223         for (i = 0; i < PTRS_PER_PMD; i++) {
 224                 if (pmd[i] & _PAGE_PRESENT)
 225                         pmd[i] += load_delta;
 226         }
 227
 228         /*
 229          * Fixup phys_base - remove the memory encryption mask to obtain
 230          * the true physical address.
 231          */
 232         *fixup_long(&phys_base, physaddr) += load_delta - sme_get_me_mask();
 233
 234         /* Encrypt the kernel and related (if SME is active) */
 235         sme_encrypt_kernel(bp);
 236
 237         /*
 238          * Return the SME encryption mask (if SME is active) to be used as a
 239          * modifier for the initial pgdir entry programmed into CR3.
 240          */
 241         return sme_get_me_mask();
 242 }
 243
 244 unsigned long __startup_secondary_64(void)
 245 {
 246         /*
 247          * Return the SME encryption mask (if SME is active) to be used as a
 248          * modifier for the initial pgdir entry programmed into CR3.
 249          */
 250         return sme_get_me_mask();
 251 }
 252
 253 /* Wipe all early page tables except for the kernel symbol map */
 254 static void __init reset_early_page_tables(void)
 255 {
 256         memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
 257         next_early_pgt = 0;
 258         write_cr3(__sme_pa_nodebug(early_top_pgt));
 259 }
 260
 261 /* Create a new PMD entry */
 262 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 263 {
 264         unsigned long physaddr = address - __PAGE_OFFSET;
 265         pgdval_t pgd, *pgd_p;
 266         p4dval_t p4d, *p4d_p;
 267         pudval_t pud, *pud_p;
 268         pmdval_t *pmd_p;
 269
 270         /* Invalid address or early pgt is done ?  */
 271         if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
 272                 return -1;
 273
 274 again:
 275         pgd_p = &early_top_pgt[pgd_index(address)].pgd;
 276         pgd = *pgd_p;
 277
 278         /*
 279          * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
 280          * critical -- __PAGE_OFFSET would point us back into the dynamic
 281          * range and we might end up looping forever...
 282          */
 283         if (!pgtable_l5_enabled())
 284                 p4d_p = pgd_p;
 285         else if (pgd)
 286                 p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 287         else {
 288                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 289                         reset_early_page_tables();
 290                         goto again;
 291                 }
 292
 293                 p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
 294                 memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
 295                 *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 296         }
 297         p4d_p += p4d_index(address);
 298         p4d = *p4d_p;
 299
 300         if (p4d)
 301                 pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 302         else {
 303                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 304                         reset_early_page_tables();
 305                         goto again;
 306                 }
 307
 308                 pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
 309                 memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
 310                 *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 311         }
 312         pud_p += pud_index(address);
 313         pud = *pud_p;
 314
 315         if (pud)
 316                 pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 317         else {
 318                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 319                         reset_early_page_tables();
 320                         goto again;
 321                 }
 322
 323                 pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
 324                 memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
 325                 *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 326         }
 327         pmd_p[pmd_index(address)] = pmd;
 328
 329         return 0;
 330 }
 331
 332 int __init early_make_pgtable(unsigned long address)
 333 {
 334         unsigned long physaddr = address - __PAGE_OFFSET;
 335         pmdval_t pmd;
 336
 337         pmd = (physaddr & PMD_MASK) + early_pmd_flags;
 338
 339         return __early_make_pgtable(address, pmd);
 340 }
 341
 342 /* Don't add a printk in there. printk relies on the PDA which is not initialized
 343    yet. */
 344 static void __init clear_bss(void)
 345 {
 346         memset(__bss_start, 0,
 347                (unsigned long) __bss_stop - (unsigned long) __bss_start);
 348 }
 349
 350 static unsigned long get_cmd_line_ptr(void)
 351 {
 352         unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
 353
 354         cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
 355
 356         return cmd_line_ptr;
 357 }
 358
 359 static void __init copy_bootdata(char *real_mode_data)
 360 {
 361         char * command_line;
 362         unsigned long cmd_line_ptr;
 363
 364         /*
 365          * If SME is active, this will create decrypted mappings of the
 366          * boot data in advance of the copy operations.
 367          */
 368         sme_map_bootdata(real_mode_data);
 369
 370         memcpy(&boot_params, real_mode_data, sizeof boot_params);
 371         sanitize_boot_params(&boot_params);
 372         cmd_line_ptr = get_cmd_line_ptr();
 373         if (cmd_line_ptr) {
 374                 command_line = __va(cmd_line_ptr);
 375                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 376         }
 377
 378         /*
 379          * The old boot data is no longer needed and won't be reserved,
 380          * freeing up that memory for use by the system. If SME is active,
 381          * we need to remove the mappings that were created so that the
 382          * memory doesn't remain mapped as decrypted.
 383          */
 384         sme_unmap_bootdata(real_mode_data);
 385 }
 386
 387 asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 388 {
 389         /*
 390          * Build-time sanity checks on the kernel image and module
 391          * area mappings. (these are purely build-time and produce no code)
 392          */
 393         BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
 394         BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
 395         BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 396         BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
 397         BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 398         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
 399         MAYBE_BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 400                                 (__START_KERNEL & PGDIR_MASK)));
 401         BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
 402
 403         cr4_init_shadow();
 404
 405         /* Kill off the identity-map trampoline */
 406         reset_early_page_tables();
 407
 408         clear_bss();
 409
 410         clear_page(init_top_pgt);
 411
 412         /*
 413          * SME support may update early_pmd_flags to include the memory
 414          * encryption mask, so it needs to be called before anything
 415          * that may generate a page fault.
 416          */
 417         sme_early_init();
 418
 419         kasan_early_init();
 420
 421         idt_setup_early_handler();
 422
 423         copy_bootdata(__va(real_mode_data));
 424
 425         /*
 426          * Load microcode early on BSP.
 427          */
 428         load_ucode_bsp();
 429
 430         /* set init_top_pgt kernel high mapping*/
 431         init_top_pgt[511] = early_top_pgt[511];
 432
 433         x86_64_start_reservations(real_mode_data);
 434 }
 435
 436 void __init x86_64_start_reservations(char *real_mode_data)
 437 {
 438         /* version is always not zero if it is copied */
 439         if (!boot_params.hdr.version)
 440                 copy_bootdata(__va(real_mode_data));
 441
 442         x86_early_init_platform_quirks();
 443
 444         switch (boot_params.hdr.hardware_subarch) {
 445         case X86_SUBARCH_INTEL_MID:
 446                 x86_intel_mid_early_setup();
 447                 break;
 448         default:
 449                 break;
 450         }
 451
 452         start_kernel();
 453 }