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 #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 #include <asm/fixmap.h>
  35
  36 /*
  37  * Manage page tables very early on.
  38  */
  39 extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
  40 static unsigned int __initdata next_early_pgt;
  41 pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
  42
  43 #define __head  __section(.head.text)
  44
  45 static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
  46 {
  47         return ptr - (void *)_text + (void *)physaddr;
  48 }
  49
  50 unsigned long __head __startup_64(unsigned long physaddr,
  51                                   struct boot_params *bp)
  52 {
  53         unsigned long load_delta, *p;
  54         unsigned long pgtable_flags;
  55         pgdval_t *pgd;
  56         p4dval_t *p4d;
  57         pudval_t *pud;
  58         pmdval_t *pmd, pmd_entry;
  59         int i;
  60         unsigned int *next_pgt_ptr;
  61
  62         /* Is the address too large? */
  63         if (physaddr >> MAX_PHYSMEM_BITS)
  64                 for (;;);
  65
  66         /*
  67          * Compute the delta between the address I am compiled to run at
  68          * and the address I am actually running at.
  69          */
  70         load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);
  71
  72         /* Is the address not 2M aligned? */
  73         if (load_delta & ~PMD_PAGE_MASK)
  74                 for (;;);
  75
  76         /* Activate Secure Memory Encryption (SME) if supported and enabled */
  77         sme_enable(bp);
  78
  79         /* Include the SME encryption mask in the fixup value */
  80         load_delta += sme_get_me_mask();
  81
  82         /* Fixup the physical addresses in the page table */
  83
  84         pgd = fixup_pointer(&early_top_pgt, physaddr);
  85         pgd[pgd_index(__START_KERNEL_map)] += load_delta;
  86
  87         if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
  88                 p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
  89                 p4d[511] += load_delta;
  90         }
  91
  92         pud = fixup_pointer(&level3_kernel_pgt, physaddr);
  93         pud[510] += load_delta;
  94         pud[511] += load_delta;
  95
  96         pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
  97         for (i = FIXMAP_PMD_TOP; i > FIXMAP_PMD_TOP - FIXMAP_PMD_NUM; i--)
  98                 pmd[i] += load_delta;
  99
 100         /*
 101          * Set up the identity mapping for the switchover.  These
 102          * entries should *NOT* have the global bit set!  This also
 103          * creates a bunch of nonsense entries but that is fine --
 104          * it avoids problems around wraparound.
 105          */
 106
 107         next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
 108         pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 109         pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 110
 111         pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
 112
 113         if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
 114                 p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
 115
 116                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 117                 pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
 118                 pgd[i + 1] = (pgdval_t)p4d + pgtable_flags;
 119
 120                 i = physaddr >> P4D_SHIFT;
 121                 p4d[(i + 0) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags;
 122                 p4d[(i + 1) % PTRS_PER_P4D] = (pgdval_t)pud + pgtable_flags;
 123         } else {
 124                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 125                 pgd[i + 0] = (pgdval_t)pud + pgtable_flags;
 126                 pgd[i + 1] = (pgdval_t)pud + pgtable_flags;
 127         }
 128
 129         i = physaddr >> PUD_SHIFT;
 130         pud[(i + 0) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags;
 131         pud[(i + 1) % PTRS_PER_PUD] = (pudval_t)pmd + pgtable_flags;
 132
 133         pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
 134         pmd_entry += sme_get_me_mask();
 135         pmd_entry +=  physaddr;
 136
 137         for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
 138                 int idx = i + (physaddr >> PMD_SHIFT);
 139
 140                 pmd[idx % PTRS_PER_PMD] = pmd_entry + i * PMD_SIZE;
 141         }
 142
 143         /*
 144          * Fixup the kernel text+data virtual addresses. Note that
 145          * we might write invalid pmds, when the kernel is relocated
 146          * cleanup_highmap() fixes this up along with the mappings
 147          * beyond _end.
 148          *
 149          * Only the region occupied by the kernel image has so far
 150          * been checked against the table of usable memory regions
 151          * provided by the firmware, so invalidate pages outside that
 152          * region. A page table entry that maps to a reserved area of
 153          * memory would allow processor speculation into that area,
 154          * and on some hardware (particularly the UV platform) even
 155          * speculative access to some reserved areas is caught as an
 156          * error, causing the BIOS to halt the system.
 157          */
 158
 159         pmd = fixup_pointer(level2_kernel_pgt, physaddr);
 160
 161         /* invalidate pages before the kernel image */
 162         for (i = 0; i < pmd_index((unsigned long)_text); i++)
 163                 pmd[i] &= ~_PAGE_PRESENT;
 164
 165         /* fixup pages that are part of the kernel image */
 166         for (; i <= pmd_index((unsigned long)_end); i++)
 167                 if (pmd[i] & _PAGE_PRESENT)
 168                         pmd[i] += load_delta;
 169
 170         /* invalidate pages after the kernel image */
 171         for (; i < PTRS_PER_PMD; i++)
 172                 pmd[i] &= ~_PAGE_PRESENT;
 173
 174         /*
 175          * Fixup phys_base - remove the memory encryption mask to obtain
 176          * the true physical address.
 177          */
 178         p = fixup_pointer(&phys_base, physaddr);
 179         *p += load_delta - sme_get_me_mask();
 180
 181         /* Encrypt the kernel and related (if SME is active) */
 182         sme_encrypt_kernel(bp);
 183
 184         /*
 185          * Return the SME encryption mask (if SME is active) to be used as a
 186          * modifier for the initial pgdir entry programmed into CR3.
 187          */
 188         return sme_get_me_mask();
 189 }
 190
 191 unsigned long __startup_secondary_64(void)
 192 {
 193         /*
 194          * Return the SME encryption mask (if SME is active) to be used as a
 195          * modifier for the initial pgdir entry programmed into CR3.
 196          */
 197         return sme_get_me_mask();
 198 }
 199
 200 /* Wipe all early page tables except for the kernel symbol map */
 201 static void __init reset_early_page_tables(void)
 202 {
 203         memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
 204         next_early_pgt = 0;
 205         write_cr3(__sme_pa_nodebug(early_top_pgt));
 206 }
 207
 208 /* Create a new PMD entry */
 209 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 210 {
 211         unsigned long physaddr = address - __PAGE_OFFSET;
 212         pgdval_t pgd, *pgd_p;
 213         p4dval_t p4d, *p4d_p;
 214         pudval_t pud, *pud_p;
 215         pmdval_t *pmd_p;
 216
 217         /* Invalid address or early pgt is done ?  */
 218         if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
 219                 return -1;
 220
 221 again:
 222         pgd_p = &early_top_pgt[pgd_index(address)].pgd;
 223         pgd = *pgd_p;
 224
 225         /*
 226          * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
 227          * critical -- __PAGE_OFFSET would point us back into the dynamic
 228          * range and we might end up looping forever...
 229          */
 230         if (!IS_ENABLED(CONFIG_X86_5LEVEL))
 231                 p4d_p = pgd_p;
 232         else if (pgd)
 233                 p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 234         else {
 235                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 236                         reset_early_page_tables();
 237                         goto again;
 238                 }
 239
 240                 p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
 241                 memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
 242                 *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 243         }
 244         p4d_p += p4d_index(address);
 245         p4d = *p4d_p;
 246
 247         if (p4d)
 248                 pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 249         else {
 250                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 251                         reset_early_page_tables();
 252                         goto again;
 253                 }
 254
 255                 pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
 256                 memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
 257                 *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 258         }
 259         pud_p += pud_index(address);
 260         pud = *pud_p;
 261
 262         if (pud)
 263                 pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 264         else {
 265                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 266                         reset_early_page_tables();
 267                         goto again;
 268                 }
 269
 270                 pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
 271                 memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
 272                 *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 273         }
 274         pmd_p[pmd_index(address)] = pmd;
 275
 276         return 0;
 277 }
 278
 279 int __init early_make_pgtable(unsigned long address)
 280 {
 281         unsigned long physaddr = address - __PAGE_OFFSET;
 282         pmdval_t pmd;
 283
 284         pmd = (physaddr & PMD_MASK) + early_pmd_flags;
 285
 286         return __early_make_pgtable(address, pmd);
 287 }
 288
 289 /* Don't add a printk in there. printk relies on the PDA which is not initialized
 290    yet. */
 291 static void __init clear_bss(void)
 292 {
 293         memset(__bss_start, 0,
 294                (unsigned long) __bss_stop - (unsigned long) __bss_start);
 295 }
 296
 297 static unsigned long get_cmd_line_ptr(void)
 298 {
 299         unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
 300
 301         cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
 302
 303         return cmd_line_ptr;
 304 }
 305
 306 static void __init copy_bootdata(char *real_mode_data)
 307 {
 308         char * command_line;
 309         unsigned long cmd_line_ptr;
 310
 311         /*
 312          * If SME is active, this will create decrypted mappings of the
 313          * boot data in advance of the copy operations.
 314          */
 315         sme_map_bootdata(real_mode_data);
 316
 317         memcpy(&boot_params, real_mode_data, sizeof boot_params);
 318         sanitize_boot_params(&boot_params);
 319         cmd_line_ptr = get_cmd_line_ptr();
 320         if (cmd_line_ptr) {
 321                 command_line = __va(cmd_line_ptr);
 322                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 323         }
 324
 325         /*
 326          * The old boot data is no longer needed and won't be reserved,
 327          * freeing up that memory for use by the system. If SME is active,
 328          * we need to remove the mappings that were created so that the
 329          * memory doesn't remain mapped as decrypted.
 330          */
 331         sme_unmap_bootdata(real_mode_data);
 332 }
 333
 334 asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 335 {
 336         /*
 337          * Build-time sanity checks on the kernel image and module
 338          * area mappings. (these are purely build-time and produce no code)
 339          */
 340         BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
 341         BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
 342         BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 343         BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
 344         BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 345         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
 346         BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 347                                 (__START_KERNEL & PGDIR_MASK)));
 348         BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
 349
 350         cr4_init_shadow();
 351
 352         /* Kill off the identity-map trampoline */
 353         reset_early_page_tables();
 354
 355         clear_bss();
 356
 357         clear_page(init_top_pgt);
 358
 359         /*
 360          * SME support may update early_pmd_flags to include the memory
 361          * encryption mask, so it needs to be called before anything
 362          * that may generate a page fault.
 363          */
 364         sme_early_init();
 365
 366         kasan_early_init();
 367
 368         idt_setup_early_handler();
 369
 370         copy_bootdata(__va(real_mode_data));
 371
 372         /*
 373          * Load microcode early on BSP.
 374          */
 375         load_ucode_bsp();
 376
 377         /* set init_top_pgt kernel high mapping*/
 378         init_top_pgt[511] = early_top_pgt[511];
 379
 380         x86_64_start_reservations(real_mode_data);
 381 }
 382
 383 void __init x86_64_start_reservations(char *real_mode_data)
 384 {
 385         /* version is always not zero if it is copied */
 386         if (!boot_params.hdr.version)
 387                 copy_bootdata(__va(real_mode_data));
 388
 389         x86_early_init_platform_quirks();
 390
 391         switch (boot_params.hdr.hardware_subarch) {
 392         case X86_SUBARCH_INTEL_MID:
 393                 x86_intel_mid_early_setup();
 394                 break;
 395         default:
 396                 break;
 397         }
 398
 399         start_kernel();
 400 }