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
  35 /*
  36  * Manage page tables very early on.
  37  */
  38 extern pmd_t early_dynamic_pgts[EARLY_DYNAMIC_PAGE_TABLES][PTRS_PER_PMD];
  39 static unsigned int __initdata next_early_pgt;
  40 pmdval_t early_pmd_flags = __PAGE_KERNEL_LARGE & ~(_PAGE_GLOBAL | _PAGE_NX);
  41
  42 #define __head  __section(.head.text)
  43
  44 static void __head *fixup_pointer(void *ptr, unsigned long physaddr)
  45 {
  46         return ptr - (void *)_text + (void *)physaddr;
  47 }
  48
  49 unsigned long __head __startup_64(unsigned long physaddr,
  50                                   struct boot_params *bp)
  51 {
  52         unsigned long load_delta, *p;
  53         unsigned long pgtable_flags;
  54         pgdval_t *pgd;
  55         p4dval_t *p4d;
  56         pudval_t *pud;
  57         pmdval_t *pmd, pmd_entry;
  58         int i;
  59         unsigned int *next_pgt_ptr;
  60
  61         /* Is the address too large? */
  62         if (physaddr >> MAX_PHYSMEM_BITS)
  63                 for (;;);
  64
  65         /*
  66          * Compute the delta between the address I am compiled to run at
  67          * and the address I am actually running at.
  68          */
  69         load_delta = physaddr - (unsigned long)(_text - __START_KERNEL_map);
  70
  71         /* Is the address not 2M aligned? */
  72         if (load_delta & ~PMD_PAGE_MASK)
  73                 for (;;);
  74
  75         /* Activate Secure Memory Encryption (SME) if supported and enabled */
  76         sme_enable(bp);
  77
  78         /* Include the SME encryption mask in the fixup value */
  79         load_delta += sme_get_me_mask();
  80
  81         /* Fixup the physical addresses in the page table */
  82
  83         pgd = fixup_pointer(&early_top_pgt, physaddr);
  84         pgd[pgd_index(__START_KERNEL_map)] += load_delta;
  85
  86         if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
  87                 p4d = fixup_pointer(&level4_kernel_pgt, physaddr);
  88                 p4d[511] += load_delta;
  89         }
  90
  91         pud = fixup_pointer(&level3_kernel_pgt, physaddr);
  92         pud[510] += load_delta;
  93         pud[511] += load_delta;
  94
  95         pmd = fixup_pointer(level2_fixmap_pgt, physaddr);
  96         pmd[506] += load_delta;
  97
  98         /*
  99          * Set up the identity mapping for the switchover.  These
 100          * entries should *NOT* have the global bit set!  This also
 101          * creates a bunch of nonsense entries but that is fine --
 102          * it avoids problems around wraparound.
 103          */
 104
 105         next_pgt_ptr = fixup_pointer(&next_early_pgt, physaddr);
 106         pud = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 107         pmd = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++], physaddr);
 108
 109         pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
 110
 111         if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
 112                 p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
 113
 114                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 115                 pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
 116                 pgd[i + 1] = (pgdval_t)p4d + pgtable_flags;
 117
 118                 i = (physaddr >> P4D_SHIFT) % PTRS_PER_P4D;
 119                 p4d[i + 0] = (pgdval_t)pud + pgtable_flags;
 120                 p4d[i + 1] = (pgdval_t)pud + pgtable_flags;
 121         } else {
 122                 i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
 123                 pgd[i + 0] = (pgdval_t)pud + pgtable_flags;
 124                 pgd[i + 1] = (pgdval_t)pud + pgtable_flags;
 125         }
 126
 127         i = (physaddr >> PUD_SHIFT) % PTRS_PER_PUD;
 128         pud[i + 0] = (pudval_t)pmd + pgtable_flags;
 129         pud[i + 1] = (pudval_t)pmd + pgtable_flags;
 130
 131         pmd_entry = __PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL;
 132         pmd_entry += sme_get_me_mask();
 133         pmd_entry +=  physaddr;
 134
 135         for (i = 0; i < DIV_ROUND_UP(_end - _text, PMD_SIZE); i++) {
 136                 int idx = i + (physaddr >> PMD_SHIFT) % PTRS_PER_PMD;
 137                 pmd[idx] = pmd_entry + i * PMD_SIZE;
 138         }
 139
 140         /*
 141          * Fixup the kernel text+data virtual addresses. Note that
 142          * we might write invalid pmds, when the kernel is relocated
 143          * cleanup_highmap() fixes this up along with the mappings
 144          * beyond _end.
 145          */
 146
 147         pmd = fixup_pointer(level2_kernel_pgt, physaddr);
 148         for (i = 0; i < PTRS_PER_PMD; i++) {
 149                 if (pmd[i] & _PAGE_PRESENT)
 150                         pmd[i] += load_delta;
 151         }
 152
 153         /*
 154          * Fixup phys_base - remove the memory encryption mask to obtain
 155          * the true physical address.
 156          */
 157         p = fixup_pointer(&phys_base, physaddr);
 158         *p += load_delta - sme_get_me_mask();
 159
 160         /* Encrypt the kernel (if SME is active) */
 161         sme_encrypt_kernel();
 162
 163         /*
 164          * Return the SME encryption mask (if SME is active) to be used as a
 165          * modifier for the initial pgdir entry programmed into CR3.
 166          */
 167         return sme_get_me_mask();
 168 }
 169
 170 unsigned long __startup_secondary_64(void)
 171 {
 172         /*
 173          * Return the SME encryption mask (if SME is active) to be used as a
 174          * modifier for the initial pgdir entry programmed into CR3.
 175          */
 176         return sme_get_me_mask();
 177 }
 178
 179 /* Wipe all early page tables except for the kernel symbol map */
 180 static void __init reset_early_page_tables(void)
 181 {
 182         memset(early_top_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
 183         next_early_pgt = 0;
 184         write_cr3(__sme_pa_nodebug(early_top_pgt));
 185 }
 186
 187 /* Create a new PMD entry */
 188 int __init __early_make_pgtable(unsigned long address, pmdval_t pmd)
 189 {
 190         unsigned long physaddr = address - __PAGE_OFFSET;
 191         pgdval_t pgd, *pgd_p;
 192         p4dval_t p4d, *p4d_p;
 193         pudval_t pud, *pud_p;
 194         pmdval_t *pmd_p;
 195
 196         /* Invalid address or early pgt is done ?  */
 197         if (physaddr >= MAXMEM || read_cr3_pa() != __pa_nodebug(early_top_pgt))
 198                 return -1;
 199
 200 again:
 201         pgd_p = &early_top_pgt[pgd_index(address)].pgd;
 202         pgd = *pgd_p;
 203
 204         /*
 205          * The use of __START_KERNEL_map rather than __PAGE_OFFSET here is
 206          * critical -- __PAGE_OFFSET would point us back into the dynamic
 207          * range and we might end up looping forever...
 208          */
 209         if (!IS_ENABLED(CONFIG_X86_5LEVEL))
 210                 p4d_p = pgd_p;
 211         else if (pgd)
 212                 p4d_p = (p4dval_t *)((pgd & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 213         else {
 214                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 215                         reset_early_page_tables();
 216                         goto again;
 217                 }
 218
 219                 p4d_p = (p4dval_t *)early_dynamic_pgts[next_early_pgt++];
 220                 memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D);
 221                 *pgd_p = (pgdval_t)p4d_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 222         }
 223         p4d_p += p4d_index(address);
 224         p4d = *p4d_p;
 225
 226         if (p4d)
 227                 pud_p = (pudval_t *)((p4d & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 228         else {
 229                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 230                         reset_early_page_tables();
 231                         goto again;
 232                 }
 233
 234                 pud_p = (pudval_t *)early_dynamic_pgts[next_early_pgt++];
 235                 memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD);
 236                 *p4d_p = (p4dval_t)pud_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 237         }
 238         pud_p += pud_index(address);
 239         pud = *pud_p;
 240
 241         if (pud)
 242                 pmd_p = (pmdval_t *)((pud & PTE_PFN_MASK) + __START_KERNEL_map - phys_base);
 243         else {
 244                 if (next_early_pgt >= EARLY_DYNAMIC_PAGE_TABLES) {
 245                         reset_early_page_tables();
 246                         goto again;
 247                 }
 248
 249                 pmd_p = (pmdval_t *)early_dynamic_pgts[next_early_pgt++];
 250                 memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD);
 251                 *pud_p = (pudval_t)pmd_p - __START_KERNEL_map + phys_base + _KERNPG_TABLE;
 252         }
 253         pmd_p[pmd_index(address)] = pmd;
 254
 255         return 0;
 256 }
 257
 258 int __init early_make_pgtable(unsigned long address)
 259 {
 260         unsigned long physaddr = address - __PAGE_OFFSET;
 261         pmdval_t pmd;
 262
 263         pmd = (physaddr & PMD_MASK) + early_pmd_flags;
 264
 265         return __early_make_pgtable(address, pmd);
 266 }
 267
 268 /* Don't add a printk in there. printk relies on the PDA which is not initialized
 269    yet. */
 270 static void __init clear_bss(void)
 271 {
 272         memset(__bss_start, 0,
 273                (unsigned long) __bss_stop - (unsigned long) __bss_start);
 274 }
 275
 276 static unsigned long get_cmd_line_ptr(void)
 277 {
 278         unsigned long cmd_line_ptr = boot_params.hdr.cmd_line_ptr;
 279
 280         cmd_line_ptr |= (u64)boot_params.ext_cmd_line_ptr << 32;
 281
 282         return cmd_line_ptr;
 283 }
 284
 285 static void __init copy_bootdata(char *real_mode_data)
 286 {
 287         char * command_line;
 288         unsigned long cmd_line_ptr;
 289
 290         /*
 291          * If SME is active, this will create decrypted mappings of the
 292          * boot data in advance of the copy operations.
 293          */
 294         sme_map_bootdata(real_mode_data);
 295
 296         memcpy(&boot_params, real_mode_data, sizeof boot_params);
 297         sanitize_boot_params(&boot_params);
 298         cmd_line_ptr = get_cmd_line_ptr();
 299         if (cmd_line_ptr) {
 300                 command_line = __va(cmd_line_ptr);
 301                 memcpy(boot_command_line, command_line, COMMAND_LINE_SIZE);
 302         }
 303
 304         /*
 305          * The old boot data is no longer needed and won't be reserved,
 306          * freeing up that memory for use by the system. If SME is active,
 307          * we need to remove the mappings that were created so that the
 308          * memory doesn't remain mapped as decrypted.
 309          */
 310         sme_unmap_bootdata(real_mode_data);
 311 }
 312
 313 asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
 314 {
 315         /*
 316          * Build-time sanity checks on the kernel image and module
 317          * area mappings. (these are purely build-time and produce no code)
 318          */
 319         BUILD_BUG_ON(MODULES_VADDR < __START_KERNEL_map);
 320         BUILD_BUG_ON(MODULES_VADDR - __START_KERNEL_map < KERNEL_IMAGE_SIZE);
 321         BUILD_BUG_ON(MODULES_LEN + KERNEL_IMAGE_SIZE > 2*PUD_SIZE);
 322         BUILD_BUG_ON((__START_KERNEL_map & ~PMD_MASK) != 0);
 323         BUILD_BUG_ON((MODULES_VADDR & ~PMD_MASK) != 0);
 324         BUILD_BUG_ON(!(MODULES_VADDR > __START_KERNEL));
 325         BUILD_BUG_ON(!(((MODULES_END - 1) & PGDIR_MASK) ==
 326                                 (__START_KERNEL & PGDIR_MASK)));
 327         BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
 328
 329         cr4_init_shadow();
 330
 331         /* Kill off the identity-map trampoline */
 332         reset_early_page_tables();
 333
 334         clear_bss();
 335
 336         clear_page(init_top_pgt);
 337
 338         /*
 339          * SME support may update early_pmd_flags to include the memory
 340          * encryption mask, so it needs to be called before anything
 341          * that may generate a page fault.
 342          */
 343         sme_early_init();
 344
 345         kasan_early_init();
 346
 347         idt_setup_early_handler();
 348
 349         copy_bootdata(__va(real_mode_data));
 350
 351         /*
 352          * Load microcode early on BSP.
 353          */
 354         load_ucode_bsp();
 355
 356         /* set init_top_pgt kernel high mapping*/
 357         init_top_pgt[511] = early_top_pgt[511];
 358
 359         x86_64_start_reservations(real_mode_data);
 360 }
 361
 362 void __init x86_64_start_reservations(char *real_mode_data)
 363 {
 364         /* version is always not zero if it is copied */
 365         if (!boot_params.hdr.version)
 366                 copy_bootdata(__va(real_mode_data));
 367
 368         x86_early_init_platform_quirks();
 369
 370         switch (boot_params.hdr.hardware_subarch) {
 371         case X86_SUBARCH_INTEL_MID:
 372                 x86_intel_mid_early_setup();
 373                 break;
 374         default:
 375                 break;
 376         }
 377
 378         start_kernel();
 379 }