arch/x86/mm/dump_pagetables.c

   1 /*
   2  * Debug helper to dump the current kernel pagetables of the system
   3  * so that we can see what the various memory ranges are set to.
   4  *
   5  * (C) Copyright 2008 Intel Corporation
   6  *
   7  * Author: Arjan van de Ven <arjan@linux.intel.com>
   8  *
   9  * This program is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU General Public License
  11  * as published by the Free Software Foundation; version 2
  12  * of the License.
  13  */
  14
  15 #include <linux/debugfs.h>
  16 #include <linux/kasan.h>
  17 #include <linux/mm.h>
  18 #include <linux/init.h>
  19 #include <linux/sched.h>
  20 #include <linux/seq_file.h>
  21
  22 #include <asm/pgtable.h>
  23
  24 /*
  25  * The dumper groups pagetable entries of the same type into one, and for
  26  * that it needs to keep some state when walking, and flush this state
  27  * when a "break" in the continuity is found.
  28  */
  29 struct pg_state {
  30         int level;
  31         pgprot_t current_prot;
  32         unsigned long start_address;
  33         unsigned long current_address;
  34         const struct addr_marker *marker;
  35         unsigned long lines;
  36         bool to_dmesg;
  37         bool check_wx;
  38         unsigned long wx_pages;
  39 };
  40
  41 struct addr_marker {
  42         unsigned long start_address;
  43         const char *name;
  44         unsigned long max_lines;
  45 };
  46
  47 /* Address space markers hints */
  48
  49 #ifdef CONFIG_X86_64
  50
  51 enum address_markers_idx {
  52         USER_SPACE_NR = 0,
  53         KERNEL_SPACE_NR,
  54         LOW_KERNEL_NR,
  55 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && defined(CONFIG_X86_5LEVEL)
  56         LDT_NR,
  57 #endif
  58         VMALLOC_START_NR,
  59         VMEMMAP_START_NR,
  60 #ifdef CONFIG_KASAN
  61         KASAN_SHADOW_START_NR,
  62         KASAN_SHADOW_END_NR,
  63 #endif
  64         CPU_ENTRY_AREA_NR,
  65 #if defined(CONFIG_MODIFY_LDT_SYSCALL) && !defined(CONFIG_X86_5LEVEL)
  66         LDT_NR,
  67 #endif
  68 #ifdef CONFIG_X86_ESPFIX64
  69         ESPFIX_START_NR,
  70 #endif
  71 #ifdef CONFIG_EFI
  72         EFI_END_NR,
  73 #endif
  74         HIGH_KERNEL_NR,
  75         MODULES_VADDR_NR,
  76         MODULES_END_NR,
  77         FIXADDR_START_NR,
  78         END_OF_SPACE_NR,
  79 };
  80
  81 static struct addr_marker address_markers[] = {
  82         [USER_SPACE_NR]         = { 0,                  "User Space" },
  83         [KERNEL_SPACE_NR]       = { (1UL << 63),        "Kernel Space" },
  84         [LOW_KERNEL_NR]         = { 0UL,                "Low Kernel Mapping" },
  85         [VMALLOC_START_NR]      = { 0UL,                "vmalloc() Area" },
  86         [VMEMMAP_START_NR]      = { 0UL,                "Vmemmap" },
  87 #ifdef CONFIG_KASAN
  88         [KASAN_SHADOW_START_NR] = { KASAN_SHADOW_START, "KASAN shadow" },
  89         [KASAN_SHADOW_END_NR]   = { KASAN_SHADOW_END,   "KASAN shadow end" },
  90 #endif
  91 #ifdef CONFIG_MODIFY_LDT_SYSCALL
  92         [LDT_NR]                = { LDT_BASE_ADDR,      "LDT remap" },
  93 #endif
  94         [CPU_ENTRY_AREA_NR]     = { CPU_ENTRY_AREA_BASE,"CPU entry Area" },
  95 #ifdef CONFIG_X86_ESPFIX64
  96         [ESPFIX_START_NR]       = { ESPFIX_BASE_ADDR,   "ESPfix Area", 16 },
  97 #endif
  98 #ifdef CONFIG_EFI
  99         [EFI_END_NR]            = { EFI_VA_END,         "EFI Runtime Services" },
 100 #endif
 101         [HIGH_KERNEL_NR]        = { __START_KERNEL_map, "High Kernel Mapping" },
 102         [MODULES_VADDR_NR]      = { MODULES_VADDR,      "Modules" },
 103         [MODULES_END_NR]        = { MODULES_END,        "End Modules" },
 104         [FIXADDR_START_NR]      = { FIXADDR_START,      "Fixmap Area" },
 105         [END_OF_SPACE_NR]       = { -1,                 NULL }
 106 };
 107
 108 #else /* CONFIG_X86_64 */
 109
 110 enum address_markers_idx {
 111         USER_SPACE_NR = 0,
 112         KERNEL_SPACE_NR,
 113         VMALLOC_START_NR,
 114         VMALLOC_END_NR,
 115 #ifdef CONFIG_HIGHMEM
 116         PKMAP_BASE_NR,
 117 #endif
 118         CPU_ENTRY_AREA_NR,
 119         FIXADDR_START_NR,
 120         END_OF_SPACE_NR,
 121 };
 122
 123 static struct addr_marker address_markers[] = {
 124         [USER_SPACE_NR]         = { 0,                  "User Space" },
 125         [KERNEL_SPACE_NR]       = { PAGE_OFFSET,        "Kernel Mapping" },
 126         [VMALLOC_START_NR]      = { 0UL,                "vmalloc() Area" },
 127         [VMALLOC_END_NR]        = { 0UL,                "vmalloc() End" },
 128 #ifdef CONFIG_HIGHMEM
 129         [PKMAP_BASE_NR]         = { 0UL,                "Persistent kmap() Area" },
 130 #endif
 131         [CPU_ENTRY_AREA_NR]     = { 0UL,                "CPU entry area" },
 132         [FIXADDR_START_NR]      = { 0UL,                "Fixmap area" },
 133         [END_OF_SPACE_NR]       = { -1,                 NULL }
 134 };
 135
 136 #endif /* !CONFIG_X86_64 */
 137
 138 /* Multipliers for offsets within the PTEs */
 139 #define PTE_LEVEL_MULT (PAGE_SIZE)
 140 #define PMD_LEVEL_MULT (PTRS_PER_PTE * PTE_LEVEL_MULT)
 141 #define PUD_LEVEL_MULT (PTRS_PER_PMD * PMD_LEVEL_MULT)
 142 #define P4D_LEVEL_MULT (PTRS_PER_PUD * PUD_LEVEL_MULT)
 143 #define PGD_LEVEL_MULT (PTRS_PER_P4D * P4D_LEVEL_MULT)
 144
 145 #define pt_dump_seq_printf(m, to_dmesg, fmt, args...)           \
 146 ({                                                              \
 147         if (to_dmesg)                                   \
 148                 printk(KERN_INFO fmt, ##args);                  \
 149         else                                                    \
 150                 if (m)                                          \
 151                         seq_printf(m, fmt, ##args);             \
 152 })
 153
 154 #define pt_dump_cont_printf(m, to_dmesg, fmt, args...)          \
 155 ({                                                              \
 156         if (to_dmesg)                                   \
 157                 printk(KERN_CONT fmt, ##args);                  \
 158         else                                                    \
 159                 if (m)                                          \
 160                         seq_printf(m, fmt, ##args);             \
 161 })
 162
 163 /*
 164  * Print a readable form of a pgprot_t to the seq_file
 165  */
 166 static void printk_prot(struct seq_file *m, pgprot_t prot, int level, bool dmsg)
 167 {
 168         pgprotval_t pr = pgprot_val(prot);
 169         static const char * const level_name[] =
 170                 { "cr3", "pgd", "p4d", "pud", "pmd", "pte" };
 171
 172         if (!(pr & _PAGE_PRESENT)) {
 173                 /* Not present */
 174                 pt_dump_cont_printf(m, dmsg, "                              ");
 175         } else {
 176                 if (pr & _PAGE_USER)
 177                         pt_dump_cont_printf(m, dmsg, "USR ");
 178                 else
 179                         pt_dump_cont_printf(m, dmsg, "    ");
 180                 if (pr & _PAGE_RW)
 181                         pt_dump_cont_printf(m, dmsg, "RW ");
 182                 else
 183                         pt_dump_cont_printf(m, dmsg, "ro ");
 184                 if (pr & _PAGE_PWT)
 185                         pt_dump_cont_printf(m, dmsg, "PWT ");
 186                 else
 187                         pt_dump_cont_printf(m, dmsg, "    ");
 188                 if (pr & _PAGE_PCD)
 189                         pt_dump_cont_printf(m, dmsg, "PCD ");
 190                 else
 191                         pt_dump_cont_printf(m, dmsg, "    ");
 192
 193                 /* Bit 7 has a different meaning on level 3 vs 4 */
 194                 if (level <= 4 && pr & _PAGE_PSE)
 195                         pt_dump_cont_printf(m, dmsg, "PSE ");
 196                 else
 197                         pt_dump_cont_printf(m, dmsg, "    ");
 198                 if ((level == 5 && pr & _PAGE_PAT) ||
 199                     ((level == 4 || level == 3) && pr & _PAGE_PAT_LARGE))
 200                         pt_dump_cont_printf(m, dmsg, "PAT ");
 201                 else
 202                         pt_dump_cont_printf(m, dmsg, "    ");
 203                 if (pr & _PAGE_GLOBAL)
 204                         pt_dump_cont_printf(m, dmsg, "GLB ");
 205                 else
 206                         pt_dump_cont_printf(m, dmsg, "    ");
 207                 if (pr & _PAGE_NX)
 208                         pt_dump_cont_printf(m, dmsg, "NX ");
 209                 else
 210                         pt_dump_cont_printf(m, dmsg, "x  ");
 211         }
 212         pt_dump_cont_printf(m, dmsg, "%s\n", level_name[level]);
 213 }
 214
 215 /*
 216  * On 64 bits, sign-extend the 48 bit address to 64 bit
 217  */
 218 static unsigned long normalize_addr(unsigned long u)
 219 {
 220         int shift;
 221         if (!IS_ENABLED(CONFIG_X86_64))
 222                 return u;
 223
 224         shift = 64 - (__VIRTUAL_MASK_SHIFT + 1);
 225         return (signed long)(u << shift) >> shift;
 226 }
 227
 228 /*
 229  * This function gets called on a break in a continuous series
 230  * of PTE entries; the next one is different so we need to
 231  * print what we collected so far.
 232  */
 233 static void note_page(struct seq_file *m, struct pg_state *st,
 234                       pgprot_t new_prot, int level)
 235 {
 236         pgprotval_t prot, cur;
 237         static const char units[] = "BKMGTPE";
 238
 239         /*
 240          * If we have a "break" in the series, we need to flush the state that
 241          * we have now. "break" is either changing perms, levels or
 242          * address space marker.
 243          */
 244         prot = pgprot_val(new_prot);
 245         cur = pgprot_val(st->current_prot);
 246
 247         if (!st->level) {
 248                 /* First entry */
 249                 st->current_prot = new_prot;
 250                 st->level = level;
 251                 st->marker = address_markers;
 252                 st->lines = 0;
 253                 pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
 254                                    st->marker->name);
 255         } else if (prot != cur || level != st->level ||
 256                    st->current_address >= st->marker[1].start_address) {
 257                 const char *unit = units;
 258                 unsigned long delta;
 259                 int width = sizeof(unsigned long) * 2;
 260                 pgprotval_t pr = pgprot_val(st->current_prot);
 261
 262                 if (st->check_wx && (pr & _PAGE_RW) && !(pr & _PAGE_NX)) {
 263                         WARN_ONCE(1,
 264                                   "x86/mm: Found insecure W+X mapping at address %p/%pS\n",
 265                                   (void *)st->start_address,
 266                                   (void *)st->start_address);
 267                         st->wx_pages += (st->current_address -
 268                                          st->start_address) / PAGE_SIZE;
 269                 }
 270
 271                 /*
 272                  * Now print the actual finished series
 273                  */
 274                 if (!st->marker->max_lines ||
 275                     st->lines < st->marker->max_lines) {
 276                         pt_dump_seq_printf(m, st->to_dmesg,
 277                                            "0x%0*lx-0x%0*lx   ",
 278                                            width, st->start_address,
 279                                            width, st->current_address);
 280
 281                         delta = st->current_address - st->start_address;
 282                         while (!(delta & 1023) && unit[1]) {
 283                                 delta >>= 10;
 284                                 unit++;
 285                         }
 286                         pt_dump_cont_printf(m, st->to_dmesg, "%9lu%c ",
 287                                             delta, *unit);
 288                         printk_prot(m, st->current_prot, st->level,
 289                                     st->to_dmesg);
 290                 }
 291                 st->lines++;
 292
 293                 /*
 294                  * We print markers for special areas of address space,
 295                  * such as the start of vmalloc space etc.
 296                  * This helps in the interpretation.
 297                  */
 298                 if (st->current_address >= st->marker[1].start_address) {
 299                         if (st->marker->max_lines &&
 300                             st->lines > st->marker->max_lines) {
 301                                 unsigned long nskip =
 302                                         st->lines - st->marker->max_lines;
 303                                 pt_dump_seq_printf(m, st->to_dmesg,
 304                                                    "... %lu entr%s skipped ... \n",
 305                                                    nskip,
 306                                                    nskip == 1 ? "y" : "ies");
 307                         }
 308                         st->marker++;
 309                         st->lines = 0;
 310                         pt_dump_seq_printf(m, st->to_dmesg, "---[ %s ]---\n",
 311                                            st->marker->name);
 312                 }
 313
 314                 st->start_address = st->current_address;
 315                 st->current_prot = new_prot;
 316                 st->level = level;
 317         }
 318 }
 319
 320 static void walk_pte_level(struct seq_file *m, struct pg_state *st, pmd_t addr, unsigned long P)
 321 {
 322         int i;
 323         pte_t *start;
 324         pgprotval_t prot;
 325
 326         start = (pte_t *)pmd_page_vaddr(addr);
 327         for (i = 0; i < PTRS_PER_PTE; i++) {
 328                 prot = pte_flags(*start);
 329                 st->current_address = normalize_addr(P + i * PTE_LEVEL_MULT);
 330                 note_page(m, st, __pgprot(prot), 5);
 331                 start++;
 332         }
 333 }
 334 #ifdef CONFIG_KASAN
 335
 336 /*
 337  * This is an optimization for KASAN=y case. Since all kasan page tables
 338  * eventually point to the kasan_zero_page we could call note_page()
 339  * right away without walking through lower level page tables. This saves
 340  * us dozens of seconds (minutes for 5-level config) while checking for
 341  * W+X mapping or reading kernel_page_tables debugfs file.
 342  */
 343 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
 344                                 void *pt)
 345 {
 346         if (__pa(pt) == __pa(kasan_zero_pmd) ||
 347 #ifdef CONFIG_X86_5LEVEL
 348             __pa(pt) == __pa(kasan_zero_p4d) ||
 349 #endif
 350             __pa(pt) == __pa(kasan_zero_pud)) {
 351                 pgprotval_t prot = pte_flags(kasan_zero_pte[0]);
 352                 note_page(m, st, __pgprot(prot), 5);
 353                 return true;
 354         }
 355         return false;
 356 }
 357 #else
 358 static inline bool kasan_page_table(struct seq_file *m, struct pg_state *st,
 359                                 void *pt)
 360 {
 361         return false;
 362 }
 363 #endif
 364
 365 #if PTRS_PER_PMD > 1
 366
 367 static void walk_pmd_level(struct seq_file *m, struct pg_state *st, pud_t addr, unsigned long P)
 368 {
 369         int i;
 370         pmd_t *start, *pmd_start;
 371         pgprotval_t prot;
 372
 373         pmd_start = start = (pmd_t *)pud_page_vaddr(addr);
 374         for (i = 0; i < PTRS_PER_PMD; i++) {
 375                 st->current_address = normalize_addr(P + i * PMD_LEVEL_MULT);
 376                 if (!pmd_none(*start)) {
 377                         if (pmd_large(*start) || !pmd_present(*start)) {
 378                                 prot = pmd_flags(*start);
 379                                 note_page(m, st, __pgprot(prot), 4);
 380                         } else if (!kasan_page_table(m, st, pmd_start)) {
 381                                 walk_pte_level(m, st, *start,
 382                                                P + i * PMD_LEVEL_MULT);
 383                         }
 384                 } else
 385                         note_page(m, st, __pgprot(0), 4);
 386                 start++;
 387         }
 388 }
 389
 390 #else
 391 #define walk_pmd_level(m,s,a,p) walk_pte_level(m,s,__pmd(pud_val(a)),p)
 392 #define pud_large(a) pmd_large(__pmd(pud_val(a)))
 393 #define pud_none(a)  pmd_none(__pmd(pud_val(a)))
 394 #endif
 395
 396 #if PTRS_PER_PUD > 1
 397
 398 static void walk_pud_level(struct seq_file *m, struct pg_state *st, p4d_t addr, unsigned long P)
 399 {
 400         int i;
 401         pud_t *start, *pud_start;
 402         pgprotval_t prot;
 403         pud_t *prev_pud = NULL;
 404
 405         pud_start = start = (pud_t *)p4d_page_vaddr(addr);
 406
 407         for (i = 0; i < PTRS_PER_PUD; i++) {
 408                 st->current_address = normalize_addr(P + i * PUD_LEVEL_MULT);
 409                 if (!pud_none(*start)) {
 410                         if (pud_large(*start) || !pud_present(*start)) {
 411                                 prot = pud_flags(*start);
 412                                 note_page(m, st, __pgprot(prot), 3);
 413                         } else if (!kasan_page_table(m, st, pud_start)) {
 414                                 walk_pmd_level(m, st, *start,
 415                                                P + i * PUD_LEVEL_MULT);
 416                         }
 417                 } else
 418                         note_page(m, st, __pgprot(0), 3);
 419
 420                 prev_pud = start;
 421                 start++;
 422         }
 423 }
 424
 425 #else
 426 #define walk_pud_level(m,s,a,p) walk_pmd_level(m,s,__pud(p4d_val(a)),p)
 427 #define p4d_large(a) pud_large(__pud(p4d_val(a)))
 428 #define p4d_none(a)  pud_none(__pud(p4d_val(a)))
 429 #endif
 430
 431 #if PTRS_PER_P4D > 1
 432
 433 static void walk_p4d_level(struct seq_file *m, struct pg_state *st, pgd_t addr, unsigned long P)
 434 {
 435         int i;
 436         p4d_t *start, *p4d_start;
 437         pgprotval_t prot;
 438
 439         p4d_start = start = (p4d_t *)pgd_page_vaddr(addr);
 440
 441         for (i = 0; i < PTRS_PER_P4D; i++) {
 442                 st->current_address = normalize_addr(P + i * P4D_LEVEL_MULT);
 443                 if (!p4d_none(*start)) {
 444                         if (p4d_large(*start) || !p4d_present(*start)) {
 445                                 prot = p4d_flags(*start);
 446                                 note_page(m, st, __pgprot(prot), 2);
 447                         } else if (!kasan_page_table(m, st, p4d_start)) {
 448                                 walk_pud_level(m, st, *start,
 449                                                P + i * P4D_LEVEL_MULT);
 450                         }
 451                 } else
 452                         note_page(m, st, __pgprot(0), 2);
 453
 454                 start++;
 455         }
 456 }
 457
 458 #else
 459 #define walk_p4d_level(m,s,a,p) walk_pud_level(m,s,__p4d(pgd_val(a)),p)
 460 #define pgd_large(a) p4d_large(__p4d(pgd_val(a)))
 461 #define pgd_none(a)  p4d_none(__p4d(pgd_val(a)))
 462 #endif
 463
 464 static inline bool is_hypervisor_range(int idx)
 465 {
 466 #ifdef CONFIG_X86_64
 467         /*
 468          * ffff800000000000 - ffff87ffffffffff is reserved for
 469          * the hypervisor.
 470          */
 471         return  (idx >= pgd_index(__PAGE_OFFSET) - 16) &&
 472                 (idx <  pgd_index(__PAGE_OFFSET));
 473 #else
 474         return false;
 475 #endif
 476 }
 477
 478 static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd,
 479                                        bool checkwx, bool dmesg)
 480 {
 481 #ifdef CONFIG_X86_64
 482         pgd_t *start = (pgd_t *) &init_top_pgt;
 483 #else
 484         pgd_t *start = swapper_pg_dir;
 485 #endif
 486         pgprotval_t prot;
 487         int i;
 488         struct pg_state st = {};
 489
 490         if (pgd) {
 491                 start = pgd;
 492                 st.to_dmesg = dmesg;
 493         }
 494
 495         st.check_wx = checkwx;
 496         if (checkwx)
 497                 st.wx_pages = 0;
 498
 499         for (i = 0; i < PTRS_PER_PGD; i++) {
 500                 st.current_address = normalize_addr(i * PGD_LEVEL_MULT);
 501                 if (!pgd_none(*start) && !is_hypervisor_range(i)) {
 502                         if (pgd_large(*start) || !pgd_present(*start)) {
 503                                 prot = pgd_flags(*start);
 504                                 note_page(m, &st, __pgprot(prot), 1);
 505                         } else {
 506                                 walk_p4d_level(m, &st, *start,
 507                                                i * PGD_LEVEL_MULT);
 508                         }
 509                 } else
 510                         note_page(m, &st, __pgprot(0), 1);
 511
 512                 cond_resched();
 513                 start++;
 514         }
 515
 516         /* Flush out the last page */
 517         st.current_address = normalize_addr(PTRS_PER_PGD*PGD_LEVEL_MULT);
 518         note_page(m, &st, __pgprot(0), 0);
 519         if (!checkwx)
 520                 return;
 521         if (st.wx_pages)
 522                 pr_info("x86/mm: Checked W+X mappings: FAILED, %lu W+X pages found.\n",
 523                         st.wx_pages);
 524         else
 525                 pr_info("x86/mm: Checked W+X mappings: passed, no W+X pages found.\n");
 526 }
 527
 528 void ptdump_walk_pgd_level(struct seq_file *m, pgd_t *pgd)
 529 {
 530         ptdump_walk_pgd_level_core(m, pgd, false, true);
 531 }
 532
 533 void ptdump_walk_pgd_level_debugfs(struct seq_file *m, pgd_t *pgd, bool user)
 534 {
 535 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 536         if (user && static_cpu_has(X86_FEATURE_PTI))
 537                 pgd = kernel_to_user_pgdp(pgd);
 538 #endif
 539         ptdump_walk_pgd_level_core(m, pgd, false, false);
 540 }
 541 EXPORT_SYMBOL_GPL(ptdump_walk_pgd_level_debugfs);
 542
 543 static void ptdump_walk_user_pgd_level_checkwx(void)
 544 {
 545 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 546         pgd_t *pgd = (pgd_t *) &init_top_pgt;
 547
 548         if (!static_cpu_has(X86_FEATURE_PTI))
 549                 return;
 550
 551         pr_info("x86/mm: Checking user space page tables\n");
 552         pgd = kernel_to_user_pgdp(pgd);
 553         ptdump_walk_pgd_level_core(NULL, pgd, true, false);
 554 #endif
 555 }
 556
 557 void ptdump_walk_pgd_level_checkwx(void)
 558 {
 559         ptdump_walk_pgd_level_core(NULL, NULL, true, false);
 560         ptdump_walk_user_pgd_level_checkwx();
 561 }
 562
 563 static int __init pt_dump_init(void)
 564 {
 565         /*
 566          * Various markers are not compile-time constants, so assign them
 567          * here.
 568          */
 569 #ifdef CONFIG_X86_64
 570         address_markers[LOW_KERNEL_NR].start_address = PAGE_OFFSET;
 571         address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
 572         address_markers[VMEMMAP_START_NR].start_address = VMEMMAP_START;
 573 #endif
 574 #ifdef CONFIG_X86_32
 575         address_markers[VMALLOC_START_NR].start_address = VMALLOC_START;
 576         address_markers[VMALLOC_END_NR].start_address = VMALLOC_END;
 577 # ifdef CONFIG_HIGHMEM
 578         address_markers[PKMAP_BASE_NR].start_address = PKMAP_BASE;
 579 # endif
 580         address_markers[FIXADDR_START_NR].start_address = FIXADDR_START;
 581         address_markers[CPU_ENTRY_AREA_NR].start_address = CPU_ENTRY_AREA_BASE;
 582 #endif
 583         return 0;
 584 }
 585 __initcall(pt_dump_init);