fs/proc/vmcore.c

   1 /*
   2  *      fs/proc/vmcore.c Interface for accessing the crash
   3  *                               dump from the system's previous life.
   4  *      Heavily borrowed from fs/proc/kcore.c
   5  *      Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
   6  *      Copyright (C) IBM Corporation, 2004. All rights reserved
   7  *
   8  */
   9
  10 #include <linux/mm.h>
  11 #include <linux/proc_fs.h>
  12 #include <linux/user.h>
  13 #include <linux/elf.h>
  14 #include <linux/elfcore.h>
  15 #include <linux/slab.h>
  16 #include <linux/highmem.h>
  17 #include <linux/bootmem.h>
  18 #include <linux/init.h>
  19 #include <linux/crash_dump.h>
  20 #include <linux/list.h>
  21 #include <asm/uaccess.h>
  22 #include <asm/io.h>
  23
  24 /* List representing chunks of contiguous memory areas and their offsets in
  25  * vmcore file.
  26  */
  27 static LIST_HEAD(vmcore_list);
  28
  29 /* Stores the pointer to the buffer containing kernel elf core headers. */
  30 static char *elfcorebuf;
  31 static size_t elfcorebuf_sz;
  32
  33 /* Total size of vmcore file. */
  34 static u64 vmcore_size;
  35
  36 static struct proc_dir_entry *proc_vmcore = NULL;
  37
  38 /*
  39  * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
  40  * The called function has to take care of module refcounting.
  41  */
  42 static int (*oldmem_pfn_is_ram)(unsigned long pfn);
  43
  44 int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn))
  45 {
  46         if (oldmem_pfn_is_ram)
  47                 return -EBUSY;
  48         oldmem_pfn_is_ram = fn;
  49         return 0;
  50 }
  51 EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram);
  52
  53 void unregister_oldmem_pfn_is_ram(void)
  54 {
  55         oldmem_pfn_is_ram = NULL;
  56         wmb();
  57 }
  58 EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram);
  59
  60 static int pfn_is_ram(unsigned long pfn)
  61 {
  62         int (*fn)(unsigned long pfn);
  63         /* pfn is ram unless fn() checks pagetype */
  64         int ret = 1;
  65
  66         /*
  67          * Ask hypervisor if the pfn is really ram.
  68          * A ballooned page contains no data and reading from such a page
  69          * will cause high load in the hypervisor.
  70          */
  71         fn = oldmem_pfn_is_ram;
  72         if (fn)
  73                 ret = fn(pfn);
  74
  75         return ret;
  76 }
  77
  78 /* Reads a page from the oldmem device from given offset. */
  79 static ssize_t read_from_oldmem(char *buf, size_t count,
  80                                 u64 *ppos, int userbuf)
  81 {
  82         unsigned long pfn, offset;
  83         size_t nr_bytes;
  84         ssize_t read = 0, tmp;
  85
  86         if (!count)
  87                 return 0;
  88
  89         offset = (unsigned long)(*ppos % PAGE_SIZE);
  90         pfn = (unsigned long)(*ppos / PAGE_SIZE);
  91
  92         do {
  93                 if (count > (PAGE_SIZE - offset))
  94                         nr_bytes = PAGE_SIZE - offset;
  95                 else
  96                         nr_bytes = count;
  97
  98                 /* If pfn is not ram, return zeros for sparse dump files */
  99                 if (pfn_is_ram(pfn) == 0)
 100                         memset(buf, 0, nr_bytes);
 101                 else {
 102                         tmp = copy_oldmem_page(pfn, buf, nr_bytes,
 103                                                 offset, userbuf);
 104                         if (tmp < 0)
 105                                 return tmp;
 106                 }
 107                 *ppos += nr_bytes;
 108                 count -= nr_bytes;
 109                 buf += nr_bytes;
 110                 read += nr_bytes;
 111                 ++pfn;
 112                 offset = 0;
 113         } while (count);
 114
 115         return read;
 116 }
 117
 118 /* Maps vmcore file offset to respective physical address in memroy. */
 119 static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list,
 120                                         struct vmcore **m_ptr)
 121 {
 122         struct vmcore *m;
 123         u64 paddr;
 124
 125         list_for_each_entry(m, vc_list, list) {
 126                 u64 start, end;
 127                 start = m->offset;
 128                 end = m->offset + m->size - 1;
 129                 if (offset >= start && offset <= end) {
 130                         paddr = m->paddr + offset - start;
 131                         *m_ptr = m;
 132                         return paddr;
 133                 }
 134         }
 135         *m_ptr = NULL;
 136         return 0;
 137 }
 138
 139 /* Read from the ELF header and then the crash dump. On error, negative value is
 140  * returned otherwise number of bytes read are returned.
 141  */
 142 static ssize_t read_vmcore(struct file *file, char __user *buffer,
 143                                 size_t buflen, loff_t *fpos)
 144 {
 145         ssize_t acc = 0, tmp;
 146         size_t tsz;
 147         u64 start, nr_bytes;
 148         struct vmcore *curr_m = NULL;
 149
 150         if (buflen == 0 || *fpos >= vmcore_size)
 151                 return 0;
 152
 153         /* trim buflen to not go beyond EOF */
 154         if (buflen > vmcore_size - *fpos)
 155                 buflen = vmcore_size - *fpos;
 156
 157         /* Read ELF core header */
 158         if (*fpos < elfcorebuf_sz) {
 159                 tsz = elfcorebuf_sz - *fpos;
 160                 if (buflen < tsz)
 161                         tsz = buflen;
 162                 if (copy_to_user(buffer, elfcorebuf + *fpos, tsz))
 163                         return -EFAULT;
 164                 buflen -= tsz;
 165                 *fpos += tsz;
 166                 buffer += tsz;
 167                 acc += tsz;
 168
 169                 /* leave now if filled buffer already */
 170                 if (buflen == 0)
 171                         return acc;
 172         }
 173
 174         start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
 175         if (!curr_m)
 176                 return -EINVAL;
 177         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 178                 tsz = buflen;
 179
 180         /* Calculate left bytes in current memory segment. */
 181         nr_bytes = (curr_m->size - (start - curr_m->paddr));
 182         if (tsz > nr_bytes)
 183                 tsz = nr_bytes;
 184
 185         while (buflen) {
 186                 tmp = read_from_oldmem(buffer, tsz, &start, 1);
 187                 if (tmp < 0)
 188                         return tmp;
 189                 buflen -= tsz;
 190                 *fpos += tsz;
 191                 buffer += tsz;
 192                 acc += tsz;
 193                 if (start >= (curr_m->paddr + curr_m->size)) {
 194                         if (curr_m->list.next == &vmcore_list)
 195                                 return acc;     /*EOF*/
 196                         curr_m = list_entry(curr_m->list.next,
 197                                                 struct vmcore, list);
 198                         start = curr_m->paddr;
 199                 }
 200                 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 201                         tsz = buflen;
 202                 /* Calculate left bytes in current memory segment. */
 203                 nr_bytes = (curr_m->size - (start - curr_m->paddr));
 204                 if (tsz > nr_bytes)
 205                         tsz = nr_bytes;
 206         }
 207         return acc;
 208 }
 209
 210 static const struct file_operations proc_vmcore_operations = {
 211         .read           = read_vmcore,
 212         .llseek         = default_llseek,
 213 };
 214
 215 static struct vmcore* __init get_new_element(void)
 216 {
 217         return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
 218 }
 219
 220 static u64 __init get_vmcore_size_elf64(char *elfptr)
 221 {
 222         int i;
 223         u64 size;
 224         Elf64_Ehdr *ehdr_ptr;
 225         Elf64_Phdr *phdr_ptr;
 226
 227         ehdr_ptr = (Elf64_Ehdr *)elfptr;
 228         phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
 229         size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
 230         for (i = 0; i < ehdr_ptr->e_phnum; i++) {
 231                 size += phdr_ptr->p_memsz;
 232                 phdr_ptr++;
 233         }
 234         return size;
 235 }
 236
 237 static u64 __init get_vmcore_size_elf32(char *elfptr)
 238 {
 239         int i;
 240         u64 size;
 241         Elf32_Ehdr *ehdr_ptr;
 242         Elf32_Phdr *phdr_ptr;
 243
 244         ehdr_ptr = (Elf32_Ehdr *)elfptr;
 245         phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
 246         size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
 247         for (i = 0; i < ehdr_ptr->e_phnum; i++) {
 248                 size += phdr_ptr->p_memsz;
 249                 phdr_ptr++;
 250         }
 251         return size;
 252 }
 253
 254 /* Merges all the PT_NOTE headers into one. */
 255 static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
 256                                                 struct list_head *vc_list)
 257 {
 258         int i, nr_ptnote=0, rc=0;
 259         char *tmp;
 260         Elf64_Ehdr *ehdr_ptr;
 261         Elf64_Phdr phdr, *phdr_ptr;
 262         Elf64_Nhdr *nhdr_ptr;
 263         u64 phdr_sz = 0, note_off;
 264
 265         ehdr_ptr = (Elf64_Ehdr *)elfptr;
 266         phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
 267         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 268                 int j;
 269                 void *notes_section;
 270                 struct vmcore *new;
 271                 u64 offset, max_sz, sz, real_sz = 0;
 272                 if (phdr_ptr->p_type != PT_NOTE)
 273                         continue;
 274                 nr_ptnote++;
 275                 max_sz = phdr_ptr->p_memsz;
 276                 offset = phdr_ptr->p_offset;
 277                 notes_section = kmalloc(max_sz, GFP_KERNEL);
 278                 if (!notes_section)
 279                         return -ENOMEM;
 280                 rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
 281                 if (rc < 0) {
 282                         kfree(notes_section);
 283                         return rc;
 284                 }
 285                 nhdr_ptr = notes_section;
 286                 for (j = 0; j < max_sz; j += sz) {
 287                         if (nhdr_ptr->n_namesz == 0)
 288                                 break;
 289                         sz = sizeof(Elf64_Nhdr) +
 290                                 ((nhdr_ptr->n_namesz + 3) & ~3) +
 291                                 ((nhdr_ptr->n_descsz + 3) & ~3);
 292                         real_sz += sz;
 293                         nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
 294                 }
 295
 296                 /* Add this contiguous chunk of notes section to vmcore list.*/
 297                 new = get_new_element();
 298                 if (!new) {
 299                         kfree(notes_section);
 300                         return -ENOMEM;
 301                 }
 302                 new->paddr = phdr_ptr->p_offset;
 303                 new->size = real_sz;
 304                 list_add_tail(&new->list, vc_list);
 305                 phdr_sz += real_sz;
 306                 kfree(notes_section);
 307         }
 308
 309         /* Prepare merged PT_NOTE program header. */
 310         phdr.p_type    = PT_NOTE;
 311         phdr.p_flags   = 0;
 312         note_off = sizeof(Elf64_Ehdr) +
 313                         (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
 314         phdr.p_offset  = note_off;
 315         phdr.p_vaddr   = phdr.p_paddr = 0;
 316         phdr.p_filesz  = phdr.p_memsz = phdr_sz;
 317         phdr.p_align   = 0;
 318
 319         /* Add merged PT_NOTE program header*/
 320         tmp = elfptr + sizeof(Elf64_Ehdr);
 321         memcpy(tmp, &phdr, sizeof(phdr));
 322         tmp += sizeof(phdr);
 323
 324         /* Remove unwanted PT_NOTE program headers. */
 325         i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
 326         *elfsz = *elfsz - i;
 327         memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
 328
 329         /* Modify e_phnum to reflect merged headers. */
 330         ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
 331
 332         return 0;
 333 }
 334
 335 /* Merges all the PT_NOTE headers into one. */
 336 static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
 337                                                 struct list_head *vc_list)
 338 {
 339         int i, nr_ptnote=0, rc=0;
 340         char *tmp;
 341         Elf32_Ehdr *ehdr_ptr;
 342         Elf32_Phdr phdr, *phdr_ptr;
 343         Elf32_Nhdr *nhdr_ptr;
 344         u64 phdr_sz = 0, note_off;
 345
 346         ehdr_ptr = (Elf32_Ehdr *)elfptr;
 347         phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
 348         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 349                 int j;
 350                 void *notes_section;
 351                 struct vmcore *new;
 352                 u64 offset, max_sz, sz, real_sz = 0;
 353                 if (phdr_ptr->p_type != PT_NOTE)
 354                         continue;
 355                 nr_ptnote++;
 356                 max_sz = phdr_ptr->p_memsz;
 357                 offset = phdr_ptr->p_offset;
 358                 notes_section = kmalloc(max_sz, GFP_KERNEL);
 359                 if (!notes_section)
 360                         return -ENOMEM;
 361                 rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
 362                 if (rc < 0) {
 363                         kfree(notes_section);
 364                         return rc;
 365                 }
 366                 nhdr_ptr = notes_section;
 367                 for (j = 0; j < max_sz; j += sz) {
 368                         if (nhdr_ptr->n_namesz == 0)
 369                                 break;
 370                         sz = sizeof(Elf32_Nhdr) +
 371                                 ((nhdr_ptr->n_namesz + 3) & ~3) +
 372                                 ((nhdr_ptr->n_descsz + 3) & ~3);
 373                         real_sz += sz;
 374                         nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
 375                 }
 376
 377                 /* Add this contiguous chunk of notes section to vmcore list.*/
 378                 new = get_new_element();
 379                 if (!new) {
 380                         kfree(notes_section);
 381                         return -ENOMEM;
 382                 }
 383                 new->paddr = phdr_ptr->p_offset;
 384                 new->size = real_sz;
 385                 list_add_tail(&new->list, vc_list);
 386                 phdr_sz += real_sz;
 387                 kfree(notes_section);
 388         }
 389
 390         /* Prepare merged PT_NOTE program header. */
 391         phdr.p_type    = PT_NOTE;
 392         phdr.p_flags   = 0;
 393         note_off = sizeof(Elf32_Ehdr) +
 394                         (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
 395         phdr.p_offset  = note_off;
 396         phdr.p_vaddr   = phdr.p_paddr = 0;
 397         phdr.p_filesz  = phdr.p_memsz = phdr_sz;
 398         phdr.p_align   = 0;
 399
 400         /* Add merged PT_NOTE program header*/
 401         tmp = elfptr + sizeof(Elf32_Ehdr);
 402         memcpy(tmp, &phdr, sizeof(phdr));
 403         tmp += sizeof(phdr);
 404
 405         /* Remove unwanted PT_NOTE program headers. */
 406         i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
 407         *elfsz = *elfsz - i;
 408         memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
 409
 410         /* Modify e_phnum to reflect merged headers. */
 411         ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
 412
 413         return 0;
 414 }
 415
 416 /* Add memory chunks represented by program headers to vmcore list. Also update
 417  * the new offset fields of exported program headers. */
 418 static int __init process_ptload_program_headers_elf64(char *elfptr,
 419                                                 size_t elfsz,
 420                                                 struct list_head *vc_list)
 421 {
 422         int i;
 423         Elf64_Ehdr *ehdr_ptr;
 424         Elf64_Phdr *phdr_ptr;
 425         loff_t vmcore_off;
 426         struct vmcore *new;
 427
 428         ehdr_ptr = (Elf64_Ehdr *)elfptr;
 429         phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
 430
 431         /* First program header is PT_NOTE header. */
 432         vmcore_off = sizeof(Elf64_Ehdr) +
 433                         (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) +
 434                         phdr_ptr->p_memsz; /* Note sections */
 435
 436         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 437                 if (phdr_ptr->p_type != PT_LOAD)
 438                         continue;
 439
 440                 /* Add this contiguous chunk of memory to vmcore list.*/
 441                 new = get_new_element();
 442                 if (!new)
 443                         return -ENOMEM;
 444                 new->paddr = phdr_ptr->p_offset;
 445                 new->size = phdr_ptr->p_memsz;
 446                 list_add_tail(&new->list, vc_list);
 447
 448                 /* Update the program header offset. */
 449                 phdr_ptr->p_offset = vmcore_off;
 450                 vmcore_off = vmcore_off + phdr_ptr->p_memsz;
 451         }
 452         return 0;
 453 }
 454
 455 static int __init process_ptload_program_headers_elf32(char *elfptr,
 456                                                 size_t elfsz,
 457                                                 struct list_head *vc_list)
 458 {
 459         int i;
 460         Elf32_Ehdr *ehdr_ptr;
 461         Elf32_Phdr *phdr_ptr;
 462         loff_t vmcore_off;
 463         struct vmcore *new;
 464
 465         ehdr_ptr = (Elf32_Ehdr *)elfptr;
 466         phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
 467
 468         /* First program header is PT_NOTE header. */
 469         vmcore_off = sizeof(Elf32_Ehdr) +
 470                         (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) +
 471                         phdr_ptr->p_memsz; /* Note sections */
 472
 473         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 474                 if (phdr_ptr->p_type != PT_LOAD)
 475                         continue;
 476
 477                 /* Add this contiguous chunk of memory to vmcore list.*/
 478                 new = get_new_element();
 479                 if (!new)
 480                         return -ENOMEM;
 481                 new->paddr = phdr_ptr->p_offset;
 482                 new->size = phdr_ptr->p_memsz;
 483                 list_add_tail(&new->list, vc_list);
 484
 485                 /* Update the program header offset */
 486                 phdr_ptr->p_offset = vmcore_off;
 487                 vmcore_off = vmcore_off + phdr_ptr->p_memsz;
 488         }
 489         return 0;
 490 }
 491
 492 /* Sets offset fields of vmcore elements. */
 493 static void __init set_vmcore_list_offsets_elf64(char *elfptr,
 494                                                 struct list_head *vc_list)
 495 {
 496         loff_t vmcore_off;
 497         Elf64_Ehdr *ehdr_ptr;
 498         struct vmcore *m;
 499
 500         ehdr_ptr = (Elf64_Ehdr *)elfptr;
 501
 502         /* Skip Elf header and program headers. */
 503         vmcore_off = sizeof(Elf64_Ehdr) +
 504                         (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);
 505
 506         list_for_each_entry(m, vc_list, list) {
 507                 m->offset = vmcore_off;
 508                 vmcore_off += m->size;
 509         }
 510 }
 511
 512 /* Sets offset fields of vmcore elements. */
 513 static void __init set_vmcore_list_offsets_elf32(char *elfptr,
 514                                                 struct list_head *vc_list)
 515 {
 516         loff_t vmcore_off;
 517         Elf32_Ehdr *ehdr_ptr;
 518         struct vmcore *m;
 519
 520         ehdr_ptr = (Elf32_Ehdr *)elfptr;
 521
 522         /* Skip Elf header and program headers. */
 523         vmcore_off = sizeof(Elf32_Ehdr) +
 524                         (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);
 525
 526         list_for_each_entry(m, vc_list, list) {
 527                 m->offset = vmcore_off;
 528                 vmcore_off += m->size;
 529         }
 530 }
 531
 532 static int __init parse_crash_elf64_headers(void)
 533 {
 534         int rc=0;
 535         Elf64_Ehdr ehdr;
 536         u64 addr;
 537
 538         addr = elfcorehdr_addr;
 539
 540         /* Read Elf header */
 541         rc = read_from_oldmem((char*)&ehdr, sizeof(Elf64_Ehdr), &addr, 0);
 542         if (rc < 0)
 543                 return rc;
 544
 545         /* Do some basic Verification. */
 546         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
 547                 (ehdr.e_type != ET_CORE) ||
 548                 !vmcore_elf64_check_arch(&ehdr) ||
 549                 ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
 550                 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
 551                 ehdr.e_version != EV_CURRENT ||
 552                 ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
 553                 ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
 554                 ehdr.e_phnum == 0) {
 555                 printk(KERN_WARNING "Warning: Core image elf header is not"
 556                                         "sane\n");
 557                 return -EINVAL;
 558         }
 559
 560         /* Read in all elf headers. */
 561         elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr);
 562         elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
 563         if (!elfcorebuf)
 564                 return -ENOMEM;
 565         addr = elfcorehdr_addr;
 566         rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
 567         if (rc < 0) {
 568                 kfree(elfcorebuf);
 569                 return rc;
 570         }
 571
 572         /* Merge all PT_NOTE headers into one. */
 573         rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
 574         if (rc) {
 575                 kfree(elfcorebuf);
 576                 return rc;
 577         }
 578         rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
 579                                                         &vmcore_list);
 580         if (rc) {
 581                 kfree(elfcorebuf);
 582                 return rc;
 583         }
 584         set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
 585         return 0;
 586 }
 587
 588 static int __init parse_crash_elf32_headers(void)
 589 {
 590         int rc=0;
 591         Elf32_Ehdr ehdr;
 592         u64 addr;
 593
 594         addr = elfcorehdr_addr;
 595
 596         /* Read Elf header */
 597         rc = read_from_oldmem((char*)&ehdr, sizeof(Elf32_Ehdr), &addr, 0);
 598         if (rc < 0)
 599                 return rc;
 600
 601         /* Do some basic Verification. */
 602         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
 603                 (ehdr.e_type != ET_CORE) ||
 604                 !elf_check_arch(&ehdr) ||
 605                 ehdr.e_ident[EI_CLASS] != ELFCLASS32||
 606                 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
 607                 ehdr.e_version != EV_CURRENT ||
 608                 ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
 609                 ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
 610                 ehdr.e_phnum == 0) {
 611                 printk(KERN_WARNING "Warning: Core image elf header is not"
 612                                         "sane\n");
 613                 return -EINVAL;
 614         }
 615
 616         /* Read in all elf headers. */
 617         elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
 618         elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
 619         if (!elfcorebuf)
 620                 return -ENOMEM;
 621         addr = elfcorehdr_addr;
 622         rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
 623         if (rc < 0) {
 624                 kfree(elfcorebuf);
 625                 return rc;
 626         }
 627
 628         /* Merge all PT_NOTE headers into one. */
 629         rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
 630         if (rc) {
 631                 kfree(elfcorebuf);
 632                 return rc;
 633         }
 634         rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
 635                                                                 &vmcore_list);
 636         if (rc) {
 637                 kfree(elfcorebuf);
 638                 return rc;
 639         }
 640         set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
 641         return 0;
 642 }
 643
 644 static int __init parse_crash_elf_headers(void)
 645 {
 646         unsigned char e_ident[EI_NIDENT];
 647         u64 addr;
 648         int rc=0;
 649
 650         addr = elfcorehdr_addr;
 651         rc = read_from_oldmem(e_ident, EI_NIDENT, &addr, 0);
 652         if (rc < 0)
 653                 return rc;
 654         if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
 655                 printk(KERN_WARNING "Warning: Core image elf header"
 656                                         " not found\n");
 657                 return -EINVAL;
 658         }
 659
 660         if (e_ident[EI_CLASS] == ELFCLASS64) {
 661                 rc = parse_crash_elf64_headers();
 662                 if (rc)
 663                         return rc;
 664
 665                 /* Determine vmcore size. */
 666                 vmcore_size = get_vmcore_size_elf64(elfcorebuf);
 667         } else if (e_ident[EI_CLASS] == ELFCLASS32) {
 668                 rc = parse_crash_elf32_headers();
 669                 if (rc)
 670                         return rc;
 671
 672                 /* Determine vmcore size. */
 673                 vmcore_size = get_vmcore_size_elf32(elfcorebuf);
 674         } else {
 675                 printk(KERN_WARNING "Warning: Core image elf header is not"
 676                                         " sane\n");
 677                 return -EINVAL;
 678         }
 679         return 0;
 680 }
 681
 682 /* Init function for vmcore module. */
 683 static int __init vmcore_init(void)
 684 {
 685         int rc = 0;
 686
 687         /* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
 688         if (!(is_vmcore_usable()))
 689                 return rc;
 690         rc = parse_crash_elf_headers();
 691         if (rc) {
 692                 printk(KERN_WARNING "Kdump: vmcore not initialized\n");
 693                 return rc;
 694         }
 695
 696         proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
 697         if (proc_vmcore)
 698                 proc_vmcore->size = vmcore_size;
 699         return 0;
 700 }
 701 module_init(vmcore_init)