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/kcore.h>
  12 #include <linux/user.h>
  13 #include <linux/elf.h>
  14 #include <linux/elfcore.h>
  15 #include <linux/export.h>
  16 #include <linux/slab.h>
  17 #include <linux/highmem.h>
  18 #include <linux/printk.h>
  19 #include <linux/bootmem.h>
  20 #include <linux/init.h>
  21 #include <linux/crash_dump.h>
  22 #include <linux/list.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/pagemap.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/io.h>
  27 #include "internal.h"
  28
  29 /* List representing chunks of contiguous memory areas and their offsets in
  30  * vmcore file.
  31  */
  32 static LIST_HEAD(vmcore_list);
  33
  34 /* Stores the pointer to the buffer containing kernel elf core headers. */
  35 static char *elfcorebuf;
  36 static size_t elfcorebuf_sz;
  37 static size_t elfcorebuf_sz_orig;
  38
  39 static char *elfnotes_buf;
  40 static size_t elfnotes_sz;
  41
  42 /* Total size of vmcore file. */
  43 static u64 vmcore_size;
  44
  45 static struct proc_dir_entry *proc_vmcore;
  46
  47 /*
  48  * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
  49  * The called function has to take care of module refcounting.
  50  */
  51 static int (*oldmem_pfn_is_ram)(unsigned long pfn);
  52
  53 int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn))
  54 {
  55         if (oldmem_pfn_is_ram)
  56                 return -EBUSY;
  57         oldmem_pfn_is_ram = fn;
  58         return 0;
  59 }
  60 EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram);
  61
  62 void unregister_oldmem_pfn_is_ram(void)
  63 {
  64         oldmem_pfn_is_ram = NULL;
  65         wmb();
  66 }
  67 EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram);
  68
  69 static int pfn_is_ram(unsigned long pfn)
  70 {
  71         int (*fn)(unsigned long pfn);
  72         /* pfn is ram unless fn() checks pagetype */
  73         int ret = 1;
  74
  75         /*
  76          * Ask hypervisor if the pfn is really ram.
  77          * A ballooned page contains no data and reading from such a page
  78          * will cause high load in the hypervisor.
  79          */
  80         fn = oldmem_pfn_is_ram;
  81         if (fn)
  82                 ret = fn(pfn);
  83
  84         return ret;
  85 }
  86
  87 /* Reads a page from the oldmem device from given offset. */
  88 static ssize_t read_from_oldmem(char *buf, size_t count,
  89                                 u64 *ppos, int userbuf)
  90 {
  91         unsigned long pfn, offset;
  92         size_t nr_bytes;
  93         ssize_t read = 0, tmp;
  94
  95         if (!count)
  96                 return 0;
  97
  98         offset = (unsigned long)(*ppos % PAGE_SIZE);
  99         pfn = (unsigned long)(*ppos / PAGE_SIZE);
 100
 101         do {
 102                 if (count > (PAGE_SIZE - offset))
 103                         nr_bytes = PAGE_SIZE - offset;
 104                 else
 105                         nr_bytes = count;
 106
 107                 /* If pfn is not ram, return zeros for sparse dump files */
 108                 if (pfn_is_ram(pfn) == 0)
 109                         memset(buf, 0, nr_bytes);
 110                 else {
 111                         tmp = copy_oldmem_page(pfn, buf, nr_bytes,
 112                                                 offset, userbuf);
 113                         if (tmp < 0)
 114                                 return tmp;
 115                 }
 116                 *ppos += nr_bytes;
 117                 count -= nr_bytes;
 118                 buf += nr_bytes;
 119                 read += nr_bytes;
 120                 ++pfn;
 121                 offset = 0;
 122         } while (count);
 123
 124         return read;
 125 }
 126
 127 /*
 128  * Architectures may override this function to allocate ELF header in 2nd kernel
 129  */
 130 int __weak elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
 131 {
 132         return 0;
 133 }
 134
 135 /*
 136  * Architectures may override this function to free header
 137  */
 138 void __weak elfcorehdr_free(unsigned long long addr)
 139 {}
 140
 141 /*
 142  * Architectures may override this function to read from ELF header
 143  */
 144 ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
 145 {
 146         return read_from_oldmem(buf, count, ppos, 0);
 147 }
 148
 149 /*
 150  * Architectures may override this function to read from notes sections
 151  */
 152 ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
 153 {
 154         return read_from_oldmem(buf, count, ppos, 0);
 155 }
 156
 157 /*
 158  * Architectures may override this function to map oldmem
 159  */
 160 int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
 161                                   unsigned long from, unsigned long pfn,
 162                                   unsigned long size, pgprot_t prot)
 163 {
 164         return remap_pfn_range(vma, from, pfn, size, prot);
 165 }
 166
 167 /*
 168  * Copy to either kernel or user space
 169  */
 170 static int copy_to(void *target, void *src, size_t size, int userbuf)
 171 {
 172         if (userbuf) {
 173                 if (copy_to_user((char __user *) target, src, size))
 174                         return -EFAULT;
 175         } else {
 176                 memcpy(target, src, size);
 177         }
 178         return 0;
 179 }
 180
 181 /* Read from the ELF header and then the crash dump. On error, negative value is
 182  * returned otherwise number of bytes read are returned.
 183  */
 184 static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
 185                              int userbuf)
 186 {
 187         ssize_t acc = 0, tmp;
 188         size_t tsz;
 189         u64 start;
 190         struct vmcore *m = NULL;
 191
 192         if (buflen == 0 || *fpos >= vmcore_size)
 193                 return 0;
 194
 195         /* trim buflen to not go beyond EOF */
 196         if (buflen > vmcore_size - *fpos)
 197                 buflen = vmcore_size - *fpos;
 198
 199         /* Read ELF core header */
 200         if (*fpos < elfcorebuf_sz) {
 201                 tsz = min(elfcorebuf_sz - (size_t)*fpos, buflen);
 202                 if (copy_to(buffer, elfcorebuf + *fpos, tsz, userbuf))
 203                         return -EFAULT;
 204                 buflen -= tsz;
 205                 *fpos += tsz;
 206                 buffer += tsz;
 207                 acc += tsz;
 208
 209                 /* leave now if filled buffer already */
 210                 if (buflen == 0)
 211                         return acc;
 212         }
 213
 214         /* Read Elf note segment */
 215         if (*fpos < elfcorebuf_sz + elfnotes_sz) {
 216                 void *kaddr;
 217
 218                 tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos, buflen);
 219                 kaddr = elfnotes_buf + *fpos - elfcorebuf_sz;
 220                 if (copy_to(buffer, kaddr, tsz, userbuf))
 221                         return -EFAULT;
 222                 buflen -= tsz;
 223                 *fpos += tsz;
 224                 buffer += tsz;
 225                 acc += tsz;
 226
 227                 /* leave now if filled buffer already */
 228                 if (buflen == 0)
 229                         return acc;
 230         }
 231
 232         list_for_each_entry(m, &vmcore_list, list) {
 233                 if (*fpos < m->offset + m->size) {
 234                         tsz = min_t(size_t, m->offset + m->size - *fpos, buflen);
 235                         start = m->paddr + *fpos - m->offset;
 236                         tmp = read_from_oldmem(buffer, tsz, &start, userbuf);
 237                         if (tmp < 0)
 238                                 return tmp;
 239                         buflen -= tsz;
 240                         *fpos += tsz;
 241                         buffer += tsz;
 242                         acc += tsz;
 243
 244                         /* leave now if filled buffer already */
 245                         if (buflen == 0)
 246                                 return acc;
 247                 }
 248         }
 249
 250         return acc;
 251 }
 252
 253 static ssize_t read_vmcore(struct file *file, char __user *buffer,
 254                            size_t buflen, loff_t *fpos)
 255 {
 256         return __read_vmcore((__force char *) buffer, buflen, fpos, 1);
 257 }
 258
 259 /*
 260  * The vmcore fault handler uses the page cache and fills data using the
 261  * standard __vmcore_read() function.
 262  *
 263  * On s390 the fault handler is used for memory regions that can't be mapped
 264  * directly with remap_pfn_range().
 265  */
 266 static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 267 {
 268 #ifdef CONFIG_S390
 269         struct address_space *mapping = vma->vm_file->f_mapping;
 270         pgoff_t index = vmf->pgoff;
 271         struct page *page;
 272         loff_t offset;
 273         char *buf;
 274         int rc;
 275
 276         page = find_or_create_page(mapping, index, GFP_KERNEL);
 277         if (!page)
 278                 return VM_FAULT_OOM;
 279         if (!PageUptodate(page)) {
 280                 offset = (loff_t) index << PAGE_CACHE_SHIFT;
 281                 buf = __va((page_to_pfn(page) << PAGE_SHIFT));
 282                 rc = __read_vmcore(buf, PAGE_SIZE, &offset, 0);
 283                 if (rc < 0) {
 284                         unlock_page(page);
 285                         page_cache_release(page);
 286                         return (rc == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
 287                 }
 288                 SetPageUptodate(page);
 289         }
 290         unlock_page(page);
 291         vmf->page = page;
 292         return 0;
 293 #else
 294         return VM_FAULT_SIGBUS;
 295 #endif
 296 }
 297
 298 static const struct vm_operations_struct vmcore_mmap_ops = {
 299         .fault = mmap_vmcore_fault,
 300 };
 301
 302 /**
 303  * alloc_elfnotes_buf - allocate buffer for ELF note segment in
 304  *                      vmalloc memory
 305  *
 306  * @notes_sz: size of buffer
 307  *
 308  * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
 309  * the buffer to user-space by means of remap_vmalloc_range().
 310  *
 311  * If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is
 312  * disabled and there's no need to allow users to mmap the buffer.
 313  */
 314 static inline char *alloc_elfnotes_buf(size_t notes_sz)
 315 {
 316 #ifdef CONFIG_MMU
 317         return vmalloc_user(notes_sz);
 318 #else
 319         return vzalloc(notes_sz);
 320 #endif
 321 }
 322
 323 /*
 324  * Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is
 325  * essential for mmap_vmcore() in order to map physically
 326  * non-contiguous objects (ELF header, ELF note segment and memory
 327  * regions in the 1st kernel pointed to by PT_LOAD entries) into
 328  * virtually contiguous user-space in ELF layout.
 329  */
 330 #ifdef CONFIG_MMU
 331 /*
 332  * remap_oldmem_pfn_checked - do remap_oldmem_pfn_range replacing all pages
 333  * reported as not being ram with the zero page.
 334  *
 335  * @vma: vm_area_struct describing requested mapping
 336  * @from: start remapping from
 337  * @pfn: page frame number to start remapping to
 338  * @size: remapping size
 339  * @prot: protection bits
 340  *
 341  * Returns zero on success, -EAGAIN on failure.
 342  */
 343 static int remap_oldmem_pfn_checked(struct vm_area_struct *vma,
 344                                     unsigned long from, unsigned long pfn,
 345                                     unsigned long size, pgprot_t prot)
 346 {
 347         unsigned long map_size;
 348         unsigned long pos_start, pos_end, pos;
 349         unsigned long zeropage_pfn = my_zero_pfn(0);
 350         size_t len = 0;
 351
 352         pos_start = pfn;
 353         pos_end = pfn + (size >> PAGE_SHIFT);
 354
 355         for (pos = pos_start; pos < pos_end; ++pos) {
 356                 if (!pfn_is_ram(pos)) {
 357                         /*
 358                          * We hit a page which is not ram. Remap the continuous
 359                          * region between pos_start and pos-1 and replace
 360                          * the non-ram page at pos with the zero page.
 361                          */
 362                         if (pos > pos_start) {
 363                                 /* Remap continuous region */
 364                                 map_size = (pos - pos_start) << PAGE_SHIFT;
 365                                 if (remap_oldmem_pfn_range(vma, from + len,
 366                                                            pos_start, map_size,
 367                                                            prot))
 368                                         goto fail;
 369                                 len += map_size;
 370                         }
 371                         /* Remap the zero page */
 372                         if (remap_oldmem_pfn_range(vma, from + len,
 373                                                    zeropage_pfn,
 374                                                    PAGE_SIZE, prot))
 375                                 goto fail;
 376                         len += PAGE_SIZE;
 377                         pos_start = pos + 1;
 378                 }
 379         }
 380         if (pos > pos_start) {
 381                 /* Remap the rest */
 382                 map_size = (pos - pos_start) << PAGE_SHIFT;
 383                 if (remap_oldmem_pfn_range(vma, from + len, pos_start,
 384                                            map_size, prot))
 385                         goto fail;
 386         }
 387         return 0;
 388 fail:
 389         do_munmap(vma->vm_mm, from, len);
 390         return -EAGAIN;
 391 }
 392
 393 static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma,
 394                             unsigned long from, unsigned long pfn,
 395                             unsigned long size, pgprot_t prot)
 396 {
 397         /*
 398          * Check if oldmem_pfn_is_ram was registered to avoid
 399          * looping over all pages without a reason.
 400          */
 401         if (oldmem_pfn_is_ram)
 402                 return remap_oldmem_pfn_checked(vma, from, pfn, size, prot);
 403         else
 404                 return remap_oldmem_pfn_range(vma, from, pfn, size, prot);
 405 }
 406
 407 static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 408 {
 409         size_t size = vma->vm_end - vma->vm_start;
 410         u64 start, end, len, tsz;
 411         struct vmcore *m;
 412
 413         start = (u64)vma->vm_pgoff << PAGE_SHIFT;
 414         end = start + size;
 415
 416         if (size > vmcore_size || end > vmcore_size)
 417                 return -EINVAL;
 418
 419         if (vma->vm_flags & (VM_WRITE | VM_EXEC))
 420                 return -EPERM;
 421
 422         vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
 423         vma->vm_flags |= VM_MIXEDMAP;
 424         vma->vm_ops = &vmcore_mmap_ops;
 425
 426         len = 0;
 427
 428         if (start < elfcorebuf_sz) {
 429                 u64 pfn;
 430
 431                 tsz = min(elfcorebuf_sz - (size_t)start, size);
 432                 pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT;
 433                 if (remap_pfn_range(vma, vma->vm_start, pfn, tsz,
 434                                     vma->vm_page_prot))
 435                         return -EAGAIN;
 436                 size -= tsz;
 437                 start += tsz;
 438                 len += tsz;
 439
 440                 if (size == 0)
 441                         return 0;
 442         }
 443
 444         if (start < elfcorebuf_sz + elfnotes_sz) {
 445                 void *kaddr;
 446
 447                 tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)start, size);
 448                 kaddr = elfnotes_buf + start - elfcorebuf_sz;
 449                 if (remap_vmalloc_range_partial(vma, vma->vm_start + len,
 450                                                 kaddr, tsz))
 451                         goto fail;
 452                 size -= tsz;
 453                 start += tsz;
 454                 len += tsz;
 455
 456                 if (size == 0)
 457                         return 0;
 458         }
 459
 460         list_for_each_entry(m, &vmcore_list, list) {
 461                 if (start < m->offset + m->size) {
 462                         u64 paddr = 0;
 463
 464                         tsz = min_t(size_t, m->offset + m->size - start, size);
 465                         paddr = m->paddr + start - m->offset;
 466                         if (vmcore_remap_oldmem_pfn(vma, vma->vm_start + len,
 467                                                     paddr >> PAGE_SHIFT, tsz,
 468                                                     vma->vm_page_prot))
 469                                 goto fail;
 470                         size -= tsz;
 471                         start += tsz;
 472                         len += tsz;
 473
 474                         if (size == 0)
 475                                 return 0;
 476                 }
 477         }
 478
 479         return 0;
 480 fail:
 481         do_munmap(vma->vm_mm, vma->vm_start, len);
 482         return -EAGAIN;
 483 }
 484 #else
 485 static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
 486 {
 487         return -ENOSYS;
 488 }
 489 #endif
 490
 491 static const struct file_operations proc_vmcore_operations = {
 492         .read           = read_vmcore,
 493         .llseek         = default_llseek,
 494         .mmap           = mmap_vmcore,
 495 };
 496
 497 static struct vmcore* __init get_new_element(void)
 498 {
 499         return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
 500 }
 501
 502 static u64 __init get_vmcore_size(size_t elfsz, size_t elfnotesegsz,
 503                                   struct list_head *vc_list)
 504 {
 505         u64 size;
 506         struct vmcore *m;
 507
 508         size = elfsz + elfnotesegsz;
 509         list_for_each_entry(m, vc_list, list) {
 510                 size += m->size;
 511         }
 512         return size;
 513 }
 514
 515 /**
 516  * update_note_header_size_elf64 - update p_memsz member of each PT_NOTE entry
 517  *
 518  * @ehdr_ptr: ELF header
 519  *
 520  * This function updates p_memsz member of each PT_NOTE entry in the
 521  * program header table pointed to by @ehdr_ptr to real size of ELF
 522  * note segment.
 523  */
 524 static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
 525 {
 526         int i, rc=0;
 527         Elf64_Phdr *phdr_ptr;
 528         Elf64_Nhdr *nhdr_ptr;
 529
 530         phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
 531         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 532                 void *notes_section;
 533                 u64 offset, max_sz, sz, real_sz = 0;
 534                 if (phdr_ptr->p_type != PT_NOTE)
 535                         continue;
 536                 max_sz = phdr_ptr->p_memsz;
 537                 offset = phdr_ptr->p_offset;
 538                 notes_section = kmalloc(max_sz, GFP_KERNEL);
 539                 if (!notes_section)
 540                         return -ENOMEM;
 541                 rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
 542                 if (rc < 0) {
 543                         kfree(notes_section);
 544                         return rc;
 545                 }
 546                 nhdr_ptr = notes_section;
 547                 while (nhdr_ptr->n_namesz != 0) {
 548                         sz = sizeof(Elf64_Nhdr) +
 549                                 (((u64)nhdr_ptr->n_namesz + 3) & ~3) +
 550                                 (((u64)nhdr_ptr->n_descsz + 3) & ~3);
 551                         if ((real_sz + sz) > max_sz) {
 552                                 pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
 553                                         nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
 554                                 break;
 555                         }
 556                         real_sz += sz;
 557                         nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
 558                 }
 559                 kfree(notes_section);
 560                 phdr_ptr->p_memsz = real_sz;
 561                 if (real_sz == 0) {
 562                         pr_warn("Warning: Zero PT_NOTE entries found\n");
 563                 }
 564         }
 565
 566         return 0;
 567 }
 568
 569 /**
 570  * get_note_number_and_size_elf64 - get the number of PT_NOTE program
 571  * headers and sum of real size of their ELF note segment headers and
 572  * data.
 573  *
 574  * @ehdr_ptr: ELF header
 575  * @nr_ptnote: buffer for the number of PT_NOTE program headers
 576  * @sz_ptnote: buffer for size of unique PT_NOTE program header
 577  *
 578  * This function is used to merge multiple PT_NOTE program headers
 579  * into a unique single one. The resulting unique entry will have
 580  * @sz_ptnote in its phdr->p_mem.
 581  *
 582  * It is assumed that program headers with PT_NOTE type pointed to by
 583  * @ehdr_ptr has already been updated by update_note_header_size_elf64
 584  * and each of PT_NOTE program headers has actual ELF note segment
 585  * size in its p_memsz member.
 586  */
 587 static int __init get_note_number_and_size_elf64(const Elf64_Ehdr *ehdr_ptr,
 588                                                  int *nr_ptnote, u64 *sz_ptnote)
 589 {
 590         int i;
 591         Elf64_Phdr *phdr_ptr;
 592
 593         *nr_ptnote = *sz_ptnote = 0;
 594
 595         phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
 596         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 597                 if (phdr_ptr->p_type != PT_NOTE)
 598                         continue;
 599                 *nr_ptnote += 1;
 600                 *sz_ptnote += phdr_ptr->p_memsz;
 601         }
 602
 603         return 0;
 604 }
 605
 606 /**
 607  * copy_notes_elf64 - copy ELF note segments in a given buffer
 608  *
 609  * @ehdr_ptr: ELF header
 610  * @notes_buf: buffer into which ELF note segments are copied
 611  *
 612  * This function is used to copy ELF note segment in the 1st kernel
 613  * into the buffer @notes_buf in the 2nd kernel. It is assumed that
 614  * size of the buffer @notes_buf is equal to or larger than sum of the
 615  * real ELF note segment headers and data.
 616  *
 617  * It is assumed that program headers with PT_NOTE type pointed to by
 618  * @ehdr_ptr has already been updated by update_note_header_size_elf64
 619  * and each of PT_NOTE program headers has actual ELF note segment
 620  * size in its p_memsz member.
 621  */
 622 static int __init copy_notes_elf64(const Elf64_Ehdr *ehdr_ptr, char *notes_buf)
 623 {
 624         int i, rc=0;
 625         Elf64_Phdr *phdr_ptr;
 626
 627         phdr_ptr = (Elf64_Phdr*)(ehdr_ptr + 1);
 628
 629         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 630                 u64 offset;
 631                 if (phdr_ptr->p_type != PT_NOTE)
 632                         continue;
 633                 offset = phdr_ptr->p_offset;
 634                 rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
 635                                            &offset);
 636                 if (rc < 0)
 637                         return rc;
 638                 notes_buf += phdr_ptr->p_memsz;
 639         }
 640
 641         return 0;
 642 }
 643
 644 /* Merges all the PT_NOTE headers into one. */
 645 static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
 646                                            char **notes_buf, size_t *notes_sz)
 647 {
 648         int i, nr_ptnote=0, rc=0;
 649         char *tmp;
 650         Elf64_Ehdr *ehdr_ptr;
 651         Elf64_Phdr phdr;
 652         u64 phdr_sz = 0, note_off;
 653
 654         ehdr_ptr = (Elf64_Ehdr *)elfptr;
 655
 656         rc = update_note_header_size_elf64(ehdr_ptr);
 657         if (rc < 0)
 658                 return rc;
 659
 660         rc = get_note_number_and_size_elf64(ehdr_ptr, &nr_ptnote, &phdr_sz);
 661         if (rc < 0)
 662                 return rc;
 663
 664         *notes_sz = roundup(phdr_sz, PAGE_SIZE);
 665         *notes_buf = alloc_elfnotes_buf(*notes_sz);
 666         if (!*notes_buf)
 667                 return -ENOMEM;
 668
 669         rc = copy_notes_elf64(ehdr_ptr, *notes_buf);
 670         if (rc < 0)
 671                 return rc;
 672
 673         /* Prepare merged PT_NOTE program header. */
 674         phdr.p_type    = PT_NOTE;
 675         phdr.p_flags   = 0;
 676         note_off = sizeof(Elf64_Ehdr) +
 677                         (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
 678         phdr.p_offset  = roundup(note_off, PAGE_SIZE);
 679         phdr.p_vaddr   = phdr.p_paddr = 0;
 680         phdr.p_filesz  = phdr.p_memsz = phdr_sz;
 681         phdr.p_align   = 0;
 682
 683         /* Add merged PT_NOTE program header*/
 684         tmp = elfptr + sizeof(Elf64_Ehdr);
 685         memcpy(tmp, &phdr, sizeof(phdr));
 686         tmp += sizeof(phdr);
 687
 688         /* Remove unwanted PT_NOTE program headers. */
 689         i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
 690         *elfsz = *elfsz - i;
 691         memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
 692         memset(elfptr + *elfsz, 0, i);
 693         *elfsz = roundup(*elfsz, PAGE_SIZE);
 694
 695         /* Modify e_phnum to reflect merged headers. */
 696         ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
 697
 698         return 0;
 699 }
 700
 701 /**
 702  * update_note_header_size_elf32 - update p_memsz member of each PT_NOTE entry
 703  *
 704  * @ehdr_ptr: ELF header
 705  *
 706  * This function updates p_memsz member of each PT_NOTE entry in the
 707  * program header table pointed to by @ehdr_ptr to real size of ELF
 708  * note segment.
 709  */
 710 static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
 711 {
 712         int i, rc=0;
 713         Elf32_Phdr *phdr_ptr;
 714         Elf32_Nhdr *nhdr_ptr;
 715
 716         phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
 717         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 718                 void *notes_section;
 719                 u64 offset, max_sz, sz, real_sz = 0;
 720                 if (phdr_ptr->p_type != PT_NOTE)
 721                         continue;
 722                 max_sz = phdr_ptr->p_memsz;
 723                 offset = phdr_ptr->p_offset;
 724                 notes_section = kmalloc(max_sz, GFP_KERNEL);
 725                 if (!notes_section)
 726                         return -ENOMEM;
 727                 rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
 728                 if (rc < 0) {
 729                         kfree(notes_section);
 730                         return rc;
 731                 }
 732                 nhdr_ptr = notes_section;
 733                 while (nhdr_ptr->n_namesz != 0) {
 734                         sz = sizeof(Elf32_Nhdr) +
 735                                 (((u64)nhdr_ptr->n_namesz + 3) & ~3) +
 736                                 (((u64)nhdr_ptr->n_descsz + 3) & ~3);
 737                         if ((real_sz + sz) > max_sz) {
 738                                 pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
 739                                         nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
 740                                 break;
 741                         }
 742                         real_sz += sz;
 743                         nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
 744                 }
 745                 kfree(notes_section);
 746                 phdr_ptr->p_memsz = real_sz;
 747                 if (real_sz == 0) {
 748                         pr_warn("Warning: Zero PT_NOTE entries found\n");
 749                 }
 750         }
 751
 752         return 0;
 753 }
 754
 755 /**
 756  * get_note_number_and_size_elf32 - get the number of PT_NOTE program
 757  * headers and sum of real size of their ELF note segment headers and
 758  * data.
 759  *
 760  * @ehdr_ptr: ELF header
 761  * @nr_ptnote: buffer for the number of PT_NOTE program headers
 762  * @sz_ptnote: buffer for size of unique PT_NOTE program header
 763  *
 764  * This function is used to merge multiple PT_NOTE program headers
 765  * into a unique single one. The resulting unique entry will have
 766  * @sz_ptnote in its phdr->p_mem.
 767  *
 768  * It is assumed that program headers with PT_NOTE type pointed to by
 769  * @ehdr_ptr has already been updated by update_note_header_size_elf32
 770  * and each of PT_NOTE program headers has actual ELF note segment
 771  * size in its p_memsz member.
 772  */
 773 static int __init get_note_number_and_size_elf32(const Elf32_Ehdr *ehdr_ptr,
 774                                                  int *nr_ptnote, u64 *sz_ptnote)
 775 {
 776         int i;
 777         Elf32_Phdr *phdr_ptr;
 778
 779         *nr_ptnote = *sz_ptnote = 0;
 780
 781         phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
 782         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 783                 if (phdr_ptr->p_type != PT_NOTE)
 784                         continue;
 785                 *nr_ptnote += 1;
 786                 *sz_ptnote += phdr_ptr->p_memsz;
 787         }
 788
 789         return 0;
 790 }
 791
 792 /**
 793  * copy_notes_elf32 - copy ELF note segments in a given buffer
 794  *
 795  * @ehdr_ptr: ELF header
 796  * @notes_buf: buffer into which ELF note segments are copied
 797  *
 798  * This function is used to copy ELF note segment in the 1st kernel
 799  * into the buffer @notes_buf in the 2nd kernel. It is assumed that
 800  * size of the buffer @notes_buf is equal to or larger than sum of the
 801  * real ELF note segment headers and data.
 802  *
 803  * It is assumed that program headers with PT_NOTE type pointed to by
 804  * @ehdr_ptr has already been updated by update_note_header_size_elf32
 805  * and each of PT_NOTE program headers has actual ELF note segment
 806  * size in its p_memsz member.
 807  */
 808 static int __init copy_notes_elf32(const Elf32_Ehdr *ehdr_ptr, char *notes_buf)
 809 {
 810         int i, rc=0;
 811         Elf32_Phdr *phdr_ptr;
 812
 813         phdr_ptr = (Elf32_Phdr*)(ehdr_ptr + 1);
 814
 815         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 816                 u64 offset;
 817                 if (phdr_ptr->p_type != PT_NOTE)
 818                         continue;
 819                 offset = phdr_ptr->p_offset;
 820                 rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
 821                                            &offset);
 822                 if (rc < 0)
 823                         return rc;
 824                 notes_buf += phdr_ptr->p_memsz;
 825         }
 826
 827         return 0;
 828 }
 829
 830 /* Merges all the PT_NOTE headers into one. */
 831 static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
 832                                            char **notes_buf, size_t *notes_sz)
 833 {
 834         int i, nr_ptnote=0, rc=0;
 835         char *tmp;
 836         Elf32_Ehdr *ehdr_ptr;
 837         Elf32_Phdr phdr;
 838         u64 phdr_sz = 0, note_off;
 839
 840         ehdr_ptr = (Elf32_Ehdr *)elfptr;
 841
 842         rc = update_note_header_size_elf32(ehdr_ptr);
 843         if (rc < 0)
 844                 return rc;
 845
 846         rc = get_note_number_and_size_elf32(ehdr_ptr, &nr_ptnote, &phdr_sz);
 847         if (rc < 0)
 848                 return rc;
 849
 850         *notes_sz = roundup(phdr_sz, PAGE_SIZE);
 851         *notes_buf = alloc_elfnotes_buf(*notes_sz);
 852         if (!*notes_buf)
 853                 return -ENOMEM;
 854
 855         rc = copy_notes_elf32(ehdr_ptr, *notes_buf);
 856         if (rc < 0)
 857                 return rc;
 858
 859         /* Prepare merged PT_NOTE program header. */
 860         phdr.p_type    = PT_NOTE;
 861         phdr.p_flags   = 0;
 862         note_off = sizeof(Elf32_Ehdr) +
 863                         (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
 864         phdr.p_offset  = roundup(note_off, PAGE_SIZE);
 865         phdr.p_vaddr   = phdr.p_paddr = 0;
 866         phdr.p_filesz  = phdr.p_memsz = phdr_sz;
 867         phdr.p_align   = 0;
 868
 869         /* Add merged PT_NOTE program header*/
 870         tmp = elfptr + sizeof(Elf32_Ehdr);
 871         memcpy(tmp, &phdr, sizeof(phdr));
 872         tmp += sizeof(phdr);
 873
 874         /* Remove unwanted PT_NOTE program headers. */
 875         i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
 876         *elfsz = *elfsz - i;
 877         memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
 878         memset(elfptr + *elfsz, 0, i);
 879         *elfsz = roundup(*elfsz, PAGE_SIZE);
 880
 881         /* Modify e_phnum to reflect merged headers. */
 882         ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
 883
 884         return 0;
 885 }
 886
 887 /* Add memory chunks represented by program headers to vmcore list. Also update
 888  * the new offset fields of exported program headers. */
 889 static int __init process_ptload_program_headers_elf64(char *elfptr,
 890                                                 size_t elfsz,
 891                                                 size_t elfnotes_sz,
 892                                                 struct list_head *vc_list)
 893 {
 894         int i;
 895         Elf64_Ehdr *ehdr_ptr;
 896         Elf64_Phdr *phdr_ptr;
 897         loff_t vmcore_off;
 898         struct vmcore *new;
 899
 900         ehdr_ptr = (Elf64_Ehdr *)elfptr;
 901         phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
 902
 903         /* Skip Elf header, program headers and Elf note segment. */
 904         vmcore_off = elfsz + elfnotes_sz;
 905
 906         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 907                 u64 paddr, start, end, size;
 908
 909                 if (phdr_ptr->p_type != PT_LOAD)
 910                         continue;
 911
 912                 paddr = phdr_ptr->p_offset;
 913                 start = rounddown(paddr, PAGE_SIZE);
 914                 end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
 915                 size = end - start;
 916
 917                 /* Add this contiguous chunk of memory to vmcore list.*/
 918                 new = get_new_element();
 919                 if (!new)
 920                         return -ENOMEM;
 921                 new->paddr = start;
 922                 new->size = size;
 923                 list_add_tail(&new->list, vc_list);
 924
 925                 /* Update the program header offset. */
 926                 phdr_ptr->p_offset = vmcore_off + (paddr - start);
 927                 vmcore_off = vmcore_off + size;
 928         }
 929         return 0;
 930 }
 931
 932 static int __init process_ptload_program_headers_elf32(char *elfptr,
 933                                                 size_t elfsz,
 934                                                 size_t elfnotes_sz,
 935                                                 struct list_head *vc_list)
 936 {
 937         int i;
 938         Elf32_Ehdr *ehdr_ptr;
 939         Elf32_Phdr *phdr_ptr;
 940         loff_t vmcore_off;
 941         struct vmcore *new;
 942
 943         ehdr_ptr = (Elf32_Ehdr *)elfptr;
 944         phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
 945
 946         /* Skip Elf header, program headers and Elf note segment. */
 947         vmcore_off = elfsz + elfnotes_sz;
 948
 949         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
 950                 u64 paddr, start, end, size;
 951
 952                 if (phdr_ptr->p_type != PT_LOAD)
 953                         continue;
 954
 955                 paddr = phdr_ptr->p_offset;
 956                 start = rounddown(paddr, PAGE_SIZE);
 957                 end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
 958                 size = end - start;
 959
 960                 /* Add this contiguous chunk of memory to vmcore list.*/
 961                 new = get_new_element();
 962                 if (!new)
 963                         return -ENOMEM;
 964                 new->paddr = start;
 965                 new->size = size;
 966                 list_add_tail(&new->list, vc_list);
 967
 968                 /* Update the program header offset */
 969                 phdr_ptr->p_offset = vmcore_off + (paddr - start);
 970                 vmcore_off = vmcore_off + size;
 971         }
 972         return 0;
 973 }
 974
 975 /* Sets offset fields of vmcore elements. */
 976 static void __init set_vmcore_list_offsets(size_t elfsz, size_t elfnotes_sz,
 977                                            struct list_head *vc_list)
 978 {
 979         loff_t vmcore_off;
 980         struct vmcore *m;
 981
 982         /* Skip Elf header, program headers and Elf note segment. */
 983         vmcore_off = elfsz + elfnotes_sz;
 984
 985         list_for_each_entry(m, vc_list, list) {
 986                 m->offset = vmcore_off;
 987                 vmcore_off += m->size;
 988         }
 989 }
 990
 991 static void free_elfcorebuf(void)
 992 {
 993         free_pages((unsigned long)elfcorebuf, get_order(elfcorebuf_sz_orig));
 994         elfcorebuf = NULL;
 995         vfree(elfnotes_buf);
 996         elfnotes_buf = NULL;
 997 }
 998
 999 static int __init parse_crash_elf64_headers(void)
1000 {
1001         int rc=0;
1002         Elf64_Ehdr ehdr;
1003         u64 addr;
1004
1005         addr = elfcorehdr_addr;
1006
1007         /* Read Elf header */
1008         rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf64_Ehdr), &addr);
1009         if (rc < 0)
1010                 return rc;
1011
1012         /* Do some basic Verification. */
1013         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
1014                 (ehdr.e_type != ET_CORE) ||
1015                 !vmcore_elf64_check_arch(&ehdr) ||
1016                 ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
1017                 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
1018                 ehdr.e_version != EV_CURRENT ||
1019                 ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
1020                 ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
1021                 ehdr.e_phnum == 0) {
1022                 pr_warn("Warning: Core image elf header is not sane\n");
1023                 return -EINVAL;
1024         }
1025
1026         /* Read in all elf headers. */
1027         elfcorebuf_sz_orig = sizeof(Elf64_Ehdr) +
1028                                 ehdr.e_phnum * sizeof(Elf64_Phdr);
1029         elfcorebuf_sz = elfcorebuf_sz_orig;
1030         elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
1031                                               get_order(elfcorebuf_sz_orig));
1032         if (!elfcorebuf)
1033                 return -ENOMEM;
1034         addr = elfcorehdr_addr;
1035         rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
1036         if (rc < 0)
1037                 goto fail;
1038
1039         /* Merge all PT_NOTE headers into one. */
1040         rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz,
1041                                       &elfnotes_buf, &elfnotes_sz);
1042         if (rc)
1043                 goto fail;
1044         rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
1045                                                   elfnotes_sz, &vmcore_list);
1046         if (rc)
1047                 goto fail;
1048         set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
1049         return 0;
1050 fail:
1051         free_elfcorebuf();
1052         return rc;
1053 }
1054
1055 static int __init parse_crash_elf32_headers(void)
1056 {
1057         int rc=0;
1058         Elf32_Ehdr ehdr;
1059         u64 addr;
1060
1061         addr = elfcorehdr_addr;
1062
1063         /* Read Elf header */
1064         rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf32_Ehdr), &addr);
1065         if (rc < 0)
1066                 return rc;
1067
1068         /* Do some basic Verification. */
1069         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
1070                 (ehdr.e_type != ET_CORE) ||
1071                 !elf_check_arch(&ehdr) ||
1072                 ehdr.e_ident[EI_CLASS] != ELFCLASS32||
1073                 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
1074                 ehdr.e_version != EV_CURRENT ||
1075                 ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
1076                 ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
1077                 ehdr.e_phnum == 0) {
1078                 pr_warn("Warning: Core image elf header is not sane\n");
1079                 return -EINVAL;
1080         }
1081
1082         /* Read in all elf headers. */
1083         elfcorebuf_sz_orig = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
1084         elfcorebuf_sz = elfcorebuf_sz_orig;
1085         elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
1086                                               get_order(elfcorebuf_sz_orig));
1087         if (!elfcorebuf)
1088                 return -ENOMEM;
1089         addr = elfcorehdr_addr;
1090         rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
1091         if (rc < 0)
1092                 goto fail;
1093
1094         /* Merge all PT_NOTE headers into one. */
1095         rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz,
1096                                       &elfnotes_buf, &elfnotes_sz);
1097         if (rc)
1098                 goto fail;
1099         rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
1100                                                   elfnotes_sz, &vmcore_list);
1101         if (rc)
1102                 goto fail;
1103         set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
1104         return 0;
1105 fail:
1106         free_elfcorebuf();
1107         return rc;
1108 }
1109
1110 static int __init parse_crash_elf_headers(void)
1111 {
1112         unsigned char e_ident[EI_NIDENT];
1113         u64 addr;
1114         int rc=0;
1115
1116         addr = elfcorehdr_addr;
1117         rc = elfcorehdr_read(e_ident, EI_NIDENT, &addr);
1118         if (rc < 0)
1119                 return rc;
1120         if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
1121                 pr_warn("Warning: Core image elf header not found\n");
1122                 return -EINVAL;
1123         }
1124
1125         if (e_ident[EI_CLASS] == ELFCLASS64) {
1126                 rc = parse_crash_elf64_headers();
1127                 if (rc)
1128                         return rc;
1129         } else if (e_ident[EI_CLASS] == ELFCLASS32) {
1130                 rc = parse_crash_elf32_headers();
1131                 if (rc)
1132                         return rc;
1133         } else {
1134                 pr_warn("Warning: Core image elf header is not sane\n");
1135                 return -EINVAL;
1136         }
1137
1138         /* Determine vmcore size. */
1139         vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
1140                                       &vmcore_list);
1141
1142         return 0;
1143 }
1144
1145 /* Init function for vmcore module. */
1146 static int __init vmcore_init(void)
1147 {
1148         int rc = 0;
1149
1150         /* Allow architectures to allocate ELF header in 2nd kernel */
1151         rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size);
1152         if (rc)
1153                 return rc;
1154         /*
1155          * If elfcorehdr= has been passed in cmdline or created in 2nd kernel,
1156          * then capture the dump.
1157          */
1158         if (!(is_vmcore_usable()))
1159                 return rc;
1160         rc = parse_crash_elf_headers();
1161         if (rc) {
1162                 pr_warn("Kdump: vmcore not initialized\n");
1163                 return rc;
1164         }
1165         elfcorehdr_free(elfcorehdr_addr);
1166         elfcorehdr_addr = ELFCORE_ADDR_ERR;
1167
1168         proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
1169         if (proc_vmcore)
1170                 proc_vmcore->size = vmcore_size;
1171         return 0;
1172 }
1173 fs_initcall(vmcore_init);
1174
1175 /* Cleanup function for vmcore module. */
1176 void vmcore_cleanup(void)
1177 {
1178         struct list_head *pos, *next;
1179
1180         if (proc_vmcore) {
1181                 proc_remove(proc_vmcore);
1182                 proc_vmcore = NULL;
1183         }
1184
1185         /* clear the vmcore list. */
1186         list_for_each_safe(pos, next, &vmcore_list) {
1187                 struct vmcore *m;
1188
1189                 m = list_entry(pos, struct vmcore, list);
1190                 list_del(&m->list);
1191                 kfree(m);
1192         }
1193         free_elfcorebuf();
1194 }