fs/proc/kcore.c

   1 /*
   2  *      fs/proc/kcore.c kernel ELF core dumper
   3  *
   4  *      Modelled on fs/exec.c:aout_core_dump()
   5  *      Jeremy Fitzhardinge <jeremy@sw.oz.au>
   6  *      ELF version written by David Howells <David.Howells@nexor.co.uk>
   7  *      Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
   8  *      Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
   9  *      Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
  10  */
  11
  12 #include <linux/mm.h>
  13 #include <linux/proc_fs.h>
  14 #include <linux/user.h>
  15 #include <linux/capability.h>
  16 #include <linux/elf.h>
  17 #include <linux/elfcore.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/highmem.h>
  20 #include <linux/bootmem.h>
  21 #include <linux/init.h>
  22 #include <linux/slab.h>
  23 #include <asm/uaccess.h>
  24 #include <asm/io.h>
  25 #include <linux/list.h>
  26 #include <linux/ioport.h>
  27 #include <linux/memory.h>
  28 #include <asm/sections.h>
  29
  30 #define CORE_STR "CORE"
  31
  32 #ifndef ELF_CORE_EFLAGS
  33 #define ELF_CORE_EFLAGS 0
  34 #endif
  35
  36 static struct proc_dir_entry *proc_root_kcore;
  37
  38
  39 #ifndef kc_vaddr_to_offset
  40 #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
  41 #endif
  42 #ifndef kc_offset_to_vaddr
  43 #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
  44 #endif
  45
  46 /* An ELF note in memory */
  47 struct memelfnote
  48 {
  49         const char *name;
  50         int type;
  51         unsigned int datasz;
  52         void *data;
  53 };
  54
  55 static LIST_HEAD(kclist_head);
  56 static DEFINE_RWLOCK(kclist_lock);
  57 static int kcore_need_update = 1;
  58
  59 void
  60 kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
  61 {
  62         new->addr = (unsigned long)addr;
  63         new->size = size;
  64         new->type = type;
  65
  66         write_lock(&kclist_lock);
  67         list_add_tail(&new->list, &kclist_head);
  68         write_unlock(&kclist_lock);
  69 }
  70
  71 static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
  72 {
  73         size_t try, size;
  74         struct kcore_list *m;
  75
  76         *nphdr = 1; /* PT_NOTE */
  77         size = 0;
  78
  79         list_for_each_entry(m, &kclist_head, list) {
  80                 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
  81                 if (try > size)
  82                         size = try;
  83                 *nphdr = *nphdr + 1;
  84         }
  85         *elf_buflen =   sizeof(struct elfhdr) +
  86                         (*nphdr + 2)*sizeof(struct elf_phdr) +
  87                         3 * ((sizeof(struct elf_note)) +
  88                              roundup(sizeof(CORE_STR), 4)) +
  89                         roundup(sizeof(struct elf_prstatus), 4) +
  90                         roundup(sizeof(struct elf_prpsinfo), 4) +
  91                         roundup(sizeof(struct task_struct), 4);
  92         *elf_buflen = PAGE_ALIGN(*elf_buflen);
  93         return size + *elf_buflen;
  94 }
  95
  96 static void free_kclist_ents(struct list_head *head)
  97 {
  98         struct kcore_list *tmp, *pos;
  99
 100         list_for_each_entry_safe(pos, tmp, head, list) {
 101                 list_del(&pos->list);
 102                 kfree(pos);
 103         }
 104 }
 105 /*
 106  * Replace all KCORE_RAM/KCORE_VMEMMAP information with passed list.
 107  */
 108 static void __kcore_update_ram(struct list_head *list)
 109 {
 110         int nphdr;
 111         size_t size;
 112         struct kcore_list *tmp, *pos;
 113         LIST_HEAD(garbage);
 114
 115         write_lock(&kclist_lock);
 116         if (kcore_need_update) {
 117                 list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
 118                         if (pos->type == KCORE_RAM
 119                                 || pos->type == KCORE_VMEMMAP)
 120                                 list_move(&pos->list, &garbage);
 121                 }
 122                 list_splice_tail(list, &kclist_head);
 123         } else
 124                 list_splice(list, &garbage);
 125         kcore_need_update = 0;
 126         proc_root_kcore->size = get_kcore_size(&nphdr, &size);
 127         write_unlock(&kclist_lock);
 128
 129         free_kclist_ents(&garbage);
 130 }
 131
 132
 133 #if defined(CONFIG_HIGHMEM) || defined(CONFIG_XEN)
 134 /*
 135  * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
 136  * because memory hole is not as big as !HIGHMEM case.
 137  * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
 138  */
 139 static int kcore_update_ram(void)
 140 {
 141         LIST_HEAD(head);
 142         struct kcore_list *ent;
 143         int ret = 0;
 144
 145         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
 146         if (!ent)
 147                 return -ENOMEM;
 148         ent->addr = (unsigned long)__va(0);
 149 #ifdef CONFIG_HIGHMEM
 150         ent->size = max_low_pfn << PAGE_SHIFT;
 151 #else
 152         ent->size = max_pfn << PAGE_SHIFT;
 153 #endif
 154         ent->type = KCORE_RAM;
 155         list_add(&ent->list, &head);
 156         __kcore_update_ram(&head);
 157         return ret;
 158 }
 159
 160 #else /* !CONFIG_HIGHMEM */
 161
 162 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 163 /* calculate vmemmap's address from given system ram pfn and register it */
 164 int get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 165 {
 166         unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
 167         unsigned long nr_pages = ent->size >> PAGE_SHIFT;
 168         unsigned long start, end;
 169         struct kcore_list *vmm, *tmp;
 170
 171
 172         start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
 173         end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
 174         end = ALIGN(end, PAGE_SIZE);
 175         /* overlap check (because we have to align page */
 176         list_for_each_entry(tmp, head, list) {
 177                 if (tmp->type != KCORE_VMEMMAP)
 178                         continue;
 179                 if (start < tmp->addr + tmp->size)
 180                         if (end > tmp->addr)
 181                                 end = tmp->addr;
 182         }
 183         if (start < end) {
 184                 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
 185                 if (!vmm)
 186                         return 0;
 187                 vmm->addr = start;
 188                 vmm->size = end - start;
 189                 vmm->type = KCORE_VMEMMAP;
 190                 list_add_tail(&vmm->list, head);
 191         }
 192         return 1;
 193
 194 }
 195 #else
 196 int get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 197 {
 198         return 1;
 199 }
 200
 201 #endif
 202
 203 static int
 204 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
 205 {
 206         struct list_head *head = (struct list_head *)arg;
 207         struct kcore_list *ent;
 208
 209         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
 210         if (!ent)
 211                 return -ENOMEM;
 212         ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT));
 213         ent->size = nr_pages << PAGE_SHIFT;
 214
 215         /* Sanity check: Can happen in 32bit arch...maybe */
 216         if (ent->addr < (unsigned long) __va(0))
 217                 goto free_out;
 218
 219         /* cut not-mapped area. ....from ppc-32 code. */
 220         if (ULONG_MAX - ent->addr < ent->size)
 221                 ent->size = ULONG_MAX - ent->addr;
 222
 223         /* cut when vmalloc() area is higher than direct-map area */
 224         if (VMALLOC_START > (unsigned long)__va(0)) {
 225                 if (ent->addr > VMALLOC_START)
 226                         goto free_out;
 227                 if (VMALLOC_START - ent->addr < ent->size)
 228                         ent->size = VMALLOC_START - ent->addr;
 229         }
 230
 231         ent->type = KCORE_RAM;
 232         list_add_tail(&ent->list, head);
 233
 234         if (!get_sparsemem_vmemmap_info(ent, head)) {
 235                 list_del(&ent->list);
 236                 goto free_out;
 237         }
 238
 239         return 0;
 240 free_out:
 241         kfree(ent);
 242         return 1;
 243 }
 244
 245 static int kcore_update_ram(void)
 246 {
 247         int nid, ret;
 248         unsigned long end_pfn;
 249         LIST_HEAD(head);
 250
 251         /* Not inialized....update now */
 252         /* find out "max pfn" */
 253         end_pfn = 0;
 254         for_each_node_state(nid, N_HIGH_MEMORY) {
 255                 unsigned long node_end;
 256                 node_end  = NODE_DATA(nid)->node_start_pfn +
 257                         NODE_DATA(nid)->node_spanned_pages;
 258                 if (end_pfn < node_end)
 259                         end_pfn = node_end;
 260         }
 261         /* scan 0 to max_pfn */
 262         ret = walk_system_ram_range(0, end_pfn, &head, kclist_add_private);
 263         if (ret) {
 264                 free_kclist_ents(&head);
 265                 return -ENOMEM;
 266         }
 267         __kcore_update_ram(&head);
 268         return ret;
 269 }
 270 #endif /* CONFIG_HIGHMEM */
 271
 272 /*****************************************************************************/
 273 /*
 274  * determine size of ELF note
 275  */
 276 static int notesize(struct memelfnote *en)
 277 {
 278         int sz;
 279
 280         sz = sizeof(struct elf_note);
 281         sz += roundup((strlen(en->name) + 1), 4);
 282         sz += roundup(en->datasz, 4);
 283
 284         return sz;
 285 } /* end notesize() */
 286
 287 /*****************************************************************************/
 288 /*
 289  * store a note in the header buffer
 290  */
 291 static char *storenote(struct memelfnote *men, char *bufp)
 292 {
 293         struct elf_note en;
 294
 295 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 296
 297         en.n_namesz = strlen(men->name) + 1;
 298         en.n_descsz = men->datasz;
 299         en.n_type = men->type;
 300
 301         DUMP_WRITE(&en, sizeof(en));
 302         DUMP_WRITE(men->name, en.n_namesz);
 303
 304         /* XXX - cast from long long to long to avoid need for libgcc.a */
 305         bufp = (char*) roundup((unsigned long)bufp,4);
 306         DUMP_WRITE(men->data, men->datasz);
 307         bufp = (char*) roundup((unsigned long)bufp,4);
 308
 309 #undef DUMP_WRITE
 310
 311         return bufp;
 312 } /* end storenote() */
 313
 314 /*
 315  * store an ELF coredump header in the supplied buffer
 316  * nphdr is the number of elf_phdr to insert
 317  */
 318 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 319 {
 320         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 321         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 322         struct elf_phdr *nhdr, *phdr;
 323         struct elfhdr *elf;
 324         struct memelfnote notes[3];
 325         off_t offset = 0;
 326         struct kcore_list *m;
 327
 328         /* setup ELF header */
 329         elf = (struct elfhdr *) bufp;
 330         bufp += sizeof(struct elfhdr);
 331         offset += sizeof(struct elfhdr);
 332         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 333         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 334         elf->e_ident[EI_DATA]   = ELF_DATA;
 335         elf->e_ident[EI_VERSION]= EV_CURRENT;
 336         elf->e_ident[EI_OSABI] = ELF_OSABI;
 337         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 338         elf->e_type     = ET_CORE;
 339         elf->e_machine  = ELF_ARCH;
 340         elf->e_version  = EV_CURRENT;
 341         elf->e_entry    = 0;
 342         elf->e_phoff    = sizeof(struct elfhdr);
 343         elf->e_shoff    = 0;
 344         elf->e_flags    = ELF_CORE_EFLAGS;
 345         elf->e_ehsize   = sizeof(struct elfhdr);
 346         elf->e_phentsize= sizeof(struct elf_phdr);
 347         elf->e_phnum    = nphdr;
 348         elf->e_shentsize= 0;
 349         elf->e_shnum    = 0;
 350         elf->e_shstrndx = 0;
 351
 352         /* setup ELF PT_NOTE program header */
 353         nhdr = (struct elf_phdr *) bufp;
 354         bufp += sizeof(struct elf_phdr);
 355         offset += sizeof(struct elf_phdr);
 356         nhdr->p_type    = PT_NOTE;
 357         nhdr->p_offset  = 0;
 358         nhdr->p_vaddr   = 0;
 359         nhdr->p_paddr   = 0;
 360         nhdr->p_filesz  = 0;
 361         nhdr->p_memsz   = 0;
 362         nhdr->p_flags   = 0;
 363         nhdr->p_align   = 0;
 364
 365         /* setup ELF PT_LOAD program header for every area */
 366         list_for_each_entry(m, &kclist_head, list) {
 367                 phdr = (struct elf_phdr *) bufp;
 368                 bufp += sizeof(struct elf_phdr);
 369                 offset += sizeof(struct elf_phdr);
 370
 371                 phdr->p_type    = PT_LOAD;
 372                 phdr->p_flags   = PF_R|PF_W|PF_X;
 373                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
 374                 phdr->p_vaddr   = (size_t)m->addr;
 375                 phdr->p_paddr   = 0;
 376                 phdr->p_filesz  = phdr->p_memsz = m->size;
 377                 phdr->p_align   = PAGE_SIZE;
 378         }
 379
 380         /*
 381          * Set up the notes in similar form to SVR4 core dumps made
 382          * with info from their /proc.
 383          */
 384         nhdr->p_offset  = offset;
 385
 386         /* set up the process status */
 387         notes[0].name = CORE_STR;
 388         notes[0].type = NT_PRSTATUS;
 389         notes[0].datasz = sizeof(struct elf_prstatus);
 390         notes[0].data = &prstatus;
 391
 392         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 393
 394         nhdr->p_filesz  = notesize(&notes[0]);
 395         bufp = storenote(&notes[0], bufp);
 396
 397         /* set up the process info */
 398         notes[1].name   = CORE_STR;
 399         notes[1].type   = NT_PRPSINFO;
 400         notes[1].datasz = sizeof(struct elf_prpsinfo);
 401         notes[1].data   = &prpsinfo;
 402
 403         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 404         prpsinfo.pr_state       = 0;
 405         prpsinfo.pr_sname       = 'R';
 406         prpsinfo.pr_zomb        = 0;
 407
 408         strcpy(prpsinfo.pr_fname, "vmlinux");
 409         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 410
 411         nhdr->p_filesz  += notesize(&notes[1]);
 412         bufp = storenote(&notes[1], bufp);
 413
 414         /* set up the task structure */
 415         notes[2].name   = CORE_STR;
 416         notes[2].type   = NT_TASKSTRUCT;
 417         notes[2].datasz = sizeof(struct task_struct);
 418         notes[2].data   = current;
 419
 420         nhdr->p_filesz  += notesize(&notes[2]);
 421         bufp = storenote(&notes[2], bufp);
 422
 423 } /* end elf_kcore_store_hdr() */
 424
 425 /*****************************************************************************/
 426 /*
 427  * read from the ELF header and then kernel memory
 428  */
 429 static ssize_t
 430 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 431 {
 432         ssize_t acc = 0;
 433         size_t size, tsz;
 434         size_t elf_buflen;
 435         int nphdr;
 436         unsigned long start;
 437
 438         read_lock(&kclist_lock);
 439         size = get_kcore_size(&nphdr, &elf_buflen);
 440
 441         if (buflen == 0 || *fpos >= size) {
 442                 read_unlock(&kclist_lock);
 443                 return 0;
 444         }
 445
 446         /* trim buflen to not go beyond EOF */
 447         if (buflen > size - *fpos)
 448                 buflen = size - *fpos;
 449
 450         /* construct an ELF core header if we'll need some of it */
 451         if (*fpos < elf_buflen) {
 452                 char * elf_buf;
 453
 454                 tsz = elf_buflen - *fpos;
 455                 if (buflen < tsz)
 456                         tsz = buflen;
 457                 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
 458                 if (!elf_buf) {
 459                         read_unlock(&kclist_lock);
 460                         return -ENOMEM;
 461                 }
 462                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
 463                 read_unlock(&kclist_lock);
 464                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 465                         kfree(elf_buf);
 466                         return -EFAULT;
 467                 }
 468                 kfree(elf_buf);
 469                 buflen -= tsz;
 470                 *fpos += tsz;
 471                 buffer += tsz;
 472                 acc += tsz;
 473
 474                 /* leave now if filled buffer already */
 475                 if (buflen == 0)
 476                         return acc;
 477         } else
 478                 read_unlock(&kclist_lock);
 479
 480         /*
 481          * Check to see if our file offset matches with any of
 482          * the addresses in the elf_phdr on our list.
 483          */
 484         start = kc_offset_to_vaddr(*fpos - elf_buflen);
 485         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 486                 tsz = buflen;
 487
 488         while (buflen) {
 489                 struct kcore_list *m;
 490
 491                 read_lock(&kclist_lock);
 492                 list_for_each_entry(m, &kclist_head, list) {
 493                         if (start >= m->addr && start < (m->addr+m->size))
 494                                 break;
 495                 }
 496                 read_unlock(&kclist_lock);
 497
 498                 if (&m->list == &kclist_head) {
 499                         if (clear_user(buffer, tsz))
 500                                 return -EFAULT;
 501                 } else if (is_vmalloc_or_module_addr((void *)start)) {
 502                         char * elf_buf;
 503
 504                         elf_buf = kzalloc(tsz, GFP_KERNEL);
 505                         if (!elf_buf)
 506                                 return -ENOMEM;
 507                         vread(elf_buf, (char *)start, tsz);
 508                         /* we have to zero-fill user buffer even if no read */
 509                         if (copy_to_user(buffer, elf_buf, tsz)) {
 510                                 kfree(elf_buf);
 511                                 return -EFAULT;
 512                         }
 513                         kfree(elf_buf);
 514                 } else {
 515                         if (kern_addr_valid(start)) {
 516                                 unsigned long n;
 517
 518                                 n = copy_to_user(buffer, (char *)start, tsz);
 519                                 /*
 520                                  * We cannot distingush between fault on source
 521                                  * and fault on destination. When this happens
 522                                  * we clear too and hope it will trigger the
 523                                  * EFAULT again.
 524                                  */
 525                                 if (n) {
 526                                         if (clear_user(buffer + tsz - n,
 527                                                                 n))
 528                                                 return -EFAULT;
 529                                 }
 530                         } else {
 531                                 if (clear_user(buffer, tsz))
 532                                         return -EFAULT;
 533                         }
 534                 }
 535                 buflen -= tsz;
 536                 *fpos += tsz;
 537                 buffer += tsz;
 538                 acc += tsz;
 539                 start += tsz;
 540                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 541         }
 542
 543         return acc;
 544 }
 545
 546
 547 static int open_kcore(struct inode *inode, struct file *filp)
 548 {
 549         if (!capable(CAP_SYS_RAWIO))
 550                 return -EPERM;
 551         if (kcore_need_update)
 552                 kcore_update_ram();
 553         if (i_size_read(inode) != proc_root_kcore->size) {
 554                 mutex_lock(&inode->i_mutex);
 555                 i_size_write(inode, proc_root_kcore->size);
 556                 mutex_unlock(&inode->i_mutex);
 557         }
 558         return 0;
 559 }
 560
 561
 562 static const struct file_operations proc_kcore_operations = {
 563         .read           = read_kcore,
 564         .open           = open_kcore,
 565         .llseek         = default_llseek,
 566 };
 567
 568 #ifdef CONFIG_MEMORY_HOTPLUG
 569 /* just remember that we have to update kcore */
 570 static int __meminit kcore_callback(struct notifier_block *self,
 571                                     unsigned long action, void *arg)
 572 {
 573         switch (action) {
 574         case MEM_ONLINE:
 575         case MEM_OFFLINE:
 576                 write_lock(&kclist_lock);
 577                 kcore_need_update = 1;
 578                 write_unlock(&kclist_lock);
 579         }
 580         return NOTIFY_OK;
 581 }
 582 #endif
 583
 584
 585 static struct kcore_list kcore_vmalloc;
 586
 587 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
 588 static struct kcore_list kcore_text;
 589 /*
 590  * If defined, special segment is used for mapping kernel text instead of
 591  * direct-map area. We need to create special TEXT section.
 592  */
 593 static void __init proc_kcore_text_init(void)
 594 {
 595         kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
 596 }
 597 #else
 598 static void __init proc_kcore_text_init(void)
 599 {
 600 }
 601 #endif
 602
 603 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
 604 /*
 605  * MODULES_VADDR has no intersection with VMALLOC_ADDR.
 606  */
 607 struct kcore_list kcore_modules;
 608 static void __init add_modules_range(void)
 609 {
 610         kclist_add(&kcore_modules, (void *)MODULES_VADDR,
 611                         MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
 612 }
 613 #else
 614 static void __init add_modules_range(void)
 615 {
 616 }
 617 #endif
 618
 619 static int __init proc_kcore_init(void)
 620 {
 621         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
 622                                       &proc_kcore_operations);
 623         if (!proc_root_kcore) {
 624                 printk(KERN_ERR "couldn't create /proc/kcore\n");
 625                 return 0; /* Always returns 0. */
 626         }
 627         /* Store text area if it's special */
 628         proc_kcore_text_init();
 629         /* Store vmalloc area */
 630         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 631                 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 632         add_modules_range();
 633         /* Store direct-map area from physical memory map */
 634         kcore_update_ram();
 635         hotplug_memory_notifier(kcore_callback, 0);
 636
 637         return 0;
 638 }
 639 module_init(proc_kcore_init);