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 #ifdef CONFIG_HIGHMEM
 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         ent->size = max_low_pfn << PAGE_SHIFT;
 150         ent->type = KCORE_RAM;
 151         list_add(&ent->list, &head);
 152         __kcore_update_ram(&head);
 153         return ret;
 154 }
 155
 156 #else /* !CONFIG_HIGHMEM */
 157
 158 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 159 /* calculate vmemmap's address from given system ram pfn and register it */
 160 static int
 161 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 162 {
 163         unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
 164         unsigned long nr_pages = ent->size >> PAGE_SHIFT;
 165         unsigned long start, end;
 166         struct kcore_list *vmm, *tmp;
 167
 168
 169         start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
 170         end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
 171         end = ALIGN(end, PAGE_SIZE);
 172         /* overlap check (because we have to align page */
 173         list_for_each_entry(tmp, head, list) {
 174                 if (tmp->type != KCORE_VMEMMAP)
 175                         continue;
 176                 if (start < tmp->addr + tmp->size)
 177                         if (end > tmp->addr)
 178                                 end = tmp->addr;
 179         }
 180         if (start < end) {
 181                 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
 182                 if (!vmm)
 183                         return 0;
 184                 vmm->addr = start;
 185                 vmm->size = end - start;
 186                 vmm->type = KCORE_VMEMMAP;
 187                 list_add_tail(&vmm->list, head);
 188         }
 189         return 1;
 190
 191 }
 192 #else
 193 static int
 194 get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
 195 {
 196         return 1;
 197 }
 198
 199 #endif
 200
 201 static int
 202 kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
 203 {
 204         struct list_head *head = (struct list_head *)arg;
 205         struct kcore_list *ent;
 206
 207         ent = kmalloc(sizeof(*ent), GFP_KERNEL);
 208         if (!ent)
 209                 return -ENOMEM;
 210         ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT));
 211         ent->size = nr_pages << PAGE_SHIFT;
 212
 213         /* Sanity check: Can happen in 32bit arch...maybe */
 214         if (ent->addr < (unsigned long) __va(0))
 215                 goto free_out;
 216
 217         /* cut not-mapped area. ....from ppc-32 code. */
 218         if (ULONG_MAX - ent->addr < ent->size)
 219                 ent->size = ULONG_MAX - ent->addr;
 220
 221         /* cut when vmalloc() area is higher than direct-map area */
 222         if (VMALLOC_START > (unsigned long)__va(0)) {
 223                 if (ent->addr > VMALLOC_START)
 224                         goto free_out;
 225                 if (VMALLOC_START - ent->addr < ent->size)
 226                         ent->size = VMALLOC_START - ent->addr;
 227         }
 228
 229         ent->type = KCORE_RAM;
 230         list_add_tail(&ent->list, head);
 231
 232         if (!get_sparsemem_vmemmap_info(ent, head)) {
 233                 list_del(&ent->list);
 234                 goto free_out;
 235         }
 236
 237         return 0;
 238 free_out:
 239         kfree(ent);
 240         return 1;
 241 }
 242
 243 static int kcore_update_ram(void)
 244 {
 245         int nid, ret;
 246         unsigned long end_pfn;
 247         LIST_HEAD(head);
 248
 249         /* Not inialized....update now */
 250         /* find out "max pfn" */
 251         end_pfn = 0;
 252         for_each_node_state(nid, N_HIGH_MEMORY) {
 253                 unsigned long node_end;
 254                 node_end  = NODE_DATA(nid)->node_start_pfn +
 255                         NODE_DATA(nid)->node_spanned_pages;
 256                 if (end_pfn < node_end)
 257                         end_pfn = node_end;
 258         }
 259         /* scan 0 to max_pfn */
 260         ret = walk_system_ram_range(0, end_pfn, &head, kclist_add_private);
 261         if (ret) {
 262                 free_kclist_ents(&head);
 263                 return -ENOMEM;
 264         }
 265         __kcore_update_ram(&head);
 266         return ret;
 267 }
 268 #endif /* CONFIG_HIGHMEM */
 269
 270 /*****************************************************************************/
 271 /*
 272  * determine size of ELF note
 273  */
 274 static int notesize(struct memelfnote *en)
 275 {
 276         int sz;
 277
 278         sz = sizeof(struct elf_note);
 279         sz += roundup((strlen(en->name) + 1), 4);
 280         sz += roundup(en->datasz, 4);
 281
 282         return sz;
 283 } /* end notesize() */
 284
 285 /*****************************************************************************/
 286 /*
 287  * store a note in the header buffer
 288  */
 289 static char *storenote(struct memelfnote *men, char *bufp)
 290 {
 291         struct elf_note en;
 292
 293 #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
 294
 295         en.n_namesz = strlen(men->name) + 1;
 296         en.n_descsz = men->datasz;
 297         en.n_type = men->type;
 298
 299         DUMP_WRITE(&en, sizeof(en));
 300         DUMP_WRITE(men->name, en.n_namesz);
 301
 302         /* XXX - cast from long long to long to avoid need for libgcc.a */
 303         bufp = (char*) roundup((unsigned long)bufp,4);
 304         DUMP_WRITE(men->data, men->datasz);
 305         bufp = (char*) roundup((unsigned long)bufp,4);
 306
 307 #undef DUMP_WRITE
 308
 309         return bufp;
 310 } /* end storenote() */
 311
 312 /*
 313  * store an ELF coredump header in the supplied buffer
 314  * nphdr is the number of elf_phdr to insert
 315  */
 316 static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
 317 {
 318         struct elf_prstatus prstatus;   /* NT_PRSTATUS */
 319         struct elf_prpsinfo prpsinfo;   /* NT_PRPSINFO */
 320         struct elf_phdr *nhdr, *phdr;
 321         struct elfhdr *elf;
 322         struct memelfnote notes[3];
 323         off_t offset = 0;
 324         struct kcore_list *m;
 325
 326         /* setup ELF header */
 327         elf = (struct elfhdr *) bufp;
 328         bufp += sizeof(struct elfhdr);
 329         offset += sizeof(struct elfhdr);
 330         memcpy(elf->e_ident, ELFMAG, SELFMAG);
 331         elf->e_ident[EI_CLASS]  = ELF_CLASS;
 332         elf->e_ident[EI_DATA]   = ELF_DATA;
 333         elf->e_ident[EI_VERSION]= EV_CURRENT;
 334         elf->e_ident[EI_OSABI] = ELF_OSABI;
 335         memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
 336         elf->e_type     = ET_CORE;
 337         elf->e_machine  = ELF_ARCH;
 338         elf->e_version  = EV_CURRENT;
 339         elf->e_entry    = 0;
 340         elf->e_phoff    = sizeof(struct elfhdr);
 341         elf->e_shoff    = 0;
 342         elf->e_flags    = ELF_CORE_EFLAGS;
 343         elf->e_ehsize   = sizeof(struct elfhdr);
 344         elf->e_phentsize= sizeof(struct elf_phdr);
 345         elf->e_phnum    = nphdr;
 346         elf->e_shentsize= 0;
 347         elf->e_shnum    = 0;
 348         elf->e_shstrndx = 0;
 349
 350         /* setup ELF PT_NOTE program header */
 351         nhdr = (struct elf_phdr *) bufp;
 352         bufp += sizeof(struct elf_phdr);
 353         offset += sizeof(struct elf_phdr);
 354         nhdr->p_type    = PT_NOTE;
 355         nhdr->p_offset  = 0;
 356         nhdr->p_vaddr   = 0;
 357         nhdr->p_paddr   = 0;
 358         nhdr->p_filesz  = 0;
 359         nhdr->p_memsz   = 0;
 360         nhdr->p_flags   = 0;
 361         nhdr->p_align   = 0;
 362
 363         /* setup ELF PT_LOAD program header for every area */
 364         list_for_each_entry(m, &kclist_head, list) {
 365                 phdr = (struct elf_phdr *) bufp;
 366                 bufp += sizeof(struct elf_phdr);
 367                 offset += sizeof(struct elf_phdr);
 368
 369                 phdr->p_type    = PT_LOAD;
 370                 phdr->p_flags   = PF_R|PF_W|PF_X;
 371                 phdr->p_offset  = kc_vaddr_to_offset(m->addr) + dataoff;
 372                 phdr->p_vaddr   = (size_t)m->addr;
 373                 phdr->p_paddr   = 0;
 374                 phdr->p_filesz  = phdr->p_memsz = m->size;
 375                 phdr->p_align   = PAGE_SIZE;
 376         }
 377
 378         /*
 379          * Set up the notes in similar form to SVR4 core dumps made
 380          * with info from their /proc.
 381          */
 382         nhdr->p_offset  = offset;
 383
 384         /* set up the process status */
 385         notes[0].name = CORE_STR;
 386         notes[0].type = NT_PRSTATUS;
 387         notes[0].datasz = sizeof(struct elf_prstatus);
 388         notes[0].data = &prstatus;
 389
 390         memset(&prstatus, 0, sizeof(struct elf_prstatus));
 391
 392         nhdr->p_filesz  = notesize(&notes[0]);
 393         bufp = storenote(&notes[0], bufp);
 394
 395         /* set up the process info */
 396         notes[1].name   = CORE_STR;
 397         notes[1].type   = NT_PRPSINFO;
 398         notes[1].datasz = sizeof(struct elf_prpsinfo);
 399         notes[1].data   = &prpsinfo;
 400
 401         memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
 402         prpsinfo.pr_state       = 0;
 403         prpsinfo.pr_sname       = 'R';
 404         prpsinfo.pr_zomb        = 0;
 405
 406         strcpy(prpsinfo.pr_fname, "vmlinux");
 407         strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ);
 408
 409         nhdr->p_filesz  += notesize(&notes[1]);
 410         bufp = storenote(&notes[1], bufp);
 411
 412         /* set up the task structure */
 413         notes[2].name   = CORE_STR;
 414         notes[2].type   = NT_TASKSTRUCT;
 415         notes[2].datasz = sizeof(struct task_struct);
 416         notes[2].data   = current;
 417
 418         nhdr->p_filesz  += notesize(&notes[2]);
 419         bufp = storenote(&notes[2], bufp);
 420
 421 } /* end elf_kcore_store_hdr() */
 422
 423 /*****************************************************************************/
 424 /*
 425  * read from the ELF header and then kernel memory
 426  */
 427 static ssize_t
 428 read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
 429 {
 430         ssize_t acc = 0;
 431         size_t size, tsz;
 432         size_t elf_buflen;
 433         int nphdr;
 434         unsigned long start;
 435
 436         read_lock(&kclist_lock);
 437         size = get_kcore_size(&nphdr, &elf_buflen);
 438
 439         if (buflen == 0 || *fpos >= size) {
 440                 read_unlock(&kclist_lock);
 441                 return 0;
 442         }
 443
 444         /* trim buflen to not go beyond EOF */
 445         if (buflen > size - *fpos)
 446                 buflen = size - *fpos;
 447
 448         /* construct an ELF core header if we'll need some of it */
 449         if (*fpos < elf_buflen) {
 450                 char * elf_buf;
 451
 452                 tsz = elf_buflen - *fpos;
 453                 if (buflen < tsz)
 454                         tsz = buflen;
 455                 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
 456                 if (!elf_buf) {
 457                         read_unlock(&kclist_lock);
 458                         return -ENOMEM;
 459                 }
 460                 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
 461                 read_unlock(&kclist_lock);
 462                 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
 463                         kfree(elf_buf);
 464                         return -EFAULT;
 465                 }
 466                 kfree(elf_buf);
 467                 buflen -= tsz;
 468                 *fpos += tsz;
 469                 buffer += tsz;
 470                 acc += tsz;
 471
 472                 /* leave now if filled buffer already */
 473                 if (buflen == 0)
 474                         return acc;
 475         } else
 476                 read_unlock(&kclist_lock);
 477
 478         /*
 479          * Check to see if our file offset matches with any of
 480          * the addresses in the elf_phdr on our list.
 481          */
 482         start = kc_offset_to_vaddr(*fpos - elf_buflen);
 483         if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
 484                 tsz = buflen;
 485
 486         while (buflen) {
 487                 struct kcore_list *m;
 488
 489                 read_lock(&kclist_lock);
 490                 list_for_each_entry(m, &kclist_head, list) {
 491                         if (start >= m->addr && start < (m->addr+m->size))
 492                                 break;
 493                 }
 494                 read_unlock(&kclist_lock);
 495
 496                 if (&m->list == &kclist_head) {
 497                         if (clear_user(buffer, tsz))
 498                                 return -EFAULT;
 499                 } else if (is_vmalloc_or_module_addr((void *)start)) {
 500                         char * elf_buf;
 501
 502                         elf_buf = kzalloc(tsz, GFP_KERNEL);
 503                         if (!elf_buf)
 504                                 return -ENOMEM;
 505                         vread(elf_buf, (char *)start, tsz);
 506                         /* we have to zero-fill user buffer even if no read */
 507                         if (copy_to_user(buffer, elf_buf, tsz)) {
 508                                 kfree(elf_buf);
 509                                 return -EFAULT;
 510                         }
 511                         kfree(elf_buf);
 512                 } else {
 513                         if (kern_addr_valid(start)) {
 514                                 unsigned long n;
 515
 516                                 n = copy_to_user(buffer, (char *)start, tsz);
 517                                 /*
 518                                  * We cannot distinguish between fault on source
 519                                  * and fault on destination. When this happens
 520                                  * we clear too and hope it will trigger the
 521                                  * EFAULT again.
 522                                  */
 523                                 if (n) {
 524                                         if (clear_user(buffer + tsz - n,
 525                                                                 n))
 526                                                 return -EFAULT;
 527                                 }
 528                         } else {
 529                                 if (clear_user(buffer, tsz))
 530                                         return -EFAULT;
 531                         }
 532                 }
 533                 buflen -= tsz;
 534                 *fpos += tsz;
 535                 buffer += tsz;
 536                 acc += tsz;
 537                 start += tsz;
 538                 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
 539         }
 540
 541         return acc;
 542 }
 543
 544
 545 static int open_kcore(struct inode *inode, struct file *filp)
 546 {
 547         if (!capable(CAP_SYS_RAWIO))
 548                 return -EPERM;
 549         if (kcore_need_update)
 550                 kcore_update_ram();
 551         if (i_size_read(inode) != proc_root_kcore->size) {
 552                 mutex_lock(&inode->i_mutex);
 553                 i_size_write(inode, proc_root_kcore->size);
 554                 mutex_unlock(&inode->i_mutex);
 555         }
 556         return 0;
 557 }
 558
 559
 560 static const struct file_operations proc_kcore_operations = {
 561         .read           = read_kcore,
 562         .open           = open_kcore,
 563         .llseek         = default_llseek,
 564 };
 565
 566 #ifdef CONFIG_MEMORY_HOTPLUG
 567 /* just remember that we have to update kcore */
 568 static int __meminit kcore_callback(struct notifier_block *self,
 569                                     unsigned long action, void *arg)
 570 {
 571         switch (action) {
 572         case MEM_ONLINE:
 573         case MEM_OFFLINE:
 574                 write_lock(&kclist_lock);
 575                 kcore_need_update = 1;
 576                 write_unlock(&kclist_lock);
 577         }
 578         return NOTIFY_OK;
 579 }
 580 #endif
 581
 582
 583 static struct kcore_list kcore_vmalloc;
 584
 585 #ifdef CONFIG_ARCH_PROC_KCORE_TEXT
 586 static struct kcore_list kcore_text;
 587 /*
 588  * If defined, special segment is used for mapping kernel text instead of
 589  * direct-map area. We need to create special TEXT section.
 590  */
 591 static void __init proc_kcore_text_init(void)
 592 {
 593         kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
 594 }
 595 #else
 596 static void __init proc_kcore_text_init(void)
 597 {
 598 }
 599 #endif
 600
 601 #if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
 602 /*
 603  * MODULES_VADDR has no intersection with VMALLOC_ADDR.
 604  */
 605 struct kcore_list kcore_modules;
 606 static void __init add_modules_range(void)
 607 {
 608         kclist_add(&kcore_modules, (void *)MODULES_VADDR,
 609                         MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
 610 }
 611 #else
 612 static void __init add_modules_range(void)
 613 {
 614 }
 615 #endif
 616
 617 static int __init proc_kcore_init(void)
 618 {
 619         proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
 620                                       &proc_kcore_operations);
 621         if (!proc_root_kcore) {
 622                 printk(KERN_ERR "couldn't create /proc/kcore\n");
 623                 return 0; /* Always returns 0. */
 624         }
 625         /* Store text area if it's special */
 626         proc_kcore_text_init();
 627         /* Store vmalloc area */
 628         kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
 629                 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
 630         add_modules_range();
 631         /* Store direct-map area from physical memory map */
 632         kcore_update_ram();
 633         hotplug_memory_notifier(kcore_callback, 0);
 634
 635         return 0;
 636 }
 637 module_init(proc_kcore_init);