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_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(¬es[0]); 393 bufp = storenote(¬es[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(¬es[1]); 410 bufp = storenote(¬es[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(¬es[2]); 419 bufp = storenote(¬es[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); 638