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 36static 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 */ 47struct memelfnote 48{ 49 const char *name; 50 int type; 51 unsigned int datasz; 52 void *data; 53}; 54 55static LIST_HEAD(kclist_head); 56static DEFINE_RWLOCK(kclist_lock); 57static int kcore_need_update = 1; 58 59void 60kclist_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 71static 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 96static 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 */ 108static 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 */ 139static 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 */ 160int get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head) 161{ 162 unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT; 163 unsigned long nr_pages = ent->size >> PAGE_SHIFT; 164 unsigned long start, end; 165 struct kcore_list *vmm, *tmp; 166 167 168 start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK; 169 end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1; 170 end = ALIGN(end, PAGE_SIZE); 171 /* overlap check (because we have to align page */ 172 list_for_each_entry(tmp, head, list) { 173 if (tmp->type != KCORE_VMEMMAP) 174 continue; 175 if (start < tmp->addr + tmp->size) 176 if (end > tmp->addr) 177 end = tmp->addr; 178 } 179 if (start < end) { 180 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL); 181 if (!vmm) 182 return 0; 183 vmm->addr = start; 184 vmm->size = end - start; 185 vmm->type = KCORE_VMEMMAP; 186 list_add_tail(&vmm->list, head); 187 } 188 return 1; 189 190} 191#else 192int get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head) 193{ 194 return 1; 195} 196 197#endif 198 199static int 200kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg) 201{ 202 struct list_head *head = (struct list_head *)arg; 203 struct kcore_list *ent; 204 205 ent = kmalloc(sizeof(*ent), GFP_KERNEL); 206 if (!ent) 207 return -ENOMEM; 208 ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT)); 209 ent->size = nr_pages << PAGE_SHIFT; 210 211 /* Sanity check: Can happen in 32bit arch...maybe */ 212 if (ent->addr < (unsigned long) __va(0)) 213 goto free_out; 214 215 /* cut not-mapped area. ....from ppc-32 code. */ 216 if (ULONG_MAX - ent->addr < ent->size) 217 ent->size = ULONG_MAX - ent->addr; 218 219 /* cut when vmalloc() area is higher than direct-map area */ 220 if (VMALLOC_START > (unsigned long)__va(0)) { 221 if (ent->addr > VMALLOC_START) 222 goto free_out; 223 if (VMALLOC_START - ent->addr < ent->size) 224 ent->size = VMALLOC_START - ent->addr; 225 } 226 227 ent->type = KCORE_RAM; 228 list_add_tail(&ent->list, head); 229 230 if (!get_sparsemem_vmemmap_info(ent, head)) { 231 list_del(&ent->list); 232 goto free_out; 233 } 234 235 return 0; 236free_out: 237 kfree(ent); 238 return 1; 239} 240 241static int kcore_update_ram(void) 242{ 243 int nid, ret; 244 unsigned long end_pfn; 245 LIST_HEAD(head); 246 247 /* Not inialized....update now */ 248 /* find out "max pfn" */ 249 end_pfn = 0; 250 for_each_node_state(nid, N_HIGH_MEMORY) { 251 unsigned long node_end; 252 node_end = NODE_DATA(nid)->node_start_pfn + 253 NODE_DATA(nid)->node_spanned_pages; 254 if (end_pfn < node_end) 255 end_pfn = node_end; 256 } 257 /* scan 0 to max_pfn */ 258 ret = walk_system_ram_range(0, end_pfn, &head, kclist_add_private); 259 if (ret) { 260 free_kclist_ents(&head); 261 return -ENOMEM; 262 } 263 __kcore_update_ram(&head); 264 return ret; 265} 266#endif /* CONFIG_HIGHMEM */ 267 268/*****************************************************************************/ 269/* 270 * determine size of ELF note 271 */ 272static int notesize(struct memelfnote *en) 273{ 274 int sz; 275 276 sz = sizeof(struct elf_note); 277 sz += roundup((strlen(en->name) + 1), 4); 278 sz += roundup(en->datasz, 4); 279 280 return sz; 281} /* end notesize() */ 282 283/*****************************************************************************/ 284/* 285 * store a note in the header buffer 286 */ 287static char *storenote(struct memelfnote *men, char *bufp) 288{ 289 struct elf_note en; 290 291#define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0) 292 293 en.n_namesz = strlen(men->name) + 1; 294 en.n_descsz = men->datasz; 295 en.n_type = men->type; 296 297 DUMP_WRITE(&en, sizeof(en)); 298 DUMP_WRITE(men->name, en.n_namesz); 299 300 /* XXX - cast from long long to long to avoid need for libgcc.a */ 301 bufp = (char*) roundup((unsigned long)bufp,4); 302 DUMP_WRITE(men->data, men->datasz); 303 bufp = (char*) roundup((unsigned long)bufp,4); 304 305#undef DUMP_WRITE 306 307 return bufp; 308} /* end storenote() */ 309 310/* 311 * store an ELF coredump header in the supplied buffer 312 * nphdr is the number of elf_phdr to insert 313 */ 314static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff) 315{ 316 struct elf_prstatus prstatus; /* NT_PRSTATUS */ 317 struct elf_prpsinfo prpsinfo; /* NT_PRPSINFO */ 318 struct elf_phdr *nhdr, *phdr; 319 struct elfhdr *elf; 320 struct memelfnote notes[3]; 321 off_t offset = 0; 322 struct kcore_list *m; 323 324 /* setup ELF header */ 325 elf = (struct elfhdr *) bufp; 326 bufp += sizeof(struct elfhdr); 327 offset += sizeof(struct elfhdr); 328 memcpy(elf->e_ident, ELFMAG, SELFMAG); 329 elf->e_ident[EI_CLASS] = ELF_CLASS; 330 elf->e_ident[EI_DATA] = ELF_DATA; 331 elf->e_ident[EI_VERSION]= EV_CURRENT; 332 elf->e_ident[EI_OSABI] = ELF_OSABI; 333 memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD); 334 elf->e_type = ET_CORE; 335 elf->e_machine = ELF_ARCH; 336 elf->e_version = EV_CURRENT; 337 elf->e_entry = 0; 338 elf->e_phoff = sizeof(struct elfhdr); 339 elf->e_shoff = 0; 340 elf->e_flags = ELF_CORE_EFLAGS; 341 elf->e_ehsize = sizeof(struct elfhdr); 342 elf->e_phentsize= sizeof(struct elf_phdr); 343 elf->e_phnum = nphdr; 344 elf->e_shentsize= 0; 345 elf->e_shnum = 0; 346 elf->e_shstrndx = 0; 347 348 /* setup ELF PT_NOTE program header */ 349 nhdr = (struct elf_phdr *) bufp; 350 bufp += sizeof(struct elf_phdr); 351 offset += sizeof(struct elf_phdr); 352 nhdr->p_type = PT_NOTE; 353 nhdr->p_offset = 0; 354 nhdr->p_vaddr = 0; 355 nhdr->p_paddr = 0; 356 nhdr->p_filesz = 0; 357 nhdr->p_memsz = 0; 358 nhdr->p_flags = 0; 359 nhdr->p_align = 0; 360 361 /* setup ELF PT_LOAD program header for every area */ 362 list_for_each_entry(m, &kclist_head, list) { 363 phdr = (struct elf_phdr *) bufp; 364 bufp += sizeof(struct elf_phdr); 365 offset += sizeof(struct elf_phdr); 366 367 phdr->p_type = PT_LOAD; 368 phdr->p_flags = PF_R|PF_W|PF_X; 369 phdr->p_offset = kc_vaddr_to_offset(m->addr) + dataoff; 370 phdr->p_vaddr = (size_t)m->addr; 371 phdr->p_paddr = 0; 372 phdr->p_filesz = phdr->p_memsz = m->size; 373 phdr->p_align = PAGE_SIZE; 374 } 375 376 /* 377 * Set up the notes in similar form to SVR4 core dumps made 378 * with info from their /proc. 379 */ 380 nhdr->p_offset = offset; 381 382 /* set up the process status */ 383 notes[0].name = CORE_STR; 384 notes[0].type = NT_PRSTATUS; 385 notes[0].datasz = sizeof(struct elf_prstatus); 386 notes[0].data = &prstatus; 387 388 memset(&prstatus, 0, sizeof(struct elf_prstatus)); 389 390 nhdr->p_filesz = notesize(¬es[0]); 391 bufp = storenote(¬es[0], bufp); 392 393 /* set up the process info */ 394 notes[1].name = CORE_STR; 395 notes[1].type = NT_PRPSINFO; 396 notes[1].datasz = sizeof(struct elf_prpsinfo); 397 notes[1].data = &prpsinfo; 398 399 memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo)); 400 prpsinfo.pr_state = 0; 401 prpsinfo.pr_sname = 'R'; 402 prpsinfo.pr_zomb = 0; 403 404 strcpy(prpsinfo.pr_fname, "vmlinux"); 405 strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ); 406 407 nhdr->p_filesz += notesize(¬es[1]); 408 bufp = storenote(¬es[1], bufp); 409 410 /* set up the task structure */ 411 notes[2].name = CORE_STR; 412 notes[2].type = NT_TASKSTRUCT; 413 notes[2].datasz = sizeof(struct task_struct); 414 notes[2].data = current; 415 416 nhdr->p_filesz += notesize(¬es[2]); 417 bufp = storenote(¬es[2], bufp); 418 419} /* end elf_kcore_store_hdr() */ 420 421/*****************************************************************************/ 422/* 423 * read from the ELF header and then kernel memory 424 */ 425static ssize_t 426read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) 427{ 428 ssize_t acc = 0; 429 size_t size, tsz; 430 size_t elf_buflen; 431 int nphdr; 432 unsigned long start; 433 434 read_lock(&kclist_lock); 435 size = get_kcore_size(&nphdr, &elf_buflen); 436 437 if (buflen == 0 || *fpos >= size) { 438 read_unlock(&kclist_lock); 439 return 0; 440 } 441 442 /* trim buflen to not go beyond EOF */ 443 if (buflen > size - *fpos) 444 buflen = size - *fpos; 445 446 /* construct an ELF core header if we'll need some of it */ 447 if (*fpos < elf_buflen) { 448 char * elf_buf; 449 450 tsz = elf_buflen - *fpos; 451 if (buflen < tsz) 452 tsz = buflen; 453 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC); 454 if (!elf_buf) { 455 read_unlock(&kclist_lock); 456 return -ENOMEM; 457 } 458 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen); 459 read_unlock(&kclist_lock); 460 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) { 461 kfree(elf_buf); 462 return -EFAULT; 463 } 464 kfree(elf_buf); 465 buflen -= tsz; 466 *fpos += tsz; 467 buffer += tsz; 468 acc += tsz; 469 470 /* leave now if filled buffer already */ 471 if (buflen == 0) 472 return acc; 473 } else 474 read_unlock(&kclist_lock); 475 476 /* 477 * Check to see if our file offset matches with any of 478 * the addresses in the elf_phdr on our list. 479 */ 480 start = kc_offset_to_vaddr(*fpos - elf_buflen); 481 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) 482 tsz = buflen; 483 484 while (buflen) { 485 struct kcore_list *m; 486 487 read_lock(&kclist_lock); 488 list_for_each_entry(m, &kclist_head, list) { 489 if (start >= m->addr && start < (m->addr+m->size)) 490 break; 491 } 492 read_unlock(&kclist_lock); 493 494 if (&m->list == &kclist_head) { 495 if (clear_user(buffer, tsz)) 496 return -EFAULT; 497 } else if (is_vmalloc_or_module_addr((void *)start)) { 498 char * elf_buf; 499 500 elf_buf = kzalloc(tsz, GFP_KERNEL); 501 if (!elf_buf) 502 return -ENOMEM; 503 vread(elf_buf, (char *)start, tsz); 504 /* we have to zero-fill user buffer even if no read */ 505 if (copy_to_user(buffer, elf_buf, tsz)) { 506 kfree(elf_buf); 507 return -EFAULT; 508 } 509 kfree(elf_buf); 510 } else { 511 if (kern_addr_valid(start)) { 512 unsigned long n; 513 514 n = copy_to_user(buffer, (char *)start, tsz); 515 /* 516 * We cannot distingush between fault on source 517 * and fault on destination. When this happens 518 * we clear too and hope it will trigger the 519 * EFAULT again. 520 */ 521 if (n) { 522 if (clear_user(buffer + tsz - n, 523 n)) 524 return -EFAULT; 525 } 526 } else { 527 if (clear_user(buffer, tsz)) 528 return -EFAULT; 529 } 530 } 531 buflen -= tsz; 532 *fpos += tsz; 533 buffer += tsz; 534 acc += tsz; 535 start += tsz; 536 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); 537 } 538 539 return acc; 540} 541 542 543static int open_kcore(struct inode *inode, struct file *filp) 544{ 545 if (!capable(CAP_SYS_RAWIO)) 546 return -EPERM; 547 if (kcore_need_update) 548 kcore_update_ram(); 549 if (i_size_read(inode) != proc_root_kcore->size) { 550 mutex_lock(&inode->i_mutex); 551 i_size_write(inode, proc_root_kcore->size); 552 mutex_unlock(&inode->i_mutex); 553 } 554 return 0; 555} 556 557 558static const struct file_operations proc_kcore_operations = { 559 .read = read_kcore, 560 .open = open_kcore, 561 .llseek = default_llseek, 562}; 563 564#ifdef CONFIG_MEMORY_HOTPLUG 565/* just remember that we have to update kcore */ 566static int __meminit kcore_callback(struct notifier_block *self, 567 unsigned long action, void *arg) 568{ 569 switch (action) { 570 case MEM_ONLINE: 571 case MEM_OFFLINE: 572 write_lock(&kclist_lock); 573 kcore_need_update = 1; 574 write_unlock(&kclist_lock); 575 } 576 return NOTIFY_OK; 577} 578#endif 579 580 581static struct kcore_list kcore_vmalloc; 582 583#ifdef CONFIG_ARCH_PROC_KCORE_TEXT 584static struct kcore_list kcore_text; 585/* 586 * If defined, special segment is used for mapping kernel text instead of 587 * direct-map area. We need to create special TEXT section. 588 */ 589static void __init proc_kcore_text_init(void) 590{ 591 kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT); 592} 593#else 594static void __init proc_kcore_text_init(void) 595{ 596} 597#endif 598 599#if defined(CONFIG_MODULES) && defined(MODULES_VADDR) 600/* 601 * MODULES_VADDR has no intersection with VMALLOC_ADDR. 602 */ 603struct kcore_list kcore_modules; 604static void __init add_modules_range(void) 605{ 606 kclist_add(&kcore_modules, (void *)MODULES_VADDR, 607 MODULES_END - MODULES_VADDR, KCORE_VMALLOC); 608} 609#else 610static void __init add_modules_range(void) 611{ 612} 613#endif 614 615static int __init proc_kcore_init(void) 616{ 617 proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, 618 &proc_kcore_operations); 619 if (!proc_root_kcore) { 620 printk(KERN_ERR "couldn't create /proc/kcore\n"); 621 return 0; /* Always returns 0. */ 622 } 623 /* Store text area if it's special */ 624 proc_kcore_text_init(); 625 /* Store vmalloc area */ 626 kclist_add(&kcore_vmalloc, (void *)VMALLOC_START, 627 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC); 628 add_modules_range(); 629 /* Store direct-map area from physical memory map */ 630 kcore_update_ram(); 631 hotplug_memory_notifier(kcore_callback, 0); 632 633 return 0; 634} 635module_init(proc_kcore_init); 636