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
11 #include <linux/proc_fs.h>
12 #include <linux/user.h>
13 #include <linux/elf.h>
14 #include <linux/elfcore.h>
15 #include <linux/highmem.h>
16 #include <linux/bootmem.h>
17 #include <linux/init.h>
18 #include <linux/crash_dump.h>
19 #include <linux/list.h>
20 #include <asm/uaccess.h>
23 /* List representing chunks of contiguous memory areas and their offsets in
26 static LIST_HEAD(vmcore_list);
28 /* Stores the pointer to the buffer containing kernel elf core headers. */
29 static char *elfcorebuf;
30 static size_t elfcorebuf_sz;
32 /* Total size of vmcore file. */
33 static u64 vmcore_size;
35 static struct proc_dir_entry *proc_vmcore = NULL;
37 /* Reads a page from the oldmem device from given offset. */
38 static ssize_t read_from_oldmem(char *buf, size_t count,
39 u64 *ppos, int userbuf)
41 unsigned long pfn, offset;
43 ssize_t read = 0, tmp;
48 offset = (unsigned long)(*ppos % PAGE_SIZE);
49 pfn = (unsigned long)(*ppos / PAGE_SIZE);
52 if (count > (PAGE_SIZE - offset))
53 nr_bytes = PAGE_SIZE - offset;
57 tmp = copy_oldmem_page(pfn, buf, nr_bytes, offset, userbuf);
71 /* Maps vmcore file offset to respective physical address in memroy. */
72 static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list,
73 struct vmcore **m_ptr)
78 list_for_each_entry(m, vc_list, list) {
81 end = m->offset + m->size - 1;
82 if (offset >= start && offset <= end) {
83 paddr = m->paddr + offset - start;
92 /* Read from the ELF header and then the crash dump. On error, negative value is
93 * returned otherwise number of bytes read are returned.
95 static ssize_t read_vmcore(struct file *file, char __user *buffer,
96 size_t buflen, loff_t *fpos)
101 struct vmcore *curr_m = NULL;
103 if (buflen == 0 || *fpos >= vmcore_size)
106 /* trim buflen to not go beyond EOF */
107 if (buflen > vmcore_size - *fpos)
108 buflen = vmcore_size - *fpos;
110 /* Read ELF core header */
111 if (*fpos < elfcorebuf_sz) {
112 tsz = elfcorebuf_sz - *fpos;
115 if (copy_to_user(buffer, elfcorebuf + *fpos, tsz))
122 /* leave now if filled buffer already */
127 start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
130 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
133 /* Calculate left bytes in current memory segment. */
134 nr_bytes = (curr_m->size - (start - curr_m->paddr));
139 tmp = read_from_oldmem(buffer, tsz, &start, 1);
146 if (start >= (curr_m->paddr + curr_m->size)) {
147 if (curr_m->list.next == &vmcore_list)
149 curr_m = list_entry(curr_m->list.next,
150 struct vmcore, list);
151 start = curr_m->paddr;
153 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
155 /* Calculate left bytes in current memory segment. */
156 nr_bytes = (curr_m->size - (start - curr_m->paddr));
163 static const struct file_operations proc_vmcore_operations = {
167 static struct vmcore* __init get_new_element(void)
171 p = kmalloc(sizeof(*p), GFP_KERNEL);
173 memset(p, 0, sizeof(*p));
177 static u64 __init get_vmcore_size_elf64(char *elfptr)
181 Elf64_Ehdr *ehdr_ptr;
182 Elf64_Phdr *phdr_ptr;
184 ehdr_ptr = (Elf64_Ehdr *)elfptr;
185 phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
186 size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
187 for (i = 0; i < ehdr_ptr->e_phnum; i++) {
188 size += phdr_ptr->p_memsz;
194 static u64 __init get_vmcore_size_elf32(char *elfptr)
198 Elf32_Ehdr *ehdr_ptr;
199 Elf32_Phdr *phdr_ptr;
201 ehdr_ptr = (Elf32_Ehdr *)elfptr;
202 phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
203 size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
204 for (i = 0; i < ehdr_ptr->e_phnum; i++) {
205 size += phdr_ptr->p_memsz;
211 /* Merges all the PT_NOTE headers into one. */
212 static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
213 struct list_head *vc_list)
215 int i, nr_ptnote=0, rc=0;
217 Elf64_Ehdr *ehdr_ptr;
218 Elf64_Phdr phdr, *phdr_ptr;
219 Elf64_Nhdr *nhdr_ptr;
220 u64 phdr_sz = 0, note_off;
222 ehdr_ptr = (Elf64_Ehdr *)elfptr;
223 phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
224 for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
228 u64 offset, max_sz, sz, real_sz = 0;
229 if (phdr_ptr->p_type != PT_NOTE)
232 max_sz = phdr_ptr->p_memsz;
233 offset = phdr_ptr->p_offset;
234 notes_section = kmalloc(max_sz, GFP_KERNEL);
237 rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
239 kfree(notes_section);
242 nhdr_ptr = notes_section;
243 for (j = 0; j < max_sz; j += sz) {
244 if (nhdr_ptr->n_namesz == 0)
246 sz = sizeof(Elf64_Nhdr) +
247 ((nhdr_ptr->n_namesz + 3) & ~3) +
248 ((nhdr_ptr->n_descsz + 3) & ~3);
250 nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
253 /* Add this contiguous chunk of notes section to vmcore list.*/
254 new = get_new_element();
256 kfree(notes_section);
259 new->paddr = phdr_ptr->p_offset;
261 list_add_tail(&new->list, vc_list);
263 kfree(notes_section);
266 /* Prepare merged PT_NOTE program header. */
267 phdr.p_type = PT_NOTE;
269 note_off = sizeof(Elf64_Ehdr) +
270 (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
271 phdr.p_offset = note_off;
272 phdr.p_vaddr = phdr.p_paddr = 0;
273 phdr.p_filesz = phdr.p_memsz = phdr_sz;
276 /* Add merged PT_NOTE program header*/
277 tmp = elfptr + sizeof(Elf64_Ehdr);
278 memcpy(tmp, &phdr, sizeof(phdr));
281 /* Remove unwanted PT_NOTE program headers. */
282 i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
284 memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
286 /* Modify e_phnum to reflect merged headers. */
287 ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
292 /* Merges all the PT_NOTE headers into one. */
293 static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
294 struct list_head *vc_list)
296 int i, nr_ptnote=0, rc=0;
298 Elf32_Ehdr *ehdr_ptr;
299 Elf32_Phdr phdr, *phdr_ptr;
300 Elf32_Nhdr *nhdr_ptr;
301 u64 phdr_sz = 0, note_off;
303 ehdr_ptr = (Elf32_Ehdr *)elfptr;
304 phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
305 for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
309 u64 offset, max_sz, sz, real_sz = 0;
310 if (phdr_ptr->p_type != PT_NOTE)
313 max_sz = phdr_ptr->p_memsz;
314 offset = phdr_ptr->p_offset;
315 notes_section = kmalloc(max_sz, GFP_KERNEL);
318 rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
320 kfree(notes_section);
323 nhdr_ptr = notes_section;
324 for (j = 0; j < max_sz; j += sz) {
325 if (nhdr_ptr->n_namesz == 0)
327 sz = sizeof(Elf32_Nhdr) +
328 ((nhdr_ptr->n_namesz + 3) & ~3) +
329 ((nhdr_ptr->n_descsz + 3) & ~3);
331 nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
334 /* Add this contiguous chunk of notes section to vmcore list.*/
335 new = get_new_element();
337 kfree(notes_section);
340 new->paddr = phdr_ptr->p_offset;
342 list_add_tail(&new->list, vc_list);
344 kfree(notes_section);
347 /* Prepare merged PT_NOTE program header. */
348 phdr.p_type = PT_NOTE;
350 note_off = sizeof(Elf32_Ehdr) +
351 (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
352 phdr.p_offset = note_off;
353 phdr.p_vaddr = phdr.p_paddr = 0;
354 phdr.p_filesz = phdr.p_memsz = phdr_sz;
357 /* Add merged PT_NOTE program header*/
358 tmp = elfptr + sizeof(Elf32_Ehdr);
359 memcpy(tmp, &phdr, sizeof(phdr));
362 /* Remove unwanted PT_NOTE program headers. */
363 i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
365 memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
367 /* Modify e_phnum to reflect merged headers. */
368 ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
373 /* Add memory chunks represented by program headers to vmcore list. Also update
374 * the new offset fields of exported program headers. */
375 static int __init process_ptload_program_headers_elf64(char *elfptr,
377 struct list_head *vc_list)
380 Elf64_Ehdr *ehdr_ptr;
381 Elf64_Phdr *phdr_ptr;
385 ehdr_ptr = (Elf64_Ehdr *)elfptr;
386 phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
388 /* First program header is PT_NOTE header. */
389 vmcore_off = sizeof(Elf64_Ehdr) +
390 (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) +
391 phdr_ptr->p_memsz; /* Note sections */
393 for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
394 if (phdr_ptr->p_type != PT_LOAD)
397 /* Add this contiguous chunk of memory to vmcore list.*/
398 new = get_new_element();
401 new->paddr = phdr_ptr->p_offset;
402 new->size = phdr_ptr->p_memsz;
403 list_add_tail(&new->list, vc_list);
405 /* Update the program header offset. */
406 phdr_ptr->p_offset = vmcore_off;
407 vmcore_off = vmcore_off + phdr_ptr->p_memsz;
412 static int __init process_ptload_program_headers_elf32(char *elfptr,
414 struct list_head *vc_list)
417 Elf32_Ehdr *ehdr_ptr;
418 Elf32_Phdr *phdr_ptr;
422 ehdr_ptr = (Elf32_Ehdr *)elfptr;
423 phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
425 /* First program header is PT_NOTE header. */
426 vmcore_off = sizeof(Elf32_Ehdr) +
427 (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) +
428 phdr_ptr->p_memsz; /* Note sections */
430 for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
431 if (phdr_ptr->p_type != PT_LOAD)
434 /* Add this contiguous chunk of memory to vmcore list.*/
435 new = get_new_element();
438 new->paddr = phdr_ptr->p_offset;
439 new->size = phdr_ptr->p_memsz;
440 list_add_tail(&new->list, vc_list);
442 /* Update the program header offset */
443 phdr_ptr->p_offset = vmcore_off;
444 vmcore_off = vmcore_off + phdr_ptr->p_memsz;
449 /* Sets offset fields of vmcore elements. */
450 static void __init set_vmcore_list_offsets_elf64(char *elfptr,
451 struct list_head *vc_list)
454 Elf64_Ehdr *ehdr_ptr;
457 ehdr_ptr = (Elf64_Ehdr *)elfptr;
459 /* Skip Elf header and program headers. */
460 vmcore_off = sizeof(Elf64_Ehdr) +
461 (ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);
463 list_for_each_entry(m, vc_list, list) {
464 m->offset = vmcore_off;
465 vmcore_off += m->size;
469 /* Sets offset fields of vmcore elements. */
470 static void __init set_vmcore_list_offsets_elf32(char *elfptr,
471 struct list_head *vc_list)
474 Elf32_Ehdr *ehdr_ptr;
477 ehdr_ptr = (Elf32_Ehdr *)elfptr;
479 /* Skip Elf header and program headers. */
480 vmcore_off = sizeof(Elf32_Ehdr) +
481 (ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);
483 list_for_each_entry(m, vc_list, list) {
484 m->offset = vmcore_off;
485 vmcore_off += m->size;
489 static int __init parse_crash_elf64_headers(void)
495 addr = elfcorehdr_addr;
497 /* Read Elf header */
498 rc = read_from_oldmem((char*)&ehdr, sizeof(Elf64_Ehdr), &addr, 0);
502 /* Do some basic Verification. */
503 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
504 (ehdr.e_type != ET_CORE) ||
505 !vmcore_elf_check_arch(&ehdr) ||
506 ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
507 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
508 ehdr.e_version != EV_CURRENT ||
509 ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
510 ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
512 printk(KERN_WARNING "Warning: Core image elf header is not"
517 /* Read in all elf headers. */
518 elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr);
519 elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
522 addr = elfcorehdr_addr;
523 rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
529 /* Merge all PT_NOTE headers into one. */
530 rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
535 rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
541 set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
545 static int __init parse_crash_elf32_headers(void)
551 addr = elfcorehdr_addr;
553 /* Read Elf header */
554 rc = read_from_oldmem((char*)&ehdr, sizeof(Elf32_Ehdr), &addr, 0);
558 /* Do some basic Verification. */
559 if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
560 (ehdr.e_type != ET_CORE) ||
561 !elf_check_arch(&ehdr) ||
562 ehdr.e_ident[EI_CLASS] != ELFCLASS32||
563 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
564 ehdr.e_version != EV_CURRENT ||
565 ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
566 ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
568 printk(KERN_WARNING "Warning: Core image elf header is not"
573 /* Read in all elf headers. */
574 elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
575 elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
578 addr = elfcorehdr_addr;
579 rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
585 /* Merge all PT_NOTE headers into one. */
586 rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
591 rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
597 set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
601 static int __init parse_crash_elf_headers(void)
603 unsigned char e_ident[EI_NIDENT];
607 addr = elfcorehdr_addr;
608 rc = read_from_oldmem(e_ident, EI_NIDENT, &addr, 0);
611 if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
612 printk(KERN_WARNING "Warning: Core image elf header"
617 if (e_ident[EI_CLASS] == ELFCLASS64) {
618 rc = parse_crash_elf64_headers();
622 /* Determine vmcore size. */
623 vmcore_size = get_vmcore_size_elf64(elfcorebuf);
624 } else if (e_ident[EI_CLASS] == ELFCLASS32) {
625 rc = parse_crash_elf32_headers();
629 /* Determine vmcore size. */
630 vmcore_size = get_vmcore_size_elf32(elfcorebuf);
632 printk(KERN_WARNING "Warning: Core image elf header is not"
639 /* Init function for vmcore module. */
640 static int __init vmcore_init(void)
644 /* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
645 if (!(is_vmcore_usable()))
647 rc = parse_crash_elf_headers();
649 printk(KERN_WARNING "Kdump: vmcore not initialized\n");
653 proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
655 proc_vmcore->size = vmcore_size;
658 module_init(vmcore_init)