1 /*
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
7  *
8  */
9 
10 #include <linux/mm.h>
11 #include <linux/proc_fs.h>
12 #include <linux/user.h>
13 #include <linux/elf.h>
14 #include <linux/elfcore.h>
15 #include <linux/export.h>
16 #include <linux/slab.h>
17 #include <linux/highmem.h>
18 #include <linux/bootmem.h>
19 #include <linux/init.h>
20 #include <linux/crash_dump.h>
21 #include <linux/list.h>
22 #include <asm/uaccess.h>
23 #include <asm/io.h>
24 
25 /* List representing chunks of contiguous memory areas and their offsets in
26  * vmcore file.
27  */
28 static LIST_HEAD(vmcore_list);
29 
30 /* Stores the pointer to the buffer containing kernel elf core headers. */
31 static char *elfcorebuf;
32 static size_t elfcorebuf_sz;
33 
34 /* Total size of vmcore file. */
35 static u64 vmcore_size;
36 
37 static struct proc_dir_entry *proc_vmcore = NULL;
38 
39 /*
40  * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
41  * The called function has to take care of module refcounting.
42  */
43 static int (*oldmem_pfn_is_ram)(unsigned long pfn);
44 
register_oldmem_pfn_is_ram(int (* fn)(unsigned long pfn))45 int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn))
46 {
47 	if (oldmem_pfn_is_ram)
48 		return -EBUSY;
49 	oldmem_pfn_is_ram = fn;
50 	return 0;
51 }
52 EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram);
53 
unregister_oldmem_pfn_is_ram(void)54 void unregister_oldmem_pfn_is_ram(void)
55 {
56 	oldmem_pfn_is_ram = NULL;
57 	wmb();
58 }
59 EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram);
60 
pfn_is_ram(unsigned long pfn)61 static int pfn_is_ram(unsigned long pfn)
62 {
63 	int (*fn)(unsigned long pfn);
64 	/* pfn is ram unless fn() checks pagetype */
65 	int ret = 1;
66 
67 	/*
68 	 * Ask hypervisor if the pfn is really ram.
69 	 * A ballooned page contains no data and reading from such a page
70 	 * will cause high load in the hypervisor.
71 	 */
72 	fn = oldmem_pfn_is_ram;
73 	if (fn)
74 		ret = fn(pfn);
75 
76 	return ret;
77 }
78 
79 /* Reads a page from the oldmem device from given offset. */
read_from_oldmem(char * buf,size_t count,u64 * ppos,int userbuf)80 static ssize_t read_from_oldmem(char *buf, size_t count,
81 				u64 *ppos, int userbuf)
82 {
83 	unsigned long pfn, offset;
84 	size_t nr_bytes;
85 	ssize_t read = 0, tmp;
86 
87 	if (!count)
88 		return 0;
89 
90 	offset = (unsigned long)(*ppos % PAGE_SIZE);
91 	pfn = (unsigned long)(*ppos / PAGE_SIZE);
92 
93 	do {
94 		if (count > (PAGE_SIZE - offset))
95 			nr_bytes = PAGE_SIZE - offset;
96 		else
97 			nr_bytes = count;
98 
99 		/* If pfn is not ram, return zeros for sparse dump files */
100 		if (pfn_is_ram(pfn) == 0)
101 			memset(buf, 0, nr_bytes);
102 		else {
103 			tmp = copy_oldmem_page(pfn, buf, nr_bytes,
104 						offset, userbuf);
105 			if (tmp < 0)
106 				return tmp;
107 		}
108 		*ppos += nr_bytes;
109 		count -= nr_bytes;
110 		buf += nr_bytes;
111 		read += nr_bytes;
112 		++pfn;
113 		offset = 0;
114 	} while (count);
115 
116 	return read;
117 }
118 
119 /* Maps vmcore file offset to respective physical address in memroy. */
map_offset_to_paddr(loff_t offset,struct list_head * vc_list,struct vmcore ** m_ptr)120 static u64 map_offset_to_paddr(loff_t offset, struct list_head *vc_list,
121 					struct vmcore **m_ptr)
122 {
123 	struct vmcore *m;
124 	u64 paddr;
125 
126 	list_for_each_entry(m, vc_list, list) {
127 		u64 start, end;
128 		start = m->offset;
129 		end = m->offset + m->size - 1;
130 		if (offset >= start && offset <= end) {
131 			paddr = m->paddr + offset - start;
132 			*m_ptr = m;
133 			return paddr;
134 		}
135 	}
136 	*m_ptr = NULL;
137 	return 0;
138 }
139 
140 /* Read from the ELF header and then the crash dump. On error, negative value is
141  * returned otherwise number of bytes read are returned.
142  */
read_vmcore(struct file * file,char __user * buffer,size_t buflen,loff_t * fpos)143 static ssize_t read_vmcore(struct file *file, char __user *buffer,
144 				size_t buflen, loff_t *fpos)
145 {
146 	ssize_t acc = 0, tmp;
147 	size_t tsz;
148 	u64 start, nr_bytes;
149 	struct vmcore *curr_m = NULL;
150 
151 	if (buflen == 0 || *fpos >= vmcore_size)
152 		return 0;
153 
154 	/* trim buflen to not go beyond EOF */
155 	if (buflen > vmcore_size - *fpos)
156 		buflen = vmcore_size - *fpos;
157 
158 	/* Read ELF core header */
159 	if (*fpos < elfcorebuf_sz) {
160 		tsz = elfcorebuf_sz - *fpos;
161 		if (buflen < tsz)
162 			tsz = buflen;
163 		if (copy_to_user(buffer, elfcorebuf + *fpos, tsz))
164 			return -EFAULT;
165 		buflen -= tsz;
166 		*fpos += tsz;
167 		buffer += tsz;
168 		acc += tsz;
169 
170 		/* leave now if filled buffer already */
171 		if (buflen == 0)
172 			return acc;
173 	}
174 
175 	start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
176 	if (!curr_m)
177         	return -EINVAL;
178 	if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
179 		tsz = buflen;
180 
181 	/* Calculate left bytes in current memory segment. */
182 	nr_bytes = (curr_m->size - (start - curr_m->paddr));
183 	if (tsz > nr_bytes)
184 		tsz = nr_bytes;
185 
186 	while (buflen) {
187 		tmp = read_from_oldmem(buffer, tsz, &start, 1);
188 		if (tmp < 0)
189 			return tmp;
190 		buflen -= tsz;
191 		*fpos += tsz;
192 		buffer += tsz;
193 		acc += tsz;
194 		if (start >= (curr_m->paddr + curr_m->size)) {
195 			if (curr_m->list.next == &vmcore_list)
196 				return acc;	/*EOF*/
197 			curr_m = list_entry(curr_m->list.next,
198 						struct vmcore, list);
199 			start = curr_m->paddr;
200 		}
201 		if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
202 			tsz = buflen;
203 		/* Calculate left bytes in current memory segment. */
204 		nr_bytes = (curr_m->size - (start - curr_m->paddr));
205 		if (tsz > nr_bytes)
206 			tsz = nr_bytes;
207 	}
208 	return acc;
209 }
210 
211 static const struct file_operations proc_vmcore_operations = {
212 	.read		= read_vmcore,
213 	.llseek		= default_llseek,
214 };
215 
get_new_element(void)216 static struct vmcore* __init get_new_element(void)
217 {
218 	return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
219 }
220 
get_vmcore_size_elf64(char * elfptr)221 static u64 __init get_vmcore_size_elf64(char *elfptr)
222 {
223 	int i;
224 	u64 size;
225 	Elf64_Ehdr *ehdr_ptr;
226 	Elf64_Phdr *phdr_ptr;
227 
228 	ehdr_ptr = (Elf64_Ehdr *)elfptr;
229 	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
230 	size = sizeof(Elf64_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr));
231 	for (i = 0; i < ehdr_ptr->e_phnum; i++) {
232 		size += phdr_ptr->p_memsz;
233 		phdr_ptr++;
234 	}
235 	return size;
236 }
237 
get_vmcore_size_elf32(char * elfptr)238 static u64 __init get_vmcore_size_elf32(char *elfptr)
239 {
240 	int i;
241 	u64 size;
242 	Elf32_Ehdr *ehdr_ptr;
243 	Elf32_Phdr *phdr_ptr;
244 
245 	ehdr_ptr = (Elf32_Ehdr *)elfptr;
246 	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
247 	size = sizeof(Elf32_Ehdr) + ((ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr));
248 	for (i = 0; i < ehdr_ptr->e_phnum; i++) {
249 		size += phdr_ptr->p_memsz;
250 		phdr_ptr++;
251 	}
252 	return size;
253 }
254 
255 /* Merges all the PT_NOTE headers into one. */
merge_note_headers_elf64(char * elfptr,size_t * elfsz,struct list_head * vc_list)256 static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
257 						struct list_head *vc_list)
258 {
259 	int i, nr_ptnote=0, rc=0;
260 	char *tmp;
261 	Elf64_Ehdr *ehdr_ptr;
262 	Elf64_Phdr phdr, *phdr_ptr;
263 	Elf64_Nhdr *nhdr_ptr;
264 	u64 phdr_sz = 0, note_off;
265 
266 	ehdr_ptr = (Elf64_Ehdr *)elfptr;
267 	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr));
268 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
269 		int j;
270 		void *notes_section;
271 		struct vmcore *new;
272 		u64 offset, max_sz, sz, real_sz = 0;
273 		if (phdr_ptr->p_type != PT_NOTE)
274 			continue;
275 		nr_ptnote++;
276 		max_sz = phdr_ptr->p_memsz;
277 		offset = phdr_ptr->p_offset;
278 		notes_section = kmalloc(max_sz, GFP_KERNEL);
279 		if (!notes_section)
280 			return -ENOMEM;
281 		rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
282 		if (rc < 0) {
283 			kfree(notes_section);
284 			return rc;
285 		}
286 		nhdr_ptr = notes_section;
287 		for (j = 0; j < max_sz; j += sz) {
288 			if (nhdr_ptr->n_namesz == 0)
289 				break;
290 			sz = sizeof(Elf64_Nhdr) +
291 				((nhdr_ptr->n_namesz + 3) & ~3) +
292 				((nhdr_ptr->n_descsz + 3) & ~3);
293 			real_sz += sz;
294 			nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
295 		}
296 
297 		/* Add this contiguous chunk of notes section to vmcore list.*/
298 		new = get_new_element();
299 		if (!new) {
300 			kfree(notes_section);
301 			return -ENOMEM;
302 		}
303 		new->paddr = phdr_ptr->p_offset;
304 		new->size = real_sz;
305 		list_add_tail(&new->list, vc_list);
306 		phdr_sz += real_sz;
307 		kfree(notes_section);
308 	}
309 
310 	/* Prepare merged PT_NOTE program header. */
311 	phdr.p_type    = PT_NOTE;
312 	phdr.p_flags   = 0;
313 	note_off = sizeof(Elf64_Ehdr) +
314 			(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
315 	phdr.p_offset  = note_off;
316 	phdr.p_vaddr   = phdr.p_paddr = 0;
317 	phdr.p_filesz  = phdr.p_memsz = phdr_sz;
318 	phdr.p_align   = 0;
319 
320 	/* Add merged PT_NOTE program header*/
321 	tmp = elfptr + sizeof(Elf64_Ehdr);
322 	memcpy(tmp, &phdr, sizeof(phdr));
323 	tmp += sizeof(phdr);
324 
325 	/* Remove unwanted PT_NOTE program headers. */
326 	i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
327 	*elfsz = *elfsz - i;
328 	memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
329 
330 	/* Modify e_phnum to reflect merged headers. */
331 	ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
332 
333 	return 0;
334 }
335 
336 /* Merges all the PT_NOTE headers into one. */
merge_note_headers_elf32(char * elfptr,size_t * elfsz,struct list_head * vc_list)337 static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
338 						struct list_head *vc_list)
339 {
340 	int i, nr_ptnote=0, rc=0;
341 	char *tmp;
342 	Elf32_Ehdr *ehdr_ptr;
343 	Elf32_Phdr phdr, *phdr_ptr;
344 	Elf32_Nhdr *nhdr_ptr;
345 	u64 phdr_sz = 0, note_off;
346 
347 	ehdr_ptr = (Elf32_Ehdr *)elfptr;
348 	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr));
349 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
350 		int j;
351 		void *notes_section;
352 		struct vmcore *new;
353 		u64 offset, max_sz, sz, real_sz = 0;
354 		if (phdr_ptr->p_type != PT_NOTE)
355 			continue;
356 		nr_ptnote++;
357 		max_sz = phdr_ptr->p_memsz;
358 		offset = phdr_ptr->p_offset;
359 		notes_section = kmalloc(max_sz, GFP_KERNEL);
360 		if (!notes_section)
361 			return -ENOMEM;
362 		rc = read_from_oldmem(notes_section, max_sz, &offset, 0);
363 		if (rc < 0) {
364 			kfree(notes_section);
365 			return rc;
366 		}
367 		nhdr_ptr = notes_section;
368 		for (j = 0; j < max_sz; j += sz) {
369 			if (nhdr_ptr->n_namesz == 0)
370 				break;
371 			sz = sizeof(Elf32_Nhdr) +
372 				((nhdr_ptr->n_namesz + 3) & ~3) +
373 				((nhdr_ptr->n_descsz + 3) & ~3);
374 			real_sz += sz;
375 			nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
376 		}
377 
378 		/* Add this contiguous chunk of notes section to vmcore list.*/
379 		new = get_new_element();
380 		if (!new) {
381 			kfree(notes_section);
382 			return -ENOMEM;
383 		}
384 		new->paddr = phdr_ptr->p_offset;
385 		new->size = real_sz;
386 		list_add_tail(&new->list, vc_list);
387 		phdr_sz += real_sz;
388 		kfree(notes_section);
389 	}
390 
391 	/* Prepare merged PT_NOTE program header. */
392 	phdr.p_type    = PT_NOTE;
393 	phdr.p_flags   = 0;
394 	note_off = sizeof(Elf32_Ehdr) +
395 			(ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
396 	phdr.p_offset  = note_off;
397 	phdr.p_vaddr   = phdr.p_paddr = 0;
398 	phdr.p_filesz  = phdr.p_memsz = phdr_sz;
399 	phdr.p_align   = 0;
400 
401 	/* Add merged PT_NOTE program header*/
402 	tmp = elfptr + sizeof(Elf32_Ehdr);
403 	memcpy(tmp, &phdr, sizeof(phdr));
404 	tmp += sizeof(phdr);
405 
406 	/* Remove unwanted PT_NOTE program headers. */
407 	i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
408 	*elfsz = *elfsz - i;
409 	memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
410 
411 	/* Modify e_phnum to reflect merged headers. */
412 	ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
413 
414 	return 0;
415 }
416 
417 /* Add memory chunks represented by program headers to vmcore list. Also update
418  * the new offset fields of exported program headers. */
process_ptload_program_headers_elf64(char * elfptr,size_t elfsz,struct list_head * vc_list)419 static int __init process_ptload_program_headers_elf64(char *elfptr,
420 						size_t elfsz,
421 						struct list_head *vc_list)
422 {
423 	int i;
424 	Elf64_Ehdr *ehdr_ptr;
425 	Elf64_Phdr *phdr_ptr;
426 	loff_t vmcore_off;
427 	struct vmcore *new;
428 
429 	ehdr_ptr = (Elf64_Ehdr *)elfptr;
430 	phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
431 
432 	/* First program header is PT_NOTE header. */
433 	vmcore_off = sizeof(Elf64_Ehdr) +
434 			(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr) +
435 			phdr_ptr->p_memsz; /* Note sections */
436 
437 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
438 		if (phdr_ptr->p_type != PT_LOAD)
439 			continue;
440 
441 		/* Add this contiguous chunk of memory to vmcore list.*/
442 		new = get_new_element();
443 		if (!new)
444 			return -ENOMEM;
445 		new->paddr = phdr_ptr->p_offset;
446 		new->size = phdr_ptr->p_memsz;
447 		list_add_tail(&new->list, vc_list);
448 
449 		/* Update the program header offset. */
450 		phdr_ptr->p_offset = vmcore_off;
451 		vmcore_off = vmcore_off + phdr_ptr->p_memsz;
452 	}
453 	return 0;
454 }
455 
process_ptload_program_headers_elf32(char * elfptr,size_t elfsz,struct list_head * vc_list)456 static int __init process_ptload_program_headers_elf32(char *elfptr,
457 						size_t elfsz,
458 						struct list_head *vc_list)
459 {
460 	int i;
461 	Elf32_Ehdr *ehdr_ptr;
462 	Elf32_Phdr *phdr_ptr;
463 	loff_t vmcore_off;
464 	struct vmcore *new;
465 
466 	ehdr_ptr = (Elf32_Ehdr *)elfptr;
467 	phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
468 
469 	/* First program header is PT_NOTE header. */
470 	vmcore_off = sizeof(Elf32_Ehdr) +
471 			(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr) +
472 			phdr_ptr->p_memsz; /* Note sections */
473 
474 	for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
475 		if (phdr_ptr->p_type != PT_LOAD)
476 			continue;
477 
478 		/* Add this contiguous chunk of memory to vmcore list.*/
479 		new = get_new_element();
480 		if (!new)
481 			return -ENOMEM;
482 		new->paddr = phdr_ptr->p_offset;
483 		new->size = phdr_ptr->p_memsz;
484 		list_add_tail(&new->list, vc_list);
485 
486 		/* Update the program header offset */
487 		phdr_ptr->p_offset = vmcore_off;
488 		vmcore_off = vmcore_off + phdr_ptr->p_memsz;
489 	}
490 	return 0;
491 }
492 
493 /* Sets offset fields of vmcore elements. */
set_vmcore_list_offsets_elf64(char * elfptr,struct list_head * vc_list)494 static void __init set_vmcore_list_offsets_elf64(char *elfptr,
495 						struct list_head *vc_list)
496 {
497 	loff_t vmcore_off;
498 	Elf64_Ehdr *ehdr_ptr;
499 	struct vmcore *m;
500 
501 	ehdr_ptr = (Elf64_Ehdr *)elfptr;
502 
503 	/* Skip Elf header and program headers. */
504 	vmcore_off = sizeof(Elf64_Ehdr) +
505 			(ehdr_ptr->e_phnum) * sizeof(Elf64_Phdr);
506 
507 	list_for_each_entry(m, vc_list, list) {
508 		m->offset = vmcore_off;
509 		vmcore_off += m->size;
510 	}
511 }
512 
513 /* Sets offset fields of vmcore elements. */
set_vmcore_list_offsets_elf32(char * elfptr,struct list_head * vc_list)514 static void __init set_vmcore_list_offsets_elf32(char *elfptr,
515 						struct list_head *vc_list)
516 {
517 	loff_t vmcore_off;
518 	Elf32_Ehdr *ehdr_ptr;
519 	struct vmcore *m;
520 
521 	ehdr_ptr = (Elf32_Ehdr *)elfptr;
522 
523 	/* Skip Elf header and program headers. */
524 	vmcore_off = sizeof(Elf32_Ehdr) +
525 			(ehdr_ptr->e_phnum) * sizeof(Elf32_Phdr);
526 
527 	list_for_each_entry(m, vc_list, list) {
528 		m->offset = vmcore_off;
529 		vmcore_off += m->size;
530 	}
531 }
532 
parse_crash_elf64_headers(void)533 static int __init parse_crash_elf64_headers(void)
534 {
535 	int rc=0;
536 	Elf64_Ehdr ehdr;
537 	u64 addr;
538 
539 	addr = elfcorehdr_addr;
540 
541 	/* Read Elf header */
542 	rc = read_from_oldmem((char*)&ehdr, sizeof(Elf64_Ehdr), &addr, 0);
543 	if (rc < 0)
544 		return rc;
545 
546 	/* Do some basic Verification. */
547 	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
548 		(ehdr.e_type != ET_CORE) ||
549 		!vmcore_elf64_check_arch(&ehdr) ||
550 		ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
551 		ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
552 		ehdr.e_version != EV_CURRENT ||
553 		ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
554 		ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
555 		ehdr.e_phnum == 0) {
556 		printk(KERN_WARNING "Warning: Core image elf header is not"
557 					"sane\n");
558 		return -EINVAL;
559 	}
560 
561 	/* Read in all elf headers. */
562 	elfcorebuf_sz = sizeof(Elf64_Ehdr) + ehdr.e_phnum * sizeof(Elf64_Phdr);
563 	elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
564 	if (!elfcorebuf)
565 		return -ENOMEM;
566 	addr = elfcorehdr_addr;
567 	rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
568 	if (rc < 0) {
569 		kfree(elfcorebuf);
570 		return rc;
571 	}
572 
573 	/* Merge all PT_NOTE headers into one. */
574 	rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
575 	if (rc) {
576 		kfree(elfcorebuf);
577 		return rc;
578 	}
579 	rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
580 							&vmcore_list);
581 	if (rc) {
582 		kfree(elfcorebuf);
583 		return rc;
584 	}
585 	set_vmcore_list_offsets_elf64(elfcorebuf, &vmcore_list);
586 	return 0;
587 }
588 
parse_crash_elf32_headers(void)589 static int __init parse_crash_elf32_headers(void)
590 {
591 	int rc=0;
592 	Elf32_Ehdr ehdr;
593 	u64 addr;
594 
595 	addr = elfcorehdr_addr;
596 
597 	/* Read Elf header */
598 	rc = read_from_oldmem((char*)&ehdr, sizeof(Elf32_Ehdr), &addr, 0);
599 	if (rc < 0)
600 		return rc;
601 
602 	/* Do some basic Verification. */
603 	if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
604 		(ehdr.e_type != ET_CORE) ||
605 		!elf_check_arch(&ehdr) ||
606 		ehdr.e_ident[EI_CLASS] != ELFCLASS32||
607 		ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
608 		ehdr.e_version != EV_CURRENT ||
609 		ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
610 		ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
611 		ehdr.e_phnum == 0) {
612 		printk(KERN_WARNING "Warning: Core image elf header is not"
613 					"sane\n");
614 		return -EINVAL;
615 	}
616 
617 	/* Read in all elf headers. */
618 	elfcorebuf_sz = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
619 	elfcorebuf = kmalloc(elfcorebuf_sz, GFP_KERNEL);
620 	if (!elfcorebuf)
621 		return -ENOMEM;
622 	addr = elfcorehdr_addr;
623 	rc = read_from_oldmem(elfcorebuf, elfcorebuf_sz, &addr, 0);
624 	if (rc < 0) {
625 		kfree(elfcorebuf);
626 		return rc;
627 	}
628 
629 	/* Merge all PT_NOTE headers into one. */
630 	rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz, &vmcore_list);
631 	if (rc) {
632 		kfree(elfcorebuf);
633 		return rc;
634 	}
635 	rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
636 								&vmcore_list);
637 	if (rc) {
638 		kfree(elfcorebuf);
639 		return rc;
640 	}
641 	set_vmcore_list_offsets_elf32(elfcorebuf, &vmcore_list);
642 	return 0;
643 }
644 
parse_crash_elf_headers(void)645 static int __init parse_crash_elf_headers(void)
646 {
647 	unsigned char e_ident[EI_NIDENT];
648 	u64 addr;
649 	int rc=0;
650 
651 	addr = elfcorehdr_addr;
652 	rc = read_from_oldmem(e_ident, EI_NIDENT, &addr, 0);
653 	if (rc < 0)
654 		return rc;
655 	if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
656 		printk(KERN_WARNING "Warning: Core image elf header"
657 					" not found\n");
658 		return -EINVAL;
659 	}
660 
661 	if (e_ident[EI_CLASS] == ELFCLASS64) {
662 		rc = parse_crash_elf64_headers();
663 		if (rc)
664 			return rc;
665 
666 		/* Determine vmcore size. */
667 		vmcore_size = get_vmcore_size_elf64(elfcorebuf);
668 	} else if (e_ident[EI_CLASS] == ELFCLASS32) {
669 		rc = parse_crash_elf32_headers();
670 		if (rc)
671 			return rc;
672 
673 		/* Determine vmcore size. */
674 		vmcore_size = get_vmcore_size_elf32(elfcorebuf);
675 	} else {
676 		printk(KERN_WARNING "Warning: Core image elf header is not"
677 					" sane\n");
678 		return -EINVAL;
679 	}
680 	return 0;
681 }
682 
683 /* Init function for vmcore module. */
vmcore_init(void)684 static int __init vmcore_init(void)
685 {
686 	int rc = 0;
687 
688 	/* If elfcorehdr= has been passed in cmdline, then capture the dump.*/
689 	if (!(is_vmcore_usable()))
690 		return rc;
691 	rc = parse_crash_elf_headers();
692 	if (rc) {
693 		printk(KERN_WARNING "Kdump: vmcore not initialized\n");
694 		return rc;
695 	}
696 
697 	proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
698 	if (proc_vmcore)
699 		proc_vmcore->size = vmcore_size;
700 	return 0;
701 }
module_init(vmcore_init)702 module_init(vmcore_init)
703 
704 /* Cleanup function for vmcore module. */
705 void vmcore_cleanup(void)
706 {
707 	struct list_head *pos, *next;
708 
709 	if (proc_vmcore) {
710 		remove_proc_entry(proc_vmcore->name, proc_vmcore->parent);
711 		proc_vmcore = NULL;
712 	}
713 
714 	/* clear the vmcore list. */
715 	list_for_each_safe(pos, next, &vmcore_list) {
716 		struct vmcore *m;
717 
718 		m = list_entry(pos, struct vmcore, list);
719 		list_del(&m->list);
720 		kfree(m);
721 	}
722 	kfree(elfcorebuf);
723 	elfcorebuf = NULL;
724 }
725 EXPORT_SYMBOL_GPL(vmcore_cleanup);
726