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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * fs/proc/kcore.c kernel ELF core dumper
4 *
5 * Modelled on fs/exec.c:aout_core_dump()
6 * Jeremy Fitzhardinge <jeremy@sw.oz.au>
7 * ELF version written by David Howells <David.Howells@nexor.co.uk>
8 * Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com>
9 * Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com>
10 * Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com>
11 */
12
13#include <linux/crash_core.h>
14#include <linux/mm.h>
15#include <linux/proc_fs.h>
16#include <linux/kcore.h>
17#include <linux/user.h>
18#include <linux/capability.h>
19#include <linux/elf.h>
20#include <linux/elfcore.h>
21#include <linux/notifier.h>
22#include <linux/vmalloc.h>
23#include <linux/highmem.h>
24#include <linux/printk.h>
25#include <linux/memblock.h>
26#include <linux/init.h>
27#include <linux/slab.h>
28#include <linux/uaccess.h>
29#include <asm/io.h>
30#include <linux/list.h>
31#include <linux/ioport.h>
32#include <linux/memory.h>
33#include <linux/sched/task.h>
34#include <linux/security.h>
35#include <asm/sections.h>
36#include "internal.h"
37
38#define CORE_STR "CORE"
39
40#ifndef ELF_CORE_EFLAGS
41#define ELF_CORE_EFLAGS 0
42#endif
43
44static struct proc_dir_entry *proc_root_kcore;
45
46
47#ifndef kc_vaddr_to_offset
48#define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
49#endif
50#ifndef kc_offset_to_vaddr
51#define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
52#endif
53
54static LIST_HEAD(kclist_head);
55static DECLARE_RWSEM(kclist_lock);
56static int kcore_need_update = 1;
57
58/*
59 * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
60 * Same as oldmem_pfn_is_ram in vmcore
61 */
62static int (*mem_pfn_is_ram)(unsigned long pfn);
63
64int __init register_mem_pfn_is_ram(int (*fn)(unsigned long pfn))
65{
66 if (mem_pfn_is_ram)
67 return -EBUSY;
68 mem_pfn_is_ram = fn;
69 return 0;
70}
71
72static int pfn_is_ram(unsigned long pfn)
73{
74 if (mem_pfn_is_ram)
75 return mem_pfn_is_ram(pfn);
76 else
77 return 1;
78}
79
80/* This doesn't grab kclist_lock, so it should only be used at init time. */
81void __init kclist_add(struct kcore_list *new, void *addr, size_t size,
82 int type)
83{
84 new->addr = (unsigned long)addr;
85 new->size = size;
86 new->type = type;
87
88 list_add_tail(&new->list, &kclist_head);
89}
90
91static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len,
92 size_t *data_offset)
93{
94 size_t try, size;
95 struct kcore_list *m;
96
97 *nphdr = 1; /* PT_NOTE */
98 size = 0;
99
100 list_for_each_entry(m, &kclist_head, list) {
101 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
102 if (try > size)
103 size = try;
104 *nphdr = *nphdr + 1;
105 }
106
107 *phdrs_len = *nphdr * sizeof(struct elf_phdr);
108 *notes_len = (4 * sizeof(struct elf_note) +
109 3 * ALIGN(sizeof(CORE_STR), 4) +
110 VMCOREINFO_NOTE_NAME_BYTES +
111 ALIGN(sizeof(struct elf_prstatus), 4) +
112 ALIGN(sizeof(struct elf_prpsinfo), 4) +
113 ALIGN(arch_task_struct_size, 4) +
114 ALIGN(vmcoreinfo_size, 4));
115 *data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len +
116 *notes_len);
117 return *data_offset + size;
118}
119
120#ifdef CONFIG_HIGHMEM
121/*
122 * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
123 * because memory hole is not as big as !HIGHMEM case.
124 * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
125 */
126static int kcore_ram_list(struct list_head *head)
127{
128 struct kcore_list *ent;
129
130 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
131 if (!ent)
132 return -ENOMEM;
133 ent->addr = (unsigned long)__va(0);
134 ent->size = max_low_pfn << PAGE_SHIFT;
135 ent->type = KCORE_RAM;
136 list_add(&ent->list, head);
137 return 0;
138}
139
140#else /* !CONFIG_HIGHMEM */
141
142#ifdef CONFIG_SPARSEMEM_VMEMMAP
143/* calculate vmemmap's address from given system ram pfn and register it */
144static int
145get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
146{
147 unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
148 unsigned long nr_pages = ent->size >> PAGE_SHIFT;
149 unsigned long start, end;
150 struct kcore_list *vmm, *tmp;
151
152
153 start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
154 end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
155 end = PAGE_ALIGN(end);
156 /* overlap check (because we have to align page */
157 list_for_each_entry(tmp, head, list) {
158 if (tmp->type != KCORE_VMEMMAP)
159 continue;
160 if (start < tmp->addr + tmp->size)
161 if (end > tmp->addr)
162 end = tmp->addr;
163 }
164 if (start < end) {
165 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
166 if (!vmm)
167 return 0;
168 vmm->addr = start;
169 vmm->size = end - start;
170 vmm->type = KCORE_VMEMMAP;
171 list_add_tail(&vmm->list, head);
172 }
173 return 1;
174
175}
176#else
177static int
178get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
179{
180 return 1;
181}
182
183#endif
184
185static int
186kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
187{
188 struct list_head *head = (struct list_head *)arg;
189 struct kcore_list *ent;
190 struct page *p;
191
192 if (!pfn_valid(pfn))
193 return 1;
194
195 p = pfn_to_page(pfn);
196
197 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
198 if (!ent)
199 return -ENOMEM;
200 ent->addr = (unsigned long)page_to_virt(p);
201 ent->size = nr_pages << PAGE_SHIFT;
202
203 if (!virt_addr_valid(ent->addr))
204 goto free_out;
205
206 /* cut not-mapped area. ....from ppc-32 code. */
207 if (ULONG_MAX - ent->addr < ent->size)
208 ent->size = ULONG_MAX - ent->addr;
209
210 /*
211 * We've already checked virt_addr_valid so we know this address
212 * is a valid pointer, therefore we can check against it to determine
213 * if we need to trim
214 */
215 if (VMALLOC_START > ent->addr) {
216 if (VMALLOC_START - ent->addr < ent->size)
217 ent->size = VMALLOC_START - ent->addr;
218 }
219
220 ent->type = KCORE_RAM;
221 list_add_tail(&ent->list, head);
222
223 if (!get_sparsemem_vmemmap_info(ent, head)) {
224 list_del(&ent->list);
225 goto free_out;
226 }
227
228 return 0;
229free_out:
230 kfree(ent);
231 return 1;
232}
233
234static int kcore_ram_list(struct list_head *list)
235{
236 int nid, ret;
237 unsigned long end_pfn;
238
239 /* Not inialized....update now */
240 /* find out "max pfn" */
241 end_pfn = 0;
242 for_each_node_state(nid, N_MEMORY) {
243 unsigned long node_end;
244 node_end = node_end_pfn(nid);
245 if (end_pfn < node_end)
246 end_pfn = node_end;
247 }
248 /* scan 0 to max_pfn */
249 ret = walk_system_ram_range(0, end_pfn, list, kclist_add_private);
250 if (ret)
251 return -ENOMEM;
252 return 0;
253}
254#endif /* CONFIG_HIGHMEM */
255
256static int kcore_update_ram(void)
257{
258 LIST_HEAD(list);
259 LIST_HEAD(garbage);
260 int nphdr;
261 size_t phdrs_len, notes_len, data_offset;
262 struct kcore_list *tmp, *pos;
263 int ret = 0;
264
265 down_write(&kclist_lock);
266 if (!xchg(&kcore_need_update, 0))
267 goto out;
268
269 ret = kcore_ram_list(&list);
270 if (ret) {
271 /* Couldn't get the RAM list, try again next time. */
272 WRITE_ONCE(kcore_need_update, 1);
273 list_splice_tail(&list, &garbage);
274 goto out;
275 }
276
277 list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
278 if (pos->type == KCORE_RAM || pos->type == KCORE_VMEMMAP)
279 list_move(&pos->list, &garbage);
280 }
281 list_splice_tail(&list, &kclist_head);
282
283 proc_root_kcore->size = get_kcore_size(&nphdr, &phdrs_len, ¬es_len,
284 &data_offset);
285
286out:
287 up_write(&kclist_lock);
288 list_for_each_entry_safe(pos, tmp, &garbage, list) {
289 list_del(&pos->list);
290 kfree(pos);
291 }
292 return ret;
293}
294
295static void append_kcore_note(char *notes, size_t *i, const char *name,
296 unsigned int type, const void *desc,
297 size_t descsz)
298{
299 struct elf_note *note = (struct elf_note *)¬es[*i];
300
301 note->n_namesz = strlen(name) + 1;
302 note->n_descsz = descsz;
303 note->n_type = type;
304 *i += sizeof(*note);
305 memcpy(¬es[*i], name, note->n_namesz);
306 *i = ALIGN(*i + note->n_namesz, 4);
307 memcpy(¬es[*i], desc, descsz);
308 *i = ALIGN(*i + descsz, 4);
309}
310
311static ssize_t
312read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
313{
314 char *buf = file->private_data;
315 size_t phdrs_offset, notes_offset, data_offset;
316 size_t page_offline_frozen = 1;
317 size_t phdrs_len, notes_len;
318 struct kcore_list *m;
319 size_t tsz;
320 int nphdr;
321 unsigned long start;
322 size_t orig_buflen = buflen;
323 int ret = 0;
324
325 down_read(&kclist_lock);
326 /*
327 * Don't race against drivers that set PageOffline() and expect no
328 * further page access.
329 */
330 page_offline_freeze();
331
332 get_kcore_size(&nphdr, &phdrs_len, ¬es_len, &data_offset);
333 phdrs_offset = sizeof(struct elfhdr);
334 notes_offset = phdrs_offset + phdrs_len;
335
336 /* ELF file header. */
337 if (buflen && *fpos < sizeof(struct elfhdr)) {
338 struct elfhdr ehdr = {
339 .e_ident = {
340 [EI_MAG0] = ELFMAG0,
341 [EI_MAG1] = ELFMAG1,
342 [EI_MAG2] = ELFMAG2,
343 [EI_MAG3] = ELFMAG3,
344 [EI_CLASS] = ELF_CLASS,
345 [EI_DATA] = ELF_DATA,
346 [EI_VERSION] = EV_CURRENT,
347 [EI_OSABI] = ELF_OSABI,
348 },
349 .e_type = ET_CORE,
350 .e_machine = ELF_ARCH,
351 .e_version = EV_CURRENT,
352 .e_phoff = sizeof(struct elfhdr),
353 .e_flags = ELF_CORE_EFLAGS,
354 .e_ehsize = sizeof(struct elfhdr),
355 .e_phentsize = sizeof(struct elf_phdr),
356 .e_phnum = nphdr,
357 };
358
359 tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos);
360 if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) {
361 ret = -EFAULT;
362 goto out;
363 }
364
365 buffer += tsz;
366 buflen -= tsz;
367 *fpos += tsz;
368 }
369
370 /* ELF program headers. */
371 if (buflen && *fpos < phdrs_offset + phdrs_len) {
372 struct elf_phdr *phdrs, *phdr;
373
374 phdrs = kzalloc(phdrs_len, GFP_KERNEL);
375 if (!phdrs) {
376 ret = -ENOMEM;
377 goto out;
378 }
379
380 phdrs[0].p_type = PT_NOTE;
381 phdrs[0].p_offset = notes_offset;
382 phdrs[0].p_filesz = notes_len;
383
384 phdr = &phdrs[1];
385 list_for_each_entry(m, &kclist_head, list) {
386 phdr->p_type = PT_LOAD;
387 phdr->p_flags = PF_R | PF_W | PF_X;
388 phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset;
389 phdr->p_vaddr = (size_t)m->addr;
390 if (m->type == KCORE_RAM)
391 phdr->p_paddr = __pa(m->addr);
392 else if (m->type == KCORE_TEXT)
393 phdr->p_paddr = __pa_symbol(m->addr);
394 else
395 phdr->p_paddr = (elf_addr_t)-1;
396 phdr->p_filesz = phdr->p_memsz = m->size;
397 phdr->p_align = PAGE_SIZE;
398 phdr++;
399 }
400
401 tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos);
402 if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset,
403 tsz)) {
404 kfree(phdrs);
405 ret = -EFAULT;
406 goto out;
407 }
408 kfree(phdrs);
409
410 buffer += tsz;
411 buflen -= tsz;
412 *fpos += tsz;
413 }
414
415 /* ELF note segment. */
416 if (buflen && *fpos < notes_offset + notes_len) {
417 struct elf_prstatus prstatus = {};
418 struct elf_prpsinfo prpsinfo = {
419 .pr_sname = 'R',
420 .pr_fname = "vmlinux",
421 };
422 char *notes;
423 size_t i = 0;
424
425 strlcpy(prpsinfo.pr_psargs, saved_command_line,
426 sizeof(prpsinfo.pr_psargs));
427
428 notes = kzalloc(notes_len, GFP_KERNEL);
429 if (!notes) {
430 ret = -ENOMEM;
431 goto out;
432 }
433
434 append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus,
435 sizeof(prstatus));
436 append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo,
437 sizeof(prpsinfo));
438 append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current,
439 arch_task_struct_size);
440 /*
441 * vmcoreinfo_size is mostly constant after init time, but it
442 * can be changed by crash_save_vmcoreinfo(). Racing here with a
443 * panic on another CPU before the machine goes down is insanely
444 * unlikely, but it's better to not leave potential buffer
445 * overflows lying around, regardless.
446 */
447 append_kcore_note(notes, &i, VMCOREINFO_NOTE_NAME, 0,
448 vmcoreinfo_data,
449 min(vmcoreinfo_size, notes_len - i));
450
451 tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos);
452 if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) {
453 kfree(notes);
454 ret = -EFAULT;
455 goto out;
456 }
457 kfree(notes);
458
459 buffer += tsz;
460 buflen -= tsz;
461 *fpos += tsz;
462 }
463
464 /*
465 * Check to see if our file offset matches with any of
466 * the addresses in the elf_phdr on our list.
467 */
468 start = kc_offset_to_vaddr(*fpos - data_offset);
469 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
470 tsz = buflen;
471
472 m = NULL;
473 while (buflen) {
474 struct page *page;
475 unsigned long pfn;
476
477 /*
478 * If this is the first iteration or the address is not within
479 * the previous entry, search for a matching entry.
480 */
481 if (!m || start < m->addr || start >= m->addr + m->size) {
482 list_for_each_entry(m, &kclist_head, list) {
483 if (start >= m->addr &&
484 start < m->addr + m->size)
485 break;
486 }
487 }
488
489 if (page_offline_frozen++ % MAX_ORDER_NR_PAGES == 0) {
490 page_offline_thaw();
491 cond_resched();
492 page_offline_freeze();
493 }
494
495 if (&m->list == &kclist_head) {
496 if (clear_user(buffer, tsz)) {
497 ret = -EFAULT;
498 goto out;
499 }
500 m = NULL; /* skip the list anchor */
501 goto skip;
502 }
503
504 switch (m->type) {
505 case KCORE_VMALLOC:
506 vread(buf, (char *)start, tsz);
507 /* we have to zero-fill user buffer even if no read */
508 if (copy_to_user(buffer, buf, tsz)) {
509 ret = -EFAULT;
510 goto out;
511 }
512 break;
513 case KCORE_USER:
514 /* User page is handled prior to normal kernel page: */
515 if (copy_to_user(buffer, (char *)start, tsz)) {
516 ret = -EFAULT;
517 goto out;
518 }
519 break;
520 case KCORE_RAM:
521 pfn = __pa(start) >> PAGE_SHIFT;
522 page = pfn_to_online_page(pfn);
523
524 /*
525 * Don't read offline sections, logically offline pages
526 * (e.g., inflated in a balloon), hwpoisoned pages,
527 * and explicitly excluded physical ranges.
528 */
529 if (!page || PageOffline(page) ||
530 is_page_hwpoison(page) || !pfn_is_ram(pfn)) {
531 if (clear_user(buffer, tsz)) {
532 ret = -EFAULT;
533 goto out;
534 }
535 break;
536 }
537 fallthrough;
538 case KCORE_VMEMMAP:
539 case KCORE_TEXT:
540 if (kern_addr_valid(start)) {
541 /*
542 * Using bounce buffer to bypass the
543 * hardened user copy kernel text checks.
544 */
545 if (copy_from_kernel_nofault(buf, (void *)start,
546 tsz)) {
547 if (clear_user(buffer, tsz)) {
548 ret = -EFAULT;
549 goto out;
550 }
551 } else {
552 if (copy_to_user(buffer, buf, tsz)) {
553 ret = -EFAULT;
554 goto out;
555 }
556 }
557 } else {
558 if (clear_user(buffer, tsz)) {
559 ret = -EFAULT;
560 goto out;
561 }
562 }
563 break;
564 default:
565 pr_warn_once("Unhandled KCORE type: %d\n", m->type);
566 if (clear_user(buffer, tsz)) {
567 ret = -EFAULT;
568 goto out;
569 }
570 }
571skip:
572 buflen -= tsz;
573 *fpos += tsz;
574 buffer += tsz;
575 start += tsz;
576 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
577 }
578
579out:
580 page_offline_thaw();
581 up_read(&kclist_lock);
582 if (ret)
583 return ret;
584 return orig_buflen - buflen;
585}
586
587static int open_kcore(struct inode *inode, struct file *filp)
588{
589 int ret = security_locked_down(LOCKDOWN_KCORE);
590
591 if (!capable(CAP_SYS_RAWIO))
592 return -EPERM;
593
594 if (ret)
595 return ret;
596
597 filp->private_data = kmalloc(PAGE_SIZE, GFP_KERNEL);
598 if (!filp->private_data)
599 return -ENOMEM;
600
601 if (kcore_need_update)
602 kcore_update_ram();
603 if (i_size_read(inode) != proc_root_kcore->size) {
604 inode_lock(inode);
605 i_size_write(inode, proc_root_kcore->size);
606 inode_unlock(inode);
607 }
608 return 0;
609}
610
611static int release_kcore(struct inode *inode, struct file *file)
612{
613 kfree(file->private_data);
614 return 0;
615}
616
617static const struct proc_ops kcore_proc_ops = {
618 .proc_read = read_kcore,
619 .proc_open = open_kcore,
620 .proc_release = release_kcore,
621 .proc_lseek = default_llseek,
622};
623
624/* just remember that we have to update kcore */
625static int __meminit kcore_callback(struct notifier_block *self,
626 unsigned long action, void *arg)
627{
628 switch (action) {
629 case MEM_ONLINE:
630 case MEM_OFFLINE:
631 kcore_need_update = 1;
632 break;
633 }
634 return NOTIFY_OK;
635}
636
637static struct notifier_block kcore_callback_nb __meminitdata = {
638 .notifier_call = kcore_callback,
639 .priority = 0,
640};
641
642static struct kcore_list kcore_vmalloc;
643
644#ifdef CONFIG_ARCH_PROC_KCORE_TEXT
645static struct kcore_list kcore_text;
646/*
647 * If defined, special segment is used for mapping kernel text instead of
648 * direct-map area. We need to create special TEXT section.
649 */
650static void __init proc_kcore_text_init(void)
651{
652 kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
653}
654#else
655static void __init proc_kcore_text_init(void)
656{
657}
658#endif
659
660#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
661/*
662 * MODULES_VADDR has no intersection with VMALLOC_ADDR.
663 */
664static struct kcore_list kcore_modules;
665static void __init add_modules_range(void)
666{
667 if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
668 kclist_add(&kcore_modules, (void *)MODULES_VADDR,
669 MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
670 }
671}
672#else
673static void __init add_modules_range(void)
674{
675}
676#endif
677
678static int __init proc_kcore_init(void)
679{
680 proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &kcore_proc_ops);
681 if (!proc_root_kcore) {
682 pr_err("couldn't create /proc/kcore\n");
683 return 0; /* Always returns 0. */
684 }
685 /* Store text area if it's special */
686 proc_kcore_text_init();
687 /* Store vmalloc area */
688 kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
689 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
690 add_modules_range();
691 /* Store direct-map area from physical memory map */
692 kcore_update_ram();
693 register_hotmemory_notifier(&kcore_callback_nb);
694
695 return 0;
696}
697fs_initcall(proc_kcore_init);
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/kcore.h>
15#include <linux/user.h>
16#include <linux/capability.h>
17#include <linux/elf.h>
18#include <linux/elfcore.h>
19#include <linux/notifier.h>
20#include <linux/vmalloc.h>
21#include <linux/highmem.h>
22#include <linux/printk.h>
23#include <linux/bootmem.h>
24#include <linux/init.h>
25#include <linux/slab.h>
26#include <asm/uaccess.h>
27#include <asm/io.h>
28#include <linux/list.h>
29#include <linux/ioport.h>
30#include <linux/memory.h>
31#include <asm/sections.h>
32#include "internal.h"
33
34#define CORE_STR "CORE"
35
36#ifndef ELF_CORE_EFLAGS
37#define ELF_CORE_EFLAGS 0
38#endif
39
40static struct proc_dir_entry *proc_root_kcore;
41
42
43#ifndef kc_vaddr_to_offset
44#define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET)
45#endif
46#ifndef kc_offset_to_vaddr
47#define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET)
48#endif
49
50/* An ELF note in memory */
51struct memelfnote
52{
53 const char *name;
54 int type;
55 unsigned int datasz;
56 void *data;
57};
58
59static LIST_HEAD(kclist_head);
60static DEFINE_RWLOCK(kclist_lock);
61static int kcore_need_update = 1;
62
63void
64kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
65{
66 new->addr = (unsigned long)addr;
67 new->size = size;
68 new->type = type;
69
70 write_lock(&kclist_lock);
71 list_add_tail(&new->list, &kclist_head);
72 write_unlock(&kclist_lock);
73}
74
75static size_t get_kcore_size(int *nphdr, size_t *elf_buflen)
76{
77 size_t try, size;
78 struct kcore_list *m;
79
80 *nphdr = 1; /* PT_NOTE */
81 size = 0;
82
83 list_for_each_entry(m, &kclist_head, list) {
84 try = kc_vaddr_to_offset((size_t)m->addr + m->size);
85 if (try > size)
86 size = try;
87 *nphdr = *nphdr + 1;
88 }
89 *elf_buflen = sizeof(struct elfhdr) +
90 (*nphdr + 2)*sizeof(struct elf_phdr) +
91 3 * ((sizeof(struct elf_note)) +
92 roundup(sizeof(CORE_STR), 4)) +
93 roundup(sizeof(struct elf_prstatus), 4) +
94 roundup(sizeof(struct elf_prpsinfo), 4) +
95 roundup(arch_task_struct_size, 4);
96 *elf_buflen = PAGE_ALIGN(*elf_buflen);
97 return size + *elf_buflen;
98}
99
100static void free_kclist_ents(struct list_head *head)
101{
102 struct kcore_list *tmp, *pos;
103
104 list_for_each_entry_safe(pos, tmp, head, list) {
105 list_del(&pos->list);
106 kfree(pos);
107 }
108}
109/*
110 * Replace all KCORE_RAM/KCORE_VMEMMAP information with passed list.
111 */
112static void __kcore_update_ram(struct list_head *list)
113{
114 int nphdr;
115 size_t size;
116 struct kcore_list *tmp, *pos;
117 LIST_HEAD(garbage);
118
119 write_lock(&kclist_lock);
120 if (kcore_need_update) {
121 list_for_each_entry_safe(pos, tmp, &kclist_head, list) {
122 if (pos->type == KCORE_RAM
123 || pos->type == KCORE_VMEMMAP)
124 list_move(&pos->list, &garbage);
125 }
126 list_splice_tail(list, &kclist_head);
127 } else
128 list_splice(list, &garbage);
129 kcore_need_update = 0;
130 proc_root_kcore->size = get_kcore_size(&nphdr, &size);
131 write_unlock(&kclist_lock);
132
133 free_kclist_ents(&garbage);
134}
135
136
137#ifdef CONFIG_HIGHMEM
138/*
139 * If no highmem, we can assume [0...max_low_pfn) continuous range of memory
140 * because memory hole is not as big as !HIGHMEM case.
141 * (HIGHMEM is special because part of memory is _invisible_ from the kernel.)
142 */
143static int kcore_update_ram(void)
144{
145 LIST_HEAD(head);
146 struct kcore_list *ent;
147 int ret = 0;
148
149 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
150 if (!ent)
151 return -ENOMEM;
152 ent->addr = (unsigned long)__va(0);
153 ent->size = max_low_pfn << PAGE_SHIFT;
154 ent->type = KCORE_RAM;
155 list_add(&ent->list, &head);
156 __kcore_update_ram(&head);
157 return ret;
158}
159
160#else /* !CONFIG_HIGHMEM */
161
162#ifdef CONFIG_SPARSEMEM_VMEMMAP
163/* calculate vmemmap's address from given system ram pfn and register it */
164static int
165get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
166{
167 unsigned long pfn = __pa(ent->addr) >> PAGE_SHIFT;
168 unsigned long nr_pages = ent->size >> PAGE_SHIFT;
169 unsigned long start, end;
170 struct kcore_list *vmm, *tmp;
171
172
173 start = ((unsigned long)pfn_to_page(pfn)) & PAGE_MASK;
174 end = ((unsigned long)pfn_to_page(pfn + nr_pages)) - 1;
175 end = PAGE_ALIGN(end);
176 /* overlap check (because we have to align page */
177 list_for_each_entry(tmp, head, list) {
178 if (tmp->type != KCORE_VMEMMAP)
179 continue;
180 if (start < tmp->addr + tmp->size)
181 if (end > tmp->addr)
182 end = tmp->addr;
183 }
184 if (start < end) {
185 vmm = kmalloc(sizeof(*vmm), GFP_KERNEL);
186 if (!vmm)
187 return 0;
188 vmm->addr = start;
189 vmm->size = end - start;
190 vmm->type = KCORE_VMEMMAP;
191 list_add_tail(&vmm->list, head);
192 }
193 return 1;
194
195}
196#else
197static int
198get_sparsemem_vmemmap_info(struct kcore_list *ent, struct list_head *head)
199{
200 return 1;
201}
202
203#endif
204
205static int
206kclist_add_private(unsigned long pfn, unsigned long nr_pages, void *arg)
207{
208 struct list_head *head = (struct list_head *)arg;
209 struct kcore_list *ent;
210
211 ent = kmalloc(sizeof(*ent), GFP_KERNEL);
212 if (!ent)
213 return -ENOMEM;
214 ent->addr = (unsigned long)__va((pfn << PAGE_SHIFT));
215 ent->size = nr_pages << PAGE_SHIFT;
216
217 /* Sanity check: Can happen in 32bit arch...maybe */
218 if (ent->addr < (unsigned long) __va(0))
219 goto free_out;
220
221 /* cut not-mapped area. ....from ppc-32 code. */
222 if (ULONG_MAX - ent->addr < ent->size)
223 ent->size = ULONG_MAX - ent->addr;
224
225 /* cut when vmalloc() area is higher than direct-map area */
226 if (VMALLOC_START > (unsigned long)__va(0)) {
227 if (ent->addr > VMALLOC_START)
228 goto free_out;
229 if (VMALLOC_START - ent->addr < ent->size)
230 ent->size = VMALLOC_START - ent->addr;
231 }
232
233 ent->type = KCORE_RAM;
234 list_add_tail(&ent->list, head);
235
236 if (!get_sparsemem_vmemmap_info(ent, head)) {
237 list_del(&ent->list);
238 goto free_out;
239 }
240
241 return 0;
242free_out:
243 kfree(ent);
244 return 1;
245}
246
247static int kcore_update_ram(void)
248{
249 int nid, ret;
250 unsigned long end_pfn;
251 LIST_HEAD(head);
252
253 /* Not inialized....update now */
254 /* find out "max pfn" */
255 end_pfn = 0;
256 for_each_node_state(nid, N_MEMORY) {
257 unsigned long node_end;
258 node_end = node_end_pfn(nid);
259 if (end_pfn < node_end)
260 end_pfn = node_end;
261 }
262 /* scan 0 to max_pfn */
263 ret = walk_system_ram_range(0, end_pfn, &head, kclist_add_private);
264 if (ret) {
265 free_kclist_ents(&head);
266 return -ENOMEM;
267 }
268 __kcore_update_ram(&head);
269 return ret;
270}
271#endif /* CONFIG_HIGHMEM */
272
273/*****************************************************************************/
274/*
275 * determine size of ELF note
276 */
277static int notesize(struct memelfnote *en)
278{
279 int sz;
280
281 sz = sizeof(struct elf_note);
282 sz += roundup((strlen(en->name) + 1), 4);
283 sz += roundup(en->datasz, 4);
284
285 return sz;
286} /* end notesize() */
287
288/*****************************************************************************/
289/*
290 * store a note in the header buffer
291 */
292static char *storenote(struct memelfnote *men, char *bufp)
293{
294 struct elf_note en;
295
296#define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0)
297
298 en.n_namesz = strlen(men->name) + 1;
299 en.n_descsz = men->datasz;
300 en.n_type = men->type;
301
302 DUMP_WRITE(&en, sizeof(en));
303 DUMP_WRITE(men->name, en.n_namesz);
304
305 /* XXX - cast from long long to long to avoid need for libgcc.a */
306 bufp = (char*) roundup((unsigned long)bufp,4);
307 DUMP_WRITE(men->data, men->datasz);
308 bufp = (char*) roundup((unsigned long)bufp,4);
309
310#undef DUMP_WRITE
311
312 return bufp;
313} /* end storenote() */
314
315/*
316 * store an ELF coredump header in the supplied buffer
317 * nphdr is the number of elf_phdr to insert
318 */
319static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff)
320{
321 struct elf_prstatus prstatus; /* NT_PRSTATUS */
322 struct elf_prpsinfo prpsinfo; /* NT_PRPSINFO */
323 struct elf_phdr *nhdr, *phdr;
324 struct elfhdr *elf;
325 struct memelfnote notes[3];
326 off_t offset = 0;
327 struct kcore_list *m;
328
329 /* setup ELF header */
330 elf = (struct elfhdr *) bufp;
331 bufp += sizeof(struct elfhdr);
332 offset += sizeof(struct elfhdr);
333 memcpy(elf->e_ident, ELFMAG, SELFMAG);
334 elf->e_ident[EI_CLASS] = ELF_CLASS;
335 elf->e_ident[EI_DATA] = ELF_DATA;
336 elf->e_ident[EI_VERSION]= EV_CURRENT;
337 elf->e_ident[EI_OSABI] = ELF_OSABI;
338 memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD);
339 elf->e_type = ET_CORE;
340 elf->e_machine = ELF_ARCH;
341 elf->e_version = EV_CURRENT;
342 elf->e_entry = 0;
343 elf->e_phoff = sizeof(struct elfhdr);
344 elf->e_shoff = 0;
345 elf->e_flags = ELF_CORE_EFLAGS;
346 elf->e_ehsize = sizeof(struct elfhdr);
347 elf->e_phentsize= sizeof(struct elf_phdr);
348 elf->e_phnum = nphdr;
349 elf->e_shentsize= 0;
350 elf->e_shnum = 0;
351 elf->e_shstrndx = 0;
352
353 /* setup ELF PT_NOTE program header */
354 nhdr = (struct elf_phdr *) bufp;
355 bufp += sizeof(struct elf_phdr);
356 offset += sizeof(struct elf_phdr);
357 nhdr->p_type = PT_NOTE;
358 nhdr->p_offset = 0;
359 nhdr->p_vaddr = 0;
360 nhdr->p_paddr = 0;
361 nhdr->p_filesz = 0;
362 nhdr->p_memsz = 0;
363 nhdr->p_flags = 0;
364 nhdr->p_align = 0;
365
366 /* setup ELF PT_LOAD program header for every area */
367 list_for_each_entry(m, &kclist_head, list) {
368 phdr = (struct elf_phdr *) bufp;
369 bufp += sizeof(struct elf_phdr);
370 offset += sizeof(struct elf_phdr);
371
372 phdr->p_type = PT_LOAD;
373 phdr->p_flags = PF_R|PF_W|PF_X;
374 phdr->p_offset = kc_vaddr_to_offset(m->addr) + dataoff;
375 phdr->p_vaddr = (size_t)m->addr;
376 phdr->p_paddr = 0;
377 phdr->p_filesz = phdr->p_memsz = m->size;
378 phdr->p_align = PAGE_SIZE;
379 }
380
381 /*
382 * Set up the notes in similar form to SVR4 core dumps made
383 * with info from their /proc.
384 */
385 nhdr->p_offset = offset;
386
387 /* set up the process status */
388 notes[0].name = CORE_STR;
389 notes[0].type = NT_PRSTATUS;
390 notes[0].datasz = sizeof(struct elf_prstatus);
391 notes[0].data = &prstatus;
392
393 memset(&prstatus, 0, sizeof(struct elf_prstatus));
394
395 nhdr->p_filesz = notesize(¬es[0]);
396 bufp = storenote(¬es[0], bufp);
397
398 /* set up the process info */
399 notes[1].name = CORE_STR;
400 notes[1].type = NT_PRPSINFO;
401 notes[1].datasz = sizeof(struct elf_prpsinfo);
402 notes[1].data = &prpsinfo;
403
404 memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo));
405 prpsinfo.pr_state = 0;
406 prpsinfo.pr_sname = 'R';
407 prpsinfo.pr_zomb = 0;
408
409 strcpy(prpsinfo.pr_fname, "vmlinux");
410 strlcpy(prpsinfo.pr_psargs, saved_command_line, sizeof(prpsinfo.pr_psargs));
411
412 nhdr->p_filesz += notesize(¬es[1]);
413 bufp = storenote(¬es[1], bufp);
414
415 /* set up the task structure */
416 notes[2].name = CORE_STR;
417 notes[2].type = NT_TASKSTRUCT;
418 notes[2].datasz = arch_task_struct_size;
419 notes[2].data = current;
420
421 nhdr->p_filesz += notesize(¬es[2]);
422 bufp = storenote(¬es[2], bufp);
423
424} /* end elf_kcore_store_hdr() */
425
426/*****************************************************************************/
427/*
428 * read from the ELF header and then kernel memory
429 */
430static ssize_t
431read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos)
432{
433 ssize_t acc = 0;
434 size_t size, tsz;
435 size_t elf_buflen;
436 int nphdr;
437 unsigned long start;
438
439 read_lock(&kclist_lock);
440 size = get_kcore_size(&nphdr, &elf_buflen);
441
442 if (buflen == 0 || *fpos >= size) {
443 read_unlock(&kclist_lock);
444 return 0;
445 }
446
447 /* trim buflen to not go beyond EOF */
448 if (buflen > size - *fpos)
449 buflen = size - *fpos;
450
451 /* construct an ELF core header if we'll need some of it */
452 if (*fpos < elf_buflen) {
453 char * elf_buf;
454
455 tsz = elf_buflen - *fpos;
456 if (buflen < tsz)
457 tsz = buflen;
458 elf_buf = kzalloc(elf_buflen, GFP_ATOMIC);
459 if (!elf_buf) {
460 read_unlock(&kclist_lock);
461 return -ENOMEM;
462 }
463 elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen);
464 read_unlock(&kclist_lock);
465 if (copy_to_user(buffer, elf_buf + *fpos, tsz)) {
466 kfree(elf_buf);
467 return -EFAULT;
468 }
469 kfree(elf_buf);
470 buflen -= tsz;
471 *fpos += tsz;
472 buffer += tsz;
473 acc += tsz;
474
475 /* leave now if filled buffer already */
476 if (buflen == 0)
477 return acc;
478 } else
479 read_unlock(&kclist_lock);
480
481 /*
482 * Check to see if our file offset matches with any of
483 * the addresses in the elf_phdr on our list.
484 */
485 start = kc_offset_to_vaddr(*fpos - elf_buflen);
486 if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
487 tsz = buflen;
488
489 while (buflen) {
490 struct kcore_list *m;
491
492 read_lock(&kclist_lock);
493 list_for_each_entry(m, &kclist_head, list) {
494 if (start >= m->addr && start < (m->addr+m->size))
495 break;
496 }
497 read_unlock(&kclist_lock);
498
499 if (&m->list == &kclist_head) {
500 if (clear_user(buffer, tsz))
501 return -EFAULT;
502 } else if (is_vmalloc_or_module_addr((void *)start)) {
503 char * elf_buf;
504
505 elf_buf = kzalloc(tsz, GFP_KERNEL);
506 if (!elf_buf)
507 return -ENOMEM;
508 vread(elf_buf, (char *)start, tsz);
509 /* we have to zero-fill user buffer even if no read */
510 if (copy_to_user(buffer, elf_buf, tsz)) {
511 kfree(elf_buf);
512 return -EFAULT;
513 }
514 kfree(elf_buf);
515 } else {
516 if (kern_addr_valid(start)) {
517 unsigned long n;
518
519 n = copy_to_user(buffer, (char *)start, tsz);
520 /*
521 * We cannot distinguish between fault on source
522 * and fault on destination. When this happens
523 * we clear too and hope it will trigger the
524 * EFAULT again.
525 */
526 if (n) {
527 if (clear_user(buffer + tsz - n,
528 n))
529 return -EFAULT;
530 }
531 } else {
532 if (clear_user(buffer, tsz))
533 return -EFAULT;
534 }
535 }
536 buflen -= tsz;
537 *fpos += tsz;
538 buffer += tsz;
539 acc += tsz;
540 start += tsz;
541 tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen);
542 }
543
544 return acc;
545}
546
547
548static int open_kcore(struct inode *inode, struct file *filp)
549{
550 if (!capable(CAP_SYS_RAWIO))
551 return -EPERM;
552 if (kcore_need_update)
553 kcore_update_ram();
554 if (i_size_read(inode) != proc_root_kcore->size) {
555 inode_lock(inode);
556 i_size_write(inode, proc_root_kcore->size);
557 inode_unlock(inode);
558 }
559 return 0;
560}
561
562
563static const struct file_operations proc_kcore_operations = {
564 .read = read_kcore,
565 .open = open_kcore,
566 .llseek = default_llseek,
567};
568
569/* just remember that we have to update kcore */
570static int __meminit kcore_callback(struct notifier_block *self,
571 unsigned long action, void *arg)
572{
573 switch (action) {
574 case MEM_ONLINE:
575 case MEM_OFFLINE:
576 write_lock(&kclist_lock);
577 kcore_need_update = 1;
578 write_unlock(&kclist_lock);
579 }
580 return NOTIFY_OK;
581}
582
583static struct notifier_block kcore_callback_nb __meminitdata = {
584 .notifier_call = kcore_callback,
585 .priority = 0,
586};
587
588static struct kcore_list kcore_vmalloc;
589
590#ifdef CONFIG_ARCH_PROC_KCORE_TEXT
591static struct kcore_list kcore_text;
592/*
593 * If defined, special segment is used for mapping kernel text instead of
594 * direct-map area. We need to create special TEXT section.
595 */
596static void __init proc_kcore_text_init(void)
597{
598 kclist_add(&kcore_text, _text, _end - _text, KCORE_TEXT);
599}
600#else
601static void __init proc_kcore_text_init(void)
602{
603}
604#endif
605
606#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
607/*
608 * MODULES_VADDR has no intersection with VMALLOC_ADDR.
609 */
610struct kcore_list kcore_modules;
611static void __init add_modules_range(void)
612{
613 if (MODULES_VADDR != VMALLOC_START && MODULES_END != VMALLOC_END) {
614 kclist_add(&kcore_modules, (void *)MODULES_VADDR,
615 MODULES_END - MODULES_VADDR, KCORE_VMALLOC);
616 }
617}
618#else
619static void __init add_modules_range(void)
620{
621}
622#endif
623
624static int __init proc_kcore_init(void)
625{
626 proc_root_kcore = proc_create("kcore", S_IRUSR, NULL,
627 &proc_kcore_operations);
628 if (!proc_root_kcore) {
629 pr_err("couldn't create /proc/kcore\n");
630 return 0; /* Always returns 0. */
631 }
632 /* Store text area if it's special */
633 proc_kcore_text_init();
634 /* Store vmalloc area */
635 kclist_add(&kcore_vmalloc, (void *)VMALLOC_START,
636 VMALLOC_END - VMALLOC_START, KCORE_VMALLOC);
637 add_modules_range();
638 /* Store direct-map area from physical memory map */
639 kcore_update_ram();
640 register_hotmemory_notifier(&kcore_callback_nb);
641
642 return 0;
643}
644fs_initcall(proc_kcore_init);