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TOMOYO Linux Cross Reference
Linux/fs/proc/vmcore.c

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  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/kcore.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/printk.h>
 19 #include <linux/bootmem.h>
 20 #include <linux/init.h>
 21 #include <linux/crash_dump.h>
 22 #include <linux/list.h>
 23 #include <linux/vmalloc.h>
 24 #include <linux/pagemap.h>
 25 #include <asm/uaccess.h>
 26 #include <asm/io.h>
 27 #include "internal.h"
 28 
 29 /* List representing chunks of contiguous memory areas and their offsets in
 30  * vmcore file.
 31  */
 32 static LIST_HEAD(vmcore_list);
 33 
 34 /* Stores the pointer to the buffer containing kernel elf core headers. */
 35 static char *elfcorebuf;
 36 static size_t elfcorebuf_sz;
 37 static size_t elfcorebuf_sz_orig;
 38 
 39 static char *elfnotes_buf;
 40 static size_t elfnotes_sz;
 41 
 42 /* Total size of vmcore file. */
 43 static u64 vmcore_size;
 44 
 45 static struct proc_dir_entry *proc_vmcore;
 46 
 47 /*
 48  * Returns > 0 for RAM pages, 0 for non-RAM pages, < 0 on error
 49  * The called function has to take care of module refcounting.
 50  */
 51 static int (*oldmem_pfn_is_ram)(unsigned long pfn);
 52 
 53 int register_oldmem_pfn_is_ram(int (*fn)(unsigned long pfn))
 54 {
 55         if (oldmem_pfn_is_ram)
 56                 return -EBUSY;
 57         oldmem_pfn_is_ram = fn;
 58         return 0;
 59 }
 60 EXPORT_SYMBOL_GPL(register_oldmem_pfn_is_ram);
 61 
 62 void unregister_oldmem_pfn_is_ram(void)
 63 {
 64         oldmem_pfn_is_ram = NULL;
 65         wmb();
 66 }
 67 EXPORT_SYMBOL_GPL(unregister_oldmem_pfn_is_ram);
 68 
 69 static int pfn_is_ram(unsigned long pfn)
 70 {
 71         int (*fn)(unsigned long pfn);
 72         /* pfn is ram unless fn() checks pagetype */
 73         int ret = 1;
 74 
 75         /*
 76          * Ask hypervisor if the pfn is really ram.
 77          * A ballooned page contains no data and reading from such a page
 78          * will cause high load in the hypervisor.
 79          */
 80         fn = oldmem_pfn_is_ram;
 81         if (fn)
 82                 ret = fn(pfn);
 83 
 84         return ret;
 85 }
 86 
 87 /* Reads a page from the oldmem device from given offset. */
 88 static ssize_t read_from_oldmem(char *buf, size_t count,
 89                                 u64 *ppos, int userbuf)
 90 {
 91         unsigned long pfn, offset;
 92         size_t nr_bytes;
 93         ssize_t read = 0, tmp;
 94 
 95         if (!count)
 96                 return 0;
 97 
 98         offset = (unsigned long)(*ppos % PAGE_SIZE);
 99         pfn = (unsigned long)(*ppos / PAGE_SIZE);
100 
101         do {
102                 if (count > (PAGE_SIZE - offset))
103                         nr_bytes = PAGE_SIZE - offset;
104                 else
105                         nr_bytes = count;
106 
107                 /* If pfn is not ram, return zeros for sparse dump files */
108                 if (pfn_is_ram(pfn) == 0)
109                         memset(buf, 0, nr_bytes);
110                 else {
111                         tmp = copy_oldmem_page(pfn, buf, nr_bytes,
112                                                 offset, userbuf);
113                         if (tmp < 0)
114                                 return tmp;
115                 }
116                 *ppos += nr_bytes;
117                 count -= nr_bytes;
118                 buf += nr_bytes;
119                 read += nr_bytes;
120                 ++pfn;
121                 offset = 0;
122         } while (count);
123 
124         return read;
125 }
126 
127 /*
128  * Architectures may override this function to allocate ELF header in 2nd kernel
129  */
130 int __weak elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size)
131 {
132         return 0;
133 }
134 
135 /*
136  * Architectures may override this function to free header
137  */
138 void __weak elfcorehdr_free(unsigned long long addr)
139 {}
140 
141 /*
142  * Architectures may override this function to read from ELF header
143  */
144 ssize_t __weak elfcorehdr_read(char *buf, size_t count, u64 *ppos)
145 {
146         return read_from_oldmem(buf, count, ppos, 0);
147 }
148 
149 /*
150  * Architectures may override this function to read from notes sections
151  */
152 ssize_t __weak elfcorehdr_read_notes(char *buf, size_t count, u64 *ppos)
153 {
154         return read_from_oldmem(buf, count, ppos, 0);
155 }
156 
157 /*
158  * Architectures may override this function to map oldmem
159  */
160 int __weak remap_oldmem_pfn_range(struct vm_area_struct *vma,
161                                   unsigned long from, unsigned long pfn,
162                                   unsigned long size, pgprot_t prot)
163 {
164         return remap_pfn_range(vma, from, pfn, size, prot);
165 }
166 
167 /*
168  * Copy to either kernel or user space
169  */
170 static int copy_to(void *target, void *src, size_t size, int userbuf)
171 {
172         if (userbuf) {
173                 if (copy_to_user((char __user *) target, src, size))
174                         return -EFAULT;
175         } else {
176                 memcpy(target, src, size);
177         }
178         return 0;
179 }
180 
181 /* Read from the ELF header and then the crash dump. On error, negative value is
182  * returned otherwise number of bytes read are returned.
183  */
184 static ssize_t __read_vmcore(char *buffer, size_t buflen, loff_t *fpos,
185                              int userbuf)
186 {
187         ssize_t acc = 0, tmp;
188         size_t tsz;
189         u64 start;
190         struct vmcore *m = NULL;
191 
192         if (buflen == 0 || *fpos >= vmcore_size)
193                 return 0;
194 
195         /* trim buflen to not go beyond EOF */
196         if (buflen > vmcore_size - *fpos)
197                 buflen = vmcore_size - *fpos;
198 
199         /* Read ELF core header */
200         if (*fpos < elfcorebuf_sz) {
201                 tsz = min(elfcorebuf_sz - (size_t)*fpos, buflen);
202                 if (copy_to(buffer, elfcorebuf + *fpos, tsz, userbuf))
203                         return -EFAULT;
204                 buflen -= tsz;
205                 *fpos += tsz;
206                 buffer += tsz;
207                 acc += tsz;
208 
209                 /* leave now if filled buffer already */
210                 if (buflen == 0)
211                         return acc;
212         }
213 
214         /* Read Elf note segment */
215         if (*fpos < elfcorebuf_sz + elfnotes_sz) {
216                 void *kaddr;
217 
218                 tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)*fpos, buflen);
219                 kaddr = elfnotes_buf + *fpos - elfcorebuf_sz;
220                 if (copy_to(buffer, kaddr, tsz, userbuf))
221                         return -EFAULT;
222                 buflen -= tsz;
223                 *fpos += tsz;
224                 buffer += tsz;
225                 acc += tsz;
226 
227                 /* leave now if filled buffer already */
228                 if (buflen == 0)
229                         return acc;
230         }
231 
232         list_for_each_entry(m, &vmcore_list, list) {
233                 if (*fpos < m->offset + m->size) {
234                         tsz = (size_t)min_t(unsigned long long,
235                                             m->offset + m->size - *fpos,
236                                             buflen);
237                         start = m->paddr + *fpos - m->offset;
238                         tmp = read_from_oldmem(buffer, tsz, &start, userbuf);
239                         if (tmp < 0)
240                                 return tmp;
241                         buflen -= tsz;
242                         *fpos += tsz;
243                         buffer += tsz;
244                         acc += tsz;
245 
246                         /* leave now if filled buffer already */
247                         if (buflen == 0)
248                                 return acc;
249                 }
250         }
251 
252         return acc;
253 }
254 
255 static ssize_t read_vmcore(struct file *file, char __user *buffer,
256                            size_t buflen, loff_t *fpos)
257 {
258         return __read_vmcore((__force char *) buffer, buflen, fpos, 1);
259 }
260 
261 /*
262  * The vmcore fault handler uses the page cache and fills data using the
263  * standard __vmcore_read() function.
264  *
265  * On s390 the fault handler is used for memory regions that can't be mapped
266  * directly with remap_pfn_range().
267  */
268 static int mmap_vmcore_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
269 {
270 #ifdef CONFIG_S390
271         struct address_space *mapping = vma->vm_file->f_mapping;
272         pgoff_t index = vmf->pgoff;
273         struct page *page;
274         loff_t offset;
275         char *buf;
276         int rc;
277 
278         page = find_or_create_page(mapping, index, GFP_KERNEL);
279         if (!page)
280                 return VM_FAULT_OOM;
281         if (!PageUptodate(page)) {
282                 offset = (loff_t) index << PAGE_SHIFT;
283                 buf = __va((page_to_pfn(page) << PAGE_SHIFT));
284                 rc = __read_vmcore(buf, PAGE_SIZE, &offset, 0);
285                 if (rc < 0) {
286                         unlock_page(page);
287                         put_page(page);
288                         return (rc == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS;
289                 }
290                 SetPageUptodate(page);
291         }
292         unlock_page(page);
293         vmf->page = page;
294         return 0;
295 #else
296         return VM_FAULT_SIGBUS;
297 #endif
298 }
299 
300 static const struct vm_operations_struct vmcore_mmap_ops = {
301         .fault = mmap_vmcore_fault,
302 };
303 
304 /**
305  * alloc_elfnotes_buf - allocate buffer for ELF note segment in
306  *                      vmalloc memory
307  *
308  * @notes_sz: size of buffer
309  *
310  * If CONFIG_MMU is defined, use vmalloc_user() to allow users to mmap
311  * the buffer to user-space by means of remap_vmalloc_range().
312  *
313  * If CONFIG_MMU is not defined, use vzalloc() since mmap_vmcore() is
314  * disabled and there's no need to allow users to mmap the buffer.
315  */
316 static inline char *alloc_elfnotes_buf(size_t notes_sz)
317 {
318 #ifdef CONFIG_MMU
319         return vmalloc_user(notes_sz);
320 #else
321         return vzalloc(notes_sz);
322 #endif
323 }
324 
325 /*
326  * Disable mmap_vmcore() if CONFIG_MMU is not defined. MMU is
327  * essential for mmap_vmcore() in order to map physically
328  * non-contiguous objects (ELF header, ELF note segment and memory
329  * regions in the 1st kernel pointed to by PT_LOAD entries) into
330  * virtually contiguous user-space in ELF layout.
331  */
332 #ifdef CONFIG_MMU
333 /*
334  * remap_oldmem_pfn_checked - do remap_oldmem_pfn_range replacing all pages
335  * reported as not being ram with the zero page.
336  *
337  * @vma: vm_area_struct describing requested mapping
338  * @from: start remapping from
339  * @pfn: page frame number to start remapping to
340  * @size: remapping size
341  * @prot: protection bits
342  *
343  * Returns zero on success, -EAGAIN on failure.
344  */
345 static int remap_oldmem_pfn_checked(struct vm_area_struct *vma,
346                                     unsigned long from, unsigned long pfn,
347                                     unsigned long size, pgprot_t prot)
348 {
349         unsigned long map_size;
350         unsigned long pos_start, pos_end, pos;
351         unsigned long zeropage_pfn = my_zero_pfn(0);
352         size_t len = 0;
353 
354         pos_start = pfn;
355         pos_end = pfn + (size >> PAGE_SHIFT);
356 
357         for (pos = pos_start; pos < pos_end; ++pos) {
358                 if (!pfn_is_ram(pos)) {
359                         /*
360                          * We hit a page which is not ram. Remap the continuous
361                          * region between pos_start and pos-1 and replace
362                          * the non-ram page at pos with the zero page.
363                          */
364                         if (pos > pos_start) {
365                                 /* Remap continuous region */
366                                 map_size = (pos - pos_start) << PAGE_SHIFT;
367                                 if (remap_oldmem_pfn_range(vma, from + len,
368                                                            pos_start, map_size,
369                                                            prot))
370                                         goto fail;
371                                 len += map_size;
372                         }
373                         /* Remap the zero page */
374                         if (remap_oldmem_pfn_range(vma, from + len,
375                                                    zeropage_pfn,
376                                                    PAGE_SIZE, prot))
377                                 goto fail;
378                         len += PAGE_SIZE;
379                         pos_start = pos + 1;
380                 }
381         }
382         if (pos > pos_start) {
383                 /* Remap the rest */
384                 map_size = (pos - pos_start) << PAGE_SHIFT;
385                 if (remap_oldmem_pfn_range(vma, from + len, pos_start,
386                                            map_size, prot))
387                         goto fail;
388         }
389         return 0;
390 fail:
391         do_munmap(vma->vm_mm, from, len);
392         return -EAGAIN;
393 }
394 
395 static int vmcore_remap_oldmem_pfn(struct vm_area_struct *vma,
396                             unsigned long from, unsigned long pfn,
397                             unsigned long size, pgprot_t prot)
398 {
399         /*
400          * Check if oldmem_pfn_is_ram was registered to avoid
401          * looping over all pages without a reason.
402          */
403         if (oldmem_pfn_is_ram)
404                 return remap_oldmem_pfn_checked(vma, from, pfn, size, prot);
405         else
406                 return remap_oldmem_pfn_range(vma, from, pfn, size, prot);
407 }
408 
409 static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
410 {
411         size_t size = vma->vm_end - vma->vm_start;
412         u64 start, end, len, tsz;
413         struct vmcore *m;
414 
415         start = (u64)vma->vm_pgoff << PAGE_SHIFT;
416         end = start + size;
417 
418         if (size > vmcore_size || end > vmcore_size)
419                 return -EINVAL;
420 
421         if (vma->vm_flags & (VM_WRITE | VM_EXEC))
422                 return -EPERM;
423 
424         vma->vm_flags &= ~(VM_MAYWRITE | VM_MAYEXEC);
425         vma->vm_flags |= VM_MIXEDMAP;
426         vma->vm_ops = &vmcore_mmap_ops;
427 
428         len = 0;
429 
430         if (start < elfcorebuf_sz) {
431                 u64 pfn;
432 
433                 tsz = min(elfcorebuf_sz - (size_t)start, size);
434                 pfn = __pa(elfcorebuf + start) >> PAGE_SHIFT;
435                 if (remap_pfn_range(vma, vma->vm_start, pfn, tsz,
436                                     vma->vm_page_prot))
437                         return -EAGAIN;
438                 size -= tsz;
439                 start += tsz;
440                 len += tsz;
441 
442                 if (size == 0)
443                         return 0;
444         }
445 
446         if (start < elfcorebuf_sz + elfnotes_sz) {
447                 void *kaddr;
448 
449                 tsz = min(elfcorebuf_sz + elfnotes_sz - (size_t)start, size);
450                 kaddr = elfnotes_buf + start - elfcorebuf_sz;
451                 if (remap_vmalloc_range_partial(vma, vma->vm_start + len,
452                                                 kaddr, tsz))
453                         goto fail;
454                 size -= tsz;
455                 start += tsz;
456                 len += tsz;
457 
458                 if (size == 0)
459                         return 0;
460         }
461 
462         list_for_each_entry(m, &vmcore_list, list) {
463                 if (start < m->offset + m->size) {
464                         u64 paddr = 0;
465 
466                         tsz = (size_t)min_t(unsigned long long,
467                                             m->offset + m->size - start, size);
468                         paddr = m->paddr + start - m->offset;
469                         if (vmcore_remap_oldmem_pfn(vma, vma->vm_start + len,
470                                                     paddr >> PAGE_SHIFT, tsz,
471                                                     vma->vm_page_prot))
472                                 goto fail;
473                         size -= tsz;
474                         start += tsz;
475                         len += tsz;
476 
477                         if (size == 0)
478                                 return 0;
479                 }
480         }
481 
482         return 0;
483 fail:
484         do_munmap(vma->vm_mm, vma->vm_start, len);
485         return -EAGAIN;
486 }
487 #else
488 static int mmap_vmcore(struct file *file, struct vm_area_struct *vma)
489 {
490         return -ENOSYS;
491 }
492 #endif
493 
494 static const struct file_operations proc_vmcore_operations = {
495         .read           = read_vmcore,
496         .llseek         = default_llseek,
497         .mmap           = mmap_vmcore,
498 };
499 
500 static struct vmcore* __init get_new_element(void)
501 {
502         return kzalloc(sizeof(struct vmcore), GFP_KERNEL);
503 }
504 
505 static u64 __init get_vmcore_size(size_t elfsz, size_t elfnotesegsz,
506                                   struct list_head *vc_list)
507 {
508         u64 size;
509         struct vmcore *m;
510 
511         size = elfsz + elfnotesegsz;
512         list_for_each_entry(m, vc_list, list) {
513                 size += m->size;
514         }
515         return size;
516 }
517 
518 /**
519  * update_note_header_size_elf64 - update p_memsz member of each PT_NOTE entry
520  *
521  * @ehdr_ptr: ELF header
522  *
523  * This function updates p_memsz member of each PT_NOTE entry in the
524  * program header table pointed to by @ehdr_ptr to real size of ELF
525  * note segment.
526  */
527 static int __init update_note_header_size_elf64(const Elf64_Ehdr *ehdr_ptr)
528 {
529         int i, rc=0;
530         Elf64_Phdr *phdr_ptr;
531         Elf64_Nhdr *nhdr_ptr;
532 
533         phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
534         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
535                 void *notes_section;
536                 u64 offset, max_sz, sz, real_sz = 0;
537                 if (phdr_ptr->p_type != PT_NOTE)
538                         continue;
539                 max_sz = phdr_ptr->p_memsz;
540                 offset = phdr_ptr->p_offset;
541                 notes_section = kmalloc(max_sz, GFP_KERNEL);
542                 if (!notes_section)
543                         return -ENOMEM;
544                 rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
545                 if (rc < 0) {
546                         kfree(notes_section);
547                         return rc;
548                 }
549                 nhdr_ptr = notes_section;
550                 while (nhdr_ptr->n_namesz != 0) {
551                         sz = sizeof(Elf64_Nhdr) +
552                                 (((u64)nhdr_ptr->n_namesz + 3) & ~3) +
553                                 (((u64)nhdr_ptr->n_descsz + 3) & ~3);
554                         if ((real_sz + sz) > max_sz) {
555                                 pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
556                                         nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
557                                 break;
558                         }
559                         real_sz += sz;
560                         nhdr_ptr = (Elf64_Nhdr*)((char*)nhdr_ptr + sz);
561                 }
562                 kfree(notes_section);
563                 phdr_ptr->p_memsz = real_sz;
564                 if (real_sz == 0) {
565                         pr_warn("Warning: Zero PT_NOTE entries found\n");
566                 }
567         }
568 
569         return 0;
570 }
571 
572 /**
573  * get_note_number_and_size_elf64 - get the number of PT_NOTE program
574  * headers and sum of real size of their ELF note segment headers and
575  * data.
576  *
577  * @ehdr_ptr: ELF header
578  * @nr_ptnote: buffer for the number of PT_NOTE program headers
579  * @sz_ptnote: buffer for size of unique PT_NOTE program header
580  *
581  * This function is used to merge multiple PT_NOTE program headers
582  * into a unique single one. The resulting unique entry will have
583  * @sz_ptnote in its phdr->p_mem.
584  *
585  * It is assumed that program headers with PT_NOTE type pointed to by
586  * @ehdr_ptr has already been updated by update_note_header_size_elf64
587  * and each of PT_NOTE program headers has actual ELF note segment
588  * size in its p_memsz member.
589  */
590 static int __init get_note_number_and_size_elf64(const Elf64_Ehdr *ehdr_ptr,
591                                                  int *nr_ptnote, u64 *sz_ptnote)
592 {
593         int i;
594         Elf64_Phdr *phdr_ptr;
595 
596         *nr_ptnote = *sz_ptnote = 0;
597 
598         phdr_ptr = (Elf64_Phdr *)(ehdr_ptr + 1);
599         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
600                 if (phdr_ptr->p_type != PT_NOTE)
601                         continue;
602                 *nr_ptnote += 1;
603                 *sz_ptnote += phdr_ptr->p_memsz;
604         }
605 
606         return 0;
607 }
608 
609 /**
610  * copy_notes_elf64 - copy ELF note segments in a given buffer
611  *
612  * @ehdr_ptr: ELF header
613  * @notes_buf: buffer into which ELF note segments are copied
614  *
615  * This function is used to copy ELF note segment in the 1st kernel
616  * into the buffer @notes_buf in the 2nd kernel. It is assumed that
617  * size of the buffer @notes_buf is equal to or larger than sum of the
618  * real ELF note segment headers and data.
619  *
620  * It is assumed that program headers with PT_NOTE type pointed to by
621  * @ehdr_ptr has already been updated by update_note_header_size_elf64
622  * and each of PT_NOTE program headers has actual ELF note segment
623  * size in its p_memsz member.
624  */
625 static int __init copy_notes_elf64(const Elf64_Ehdr *ehdr_ptr, char *notes_buf)
626 {
627         int i, rc=0;
628         Elf64_Phdr *phdr_ptr;
629 
630         phdr_ptr = (Elf64_Phdr*)(ehdr_ptr + 1);
631 
632         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
633                 u64 offset;
634                 if (phdr_ptr->p_type != PT_NOTE)
635                         continue;
636                 offset = phdr_ptr->p_offset;
637                 rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
638                                            &offset);
639                 if (rc < 0)
640                         return rc;
641                 notes_buf += phdr_ptr->p_memsz;
642         }
643 
644         return 0;
645 }
646 
647 /* Merges all the PT_NOTE headers into one. */
648 static int __init merge_note_headers_elf64(char *elfptr, size_t *elfsz,
649                                            char **notes_buf, size_t *notes_sz)
650 {
651         int i, nr_ptnote=0, rc=0;
652         char *tmp;
653         Elf64_Ehdr *ehdr_ptr;
654         Elf64_Phdr phdr;
655         u64 phdr_sz = 0, note_off;
656 
657         ehdr_ptr = (Elf64_Ehdr *)elfptr;
658 
659         rc = update_note_header_size_elf64(ehdr_ptr);
660         if (rc < 0)
661                 return rc;
662 
663         rc = get_note_number_and_size_elf64(ehdr_ptr, &nr_ptnote, &phdr_sz);
664         if (rc < 0)
665                 return rc;
666 
667         *notes_sz = roundup(phdr_sz, PAGE_SIZE);
668         *notes_buf = alloc_elfnotes_buf(*notes_sz);
669         if (!*notes_buf)
670                 return -ENOMEM;
671 
672         rc = copy_notes_elf64(ehdr_ptr, *notes_buf);
673         if (rc < 0)
674                 return rc;
675 
676         /* Prepare merged PT_NOTE program header. */
677         phdr.p_type    = PT_NOTE;
678         phdr.p_flags   = 0;
679         note_off = sizeof(Elf64_Ehdr) +
680                         (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf64_Phdr);
681         phdr.p_offset  = roundup(note_off, PAGE_SIZE);
682         phdr.p_vaddr   = phdr.p_paddr = 0;
683         phdr.p_filesz  = phdr.p_memsz = phdr_sz;
684         phdr.p_align   = 0;
685 
686         /* Add merged PT_NOTE program header*/
687         tmp = elfptr + sizeof(Elf64_Ehdr);
688         memcpy(tmp, &phdr, sizeof(phdr));
689         tmp += sizeof(phdr);
690 
691         /* Remove unwanted PT_NOTE program headers. */
692         i = (nr_ptnote - 1) * sizeof(Elf64_Phdr);
693         *elfsz = *elfsz - i;
694         memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf64_Ehdr)-sizeof(Elf64_Phdr)));
695         memset(elfptr + *elfsz, 0, i);
696         *elfsz = roundup(*elfsz, PAGE_SIZE);
697 
698         /* Modify e_phnum to reflect merged headers. */
699         ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
700 
701         return 0;
702 }
703 
704 /**
705  * update_note_header_size_elf32 - update p_memsz member of each PT_NOTE entry
706  *
707  * @ehdr_ptr: ELF header
708  *
709  * This function updates p_memsz member of each PT_NOTE entry in the
710  * program header table pointed to by @ehdr_ptr to real size of ELF
711  * note segment.
712  */
713 static int __init update_note_header_size_elf32(const Elf32_Ehdr *ehdr_ptr)
714 {
715         int i, rc=0;
716         Elf32_Phdr *phdr_ptr;
717         Elf32_Nhdr *nhdr_ptr;
718 
719         phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
720         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
721                 void *notes_section;
722                 u64 offset, max_sz, sz, real_sz = 0;
723                 if (phdr_ptr->p_type != PT_NOTE)
724                         continue;
725                 max_sz = phdr_ptr->p_memsz;
726                 offset = phdr_ptr->p_offset;
727                 notes_section = kmalloc(max_sz, GFP_KERNEL);
728                 if (!notes_section)
729                         return -ENOMEM;
730                 rc = elfcorehdr_read_notes(notes_section, max_sz, &offset);
731                 if (rc < 0) {
732                         kfree(notes_section);
733                         return rc;
734                 }
735                 nhdr_ptr = notes_section;
736                 while (nhdr_ptr->n_namesz != 0) {
737                         sz = sizeof(Elf32_Nhdr) +
738                                 (((u64)nhdr_ptr->n_namesz + 3) & ~3) +
739                                 (((u64)nhdr_ptr->n_descsz + 3) & ~3);
740                         if ((real_sz + sz) > max_sz) {
741                                 pr_warn("Warning: Exceeded p_memsz, dropping PT_NOTE entry n_namesz=0x%x, n_descsz=0x%x\n",
742                                         nhdr_ptr->n_namesz, nhdr_ptr->n_descsz);
743                                 break;
744                         }
745                         real_sz += sz;
746                         nhdr_ptr = (Elf32_Nhdr*)((char*)nhdr_ptr + sz);
747                 }
748                 kfree(notes_section);
749                 phdr_ptr->p_memsz = real_sz;
750                 if (real_sz == 0) {
751                         pr_warn("Warning: Zero PT_NOTE entries found\n");
752                 }
753         }
754 
755         return 0;
756 }
757 
758 /**
759  * get_note_number_and_size_elf32 - get the number of PT_NOTE program
760  * headers and sum of real size of their ELF note segment headers and
761  * data.
762  *
763  * @ehdr_ptr: ELF header
764  * @nr_ptnote: buffer for the number of PT_NOTE program headers
765  * @sz_ptnote: buffer for size of unique PT_NOTE program header
766  *
767  * This function is used to merge multiple PT_NOTE program headers
768  * into a unique single one. The resulting unique entry will have
769  * @sz_ptnote in its phdr->p_mem.
770  *
771  * It is assumed that program headers with PT_NOTE type pointed to by
772  * @ehdr_ptr has already been updated by update_note_header_size_elf32
773  * and each of PT_NOTE program headers has actual ELF note segment
774  * size in its p_memsz member.
775  */
776 static int __init get_note_number_and_size_elf32(const Elf32_Ehdr *ehdr_ptr,
777                                                  int *nr_ptnote, u64 *sz_ptnote)
778 {
779         int i;
780         Elf32_Phdr *phdr_ptr;
781 
782         *nr_ptnote = *sz_ptnote = 0;
783 
784         phdr_ptr = (Elf32_Phdr *)(ehdr_ptr + 1);
785         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
786                 if (phdr_ptr->p_type != PT_NOTE)
787                         continue;
788                 *nr_ptnote += 1;
789                 *sz_ptnote += phdr_ptr->p_memsz;
790         }
791 
792         return 0;
793 }
794 
795 /**
796  * copy_notes_elf32 - copy ELF note segments in a given buffer
797  *
798  * @ehdr_ptr: ELF header
799  * @notes_buf: buffer into which ELF note segments are copied
800  *
801  * This function is used to copy ELF note segment in the 1st kernel
802  * into the buffer @notes_buf in the 2nd kernel. It is assumed that
803  * size of the buffer @notes_buf is equal to or larger than sum of the
804  * real ELF note segment headers and data.
805  *
806  * It is assumed that program headers with PT_NOTE type pointed to by
807  * @ehdr_ptr has already been updated by update_note_header_size_elf32
808  * and each of PT_NOTE program headers has actual ELF note segment
809  * size in its p_memsz member.
810  */
811 static int __init copy_notes_elf32(const Elf32_Ehdr *ehdr_ptr, char *notes_buf)
812 {
813         int i, rc=0;
814         Elf32_Phdr *phdr_ptr;
815 
816         phdr_ptr = (Elf32_Phdr*)(ehdr_ptr + 1);
817 
818         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
819                 u64 offset;
820                 if (phdr_ptr->p_type != PT_NOTE)
821                         continue;
822                 offset = phdr_ptr->p_offset;
823                 rc = elfcorehdr_read_notes(notes_buf, phdr_ptr->p_memsz,
824                                            &offset);
825                 if (rc < 0)
826                         return rc;
827                 notes_buf += phdr_ptr->p_memsz;
828         }
829 
830         return 0;
831 }
832 
833 /* Merges all the PT_NOTE headers into one. */
834 static int __init merge_note_headers_elf32(char *elfptr, size_t *elfsz,
835                                            char **notes_buf, size_t *notes_sz)
836 {
837         int i, nr_ptnote=0, rc=0;
838         char *tmp;
839         Elf32_Ehdr *ehdr_ptr;
840         Elf32_Phdr phdr;
841         u64 phdr_sz = 0, note_off;
842 
843         ehdr_ptr = (Elf32_Ehdr *)elfptr;
844 
845         rc = update_note_header_size_elf32(ehdr_ptr);
846         if (rc < 0)
847                 return rc;
848 
849         rc = get_note_number_and_size_elf32(ehdr_ptr, &nr_ptnote, &phdr_sz);
850         if (rc < 0)
851                 return rc;
852 
853         *notes_sz = roundup(phdr_sz, PAGE_SIZE);
854         *notes_buf = alloc_elfnotes_buf(*notes_sz);
855         if (!*notes_buf)
856                 return -ENOMEM;
857 
858         rc = copy_notes_elf32(ehdr_ptr, *notes_buf);
859         if (rc < 0)
860                 return rc;
861 
862         /* Prepare merged PT_NOTE program header. */
863         phdr.p_type    = PT_NOTE;
864         phdr.p_flags   = 0;
865         note_off = sizeof(Elf32_Ehdr) +
866                         (ehdr_ptr->e_phnum - nr_ptnote +1) * sizeof(Elf32_Phdr);
867         phdr.p_offset  = roundup(note_off, PAGE_SIZE);
868         phdr.p_vaddr   = phdr.p_paddr = 0;
869         phdr.p_filesz  = phdr.p_memsz = phdr_sz;
870         phdr.p_align   = 0;
871 
872         /* Add merged PT_NOTE program header*/
873         tmp = elfptr + sizeof(Elf32_Ehdr);
874         memcpy(tmp, &phdr, sizeof(phdr));
875         tmp += sizeof(phdr);
876 
877         /* Remove unwanted PT_NOTE program headers. */
878         i = (nr_ptnote - 1) * sizeof(Elf32_Phdr);
879         *elfsz = *elfsz - i;
880         memmove(tmp, tmp+i, ((*elfsz)-sizeof(Elf32_Ehdr)-sizeof(Elf32_Phdr)));
881         memset(elfptr + *elfsz, 0, i);
882         *elfsz = roundup(*elfsz, PAGE_SIZE);
883 
884         /* Modify e_phnum to reflect merged headers. */
885         ehdr_ptr->e_phnum = ehdr_ptr->e_phnum - nr_ptnote + 1;
886 
887         return 0;
888 }
889 
890 /* Add memory chunks represented by program headers to vmcore list. Also update
891  * the new offset fields of exported program headers. */
892 static int __init process_ptload_program_headers_elf64(char *elfptr,
893                                                 size_t elfsz,
894                                                 size_t elfnotes_sz,
895                                                 struct list_head *vc_list)
896 {
897         int i;
898         Elf64_Ehdr *ehdr_ptr;
899         Elf64_Phdr *phdr_ptr;
900         loff_t vmcore_off;
901         struct vmcore *new;
902 
903         ehdr_ptr = (Elf64_Ehdr *)elfptr;
904         phdr_ptr = (Elf64_Phdr*)(elfptr + sizeof(Elf64_Ehdr)); /* PT_NOTE hdr */
905 
906         /* Skip Elf header, program headers and Elf note segment. */
907         vmcore_off = elfsz + elfnotes_sz;
908 
909         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
910                 u64 paddr, start, end, size;
911 
912                 if (phdr_ptr->p_type != PT_LOAD)
913                         continue;
914 
915                 paddr = phdr_ptr->p_offset;
916                 start = rounddown(paddr, PAGE_SIZE);
917                 end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
918                 size = end - start;
919 
920                 /* Add this contiguous chunk of memory to vmcore list.*/
921                 new = get_new_element();
922                 if (!new)
923                         return -ENOMEM;
924                 new->paddr = start;
925                 new->size = size;
926                 list_add_tail(&new->list, vc_list);
927 
928                 /* Update the program header offset. */
929                 phdr_ptr->p_offset = vmcore_off + (paddr - start);
930                 vmcore_off = vmcore_off + size;
931         }
932         return 0;
933 }
934 
935 static int __init process_ptload_program_headers_elf32(char *elfptr,
936                                                 size_t elfsz,
937                                                 size_t elfnotes_sz,
938                                                 struct list_head *vc_list)
939 {
940         int i;
941         Elf32_Ehdr *ehdr_ptr;
942         Elf32_Phdr *phdr_ptr;
943         loff_t vmcore_off;
944         struct vmcore *new;
945 
946         ehdr_ptr = (Elf32_Ehdr *)elfptr;
947         phdr_ptr = (Elf32_Phdr*)(elfptr + sizeof(Elf32_Ehdr)); /* PT_NOTE hdr */
948 
949         /* Skip Elf header, program headers and Elf note segment. */
950         vmcore_off = elfsz + elfnotes_sz;
951 
952         for (i = 0; i < ehdr_ptr->e_phnum; i++, phdr_ptr++) {
953                 u64 paddr, start, end, size;
954 
955                 if (phdr_ptr->p_type != PT_LOAD)
956                         continue;
957 
958                 paddr = phdr_ptr->p_offset;
959                 start = rounddown(paddr, PAGE_SIZE);
960                 end = roundup(paddr + phdr_ptr->p_memsz, PAGE_SIZE);
961                 size = end - start;
962 
963                 /* Add this contiguous chunk of memory to vmcore list.*/
964                 new = get_new_element();
965                 if (!new)
966                         return -ENOMEM;
967                 new->paddr = start;
968                 new->size = size;
969                 list_add_tail(&new->list, vc_list);
970 
971                 /* Update the program header offset */
972                 phdr_ptr->p_offset = vmcore_off + (paddr - start);
973                 vmcore_off = vmcore_off + size;
974         }
975         return 0;
976 }
977 
978 /* Sets offset fields of vmcore elements. */
979 static void __init set_vmcore_list_offsets(size_t elfsz, size_t elfnotes_sz,
980                                            struct list_head *vc_list)
981 {
982         loff_t vmcore_off;
983         struct vmcore *m;
984 
985         /* Skip Elf header, program headers and Elf note segment. */
986         vmcore_off = elfsz + elfnotes_sz;
987 
988         list_for_each_entry(m, vc_list, list) {
989                 m->offset = vmcore_off;
990                 vmcore_off += m->size;
991         }
992 }
993 
994 static void free_elfcorebuf(void)
995 {
996         free_pages((unsigned long)elfcorebuf, get_order(elfcorebuf_sz_orig));
997         elfcorebuf = NULL;
998         vfree(elfnotes_buf);
999         elfnotes_buf = NULL;
1000 }
1001 
1002 static int __init parse_crash_elf64_headers(void)
1003 {
1004         int rc=0;
1005         Elf64_Ehdr ehdr;
1006         u64 addr;
1007 
1008         addr = elfcorehdr_addr;
1009 
1010         /* Read Elf header */
1011         rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf64_Ehdr), &addr);
1012         if (rc < 0)
1013                 return rc;
1014 
1015         /* Do some basic Verification. */
1016         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
1017                 (ehdr.e_type != ET_CORE) ||
1018                 !vmcore_elf64_check_arch(&ehdr) ||
1019                 ehdr.e_ident[EI_CLASS] != ELFCLASS64 ||
1020                 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
1021                 ehdr.e_version != EV_CURRENT ||
1022                 ehdr.e_ehsize != sizeof(Elf64_Ehdr) ||
1023                 ehdr.e_phentsize != sizeof(Elf64_Phdr) ||
1024                 ehdr.e_phnum == 0) {
1025                 pr_warn("Warning: Core image elf header is not sane\n");
1026                 return -EINVAL;
1027         }
1028 
1029         /* Read in all elf headers. */
1030         elfcorebuf_sz_orig = sizeof(Elf64_Ehdr) +
1031                                 ehdr.e_phnum * sizeof(Elf64_Phdr);
1032         elfcorebuf_sz = elfcorebuf_sz_orig;
1033         elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
1034                                               get_order(elfcorebuf_sz_orig));
1035         if (!elfcorebuf)
1036                 return -ENOMEM;
1037         addr = elfcorehdr_addr;
1038         rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
1039         if (rc < 0)
1040                 goto fail;
1041 
1042         /* Merge all PT_NOTE headers into one. */
1043         rc = merge_note_headers_elf64(elfcorebuf, &elfcorebuf_sz,
1044                                       &elfnotes_buf, &elfnotes_sz);
1045         if (rc)
1046                 goto fail;
1047         rc = process_ptload_program_headers_elf64(elfcorebuf, elfcorebuf_sz,
1048                                                   elfnotes_sz, &vmcore_list);
1049         if (rc)
1050                 goto fail;
1051         set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
1052         return 0;
1053 fail:
1054         free_elfcorebuf();
1055         return rc;
1056 }
1057 
1058 static int __init parse_crash_elf32_headers(void)
1059 {
1060         int rc=0;
1061         Elf32_Ehdr ehdr;
1062         u64 addr;
1063 
1064         addr = elfcorehdr_addr;
1065 
1066         /* Read Elf header */
1067         rc = elfcorehdr_read((char *)&ehdr, sizeof(Elf32_Ehdr), &addr);
1068         if (rc < 0)
1069                 return rc;
1070 
1071         /* Do some basic Verification. */
1072         if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0 ||
1073                 (ehdr.e_type != ET_CORE) ||
1074                 !vmcore_elf32_check_arch(&ehdr) ||
1075                 ehdr.e_ident[EI_CLASS] != ELFCLASS32||
1076                 ehdr.e_ident[EI_VERSION] != EV_CURRENT ||
1077                 ehdr.e_version != EV_CURRENT ||
1078                 ehdr.e_ehsize != sizeof(Elf32_Ehdr) ||
1079                 ehdr.e_phentsize != sizeof(Elf32_Phdr) ||
1080                 ehdr.e_phnum == 0) {
1081                 pr_warn("Warning: Core image elf header is not sane\n");
1082                 return -EINVAL;
1083         }
1084 
1085         /* Read in all elf headers. */
1086         elfcorebuf_sz_orig = sizeof(Elf32_Ehdr) + ehdr.e_phnum * sizeof(Elf32_Phdr);
1087         elfcorebuf_sz = elfcorebuf_sz_orig;
1088         elfcorebuf = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
1089                                               get_order(elfcorebuf_sz_orig));
1090         if (!elfcorebuf)
1091                 return -ENOMEM;
1092         addr = elfcorehdr_addr;
1093         rc = elfcorehdr_read(elfcorebuf, elfcorebuf_sz_orig, &addr);
1094         if (rc < 0)
1095                 goto fail;
1096 
1097         /* Merge all PT_NOTE headers into one. */
1098         rc = merge_note_headers_elf32(elfcorebuf, &elfcorebuf_sz,
1099                                       &elfnotes_buf, &elfnotes_sz);
1100         if (rc)
1101                 goto fail;
1102         rc = process_ptload_program_headers_elf32(elfcorebuf, elfcorebuf_sz,
1103                                                   elfnotes_sz, &vmcore_list);
1104         if (rc)
1105                 goto fail;
1106         set_vmcore_list_offsets(elfcorebuf_sz, elfnotes_sz, &vmcore_list);
1107         return 0;
1108 fail:
1109         free_elfcorebuf();
1110         return rc;
1111 }
1112 
1113 static int __init parse_crash_elf_headers(void)
1114 {
1115         unsigned char e_ident[EI_NIDENT];
1116         u64 addr;
1117         int rc=0;
1118 
1119         addr = elfcorehdr_addr;
1120         rc = elfcorehdr_read(e_ident, EI_NIDENT, &addr);
1121         if (rc < 0)
1122                 return rc;
1123         if (memcmp(e_ident, ELFMAG, SELFMAG) != 0) {
1124                 pr_warn("Warning: Core image elf header not found\n");
1125                 return -EINVAL;
1126         }
1127 
1128         if (e_ident[EI_CLASS] == ELFCLASS64) {
1129                 rc = parse_crash_elf64_headers();
1130                 if (rc)
1131                         return rc;
1132         } else if (e_ident[EI_CLASS] == ELFCLASS32) {
1133                 rc = parse_crash_elf32_headers();
1134                 if (rc)
1135                         return rc;
1136         } else {
1137                 pr_warn("Warning: Core image elf header is not sane\n");
1138                 return -EINVAL;
1139         }
1140 
1141         /* Determine vmcore size. */
1142         vmcore_size = get_vmcore_size(elfcorebuf_sz, elfnotes_sz,
1143                                       &vmcore_list);
1144 
1145         return 0;
1146 }
1147 
1148 /* Init function for vmcore module. */
1149 static int __init vmcore_init(void)
1150 {
1151         int rc = 0;
1152 
1153         /* Allow architectures to allocate ELF header in 2nd kernel */
1154         rc = elfcorehdr_alloc(&elfcorehdr_addr, &elfcorehdr_size);
1155         if (rc)
1156                 return rc;
1157         /*
1158          * If elfcorehdr= has been passed in cmdline or created in 2nd kernel,
1159          * then capture the dump.
1160          */
1161         if (!(is_vmcore_usable()))
1162                 return rc;
1163         rc = parse_crash_elf_headers();
1164         if (rc) {
1165                 pr_warn("Kdump: vmcore not initialized\n");
1166                 return rc;
1167         }
1168         elfcorehdr_free(elfcorehdr_addr);
1169         elfcorehdr_addr = ELFCORE_ADDR_ERR;
1170 
1171         proc_vmcore = proc_create("vmcore", S_IRUSR, NULL, &proc_vmcore_operations);
1172         if (proc_vmcore)
1173                 proc_vmcore->size = vmcore_size;
1174         return 0;
1175 }
1176 fs_initcall(vmcore_init);
1177 
1178 /* Cleanup function for vmcore module. */
1179 void vmcore_cleanup(void)
1180 {
1181         struct list_head *pos, *next;
1182 
1183         if (proc_vmcore) {
1184                 proc_remove(proc_vmcore);
1185                 proc_vmcore = NULL;
1186         }
1187 
1188         /* clear the vmcore list. */
1189         list_for_each_safe(pos, next, &vmcore_list) {
1190                 struct vmcore *m;
1191 
1192                 m = list_entry(pos, struct vmcore, list);
1193                 list_del(&m->list);
1194                 kfree(m);
1195         }
1196         free_elfcorebuf();
1197 }
1198 

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