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

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