kthread: rename probe_kthread_data() to kthread_probe_data()
[linux-2.6-block.git] / kernel / kexec_file.c
1 /*
2  * kexec: kexec_file_load system call
3  *
4  * Copyright (C) 2014 Red Hat Inc.
5  * Authors:
6  *      Vivek Goyal <vgoyal@redhat.com>
7  *
8  * This source code is licensed under the GNU General Public License,
9  * Version 2.  See the file COPYING for more details.
10  */
11
12 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14 #include <linux/capability.h>
15 #include <linux/mm.h>
16 #include <linux/file.h>
17 #include <linux/slab.h>
18 #include <linux/kexec.h>
19 #include <linux/mutex.h>
20 #include <linux/list.h>
21 #include <linux/fs.h>
22 #include <crypto/hash.h>
23 #include <crypto/sha.h>
24 #include <linux/syscalls.h>
25 #include <linux/vmalloc.h>
26 #include "kexec_internal.h"
27
28 /*
29  * Declare these symbols weak so that if architecture provides a purgatory,
30  * these will be overridden.
31  */
32 char __weak kexec_purgatory[0];
33 size_t __weak kexec_purgatory_size = 0;
34
35 static int kexec_calculate_store_digests(struct kimage *image);
36
37 /* Architectures can provide this probe function */
38 int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
39                                          unsigned long buf_len)
40 {
41         return -ENOEXEC;
42 }
43
44 void * __weak arch_kexec_kernel_image_load(struct kimage *image)
45 {
46         return ERR_PTR(-ENOEXEC);
47 }
48
49 int __weak arch_kimage_file_post_load_cleanup(struct kimage *image)
50 {
51         return -EINVAL;
52 }
53
54 #ifdef CONFIG_KEXEC_VERIFY_SIG
55 int __weak arch_kexec_kernel_verify_sig(struct kimage *image, void *buf,
56                                         unsigned long buf_len)
57 {
58         return -EKEYREJECTED;
59 }
60 #endif
61
62 /* Apply relocations of type RELA */
63 int __weak
64 arch_kexec_apply_relocations_add(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
65                                  unsigned int relsec)
66 {
67         pr_err("RELA relocation unsupported.\n");
68         return -ENOEXEC;
69 }
70
71 /* Apply relocations of type REL */
72 int __weak
73 arch_kexec_apply_relocations(const Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
74                              unsigned int relsec)
75 {
76         pr_err("REL relocation unsupported.\n");
77         return -ENOEXEC;
78 }
79
80 /*
81  * Free up memory used by kernel, initrd, and command line. This is temporary
82  * memory allocation which is not needed any more after these buffers have
83  * been loaded into separate segments and have been copied elsewhere.
84  */
85 void kimage_file_post_load_cleanup(struct kimage *image)
86 {
87         struct purgatory_info *pi = &image->purgatory_info;
88
89         vfree(image->kernel_buf);
90         image->kernel_buf = NULL;
91
92         vfree(image->initrd_buf);
93         image->initrd_buf = NULL;
94
95         kfree(image->cmdline_buf);
96         image->cmdline_buf = NULL;
97
98         vfree(pi->purgatory_buf);
99         pi->purgatory_buf = NULL;
100
101         vfree(pi->sechdrs);
102         pi->sechdrs = NULL;
103
104         /* See if architecture has anything to cleanup post load */
105         arch_kimage_file_post_load_cleanup(image);
106
107         /*
108          * Above call should have called into bootloader to free up
109          * any data stored in kimage->image_loader_data. It should
110          * be ok now to free it up.
111          */
112         kfree(image->image_loader_data);
113         image->image_loader_data = NULL;
114 }
115
116 /*
117  * In file mode list of segments is prepared by kernel. Copy relevant
118  * data from user space, do error checking, prepare segment list
119  */
120 static int
121 kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd,
122                              const char __user *cmdline_ptr,
123                              unsigned long cmdline_len, unsigned flags)
124 {
125         int ret = 0;
126         void *ldata;
127         loff_t size;
128
129         ret = kernel_read_file_from_fd(kernel_fd, &image->kernel_buf,
130                                        &size, INT_MAX, READING_KEXEC_IMAGE);
131         if (ret)
132                 return ret;
133         image->kernel_buf_len = size;
134
135         /* Call arch image probe handlers */
136         ret = arch_kexec_kernel_image_probe(image, image->kernel_buf,
137                                             image->kernel_buf_len);
138         if (ret)
139                 goto out;
140
141 #ifdef CONFIG_KEXEC_VERIFY_SIG
142         ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf,
143                                            image->kernel_buf_len);
144         if (ret) {
145                 pr_debug("kernel signature verification failed.\n");
146                 goto out;
147         }
148         pr_debug("kernel signature verification successful.\n");
149 #endif
150         /* It is possible that there no initramfs is being loaded */
151         if (!(flags & KEXEC_FILE_NO_INITRAMFS)) {
152                 ret = kernel_read_file_from_fd(initrd_fd, &image->initrd_buf,
153                                                &size, INT_MAX,
154                                                READING_KEXEC_INITRAMFS);
155                 if (ret)
156                         goto out;
157                 image->initrd_buf_len = size;
158         }
159
160         if (cmdline_len) {
161                 image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL);
162                 if (!image->cmdline_buf) {
163                         ret = -ENOMEM;
164                         goto out;
165                 }
166
167                 ret = copy_from_user(image->cmdline_buf, cmdline_ptr,
168                                      cmdline_len);
169                 if (ret) {
170                         ret = -EFAULT;
171                         goto out;
172                 }
173
174                 image->cmdline_buf_len = cmdline_len;
175
176                 /* command line should be a string with last byte null */
177                 if (image->cmdline_buf[cmdline_len - 1] != '\0') {
178                         ret = -EINVAL;
179                         goto out;
180                 }
181         }
182
183         /* Call arch image load handlers */
184         ldata = arch_kexec_kernel_image_load(image);
185
186         if (IS_ERR(ldata)) {
187                 ret = PTR_ERR(ldata);
188                 goto out;
189         }
190
191         image->image_loader_data = ldata;
192 out:
193         /* In case of error, free up all allocated memory in this function */
194         if (ret)
195                 kimage_file_post_load_cleanup(image);
196         return ret;
197 }
198
199 static int
200 kimage_file_alloc_init(struct kimage **rimage, int kernel_fd,
201                        int initrd_fd, const char __user *cmdline_ptr,
202                        unsigned long cmdline_len, unsigned long flags)
203 {
204         int ret;
205         struct kimage *image;
206         bool kexec_on_panic = flags & KEXEC_FILE_ON_CRASH;
207
208         image = do_kimage_alloc_init();
209         if (!image)
210                 return -ENOMEM;
211
212         image->file_mode = 1;
213
214         if (kexec_on_panic) {
215                 /* Enable special crash kernel control page alloc policy. */
216                 image->control_page = crashk_res.start;
217                 image->type = KEXEC_TYPE_CRASH;
218         }
219
220         ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd,
221                                            cmdline_ptr, cmdline_len, flags);
222         if (ret)
223                 goto out_free_image;
224
225         ret = sanity_check_segment_list(image);
226         if (ret)
227                 goto out_free_post_load_bufs;
228
229         ret = -ENOMEM;
230         image->control_code_page = kimage_alloc_control_pages(image,
231                                            get_order(KEXEC_CONTROL_PAGE_SIZE));
232         if (!image->control_code_page) {
233                 pr_err("Could not allocate control_code_buffer\n");
234                 goto out_free_post_load_bufs;
235         }
236
237         if (!kexec_on_panic) {
238                 image->swap_page = kimage_alloc_control_pages(image, 0);
239                 if (!image->swap_page) {
240                         pr_err("Could not allocate swap buffer\n");
241                         goto out_free_control_pages;
242                 }
243         }
244
245         *rimage = image;
246         return 0;
247 out_free_control_pages:
248         kimage_free_page_list(&image->control_pages);
249 out_free_post_load_bufs:
250         kimage_file_post_load_cleanup(image);
251 out_free_image:
252         kfree(image);
253         return ret;
254 }
255
256 SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd,
257                 unsigned long, cmdline_len, const char __user *, cmdline_ptr,
258                 unsigned long, flags)
259 {
260         int ret = 0, i;
261         struct kimage **dest_image, *image;
262
263         /* We only trust the superuser with rebooting the system. */
264         if (!capable(CAP_SYS_BOOT) || kexec_load_disabled)
265                 return -EPERM;
266
267         /* Make sure we have a legal set of flags */
268         if (flags != (flags & KEXEC_FILE_FLAGS))
269                 return -EINVAL;
270
271         image = NULL;
272
273         if (!mutex_trylock(&kexec_mutex))
274                 return -EBUSY;
275
276         dest_image = &kexec_image;
277         if (flags & KEXEC_FILE_ON_CRASH) {
278                 dest_image = &kexec_crash_image;
279                 if (kexec_crash_image)
280                         arch_kexec_unprotect_crashkres();
281         }
282
283         if (flags & KEXEC_FILE_UNLOAD)
284                 goto exchange;
285
286         /*
287          * In case of crash, new kernel gets loaded in reserved region. It is
288          * same memory where old crash kernel might be loaded. Free any
289          * current crash dump kernel before we corrupt it.
290          */
291         if (flags & KEXEC_FILE_ON_CRASH)
292                 kimage_free(xchg(&kexec_crash_image, NULL));
293
294         ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr,
295                                      cmdline_len, flags);
296         if (ret)
297                 goto out;
298
299         ret = machine_kexec_prepare(image);
300         if (ret)
301                 goto out;
302
303         ret = kexec_calculate_store_digests(image);
304         if (ret)
305                 goto out;
306
307         for (i = 0; i < image->nr_segments; i++) {
308                 struct kexec_segment *ksegment;
309
310                 ksegment = &image->segment[i];
311                 pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
312                          i, ksegment->buf, ksegment->bufsz, ksegment->mem,
313                          ksegment->memsz);
314
315                 ret = kimage_load_segment(image, &image->segment[i]);
316                 if (ret)
317                         goto out;
318         }
319
320         kimage_terminate(image);
321
322         /*
323          * Free up any temporary buffers allocated which are not needed
324          * after image has been loaded
325          */
326         kimage_file_post_load_cleanup(image);
327 exchange:
328         image = xchg(dest_image, image);
329 out:
330         if ((flags & KEXEC_FILE_ON_CRASH) && kexec_crash_image)
331                 arch_kexec_protect_crashkres();
332
333         mutex_unlock(&kexec_mutex);
334         kimage_free(image);
335         return ret;
336 }
337
338 static int locate_mem_hole_top_down(unsigned long start, unsigned long end,
339                                     struct kexec_buf *kbuf)
340 {
341         struct kimage *image = kbuf->image;
342         unsigned long temp_start, temp_end;
343
344         temp_end = min(end, kbuf->buf_max);
345         temp_start = temp_end - kbuf->memsz;
346
347         do {
348                 /* align down start */
349                 temp_start = temp_start & (~(kbuf->buf_align - 1));
350
351                 if (temp_start < start || temp_start < kbuf->buf_min)
352                         return 0;
353
354                 temp_end = temp_start + kbuf->memsz - 1;
355
356                 /*
357                  * Make sure this does not conflict with any of existing
358                  * segments
359                  */
360                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
361                         temp_start = temp_start - PAGE_SIZE;
362                         continue;
363                 }
364
365                 /* We found a suitable memory range */
366                 break;
367         } while (1);
368
369         /* If we are here, we found a suitable memory range */
370         kbuf->mem = temp_start;
371
372         /* Success, stop navigating through remaining System RAM ranges */
373         return 1;
374 }
375
376 static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end,
377                                      struct kexec_buf *kbuf)
378 {
379         struct kimage *image = kbuf->image;
380         unsigned long temp_start, temp_end;
381
382         temp_start = max(start, kbuf->buf_min);
383
384         do {
385                 temp_start = ALIGN(temp_start, kbuf->buf_align);
386                 temp_end = temp_start + kbuf->memsz - 1;
387
388                 if (temp_end > end || temp_end > kbuf->buf_max)
389                         return 0;
390                 /*
391                  * Make sure this does not conflict with any of existing
392                  * segments
393                  */
394                 if (kimage_is_destination_range(image, temp_start, temp_end)) {
395                         temp_start = temp_start + PAGE_SIZE;
396                         continue;
397                 }
398
399                 /* We found a suitable memory range */
400                 break;
401         } while (1);
402
403         /* If we are here, we found a suitable memory range */
404         kbuf->mem = temp_start;
405
406         /* Success, stop navigating through remaining System RAM ranges */
407         return 1;
408 }
409
410 static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
411 {
412         struct kexec_buf *kbuf = (struct kexec_buf *)arg;
413         unsigned long sz = end - start + 1;
414
415         /* Returning 0 will take to next memory range */
416         if (sz < kbuf->memsz)
417                 return 0;
418
419         if (end < kbuf->buf_min || start > kbuf->buf_max)
420                 return 0;
421
422         /*
423          * Allocate memory top down with-in ram range. Otherwise bottom up
424          * allocation.
425          */
426         if (kbuf->top_down)
427                 return locate_mem_hole_top_down(start, end, kbuf);
428         return locate_mem_hole_bottom_up(start, end, kbuf);
429 }
430
431 /*
432  * Helper function for placing a buffer in a kexec segment. This assumes
433  * that kexec_mutex is held.
434  */
435 int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
436                      unsigned long memsz, unsigned long buf_align,
437                      unsigned long buf_min, unsigned long buf_max,
438                      bool top_down, unsigned long *load_addr)
439 {
440
441         struct kexec_segment *ksegment;
442         struct kexec_buf buf, *kbuf;
443         int ret;
444
445         /* Currently adding segment this way is allowed only in file mode */
446         if (!image->file_mode)
447                 return -EINVAL;
448
449         if (image->nr_segments >= KEXEC_SEGMENT_MAX)
450                 return -EINVAL;
451
452         /*
453          * Make sure we are not trying to add buffer after allocating
454          * control pages. All segments need to be placed first before
455          * any control pages are allocated. As control page allocation
456          * logic goes through list of segments to make sure there are
457          * no destination overlaps.
458          */
459         if (!list_empty(&image->control_pages)) {
460                 WARN_ON(1);
461                 return -EINVAL;
462         }
463
464         memset(&buf, 0, sizeof(struct kexec_buf));
465         kbuf = &buf;
466         kbuf->image = image;
467         kbuf->buffer = buffer;
468         kbuf->bufsz = bufsz;
469
470         kbuf->memsz = ALIGN(memsz, PAGE_SIZE);
471         kbuf->buf_align = max(buf_align, PAGE_SIZE);
472         kbuf->buf_min = buf_min;
473         kbuf->buf_max = buf_max;
474         kbuf->top_down = top_down;
475
476         /* Walk the RAM ranges and allocate a suitable range for the buffer */
477         if (image->type == KEXEC_TYPE_CRASH)
478                 ret = walk_iomem_res_desc(crashk_res.desc,
479                                 IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
480                                 crashk_res.start, crashk_res.end, kbuf,
481                                 locate_mem_hole_callback);
482         else
483                 ret = walk_system_ram_res(0, -1, kbuf,
484                                           locate_mem_hole_callback);
485         if (ret != 1) {
486                 /* A suitable memory range could not be found for buffer */
487                 return -EADDRNOTAVAIL;
488         }
489
490         /* Found a suitable memory range */
491         ksegment = &image->segment[image->nr_segments];
492         ksegment->kbuf = kbuf->buffer;
493         ksegment->bufsz = kbuf->bufsz;
494         ksegment->mem = kbuf->mem;
495         ksegment->memsz = kbuf->memsz;
496         image->nr_segments++;
497         *load_addr = ksegment->mem;
498         return 0;
499 }
500
501 /* Calculate and store the digest of segments */
502 static int kexec_calculate_store_digests(struct kimage *image)
503 {
504         struct crypto_shash *tfm;
505         struct shash_desc *desc;
506         int ret = 0, i, j, zero_buf_sz, sha_region_sz;
507         size_t desc_size, nullsz;
508         char *digest;
509         void *zero_buf;
510         struct kexec_sha_region *sha_regions;
511         struct purgatory_info *pi = &image->purgatory_info;
512
513         zero_buf = __va(page_to_pfn(ZERO_PAGE(0)) << PAGE_SHIFT);
514         zero_buf_sz = PAGE_SIZE;
515
516         tfm = crypto_alloc_shash("sha256", 0, 0);
517         if (IS_ERR(tfm)) {
518                 ret = PTR_ERR(tfm);
519                 goto out;
520         }
521
522         desc_size = crypto_shash_descsize(tfm) + sizeof(*desc);
523         desc = kzalloc(desc_size, GFP_KERNEL);
524         if (!desc) {
525                 ret = -ENOMEM;
526                 goto out_free_tfm;
527         }
528
529         sha_region_sz = KEXEC_SEGMENT_MAX * sizeof(struct kexec_sha_region);
530         sha_regions = vzalloc(sha_region_sz);
531         if (!sha_regions)
532                 goto out_free_desc;
533
534         desc->tfm   = tfm;
535         desc->flags = 0;
536
537         ret = crypto_shash_init(desc);
538         if (ret < 0)
539                 goto out_free_sha_regions;
540
541         digest = kzalloc(SHA256_DIGEST_SIZE, GFP_KERNEL);
542         if (!digest) {
543                 ret = -ENOMEM;
544                 goto out_free_sha_regions;
545         }
546
547         for (j = i = 0; i < image->nr_segments; i++) {
548                 struct kexec_segment *ksegment;
549
550                 ksegment = &image->segment[i];
551                 /*
552                  * Skip purgatory as it will be modified once we put digest
553                  * info in purgatory.
554                  */
555                 if (ksegment->kbuf == pi->purgatory_buf)
556                         continue;
557
558                 ret = crypto_shash_update(desc, ksegment->kbuf,
559                                           ksegment->bufsz);
560                 if (ret)
561                         break;
562
563                 /*
564                  * Assume rest of the buffer is filled with zero and
565                  * update digest accordingly.
566                  */
567                 nullsz = ksegment->memsz - ksegment->bufsz;
568                 while (nullsz) {
569                         unsigned long bytes = nullsz;
570
571                         if (bytes > zero_buf_sz)
572                                 bytes = zero_buf_sz;
573                         ret = crypto_shash_update(desc, zero_buf, bytes);
574                         if (ret)
575                                 break;
576                         nullsz -= bytes;
577                 }
578
579                 if (ret)
580                         break;
581
582                 sha_regions[j].start = ksegment->mem;
583                 sha_regions[j].len = ksegment->memsz;
584                 j++;
585         }
586
587         if (!ret) {
588                 ret = crypto_shash_final(desc, digest);
589                 if (ret)
590                         goto out_free_digest;
591                 ret = kexec_purgatory_get_set_symbol(image, "sha_regions",
592                                                 sha_regions, sha_region_sz, 0);
593                 if (ret)
594                         goto out_free_digest;
595
596                 ret = kexec_purgatory_get_set_symbol(image, "sha256_digest",
597                                                 digest, SHA256_DIGEST_SIZE, 0);
598                 if (ret)
599                         goto out_free_digest;
600         }
601
602 out_free_digest:
603         kfree(digest);
604 out_free_sha_regions:
605         vfree(sha_regions);
606 out_free_desc:
607         kfree(desc);
608 out_free_tfm:
609         kfree(tfm);
610 out:
611         return ret;
612 }
613
614 /* Actually load purgatory. Lot of code taken from kexec-tools */
615 static int __kexec_load_purgatory(struct kimage *image, unsigned long min,
616                                   unsigned long max, int top_down)
617 {
618         struct purgatory_info *pi = &image->purgatory_info;
619         unsigned long align, buf_align, bss_align, buf_sz, bss_sz, bss_pad;
620         unsigned long memsz, entry, load_addr, curr_load_addr, bss_addr, offset;
621         unsigned char *buf_addr, *src;
622         int i, ret = 0, entry_sidx = -1;
623         const Elf_Shdr *sechdrs_c;
624         Elf_Shdr *sechdrs = NULL;
625         void *purgatory_buf = NULL;
626
627         /*
628          * sechdrs_c points to section headers in purgatory and are read
629          * only. No modifications allowed.
630          */
631         sechdrs_c = (void *)pi->ehdr + pi->ehdr->e_shoff;
632
633         /*
634          * We can not modify sechdrs_c[] and its fields. It is read only.
635          * Copy it over to a local copy where one can store some temporary
636          * data and free it at the end. We need to modify ->sh_addr and
637          * ->sh_offset fields to keep track of permanent and temporary
638          * locations of sections.
639          */
640         sechdrs = vzalloc(pi->ehdr->e_shnum * sizeof(Elf_Shdr));
641         if (!sechdrs)
642                 return -ENOMEM;
643
644         memcpy(sechdrs, sechdrs_c, pi->ehdr->e_shnum * sizeof(Elf_Shdr));
645
646         /*
647          * We seem to have multiple copies of sections. First copy is which
648          * is embedded in kernel in read only section. Some of these sections
649          * will be copied to a temporary buffer and relocated. And these
650          * sections will finally be copied to their final destination at
651          * segment load time.
652          *
653          * Use ->sh_offset to reflect section address in memory. It will
654          * point to original read only copy if section is not allocatable.
655          * Otherwise it will point to temporary copy which will be relocated.
656          *
657          * Use ->sh_addr to contain final address of the section where it
658          * will go during execution time.
659          */
660         for (i = 0; i < pi->ehdr->e_shnum; i++) {
661                 if (sechdrs[i].sh_type == SHT_NOBITS)
662                         continue;
663
664                 sechdrs[i].sh_offset = (unsigned long)pi->ehdr +
665                                                 sechdrs[i].sh_offset;
666         }
667
668         /*
669          * Identify entry point section and make entry relative to section
670          * start.
671          */
672         entry = pi->ehdr->e_entry;
673         for (i = 0; i < pi->ehdr->e_shnum; i++) {
674                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
675                         continue;
676
677                 if (!(sechdrs[i].sh_flags & SHF_EXECINSTR))
678                         continue;
679
680                 /* Make entry section relative */
681                 if (sechdrs[i].sh_addr <= pi->ehdr->e_entry &&
682                     ((sechdrs[i].sh_addr + sechdrs[i].sh_size) >
683                      pi->ehdr->e_entry)) {
684                         entry_sidx = i;
685                         entry -= sechdrs[i].sh_addr;
686                         break;
687                 }
688         }
689
690         /* Determine how much memory is needed to load relocatable object. */
691         buf_align = 1;
692         bss_align = 1;
693         buf_sz = 0;
694         bss_sz = 0;
695
696         for (i = 0; i < pi->ehdr->e_shnum; i++) {
697                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
698                         continue;
699
700                 align = sechdrs[i].sh_addralign;
701                 if (sechdrs[i].sh_type != SHT_NOBITS) {
702                         if (buf_align < align)
703                                 buf_align = align;
704                         buf_sz = ALIGN(buf_sz, align);
705                         buf_sz += sechdrs[i].sh_size;
706                 } else {
707                         /* bss section */
708                         if (bss_align < align)
709                                 bss_align = align;
710                         bss_sz = ALIGN(bss_sz, align);
711                         bss_sz += sechdrs[i].sh_size;
712                 }
713         }
714
715         /* Determine the bss padding required to align bss properly */
716         bss_pad = 0;
717         if (buf_sz & (bss_align - 1))
718                 bss_pad = bss_align - (buf_sz & (bss_align - 1));
719
720         memsz = buf_sz + bss_pad + bss_sz;
721
722         /* Allocate buffer for purgatory */
723         purgatory_buf = vzalloc(buf_sz);
724         if (!purgatory_buf) {
725                 ret = -ENOMEM;
726                 goto out;
727         }
728
729         if (buf_align < bss_align)
730                 buf_align = bss_align;
731
732         /* Add buffer to segment list */
733         ret = kexec_add_buffer(image, purgatory_buf, buf_sz, memsz,
734                                 buf_align, min, max, top_down,
735                                 &pi->purgatory_load_addr);
736         if (ret)
737                 goto out;
738
739         /* Load SHF_ALLOC sections */
740         buf_addr = purgatory_buf;
741         load_addr = curr_load_addr = pi->purgatory_load_addr;
742         bss_addr = load_addr + buf_sz + bss_pad;
743
744         for (i = 0; i < pi->ehdr->e_shnum; i++) {
745                 if (!(sechdrs[i].sh_flags & SHF_ALLOC))
746                         continue;
747
748                 align = sechdrs[i].sh_addralign;
749                 if (sechdrs[i].sh_type != SHT_NOBITS) {
750                         curr_load_addr = ALIGN(curr_load_addr, align);
751                         offset = curr_load_addr - load_addr;
752                         /* We already modifed ->sh_offset to keep src addr */
753                         src = (char *) sechdrs[i].sh_offset;
754                         memcpy(buf_addr + offset, src, sechdrs[i].sh_size);
755
756                         /* Store load address and source address of section */
757                         sechdrs[i].sh_addr = curr_load_addr;
758
759                         /*
760                          * This section got copied to temporary buffer. Update
761                          * ->sh_offset accordingly.
762                          */
763                         sechdrs[i].sh_offset = (unsigned long)(buf_addr + offset);
764
765                         /* Advance to the next address */
766                         curr_load_addr += sechdrs[i].sh_size;
767                 } else {
768                         bss_addr = ALIGN(bss_addr, align);
769                         sechdrs[i].sh_addr = bss_addr;
770                         bss_addr += sechdrs[i].sh_size;
771                 }
772         }
773
774         /* Update entry point based on load address of text section */
775         if (entry_sidx >= 0)
776                 entry += sechdrs[entry_sidx].sh_addr;
777
778         /* Make kernel jump to purgatory after shutdown */
779         image->start = entry;
780
781         /* Used later to get/set symbol values */
782         pi->sechdrs = sechdrs;
783
784         /*
785          * Used later to identify which section is purgatory and skip it
786          * from checksumming.
787          */
788         pi->purgatory_buf = purgatory_buf;
789         return ret;
790 out:
791         vfree(sechdrs);
792         vfree(purgatory_buf);
793         return ret;
794 }
795
796 static int kexec_apply_relocations(struct kimage *image)
797 {
798         int i, ret;
799         struct purgatory_info *pi = &image->purgatory_info;
800         Elf_Shdr *sechdrs = pi->sechdrs;
801
802         /* Apply relocations */
803         for (i = 0; i < pi->ehdr->e_shnum; i++) {
804                 Elf_Shdr *section, *symtab;
805
806                 if (sechdrs[i].sh_type != SHT_RELA &&
807                     sechdrs[i].sh_type != SHT_REL)
808                         continue;
809
810                 /*
811                  * For section of type SHT_RELA/SHT_REL,
812                  * ->sh_link contains section header index of associated
813                  * symbol table. And ->sh_info contains section header
814                  * index of section to which relocations apply.
815                  */
816                 if (sechdrs[i].sh_info >= pi->ehdr->e_shnum ||
817                     sechdrs[i].sh_link >= pi->ehdr->e_shnum)
818                         return -ENOEXEC;
819
820                 section = &sechdrs[sechdrs[i].sh_info];
821                 symtab = &sechdrs[sechdrs[i].sh_link];
822
823                 if (!(section->sh_flags & SHF_ALLOC))
824                         continue;
825
826                 /*
827                  * symtab->sh_link contain section header index of associated
828                  * string table.
829                  */
830                 if (symtab->sh_link >= pi->ehdr->e_shnum)
831                         /* Invalid section number? */
832                         continue;
833
834                 /*
835                  * Respective architecture needs to provide support for applying
836                  * relocations of type SHT_RELA/SHT_REL.
837                  */
838                 if (sechdrs[i].sh_type == SHT_RELA)
839                         ret = arch_kexec_apply_relocations_add(pi->ehdr,
840                                                                sechdrs, i);
841                 else if (sechdrs[i].sh_type == SHT_REL)
842                         ret = arch_kexec_apply_relocations(pi->ehdr,
843                                                            sechdrs, i);
844                 if (ret)
845                         return ret;
846         }
847
848         return 0;
849 }
850
851 /* Load relocatable purgatory object and relocate it appropriately */
852 int kexec_load_purgatory(struct kimage *image, unsigned long min,
853                          unsigned long max, int top_down,
854                          unsigned long *load_addr)
855 {
856         struct purgatory_info *pi = &image->purgatory_info;
857         int ret;
858
859         if (kexec_purgatory_size <= 0)
860                 return -EINVAL;
861
862         if (kexec_purgatory_size < sizeof(Elf_Ehdr))
863                 return -ENOEXEC;
864
865         pi->ehdr = (Elf_Ehdr *)kexec_purgatory;
866
867         if (memcmp(pi->ehdr->e_ident, ELFMAG, SELFMAG) != 0
868             || pi->ehdr->e_type != ET_REL
869             || !elf_check_arch(pi->ehdr)
870             || pi->ehdr->e_shentsize != sizeof(Elf_Shdr))
871                 return -ENOEXEC;
872
873         if (pi->ehdr->e_shoff >= kexec_purgatory_size
874             || (pi->ehdr->e_shnum * sizeof(Elf_Shdr) >
875             kexec_purgatory_size - pi->ehdr->e_shoff))
876                 return -ENOEXEC;
877
878         ret = __kexec_load_purgatory(image, min, max, top_down);
879         if (ret)
880                 return ret;
881
882         ret = kexec_apply_relocations(image);
883         if (ret)
884                 goto out;
885
886         *load_addr = pi->purgatory_load_addr;
887         return 0;
888 out:
889         vfree(pi->sechdrs);
890         pi->sechdrs = NULL;
891
892         vfree(pi->purgatory_buf);
893         pi->purgatory_buf = NULL;
894         return ret;
895 }
896
897 static Elf_Sym *kexec_purgatory_find_symbol(struct purgatory_info *pi,
898                                             const char *name)
899 {
900         Elf_Sym *syms;
901         Elf_Shdr *sechdrs;
902         Elf_Ehdr *ehdr;
903         int i, k;
904         const char *strtab;
905
906         if (!pi->sechdrs || !pi->ehdr)
907                 return NULL;
908
909         sechdrs = pi->sechdrs;
910         ehdr = pi->ehdr;
911
912         for (i = 0; i < ehdr->e_shnum; i++) {
913                 if (sechdrs[i].sh_type != SHT_SYMTAB)
914                         continue;
915
916                 if (sechdrs[i].sh_link >= ehdr->e_shnum)
917                         /* Invalid strtab section number */
918                         continue;
919                 strtab = (char *)sechdrs[sechdrs[i].sh_link].sh_offset;
920                 syms = (Elf_Sym *)sechdrs[i].sh_offset;
921
922                 /* Go through symbols for a match */
923                 for (k = 0; k < sechdrs[i].sh_size/sizeof(Elf_Sym); k++) {
924                         if (ELF_ST_BIND(syms[k].st_info) != STB_GLOBAL)
925                                 continue;
926
927                         if (strcmp(strtab + syms[k].st_name, name) != 0)
928                                 continue;
929
930                         if (syms[k].st_shndx == SHN_UNDEF ||
931                             syms[k].st_shndx >= ehdr->e_shnum) {
932                                 pr_debug("Symbol: %s has bad section index %d.\n",
933                                                 name, syms[k].st_shndx);
934                                 return NULL;
935                         }
936
937                         /* Found the symbol we are looking for */
938                         return &syms[k];
939                 }
940         }
941
942         return NULL;
943 }
944
945 void *kexec_purgatory_get_symbol_addr(struct kimage *image, const char *name)
946 {
947         struct purgatory_info *pi = &image->purgatory_info;
948         Elf_Sym *sym;
949         Elf_Shdr *sechdr;
950
951         sym = kexec_purgatory_find_symbol(pi, name);
952         if (!sym)
953                 return ERR_PTR(-EINVAL);
954
955         sechdr = &pi->sechdrs[sym->st_shndx];
956
957         /*
958          * Returns the address where symbol will finally be loaded after
959          * kexec_load_segment()
960          */
961         return (void *)(sechdr->sh_addr + sym->st_value);
962 }
963
964 /*
965  * Get or set value of a symbol. If "get_value" is true, symbol value is
966  * returned in buf otherwise symbol value is set based on value in buf.
967  */
968 int kexec_purgatory_get_set_symbol(struct kimage *image, const char *name,
969                                    void *buf, unsigned int size, bool get_value)
970 {
971         Elf_Sym *sym;
972         Elf_Shdr *sechdrs;
973         struct purgatory_info *pi = &image->purgatory_info;
974         char *sym_buf;
975
976         sym = kexec_purgatory_find_symbol(pi, name);
977         if (!sym)
978                 return -EINVAL;
979
980         if (sym->st_size != size) {
981                 pr_err("symbol %s size mismatch: expected %lu actual %u\n",
982                        name, (unsigned long)sym->st_size, size);
983                 return -EINVAL;
984         }
985
986         sechdrs = pi->sechdrs;
987
988         if (sechdrs[sym->st_shndx].sh_type == SHT_NOBITS) {
989                 pr_err("symbol %s is in a bss section. Cannot %s\n", name,
990                        get_value ? "get" : "set");
991                 return -EINVAL;
992         }
993
994         sym_buf = (unsigned char *)sechdrs[sym->st_shndx].sh_offset +
995                                         sym->st_value;
996
997         if (get_value)
998                 memcpy((void *)buf, sym_buf, size);
999         else
1000                 memcpy((void *)sym_buf, buf, size);
1001
1002         return 0;
1003 }