Commit | Line | Data |
---|---|---|
dc009d92 EB |
1 | /* |
2 | * kexec.c - kexec system call | |
3 | * Copyright (C) 2002-2004 Eric Biederman <ebiederm@xmission.com> | |
4 | * | |
5 | * This source code is licensed under the GNU General Public License, | |
6 | * Version 2. See the file COPYING for more details. | |
7 | */ | |
8 | ||
9 | #include <linux/mm.h> | |
10 | #include <linux/file.h> | |
11 | #include <linux/slab.h> | |
12 | #include <linux/fs.h> | |
13 | #include <linux/kexec.h> | |
14 | #include <linux/spinlock.h> | |
15 | #include <linux/list.h> | |
16 | #include <linux/highmem.h> | |
17 | #include <linux/syscalls.h> | |
18 | #include <linux/reboot.h> | |
19 | #include <linux/syscalls.h> | |
20 | #include <linux/ioport.h> | |
21 | #include <asm/page.h> | |
22 | #include <asm/uaccess.h> | |
23 | #include <asm/io.h> | |
24 | #include <asm/system.h> | |
25 | #include <asm/semaphore.h> | |
26 | ||
27 | /* Location of the reserved area for the crash kernel */ | |
28 | struct resource crashk_res = { | |
29 | .name = "Crash kernel", | |
30 | .start = 0, | |
31 | .end = 0, | |
32 | .flags = IORESOURCE_BUSY | IORESOURCE_MEM | |
33 | }; | |
34 | ||
35 | /* | |
36 | * When kexec transitions to the new kernel there is a one-to-one | |
37 | * mapping between physical and virtual addresses. On processors | |
38 | * where you can disable the MMU this is trivial, and easy. For | |
39 | * others it is still a simple predictable page table to setup. | |
40 | * | |
41 | * In that environment kexec copies the new kernel to its final | |
42 | * resting place. This means I can only support memory whose | |
43 | * physical address can fit in an unsigned long. In particular | |
44 | * addresses where (pfn << PAGE_SHIFT) > ULONG_MAX cannot be handled. | |
45 | * If the assembly stub has more restrictive requirements | |
46 | * KEXEC_SOURCE_MEMORY_LIMIT and KEXEC_DEST_MEMORY_LIMIT can be | |
47 | * defined more restrictively in <asm/kexec.h>. | |
48 | * | |
49 | * The code for the transition from the current kernel to the | |
50 | * the new kernel is placed in the control_code_buffer, whose size | |
51 | * is given by KEXEC_CONTROL_CODE_SIZE. In the best case only a single | |
52 | * page of memory is necessary, but some architectures require more. | |
53 | * Because this memory must be identity mapped in the transition from | |
54 | * virtual to physical addresses it must live in the range | |
55 | * 0 - TASK_SIZE, as only the user space mappings are arbitrarily | |
56 | * modifiable. | |
57 | * | |
58 | * The assembly stub in the control code buffer is passed a linked list | |
59 | * of descriptor pages detailing the source pages of the new kernel, | |
60 | * and the destination addresses of those source pages. As this data | |
61 | * structure is not used in the context of the current OS, it must | |
62 | * be self-contained. | |
63 | * | |
64 | * The code has been made to work with highmem pages and will use a | |
65 | * destination page in its final resting place (if it happens | |
66 | * to allocate it). The end product of this is that most of the | |
67 | * physical address space, and most of RAM can be used. | |
68 | * | |
69 | * Future directions include: | |
70 | * - allocating a page table with the control code buffer identity | |
71 | * mapped, to simplify machine_kexec and make kexec_on_panic more | |
72 | * reliable. | |
73 | */ | |
74 | ||
75 | /* | |
76 | * KIMAGE_NO_DEST is an impossible destination address..., for | |
77 | * allocating pages whose destination address we do not care about. | |
78 | */ | |
79 | #define KIMAGE_NO_DEST (-1UL) | |
80 | ||
81 | static int kimage_is_destination_range( | |
82 | struct kimage *image, unsigned long start, unsigned long end); | |
83 | static struct page *kimage_alloc_page(struct kimage *image, unsigned int gfp_mask, unsigned long dest); | |
84 | ||
85 | static int do_kimage_alloc(struct kimage **rimage, unsigned long entry, | |
86 | unsigned long nr_segments, struct kexec_segment __user *segments) | |
87 | { | |
88 | size_t segment_bytes; | |
89 | struct kimage *image; | |
90 | unsigned long i; | |
91 | int result; | |
92 | ||
93 | /* Allocate a controlling structure */ | |
94 | result = -ENOMEM; | |
95 | image = kmalloc(sizeof(*image), GFP_KERNEL); | |
96 | if (!image) { | |
97 | goto out; | |
98 | } | |
99 | memset(image, 0, sizeof(*image)); | |
100 | image->head = 0; | |
101 | image->entry = &image->head; | |
102 | image->last_entry = &image->head; | |
103 | image->control_page = ~0; /* By default this does not apply */ | |
104 | image->start = entry; | |
105 | image->type = KEXEC_TYPE_DEFAULT; | |
106 | ||
107 | /* Initialize the list of control pages */ | |
108 | INIT_LIST_HEAD(&image->control_pages); | |
109 | ||
110 | /* Initialize the list of destination pages */ | |
111 | INIT_LIST_HEAD(&image->dest_pages); | |
112 | ||
113 | /* Initialize the list of unuseable pages */ | |
114 | INIT_LIST_HEAD(&image->unuseable_pages); | |
115 | ||
116 | /* Read in the segments */ | |
117 | image->nr_segments = nr_segments; | |
118 | segment_bytes = nr_segments * sizeof(*segments); | |
119 | result = copy_from_user(image->segment, segments, segment_bytes); | |
120 | if (result) | |
121 | goto out; | |
122 | ||
123 | /* | |
124 | * Verify we have good destination addresses. The caller is | |
125 | * responsible for making certain we don't attempt to load | |
126 | * the new image into invalid or reserved areas of RAM. This | |
127 | * just verifies it is an address we can use. | |
128 | * | |
129 | * Since the kernel does everything in page size chunks ensure | |
130 | * the destination addreses are page aligned. Too many | |
131 | * special cases crop of when we don't do this. The most | |
132 | * insidious is getting overlapping destination addresses | |
133 | * simply because addresses are changed to page size | |
134 | * granularity. | |
135 | */ | |
136 | result = -EADDRNOTAVAIL; | |
137 | for (i = 0; i < nr_segments; i++) { | |
138 | unsigned long mstart, mend; | |
139 | mstart = image->segment[i].mem; | |
140 | mend = mstart + image->segment[i].memsz; | |
141 | if ((mstart & ~PAGE_MASK) || (mend & ~PAGE_MASK)) | |
142 | goto out; | |
143 | if (mend >= KEXEC_DESTINATION_MEMORY_LIMIT) | |
144 | goto out; | |
145 | } | |
146 | ||
147 | /* Verify our destination addresses do not overlap. | |
148 | * If we alloed overlapping destination addresses | |
149 | * through very weird things can happen with no | |
150 | * easy explanation as one segment stops on another. | |
151 | */ | |
152 | result = -EINVAL; | |
153 | for(i = 0; i < nr_segments; i++) { | |
154 | unsigned long mstart, mend; | |
155 | unsigned long j; | |
156 | mstart = image->segment[i].mem; | |
157 | mend = mstart + image->segment[i].memsz; | |
158 | for(j = 0; j < i; j++) { | |
159 | unsigned long pstart, pend; | |
160 | pstart = image->segment[j].mem; | |
161 | pend = pstart + image->segment[j].memsz; | |
162 | /* Do the segments overlap ? */ | |
163 | if ((mend > pstart) && (mstart < pend)) | |
164 | goto out; | |
165 | } | |
166 | } | |
167 | ||
168 | /* Ensure our buffer sizes are strictly less than | |
169 | * our memory sizes. This should always be the case, | |
170 | * and it is easier to check up front than to be surprised | |
171 | * later on. | |
172 | */ | |
173 | result = -EINVAL; | |
174 | for(i = 0; i < nr_segments; i++) { | |
175 | if (image->segment[i].bufsz > image->segment[i].memsz) | |
176 | goto out; | |
177 | } | |
178 | ||
179 | ||
180 | result = 0; | |
181 | out: | |
182 | if (result == 0) { | |
183 | *rimage = image; | |
184 | } else { | |
185 | kfree(image); | |
186 | } | |
187 | return result; | |
188 | ||
189 | } | |
190 | ||
191 | static int kimage_normal_alloc(struct kimage **rimage, unsigned long entry, | |
192 | unsigned long nr_segments, struct kexec_segment __user *segments) | |
193 | { | |
194 | int result; | |
195 | struct kimage *image; | |
196 | ||
197 | /* Allocate and initialize a controlling structure */ | |
198 | image = NULL; | |
199 | result = do_kimage_alloc(&image, entry, nr_segments, segments); | |
200 | if (result) { | |
201 | goto out; | |
202 | } | |
203 | *rimage = image; | |
204 | ||
205 | /* | |
206 | * Find a location for the control code buffer, and add it | |
207 | * the vector of segments so that it's pages will also be | |
208 | * counted as destination pages. | |
209 | */ | |
210 | result = -ENOMEM; | |
211 | image->control_code_page = kimage_alloc_control_pages(image, | |
212 | get_order(KEXEC_CONTROL_CODE_SIZE)); | |
213 | if (!image->control_code_page) { | |
214 | printk(KERN_ERR "Could not allocate control_code_buffer\n"); | |
215 | goto out; | |
216 | } | |
217 | ||
218 | result = 0; | |
219 | out: | |
220 | if (result == 0) { | |
221 | *rimage = image; | |
222 | } else { | |
223 | kfree(image); | |
224 | } | |
225 | return result; | |
226 | } | |
227 | ||
228 | static int kimage_crash_alloc(struct kimage **rimage, unsigned long entry, | |
229 | unsigned long nr_segments, struct kexec_segment *segments) | |
230 | { | |
231 | int result; | |
232 | struct kimage *image; | |
233 | unsigned long i; | |
234 | ||
235 | image = NULL; | |
236 | /* Verify we have a valid entry point */ | |
237 | if ((entry < crashk_res.start) || (entry > crashk_res.end)) { | |
238 | result = -EADDRNOTAVAIL; | |
239 | goto out; | |
240 | } | |
241 | ||
242 | /* Allocate and initialize a controlling structure */ | |
243 | result = do_kimage_alloc(&image, entry, nr_segments, segments); | |
244 | if (result) { | |
245 | goto out; | |
246 | } | |
247 | ||
248 | /* Enable the special crash kernel control page | |
249 | * allocation policy. | |
250 | */ | |
251 | image->control_page = crashk_res.start; | |
252 | image->type = KEXEC_TYPE_CRASH; | |
253 | ||
254 | /* | |
255 | * Verify we have good destination addresses. Normally | |
256 | * the caller is responsible for making certain we don't | |
257 | * attempt to load the new image into invalid or reserved | |
258 | * areas of RAM. But crash kernels are preloaded into a | |
259 | * reserved area of ram. We must ensure the addresses | |
260 | * are in the reserved area otherwise preloading the | |
261 | * kernel could corrupt things. | |
262 | */ | |
263 | result = -EADDRNOTAVAIL; | |
264 | for (i = 0; i < nr_segments; i++) { | |
265 | unsigned long mstart, mend; | |
266 | mstart = image->segment[i].mem; | |
50cccc69 | 267 | mend = mstart + image->segment[i].memsz - 1; |
dc009d92 EB |
268 | /* Ensure we are within the crash kernel limits */ |
269 | if ((mstart < crashk_res.start) || (mend > crashk_res.end)) | |
270 | goto out; | |
271 | } | |
272 | ||
273 | ||
274 | /* | |
275 | * Find a location for the control code buffer, and add | |
276 | * the vector of segments so that it's pages will also be | |
277 | * counted as destination pages. | |
278 | */ | |
279 | result = -ENOMEM; | |
280 | image->control_code_page = kimage_alloc_control_pages(image, | |
281 | get_order(KEXEC_CONTROL_CODE_SIZE)); | |
282 | if (!image->control_code_page) { | |
283 | printk(KERN_ERR "Could not allocate control_code_buffer\n"); | |
284 | goto out; | |
285 | } | |
286 | ||
287 | result = 0; | |
288 | out: | |
289 | if (result == 0) { | |
290 | *rimage = image; | |
291 | } else { | |
292 | kfree(image); | |
293 | } | |
294 | return result; | |
295 | } | |
296 | ||
297 | static int kimage_is_destination_range( | |
298 | struct kimage *image, unsigned long start, unsigned long end) | |
299 | { | |
300 | unsigned long i; | |
301 | ||
302 | for (i = 0; i < image->nr_segments; i++) { | |
303 | unsigned long mstart, mend; | |
304 | mstart = image->segment[i].mem; | |
305 | mend = mstart + image->segment[i].memsz; | |
306 | if ((end > mstart) && (start < mend)) { | |
307 | return 1; | |
308 | } | |
309 | } | |
310 | return 0; | |
311 | } | |
312 | ||
313 | static struct page *kimage_alloc_pages(unsigned int gfp_mask, unsigned int order) | |
314 | { | |
315 | struct page *pages; | |
316 | pages = alloc_pages(gfp_mask, order); | |
317 | if (pages) { | |
318 | unsigned int count, i; | |
319 | pages->mapping = NULL; | |
320 | pages->private = order; | |
321 | count = 1 << order; | |
322 | for(i = 0; i < count; i++) { | |
323 | SetPageReserved(pages + i); | |
324 | } | |
325 | } | |
326 | return pages; | |
327 | } | |
328 | ||
329 | static void kimage_free_pages(struct page *page) | |
330 | { | |
331 | unsigned int order, count, i; | |
332 | order = page->private; | |
333 | count = 1 << order; | |
334 | for(i = 0; i < count; i++) { | |
335 | ClearPageReserved(page + i); | |
336 | } | |
337 | __free_pages(page, order); | |
338 | } | |
339 | ||
340 | static void kimage_free_page_list(struct list_head *list) | |
341 | { | |
342 | struct list_head *pos, *next; | |
343 | list_for_each_safe(pos, next, list) { | |
344 | struct page *page; | |
345 | ||
346 | page = list_entry(pos, struct page, lru); | |
347 | list_del(&page->lru); | |
348 | ||
349 | kimage_free_pages(page); | |
350 | } | |
351 | } | |
352 | ||
353 | static struct page *kimage_alloc_normal_control_pages( | |
354 | struct kimage *image, unsigned int order) | |
355 | { | |
356 | /* Control pages are special, they are the intermediaries | |
357 | * that are needed while we copy the rest of the pages | |
358 | * to their final resting place. As such they must | |
359 | * not conflict with either the destination addresses | |
360 | * or memory the kernel is already using. | |
361 | * | |
362 | * The only case where we really need more than one of | |
363 | * these are for architectures where we cannot disable | |
364 | * the MMU and must instead generate an identity mapped | |
365 | * page table for all of the memory. | |
366 | * | |
367 | * At worst this runs in O(N) of the image size. | |
368 | */ | |
369 | struct list_head extra_pages; | |
370 | struct page *pages; | |
371 | unsigned int count; | |
372 | ||
373 | count = 1 << order; | |
374 | INIT_LIST_HEAD(&extra_pages); | |
375 | ||
376 | /* Loop while I can allocate a page and the page allocated | |
377 | * is a destination page. | |
378 | */ | |
379 | do { | |
380 | unsigned long pfn, epfn, addr, eaddr; | |
381 | pages = kimage_alloc_pages(GFP_KERNEL, order); | |
382 | if (!pages) | |
383 | break; | |
384 | pfn = page_to_pfn(pages); | |
385 | epfn = pfn + count; | |
386 | addr = pfn << PAGE_SHIFT; | |
387 | eaddr = epfn << PAGE_SHIFT; | |
388 | if ((epfn >= (KEXEC_CONTROL_MEMORY_LIMIT >> PAGE_SHIFT)) || | |
389 | kimage_is_destination_range(image, addr, eaddr)) | |
390 | { | |
391 | list_add(&pages->lru, &extra_pages); | |
392 | pages = NULL; | |
393 | } | |
394 | } while(!pages); | |
395 | if (pages) { | |
396 | /* Remember the allocated page... */ | |
397 | list_add(&pages->lru, &image->control_pages); | |
398 | ||
399 | /* Because the page is already in it's destination | |
400 | * location we will never allocate another page at | |
401 | * that address. Therefore kimage_alloc_pages | |
402 | * will not return it (again) and we don't need | |
403 | * to give it an entry in image->segment[]. | |
404 | */ | |
405 | } | |
406 | /* Deal with the destination pages I have inadvertently allocated. | |
407 | * | |
408 | * Ideally I would convert multi-page allocations into single | |
409 | * page allocations, and add everyting to image->dest_pages. | |
410 | * | |
411 | * For now it is simpler to just free the pages. | |
412 | */ | |
413 | kimage_free_page_list(&extra_pages); | |
414 | return pages; | |
415 | ||
416 | } | |
417 | ||
418 | static struct page *kimage_alloc_crash_control_pages( | |
419 | struct kimage *image, unsigned int order) | |
420 | { | |
421 | /* Control pages are special, they are the intermediaries | |
422 | * that are needed while we copy the rest of the pages | |
423 | * to their final resting place. As such they must | |
424 | * not conflict with either the destination addresses | |
425 | * or memory the kernel is already using. | |
426 | * | |
427 | * Control pages are also the only pags we must allocate | |
428 | * when loading a crash kernel. All of the other pages | |
429 | * are specified by the segments and we just memcpy | |
430 | * into them directly. | |
431 | * | |
432 | * The only case where we really need more than one of | |
433 | * these are for architectures where we cannot disable | |
434 | * the MMU and must instead generate an identity mapped | |
435 | * page table for all of the memory. | |
436 | * | |
437 | * Given the low demand this implements a very simple | |
438 | * allocator that finds the first hole of the appropriate | |
439 | * size in the reserved memory region, and allocates all | |
440 | * of the memory up to and including the hole. | |
441 | */ | |
442 | unsigned long hole_start, hole_end, size; | |
443 | struct page *pages; | |
444 | pages = NULL; | |
445 | size = (1 << order) << PAGE_SHIFT; | |
446 | hole_start = (image->control_page + (size - 1)) & ~(size - 1); | |
447 | hole_end = hole_start + size - 1; | |
448 | while(hole_end <= crashk_res.end) { | |
449 | unsigned long i; | |
450 | if (hole_end > KEXEC_CONTROL_MEMORY_LIMIT) { | |
451 | break; | |
452 | } | |
453 | if (hole_end > crashk_res.end) { | |
454 | break; | |
455 | } | |
456 | /* See if I overlap any of the segments */ | |
457 | for(i = 0; i < image->nr_segments; i++) { | |
458 | unsigned long mstart, mend; | |
459 | mstart = image->segment[i].mem; | |
460 | mend = mstart + image->segment[i].memsz - 1; | |
461 | if ((hole_end >= mstart) && (hole_start <= mend)) { | |
462 | /* Advance the hole to the end of the segment */ | |
463 | hole_start = (mend + (size - 1)) & ~(size - 1); | |
464 | hole_end = hole_start + size - 1; | |
465 | break; | |
466 | } | |
467 | } | |
468 | /* If I don't overlap any segments I have found my hole! */ | |
469 | if (i == image->nr_segments) { | |
470 | pages = pfn_to_page(hole_start >> PAGE_SHIFT); | |
471 | break; | |
472 | } | |
473 | } | |
474 | if (pages) { | |
475 | image->control_page = hole_end; | |
476 | } | |
477 | return pages; | |
478 | } | |
479 | ||
480 | ||
481 | struct page *kimage_alloc_control_pages( | |
482 | struct kimage *image, unsigned int order) | |
483 | { | |
484 | struct page *pages = NULL; | |
485 | switch(image->type) { | |
486 | case KEXEC_TYPE_DEFAULT: | |
487 | pages = kimage_alloc_normal_control_pages(image, order); | |
488 | break; | |
489 | case KEXEC_TYPE_CRASH: | |
490 | pages = kimage_alloc_crash_control_pages(image, order); | |
491 | break; | |
492 | } | |
493 | return pages; | |
494 | } | |
495 | ||
496 | static int kimage_add_entry(struct kimage *image, kimage_entry_t entry) | |
497 | { | |
498 | if (*image->entry != 0) { | |
499 | image->entry++; | |
500 | } | |
501 | if (image->entry == image->last_entry) { | |
502 | kimage_entry_t *ind_page; | |
503 | struct page *page; | |
504 | page = kimage_alloc_page(image, GFP_KERNEL, KIMAGE_NO_DEST); | |
505 | if (!page) { | |
506 | return -ENOMEM; | |
507 | } | |
508 | ind_page = page_address(page); | |
509 | *image->entry = virt_to_phys(ind_page) | IND_INDIRECTION; | |
510 | image->entry = ind_page; | |
511 | image->last_entry = | |
512 | ind_page + ((PAGE_SIZE/sizeof(kimage_entry_t)) - 1); | |
513 | } | |
514 | *image->entry = entry; | |
515 | image->entry++; | |
516 | *image->entry = 0; | |
517 | return 0; | |
518 | } | |
519 | ||
520 | static int kimage_set_destination( | |
521 | struct kimage *image, unsigned long destination) | |
522 | { | |
523 | int result; | |
524 | ||
525 | destination &= PAGE_MASK; | |
526 | result = kimage_add_entry(image, destination | IND_DESTINATION); | |
527 | if (result == 0) { | |
528 | image->destination = destination; | |
529 | } | |
530 | return result; | |
531 | } | |
532 | ||
533 | ||
534 | static int kimage_add_page(struct kimage *image, unsigned long page) | |
535 | { | |
536 | int result; | |
537 | ||
538 | page &= PAGE_MASK; | |
539 | result = kimage_add_entry(image, page | IND_SOURCE); | |
540 | if (result == 0) { | |
541 | image->destination += PAGE_SIZE; | |
542 | } | |
543 | return result; | |
544 | } | |
545 | ||
546 | ||
547 | static void kimage_free_extra_pages(struct kimage *image) | |
548 | { | |
549 | /* Walk through and free any extra destination pages I may have */ | |
550 | kimage_free_page_list(&image->dest_pages); | |
551 | ||
552 | /* Walk through and free any unuseable pages I have cached */ | |
553 | kimage_free_page_list(&image->unuseable_pages); | |
554 | ||
555 | } | |
556 | static int kimage_terminate(struct kimage *image) | |
557 | { | |
558 | if (*image->entry != 0) { | |
559 | image->entry++; | |
560 | } | |
561 | *image->entry = IND_DONE; | |
562 | return 0; | |
563 | } | |
564 | ||
565 | #define for_each_kimage_entry(image, ptr, entry) \ | |
566 | for (ptr = &image->head; (entry = *ptr) && !(entry & IND_DONE); \ | |
567 | ptr = (entry & IND_INDIRECTION)? \ | |
568 | phys_to_virt((entry & PAGE_MASK)): ptr +1) | |
569 | ||
570 | static void kimage_free_entry(kimage_entry_t entry) | |
571 | { | |
572 | struct page *page; | |
573 | ||
574 | page = pfn_to_page(entry >> PAGE_SHIFT); | |
575 | kimage_free_pages(page); | |
576 | } | |
577 | ||
578 | static void kimage_free(struct kimage *image) | |
579 | { | |
580 | kimage_entry_t *ptr, entry; | |
581 | kimage_entry_t ind = 0; | |
582 | ||
583 | if (!image) | |
584 | return; | |
585 | kimage_free_extra_pages(image); | |
586 | for_each_kimage_entry(image, ptr, entry) { | |
587 | if (entry & IND_INDIRECTION) { | |
588 | /* Free the previous indirection page */ | |
589 | if (ind & IND_INDIRECTION) { | |
590 | kimage_free_entry(ind); | |
591 | } | |
592 | /* Save this indirection page until we are | |
593 | * done with it. | |
594 | */ | |
595 | ind = entry; | |
596 | } | |
597 | else if (entry & IND_SOURCE) { | |
598 | kimage_free_entry(entry); | |
599 | } | |
600 | } | |
601 | /* Free the final indirection page */ | |
602 | if (ind & IND_INDIRECTION) { | |
603 | kimage_free_entry(ind); | |
604 | } | |
605 | ||
606 | /* Handle any machine specific cleanup */ | |
607 | machine_kexec_cleanup(image); | |
608 | ||
609 | /* Free the kexec control pages... */ | |
610 | kimage_free_page_list(&image->control_pages); | |
611 | kfree(image); | |
612 | } | |
613 | ||
614 | static kimage_entry_t *kimage_dst_used(struct kimage *image, unsigned long page) | |
615 | { | |
616 | kimage_entry_t *ptr, entry; | |
617 | unsigned long destination = 0; | |
618 | ||
619 | for_each_kimage_entry(image, ptr, entry) { | |
620 | if (entry & IND_DESTINATION) { | |
621 | destination = entry & PAGE_MASK; | |
622 | } | |
623 | else if (entry & IND_SOURCE) { | |
624 | if (page == destination) { | |
625 | return ptr; | |
626 | } | |
627 | destination += PAGE_SIZE; | |
628 | } | |
629 | } | |
630 | return 0; | |
631 | } | |
632 | ||
633 | static struct page *kimage_alloc_page(struct kimage *image, unsigned int gfp_mask, unsigned long destination) | |
634 | { | |
635 | /* | |
636 | * Here we implement safeguards to ensure that a source page | |
637 | * is not copied to its destination page before the data on | |
638 | * the destination page is no longer useful. | |
639 | * | |
640 | * To do this we maintain the invariant that a source page is | |
641 | * either its own destination page, or it is not a | |
642 | * destination page at all. | |
643 | * | |
644 | * That is slightly stronger than required, but the proof | |
645 | * that no problems will not occur is trivial, and the | |
646 | * implementation is simply to verify. | |
647 | * | |
648 | * When allocating all pages normally this algorithm will run | |
649 | * in O(N) time, but in the worst case it will run in O(N^2) | |
650 | * time. If the runtime is a problem the data structures can | |
651 | * be fixed. | |
652 | */ | |
653 | struct page *page; | |
654 | unsigned long addr; | |
655 | ||
656 | /* | |
657 | * Walk through the list of destination pages, and see if I | |
658 | * have a match. | |
659 | */ | |
660 | list_for_each_entry(page, &image->dest_pages, lru) { | |
661 | addr = page_to_pfn(page) << PAGE_SHIFT; | |
662 | if (addr == destination) { | |
663 | list_del(&page->lru); | |
664 | return page; | |
665 | } | |
666 | } | |
667 | page = NULL; | |
668 | while (1) { | |
669 | kimage_entry_t *old; | |
670 | ||
671 | /* Allocate a page, if we run out of memory give up */ | |
672 | page = kimage_alloc_pages(gfp_mask, 0); | |
673 | if (!page) { | |
674 | return 0; | |
675 | } | |
676 | /* If the page cannot be used file it away */ | |
677 | if (page_to_pfn(page) > (KEXEC_SOURCE_MEMORY_LIMIT >> PAGE_SHIFT)) { | |
678 | list_add(&page->lru, &image->unuseable_pages); | |
679 | continue; | |
680 | } | |
681 | addr = page_to_pfn(page) << PAGE_SHIFT; | |
682 | ||
683 | /* If it is the destination page we want use it */ | |
684 | if (addr == destination) | |
685 | break; | |
686 | ||
687 | /* If the page is not a destination page use it */ | |
688 | if (!kimage_is_destination_range(image, addr, addr + PAGE_SIZE)) | |
689 | break; | |
690 | ||
691 | /* | |
692 | * I know that the page is someones destination page. | |
693 | * See if there is already a source page for this | |
694 | * destination page. And if so swap the source pages. | |
695 | */ | |
696 | old = kimage_dst_used(image, addr); | |
697 | if (old) { | |
698 | /* If so move it */ | |
699 | unsigned long old_addr; | |
700 | struct page *old_page; | |
701 | ||
702 | old_addr = *old & PAGE_MASK; | |
703 | old_page = pfn_to_page(old_addr >> PAGE_SHIFT); | |
704 | copy_highpage(page, old_page); | |
705 | *old = addr | (*old & ~PAGE_MASK); | |
706 | ||
707 | /* The old page I have found cannot be a | |
708 | * destination page, so return it. | |
709 | */ | |
710 | addr = old_addr; | |
711 | page = old_page; | |
712 | break; | |
713 | } | |
714 | else { | |
715 | /* Place the page on the destination list I | |
716 | * will use it later. | |
717 | */ | |
718 | list_add(&page->lru, &image->dest_pages); | |
719 | } | |
720 | } | |
721 | return page; | |
722 | } | |
723 | ||
724 | static int kimage_load_normal_segment(struct kimage *image, | |
725 | struct kexec_segment *segment) | |
726 | { | |
727 | unsigned long maddr; | |
728 | unsigned long ubytes, mbytes; | |
729 | int result; | |
730 | unsigned char *buf; | |
731 | ||
732 | result = 0; | |
733 | buf = segment->buf; | |
734 | ubytes = segment->bufsz; | |
735 | mbytes = segment->memsz; | |
736 | maddr = segment->mem; | |
737 | ||
738 | result = kimage_set_destination(image, maddr); | |
739 | if (result < 0) { | |
740 | goto out; | |
741 | } | |
742 | while(mbytes) { | |
743 | struct page *page; | |
744 | char *ptr; | |
745 | size_t uchunk, mchunk; | |
746 | page = kimage_alloc_page(image, GFP_HIGHUSER, maddr); | |
747 | if (page == 0) { | |
748 | result = -ENOMEM; | |
749 | goto out; | |
750 | } | |
751 | result = kimage_add_page(image, page_to_pfn(page) << PAGE_SHIFT); | |
752 | if (result < 0) { | |
753 | goto out; | |
754 | } | |
755 | ptr = kmap(page); | |
756 | /* Start with a clear page */ | |
757 | memset(ptr, 0, PAGE_SIZE); | |
758 | ptr += maddr & ~PAGE_MASK; | |
759 | mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK); | |
760 | if (mchunk > mbytes) { | |
761 | mchunk = mbytes; | |
762 | } | |
763 | uchunk = mchunk; | |
764 | if (uchunk > ubytes) { | |
765 | uchunk = ubytes; | |
766 | } | |
767 | result = copy_from_user(ptr, buf, uchunk); | |
768 | kunmap(page); | |
769 | if (result) { | |
770 | result = (result < 0) ? result : -EIO; | |
771 | goto out; | |
772 | } | |
773 | ubytes -= uchunk; | |
774 | maddr += mchunk; | |
775 | buf += mchunk; | |
776 | mbytes -= mchunk; | |
777 | } | |
778 | out: | |
779 | return result; | |
780 | } | |
781 | ||
782 | static int kimage_load_crash_segment(struct kimage *image, | |
783 | struct kexec_segment *segment) | |
784 | { | |
785 | /* For crash dumps kernels we simply copy the data from | |
786 | * user space to it's destination. | |
787 | * We do things a page at a time for the sake of kmap. | |
788 | */ | |
789 | unsigned long maddr; | |
790 | unsigned long ubytes, mbytes; | |
791 | int result; | |
792 | unsigned char *buf; | |
793 | ||
794 | result = 0; | |
795 | buf = segment->buf; | |
796 | ubytes = segment->bufsz; | |
797 | mbytes = segment->memsz; | |
798 | maddr = segment->mem; | |
799 | while(mbytes) { | |
800 | struct page *page; | |
801 | char *ptr; | |
802 | size_t uchunk, mchunk; | |
803 | page = pfn_to_page(maddr >> PAGE_SHIFT); | |
804 | if (page == 0) { | |
805 | result = -ENOMEM; | |
806 | goto out; | |
807 | } | |
808 | ptr = kmap(page); | |
809 | ptr += maddr & ~PAGE_MASK; | |
810 | mchunk = PAGE_SIZE - (maddr & ~PAGE_MASK); | |
811 | if (mchunk > mbytes) { | |
812 | mchunk = mbytes; | |
813 | } | |
814 | uchunk = mchunk; | |
815 | if (uchunk > ubytes) { | |
816 | uchunk = ubytes; | |
817 | /* Zero the trailing part of the page */ | |
818 | memset(ptr + uchunk, 0, mchunk - uchunk); | |
819 | } | |
820 | result = copy_from_user(ptr, buf, uchunk); | |
821 | kunmap(page); | |
822 | if (result) { | |
823 | result = (result < 0) ? result : -EIO; | |
824 | goto out; | |
825 | } | |
826 | ubytes -= uchunk; | |
827 | maddr += mchunk; | |
828 | buf += mchunk; | |
829 | mbytes -= mchunk; | |
830 | } | |
831 | out: | |
832 | return result; | |
833 | } | |
834 | ||
835 | static int kimage_load_segment(struct kimage *image, | |
836 | struct kexec_segment *segment) | |
837 | { | |
838 | int result = -ENOMEM; | |
839 | switch(image->type) { | |
840 | case KEXEC_TYPE_DEFAULT: | |
841 | result = kimage_load_normal_segment(image, segment); | |
842 | break; | |
843 | case KEXEC_TYPE_CRASH: | |
844 | result = kimage_load_crash_segment(image, segment); | |
845 | break; | |
846 | } | |
847 | return result; | |
848 | } | |
849 | ||
850 | /* | |
851 | * Exec Kernel system call: for obvious reasons only root may call it. | |
852 | * | |
853 | * This call breaks up into three pieces. | |
854 | * - A generic part which loads the new kernel from the current | |
855 | * address space, and very carefully places the data in the | |
856 | * allocated pages. | |
857 | * | |
858 | * - A generic part that interacts with the kernel and tells all of | |
859 | * the devices to shut down. Preventing on-going dmas, and placing | |
860 | * the devices in a consistent state so a later kernel can | |
861 | * reinitialize them. | |
862 | * | |
863 | * - A machine specific part that includes the syscall number | |
864 | * and the copies the image to it's final destination. And | |
865 | * jumps into the image at entry. | |
866 | * | |
867 | * kexec does not sync, or unmount filesystems so if you need | |
868 | * that to happen you need to do that yourself. | |
869 | */ | |
870 | struct kimage *kexec_image = NULL; | |
871 | static struct kimage *kexec_crash_image = NULL; | |
872 | /* | |
873 | * A home grown binary mutex. | |
874 | * Nothing can wait so this mutex is safe to use | |
875 | * in interrupt context :) | |
876 | */ | |
877 | static int kexec_lock = 0; | |
878 | ||
879 | asmlinkage long sys_kexec_load(unsigned long entry, | |
880 | unsigned long nr_segments, struct kexec_segment __user *segments, | |
881 | unsigned long flags) | |
882 | { | |
883 | struct kimage **dest_image, *image; | |
884 | int locked; | |
885 | int result; | |
886 | ||
887 | /* We only trust the superuser with rebooting the system. */ | |
888 | if (!capable(CAP_SYS_BOOT)) | |
889 | return -EPERM; | |
890 | ||
891 | /* | |
892 | * Verify we have a legal set of flags | |
893 | * This leaves us room for future extensions. | |
894 | */ | |
895 | if ((flags & KEXEC_FLAGS) != (flags & ~KEXEC_ARCH_MASK)) | |
896 | return -EINVAL; | |
897 | ||
898 | /* Verify we are on the appropriate architecture */ | |
899 | if (((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH) && | |
900 | ((flags & KEXEC_ARCH_MASK) != KEXEC_ARCH_DEFAULT)) | |
901 | { | |
902 | return -EINVAL; | |
903 | } | |
904 | ||
905 | /* Put an artificial cap on the number | |
906 | * of segments passed to kexec_load. | |
907 | */ | |
908 | if (nr_segments > KEXEC_SEGMENT_MAX) | |
909 | return -EINVAL; | |
910 | ||
911 | image = NULL; | |
912 | result = 0; | |
913 | ||
914 | /* Because we write directly to the reserved memory | |
915 | * region when loading crash kernels we need a mutex here to | |
916 | * prevent multiple crash kernels from attempting to load | |
917 | * simultaneously, and to prevent a crash kernel from loading | |
918 | * over the top of a in use crash kernel. | |
919 | * | |
920 | * KISS: always take the mutex. | |
921 | */ | |
922 | locked = xchg(&kexec_lock, 1); | |
923 | if (locked) { | |
924 | return -EBUSY; | |
925 | } | |
926 | dest_image = &kexec_image; | |
927 | if (flags & KEXEC_ON_CRASH) { | |
928 | dest_image = &kexec_crash_image; | |
929 | } | |
930 | if (nr_segments > 0) { | |
931 | unsigned long i; | |
932 | /* Loading another kernel to reboot into */ | |
933 | if ((flags & KEXEC_ON_CRASH) == 0) { | |
934 | result = kimage_normal_alloc(&image, entry, nr_segments, segments); | |
935 | } | |
936 | /* Loading another kernel to switch to if this one crashes */ | |
937 | else if (flags & KEXEC_ON_CRASH) { | |
938 | /* Free any current crash dump kernel before | |
939 | * we corrupt it. | |
940 | */ | |
941 | kimage_free(xchg(&kexec_crash_image, NULL)); | |
942 | result = kimage_crash_alloc(&image, entry, nr_segments, segments); | |
943 | } | |
944 | if (result) { | |
945 | goto out; | |
946 | } | |
947 | result = machine_kexec_prepare(image); | |
948 | if (result) { | |
949 | goto out; | |
950 | } | |
951 | for(i = 0; i < nr_segments; i++) { | |
952 | result = kimage_load_segment(image, &image->segment[i]); | |
953 | if (result) { | |
954 | goto out; | |
955 | } | |
956 | } | |
957 | result = kimage_terminate(image); | |
958 | if (result) { | |
959 | goto out; | |
960 | } | |
961 | } | |
962 | /* Install the new kernel, and Uninstall the old */ | |
963 | image = xchg(dest_image, image); | |
964 | ||
965 | out: | |
966 | xchg(&kexec_lock, 0); /* Release the mutex */ | |
967 | kimage_free(image); | |
968 | return result; | |
969 | } | |
970 | ||
971 | #ifdef CONFIG_COMPAT | |
972 | asmlinkage long compat_sys_kexec_load(unsigned long entry, | |
973 | unsigned long nr_segments, struct compat_kexec_segment __user *segments, | |
974 | unsigned long flags) | |
975 | { | |
976 | struct compat_kexec_segment in; | |
977 | struct kexec_segment out, __user *ksegments; | |
978 | unsigned long i, result; | |
979 | ||
980 | /* Don't allow clients that don't understand the native | |
981 | * architecture to do anything. | |
982 | */ | |
983 | if ((flags & KEXEC_ARCH_MASK) == KEXEC_ARCH_DEFAULT) { | |
984 | return -EINVAL; | |
985 | } | |
986 | ||
987 | if (nr_segments > KEXEC_SEGMENT_MAX) { | |
988 | return -EINVAL; | |
989 | } | |
990 | ||
991 | ksegments = compat_alloc_user_space(nr_segments * sizeof(out)); | |
992 | for (i=0; i < nr_segments; i++) { | |
993 | result = copy_from_user(&in, &segments[i], sizeof(in)); | |
994 | if (result) { | |
995 | return -EFAULT; | |
996 | } | |
997 | ||
998 | out.buf = compat_ptr(in.buf); | |
999 | out.bufsz = in.bufsz; | |
1000 | out.mem = in.mem; | |
1001 | out.memsz = in.memsz; | |
1002 | ||
1003 | result = copy_to_user(&ksegments[i], &out, sizeof(out)); | |
1004 | if (result) { | |
1005 | return -EFAULT; | |
1006 | } | |
1007 | } | |
1008 | ||
1009 | return sys_kexec_load(entry, nr_segments, ksegments, flags); | |
1010 | } | |
1011 | #endif | |
1012 | ||
1013 | void crash_kexec(void) | |
1014 | { | |
1015 | struct kimage *image; | |
1016 | int locked; | |
1017 | ||
1018 | ||
1019 | /* Take the kexec_lock here to prevent sys_kexec_load | |
1020 | * running on one cpu from replacing the crash kernel | |
1021 | * we are using after a panic on a different cpu. | |
1022 | * | |
1023 | * If the crash kernel was not located in a fixed area | |
1024 | * of memory the xchg(&kexec_crash_image) would be | |
1025 | * sufficient. But since I reuse the memory... | |
1026 | */ | |
1027 | locked = xchg(&kexec_lock, 1); | |
1028 | if (!locked) { | |
1029 | image = xchg(&kexec_crash_image, NULL); | |
1030 | if (image) { | |
1031 | machine_crash_shutdown(); | |
1032 | machine_kexec(image); | |
1033 | } | |
1034 | xchg(&kexec_lock, 0); | |
1035 | } | |
1036 | } |