1 /*
2  * handle transition of Linux booting another kernel
3  * Copyright (C) 2002-2005 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 #define pr_fmt(fmt)	"kexec: " fmt
10 
11 #include <linux/mm.h>
12 #include <linux/kexec.h>
13 #include <linux/string.h>
14 #include <linux/gfp.h>
15 #include <linux/reboot.h>
16 #include <linux/numa.h>
17 #include <linux/ftrace.h>
18 #include <linux/io.h>
19 #include <linux/suspend.h>
20 #include <linux/vmalloc.h>
21 
22 #include <asm/init.h>
23 #include <asm/pgtable.h>
24 #include <asm/tlbflush.h>
25 #include <asm/mmu_context.h>
26 #include <asm/io_apic.h>
27 #include <asm/debugreg.h>
28 #include <asm/kexec-bzimage64.h>
29 #include <asm/setup.h>
30 #include <asm/set_memory.h>
31 
32 #ifdef CONFIG_KEXEC_FILE
33 static struct kexec_file_ops *kexec_file_loaders[] = {
34 		&kexec_bzImage64_ops,
35 };
36 #endif
37 
38 static void free_transition_pgtable(struct kimage *image)
39 {
40 	free_page((unsigned long)image->arch.p4d);
41 	free_page((unsigned long)image->arch.pud);
42 	free_page((unsigned long)image->arch.pmd);
43 	free_page((unsigned long)image->arch.pte);
44 }
45 
46 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
47 {
48 	p4d_t *p4d;
49 	pud_t *pud;
50 	pmd_t *pmd;
51 	pte_t *pte;
52 	unsigned long vaddr, paddr;
53 	int result = -ENOMEM;
54 
55 	vaddr = (unsigned long)relocate_kernel;
56 	paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
57 	pgd += pgd_index(vaddr);
58 	if (!pgd_present(*pgd)) {
59 		p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
60 		if (!p4d)
61 			goto err;
62 		image->arch.p4d = p4d;
63 		set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
64 	}
65 	p4d = p4d_offset(pgd, vaddr);
66 	if (!p4d_present(*p4d)) {
67 		pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
68 		if (!pud)
69 			goto err;
70 		image->arch.pud = pud;
71 		set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
72 	}
73 	pud = pud_offset(p4d, vaddr);
74 	if (!pud_present(*pud)) {
75 		pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
76 		if (!pmd)
77 			goto err;
78 		image->arch.pmd = pmd;
79 		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
80 	}
81 	pmd = pmd_offset(pud, vaddr);
82 	if (!pmd_present(*pmd)) {
83 		pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
84 		if (!pte)
85 			goto err;
86 		image->arch.pte = pte;
87 		set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
88 	}
89 	pte = pte_offset_kernel(pmd, vaddr);
90 	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
91 	return 0;
92 err:
93 	free_transition_pgtable(image);
94 	return result;
95 }
96 
97 static void *alloc_pgt_page(void *data)
98 {
99 	struct kimage *image = (struct kimage *)data;
100 	struct page *page;
101 	void *p = NULL;
102 
103 	page = kimage_alloc_control_pages(image, 0);
104 	if (page) {
105 		p = page_address(page);
106 		clear_page(p);
107 	}
108 
109 	return p;
110 }
111 
112 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
113 {
114 	struct x86_mapping_info info = {
115 		.alloc_pgt_page	= alloc_pgt_page,
116 		.context	= image,
117 		.page_flag	= __PAGE_KERNEL_LARGE_EXEC,
118 	};
119 	unsigned long mstart, mend;
120 	pgd_t *level4p;
121 	int result;
122 	int i;
123 
124 	level4p = (pgd_t *)__va(start_pgtable);
125 	clear_page(level4p);
126 
127 	if (direct_gbpages)
128 		info.direct_gbpages = true;
129 
130 	for (i = 0; i < nr_pfn_mapped; i++) {
131 		mstart = pfn_mapped[i].start << PAGE_SHIFT;
132 		mend   = pfn_mapped[i].end << PAGE_SHIFT;
133 
134 		result = kernel_ident_mapping_init(&info,
135 						 level4p, mstart, mend);
136 		if (result)
137 			return result;
138 	}
139 
140 	/*
141 	 * segments's mem ranges could be outside 0 ~ max_pfn,
142 	 * for example when jump back to original kernel from kexeced kernel.
143 	 * or first kernel is booted with user mem map, and second kernel
144 	 * could be loaded out of that range.
145 	 */
146 	for (i = 0; i < image->nr_segments; i++) {
147 		mstart = image->segment[i].mem;
148 		mend   = mstart + image->segment[i].memsz;
149 
150 		result = kernel_ident_mapping_init(&info,
151 						 level4p, mstart, mend);
152 
153 		if (result)
154 			return result;
155 	}
156 
157 	return init_transition_pgtable(image, level4p);
158 }
159 
160 static void set_idt(void *newidt, u16 limit)
161 {
162 	struct desc_ptr curidt;
163 
164 	/* x86-64 supports unaliged loads & stores */
165 	curidt.size    = limit;
166 	curidt.address = (unsigned long)newidt;
167 
168 	__asm__ __volatile__ (
169 		"lidtq %0\n"
170 		: : "m" (curidt)
171 		);
172 };
173 
174 
175 static void set_gdt(void *newgdt, u16 limit)
176 {
177 	struct desc_ptr curgdt;
178 
179 	/* x86-64 supports unaligned loads & stores */
180 	curgdt.size    = limit;
181 	curgdt.address = (unsigned long)newgdt;
182 
183 	__asm__ __volatile__ (
184 		"lgdtq %0\n"
185 		: : "m" (curgdt)
186 		);
187 };
188 
189 static void load_segments(void)
190 {
191 	__asm__ __volatile__ (
192 		"\tmovl %0,%%ds\n"
193 		"\tmovl %0,%%es\n"
194 		"\tmovl %0,%%ss\n"
195 		"\tmovl %0,%%fs\n"
196 		"\tmovl %0,%%gs\n"
197 		: : "a" (__KERNEL_DS) : "memory"
198 		);
199 }
200 
201 #ifdef CONFIG_KEXEC_FILE
202 /* Update purgatory as needed after various image segments have been prepared */
203 static int arch_update_purgatory(struct kimage *image)
204 {
205 	int ret = 0;
206 
207 	if (!image->file_mode)
208 		return 0;
209 
210 	/* Setup copying of backup region */
211 	if (image->type == KEXEC_TYPE_CRASH) {
212 		ret = kexec_purgatory_get_set_symbol(image,
213 				"purgatory_backup_dest",
214 				&image->arch.backup_load_addr,
215 				sizeof(image->arch.backup_load_addr), 0);
216 		if (ret)
217 			return ret;
218 
219 		ret = kexec_purgatory_get_set_symbol(image,
220 				"purgatory_backup_src",
221 				&image->arch.backup_src_start,
222 				sizeof(image->arch.backup_src_start), 0);
223 		if (ret)
224 			return ret;
225 
226 		ret = kexec_purgatory_get_set_symbol(image,
227 				"purgatory_backup_sz",
228 				&image->arch.backup_src_sz,
229 				sizeof(image->arch.backup_src_sz), 0);
230 		if (ret)
231 			return ret;
232 	}
233 
234 	return ret;
235 }
236 #else /* !CONFIG_KEXEC_FILE */
237 static inline int arch_update_purgatory(struct kimage *image)
238 {
239 	return 0;
240 }
241 #endif /* CONFIG_KEXEC_FILE */
242 
243 int machine_kexec_prepare(struct kimage *image)
244 {
245 	unsigned long start_pgtable;
246 	int result;
247 
248 	/* Calculate the offsets */
249 	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
250 
251 	/* Setup the identity mapped 64bit page table */
252 	result = init_pgtable(image, start_pgtable);
253 	if (result)
254 		return result;
255 
256 	/* update purgatory as needed */
257 	result = arch_update_purgatory(image);
258 	if (result)
259 		return result;
260 
261 	return 0;
262 }
263 
264 void machine_kexec_cleanup(struct kimage *image)
265 {
266 	free_transition_pgtable(image);
267 }
268 
269 /*
270  * Do not allocate memory (or fail in any way) in machine_kexec().
271  * We are past the point of no return, committed to rebooting now.
272  */
273 void machine_kexec(struct kimage *image)
274 {
275 	unsigned long page_list[PAGES_NR];
276 	void *control_page;
277 	int save_ftrace_enabled;
278 
279 #ifdef CONFIG_KEXEC_JUMP
280 	if (image->preserve_context)
281 		save_processor_state();
282 #endif
283 
284 	save_ftrace_enabled = __ftrace_enabled_save();
285 
286 	/* Interrupts aren't acceptable while we reboot */
287 	local_irq_disable();
288 	hw_breakpoint_disable();
289 
290 	if (image->preserve_context) {
291 #ifdef CONFIG_X86_IO_APIC
292 		/*
293 		 * We need to put APICs in legacy mode so that we can
294 		 * get timer interrupts in second kernel. kexec/kdump
295 		 * paths already have calls to disable_IO_APIC() in
296 		 * one form or other. kexec jump path also need
297 		 * one.
298 		 */
299 		disable_IO_APIC();
300 #endif
301 	}
302 
303 	control_page = page_address(image->control_code_page) + PAGE_SIZE;
304 	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
305 
306 	page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
307 	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
308 	page_list[PA_TABLE_PAGE] =
309 	  (unsigned long)__pa(page_address(image->control_code_page));
310 
311 	if (image->type == KEXEC_TYPE_DEFAULT)
312 		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
313 						<< PAGE_SHIFT);
314 
315 	/*
316 	 * The segment registers are funny things, they have both a
317 	 * visible and an invisible part.  Whenever the visible part is
318 	 * set to a specific selector, the invisible part is loaded
319 	 * with from a table in memory.  At no other time is the
320 	 * descriptor table in memory accessed.
321 	 *
322 	 * I take advantage of this here by force loading the
323 	 * segments, before I zap the gdt with an invalid value.
324 	 */
325 	load_segments();
326 	/*
327 	 * The gdt & idt are now invalid.
328 	 * If you want to load them you must set up your own idt & gdt.
329 	 */
330 	set_gdt(phys_to_virt(0), 0);
331 	set_idt(phys_to_virt(0), 0);
332 
333 	/* now call it */
334 	image->start = relocate_kernel((unsigned long)image->head,
335 				       (unsigned long)page_list,
336 				       image->start,
337 				       image->preserve_context);
338 
339 #ifdef CONFIG_KEXEC_JUMP
340 	if (image->preserve_context)
341 		restore_processor_state();
342 #endif
343 
344 	__ftrace_enabled_restore(save_ftrace_enabled);
345 }
346 
347 void arch_crash_save_vmcoreinfo(void)
348 {
349 	VMCOREINFO_NUMBER(phys_base);
350 	VMCOREINFO_SYMBOL(init_level4_pgt);
351 
352 #ifdef CONFIG_NUMA
353 	VMCOREINFO_SYMBOL(node_data);
354 	VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
355 #endif
356 	vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
357 			      kaslr_offset());
358 	VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
359 }
360 
361 /* arch-dependent functionality related to kexec file-based syscall */
362 
363 #ifdef CONFIG_KEXEC_FILE
364 int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
365 				  unsigned long buf_len)
366 {
367 	int i, ret = -ENOEXEC;
368 	struct kexec_file_ops *fops;
369 
370 	for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
371 		fops = kexec_file_loaders[i];
372 		if (!fops || !fops->probe)
373 			continue;
374 
375 		ret = fops->probe(buf, buf_len);
376 		if (!ret) {
377 			image->fops = fops;
378 			return ret;
379 		}
380 	}
381 
382 	return ret;
383 }
384 
385 void *arch_kexec_kernel_image_load(struct kimage *image)
386 {
387 	vfree(image->arch.elf_headers);
388 	image->arch.elf_headers = NULL;
389 
390 	if (!image->fops || !image->fops->load)
391 		return ERR_PTR(-ENOEXEC);
392 
393 	return image->fops->load(image, image->kernel_buf,
394 				 image->kernel_buf_len, image->initrd_buf,
395 				 image->initrd_buf_len, image->cmdline_buf,
396 				 image->cmdline_buf_len);
397 }
398 
399 int arch_kimage_file_post_load_cleanup(struct kimage *image)
400 {
401 	if (!image->fops || !image->fops->cleanup)
402 		return 0;
403 
404 	return image->fops->cleanup(image->image_loader_data);
405 }
406 
407 #ifdef CONFIG_KEXEC_VERIFY_SIG
408 int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
409 				 unsigned long kernel_len)
410 {
411 	if (!image->fops || !image->fops->verify_sig) {
412 		pr_debug("kernel loader does not support signature verification.");
413 		return -EKEYREJECTED;
414 	}
415 
416 	return image->fops->verify_sig(kernel, kernel_len);
417 }
418 #endif
419 
420 /*
421  * Apply purgatory relocations.
422  *
423  * ehdr: Pointer to elf headers
424  * sechdrs: Pointer to section headers.
425  * relsec: section index of SHT_RELA section.
426  *
427  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
428  */
429 int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
430 				     Elf64_Shdr *sechdrs, unsigned int relsec)
431 {
432 	unsigned int i;
433 	Elf64_Rela *rel;
434 	Elf64_Sym *sym;
435 	void *location;
436 	Elf64_Shdr *section, *symtabsec;
437 	unsigned long address, sec_base, value;
438 	const char *strtab, *name, *shstrtab;
439 
440 	/*
441 	 * ->sh_offset has been modified to keep the pointer to section
442 	 * contents in memory
443 	 */
444 	rel = (void *)sechdrs[relsec].sh_offset;
445 
446 	/* Section to which relocations apply */
447 	section = &sechdrs[sechdrs[relsec].sh_info];
448 
449 	pr_debug("Applying relocate section %u to %u\n", relsec,
450 		 sechdrs[relsec].sh_info);
451 
452 	/* Associated symbol table */
453 	symtabsec = &sechdrs[sechdrs[relsec].sh_link];
454 
455 	/* String table */
456 	if (symtabsec->sh_link >= ehdr->e_shnum) {
457 		/* Invalid strtab section number */
458 		pr_err("Invalid string table section index %d\n",
459 		       symtabsec->sh_link);
460 		return -ENOEXEC;
461 	}
462 
463 	strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
464 
465 	/* section header string table */
466 	shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
467 
468 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
469 
470 		/*
471 		 * rel[i].r_offset contains byte offset from beginning
472 		 * of section to the storage unit affected.
473 		 *
474 		 * This is location to update (->sh_offset). This is temporary
475 		 * buffer where section is currently loaded. This will finally
476 		 * be loaded to a different address later, pointed to by
477 		 * ->sh_addr. kexec takes care of moving it
478 		 *  (kexec_load_segment()).
479 		 */
480 		location = (void *)(section->sh_offset + rel[i].r_offset);
481 
482 		/* Final address of the location */
483 		address = section->sh_addr + rel[i].r_offset;
484 
485 		/*
486 		 * rel[i].r_info contains information about symbol table index
487 		 * w.r.t which relocation must be made and type of relocation
488 		 * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
489 		 * these respectively.
490 		 */
491 		sym = (Elf64_Sym *)symtabsec->sh_offset +
492 				ELF64_R_SYM(rel[i].r_info);
493 
494 		if (sym->st_name)
495 			name = strtab + sym->st_name;
496 		else
497 			name = shstrtab + sechdrs[sym->st_shndx].sh_name;
498 
499 		pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
500 			 name, sym->st_info, sym->st_shndx, sym->st_value,
501 			 sym->st_size);
502 
503 		if (sym->st_shndx == SHN_UNDEF) {
504 			pr_err("Undefined symbol: %s\n", name);
505 			return -ENOEXEC;
506 		}
507 
508 		if (sym->st_shndx == SHN_COMMON) {
509 			pr_err("symbol '%s' in common section\n", name);
510 			return -ENOEXEC;
511 		}
512 
513 		if (sym->st_shndx == SHN_ABS)
514 			sec_base = 0;
515 		else if (sym->st_shndx >= ehdr->e_shnum) {
516 			pr_err("Invalid section %d for symbol %s\n",
517 			       sym->st_shndx, name);
518 			return -ENOEXEC;
519 		} else
520 			sec_base = sechdrs[sym->st_shndx].sh_addr;
521 
522 		value = sym->st_value;
523 		value += sec_base;
524 		value += rel[i].r_addend;
525 
526 		switch (ELF64_R_TYPE(rel[i].r_info)) {
527 		case R_X86_64_NONE:
528 			break;
529 		case R_X86_64_64:
530 			*(u64 *)location = value;
531 			break;
532 		case R_X86_64_32:
533 			*(u32 *)location = value;
534 			if (value != *(u32 *)location)
535 				goto overflow;
536 			break;
537 		case R_X86_64_32S:
538 			*(s32 *)location = value;
539 			if ((s64)value != *(s32 *)location)
540 				goto overflow;
541 			break;
542 		case R_X86_64_PC32:
543 			value -= (u64)address;
544 			*(u32 *)location = value;
545 			break;
546 		default:
547 			pr_err("Unknown rela relocation: %llu\n",
548 			       ELF64_R_TYPE(rel[i].r_info));
549 			return -ENOEXEC;
550 		}
551 	}
552 	return 0;
553 
554 overflow:
555 	pr_err("Overflow in relocation type %d value 0x%lx\n",
556 	       (int)ELF64_R_TYPE(rel[i].r_info), value);
557 	return -ENOEXEC;
558 }
559 #endif /* CONFIG_KEXEC_FILE */
560 
561 static int
562 kexec_mark_range(unsigned long start, unsigned long end, bool protect)
563 {
564 	struct page *page;
565 	unsigned int nr_pages;
566 
567 	/*
568 	 * For physical range: [start, end]. We must skip the unassigned
569 	 * crashk resource with zero-valued "end" member.
570 	 */
571 	if (!end || start > end)
572 		return 0;
573 
574 	page = pfn_to_page(start >> PAGE_SHIFT);
575 	nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
576 	if (protect)
577 		return set_pages_ro(page, nr_pages);
578 	else
579 		return set_pages_rw(page, nr_pages);
580 }
581 
582 static void kexec_mark_crashkres(bool protect)
583 {
584 	unsigned long control;
585 
586 	kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
587 
588 	/* Don't touch the control code page used in crash_kexec().*/
589 	control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
590 	/* Control code page is located in the 2nd page. */
591 	kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
592 	control += KEXEC_CONTROL_PAGE_SIZE;
593 	kexec_mark_range(control, crashk_res.end, protect);
594 }
595 
596 void arch_kexec_protect_crashkres(void)
597 {
598 	kexec_mark_crashkres(true);
599 }
600 
601 void arch_kexec_unprotect_crashkres(void)
602 {
603 	kexec_mark_crashkres(false);
604 }
605