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_NOENC));
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 		.kernpg_flag	= _KERNPG_TABLE_NOENC,
119 	};
120 	unsigned long mstart, mend;
121 	pgd_t *level4p;
122 	int result;
123 	int i;
124 
125 	level4p = (pgd_t *)__va(start_pgtable);
126 	clear_page(level4p);
127 
128 	if (direct_gbpages)
129 		info.direct_gbpages = true;
130 
131 	for (i = 0; i < nr_pfn_mapped; i++) {
132 		mstart = pfn_mapped[i].start << PAGE_SHIFT;
133 		mend   = pfn_mapped[i].end << PAGE_SHIFT;
134 
135 		result = kernel_ident_mapping_init(&info,
136 						 level4p, mstart, mend);
137 		if (result)
138 			return result;
139 	}
140 
141 	/*
142 	 * segments's mem ranges could be outside 0 ~ max_pfn,
143 	 * for example when jump back to original kernel from kexeced kernel.
144 	 * or first kernel is booted with user mem map, and second kernel
145 	 * could be loaded out of that range.
146 	 */
147 	for (i = 0; i < image->nr_segments; i++) {
148 		mstart = image->segment[i].mem;
149 		mend   = mstart + image->segment[i].memsz;
150 
151 		result = kernel_ident_mapping_init(&info,
152 						 level4p, mstart, mend);
153 
154 		if (result)
155 			return result;
156 	}
157 
158 	return init_transition_pgtable(image, level4p);
159 }
160 
161 static void set_idt(void *newidt, u16 limit)
162 {
163 	struct desc_ptr curidt;
164 
165 	/* x86-64 supports unaliged loads & stores */
166 	curidt.size    = limit;
167 	curidt.address = (unsigned long)newidt;
168 
169 	__asm__ __volatile__ (
170 		"lidtq %0\n"
171 		: : "m" (curidt)
172 		);
173 };
174 
175 
176 static void set_gdt(void *newgdt, u16 limit)
177 {
178 	struct desc_ptr curgdt;
179 
180 	/* x86-64 supports unaligned loads & stores */
181 	curgdt.size    = limit;
182 	curgdt.address = (unsigned long)newgdt;
183 
184 	__asm__ __volatile__ (
185 		"lgdtq %0\n"
186 		: : "m" (curgdt)
187 		);
188 };
189 
190 static void load_segments(void)
191 {
192 	__asm__ __volatile__ (
193 		"\tmovl %0,%%ds\n"
194 		"\tmovl %0,%%es\n"
195 		"\tmovl %0,%%ss\n"
196 		"\tmovl %0,%%fs\n"
197 		"\tmovl %0,%%gs\n"
198 		: : "a" (__KERNEL_DS) : "memory"
199 		);
200 }
201 
202 #ifdef CONFIG_KEXEC_FILE
203 /* Update purgatory as needed after various image segments have been prepared */
204 static int arch_update_purgatory(struct kimage *image)
205 {
206 	int ret = 0;
207 
208 	if (!image->file_mode)
209 		return 0;
210 
211 	/* Setup copying of backup region */
212 	if (image->type == KEXEC_TYPE_CRASH) {
213 		ret = kexec_purgatory_get_set_symbol(image,
214 				"purgatory_backup_dest",
215 				&image->arch.backup_load_addr,
216 				sizeof(image->arch.backup_load_addr), 0);
217 		if (ret)
218 			return ret;
219 
220 		ret = kexec_purgatory_get_set_symbol(image,
221 				"purgatory_backup_src",
222 				&image->arch.backup_src_start,
223 				sizeof(image->arch.backup_src_start), 0);
224 		if (ret)
225 			return ret;
226 
227 		ret = kexec_purgatory_get_set_symbol(image,
228 				"purgatory_backup_sz",
229 				&image->arch.backup_src_sz,
230 				sizeof(image->arch.backup_src_sz), 0);
231 		if (ret)
232 			return ret;
233 	}
234 
235 	return ret;
236 }
237 #else /* !CONFIG_KEXEC_FILE */
238 static inline int arch_update_purgatory(struct kimage *image)
239 {
240 	return 0;
241 }
242 #endif /* CONFIG_KEXEC_FILE */
243 
244 int machine_kexec_prepare(struct kimage *image)
245 {
246 	unsigned long start_pgtable;
247 	int result;
248 
249 	/* Calculate the offsets */
250 	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
251 
252 	/* Setup the identity mapped 64bit page table */
253 	result = init_pgtable(image, start_pgtable);
254 	if (result)
255 		return result;
256 
257 	/* update purgatory as needed */
258 	result = arch_update_purgatory(image);
259 	if (result)
260 		return result;
261 
262 	return 0;
263 }
264 
265 void machine_kexec_cleanup(struct kimage *image)
266 {
267 	free_transition_pgtable(image);
268 }
269 
270 /*
271  * Do not allocate memory (or fail in any way) in machine_kexec().
272  * We are past the point of no return, committed to rebooting now.
273  */
274 void machine_kexec(struct kimage *image)
275 {
276 	unsigned long page_list[PAGES_NR];
277 	void *control_page;
278 	int save_ftrace_enabled;
279 
280 #ifdef CONFIG_KEXEC_JUMP
281 	if (image->preserve_context)
282 		save_processor_state();
283 #endif
284 
285 	save_ftrace_enabled = __ftrace_enabled_save();
286 
287 	/* Interrupts aren't acceptable while we reboot */
288 	local_irq_disable();
289 	hw_breakpoint_disable();
290 
291 	if (image->preserve_context) {
292 #ifdef CONFIG_X86_IO_APIC
293 		/*
294 		 * We need to put APICs in legacy mode so that we can
295 		 * get timer interrupts in second kernel. kexec/kdump
296 		 * paths already have calls to disable_IO_APIC() in
297 		 * one form or other. kexec jump path also need
298 		 * one.
299 		 */
300 		disable_IO_APIC();
301 #endif
302 	}
303 
304 	control_page = page_address(image->control_code_page) + PAGE_SIZE;
305 	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
306 
307 	page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
308 	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
309 	page_list[PA_TABLE_PAGE] =
310 	  (unsigned long)__pa(page_address(image->control_code_page));
311 
312 	if (image->type == KEXEC_TYPE_DEFAULT)
313 		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
314 						<< PAGE_SHIFT);
315 
316 	/*
317 	 * The segment registers are funny things, they have both a
318 	 * visible and an invisible part.  Whenever the visible part is
319 	 * set to a specific selector, the invisible part is loaded
320 	 * with from a table in memory.  At no other time is the
321 	 * descriptor table in memory accessed.
322 	 *
323 	 * I take advantage of this here by force loading the
324 	 * segments, before I zap the gdt with an invalid value.
325 	 */
326 	load_segments();
327 	/*
328 	 * The gdt & idt are now invalid.
329 	 * If you want to load them you must set up your own idt & gdt.
330 	 */
331 	set_gdt(phys_to_virt(0), 0);
332 	set_idt(phys_to_virt(0), 0);
333 
334 	/* now call it */
335 	image->start = relocate_kernel((unsigned long)image->head,
336 				       (unsigned long)page_list,
337 				       image->start,
338 				       image->preserve_context,
339 				       sme_active());
340 
341 #ifdef CONFIG_KEXEC_JUMP
342 	if (image->preserve_context)
343 		restore_processor_state();
344 #endif
345 
346 	__ftrace_enabled_restore(save_ftrace_enabled);
347 }
348 
349 void arch_crash_save_vmcoreinfo(void)
350 {
351 	VMCOREINFO_NUMBER(phys_base);
352 	VMCOREINFO_SYMBOL(init_top_pgt);
353 
354 #ifdef CONFIG_NUMA
355 	VMCOREINFO_SYMBOL(node_data);
356 	VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
357 #endif
358 	vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
359 			      kaslr_offset());
360 	VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
361 }
362 
363 /* arch-dependent functionality related to kexec file-based syscall */
364 
365 #ifdef CONFIG_KEXEC_FILE
366 int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
367 				  unsigned long buf_len)
368 {
369 	int i, ret = -ENOEXEC;
370 	struct kexec_file_ops *fops;
371 
372 	for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
373 		fops = kexec_file_loaders[i];
374 		if (!fops || !fops->probe)
375 			continue;
376 
377 		ret = fops->probe(buf, buf_len);
378 		if (!ret) {
379 			image->fops = fops;
380 			return ret;
381 		}
382 	}
383 
384 	return ret;
385 }
386 
387 void *arch_kexec_kernel_image_load(struct kimage *image)
388 {
389 	vfree(image->arch.elf_headers);
390 	image->arch.elf_headers = NULL;
391 
392 	if (!image->fops || !image->fops->load)
393 		return ERR_PTR(-ENOEXEC);
394 
395 	return image->fops->load(image, image->kernel_buf,
396 				 image->kernel_buf_len, image->initrd_buf,
397 				 image->initrd_buf_len, image->cmdline_buf,
398 				 image->cmdline_buf_len);
399 }
400 
401 int arch_kimage_file_post_load_cleanup(struct kimage *image)
402 {
403 	if (!image->fops || !image->fops->cleanup)
404 		return 0;
405 
406 	return image->fops->cleanup(image->image_loader_data);
407 }
408 
409 #ifdef CONFIG_KEXEC_VERIFY_SIG
410 int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
411 				 unsigned long kernel_len)
412 {
413 	if (!image->fops || !image->fops->verify_sig) {
414 		pr_debug("kernel loader does not support signature verification.");
415 		return -EKEYREJECTED;
416 	}
417 
418 	return image->fops->verify_sig(kernel, kernel_len);
419 }
420 #endif
421 
422 /*
423  * Apply purgatory relocations.
424  *
425  * ehdr: Pointer to elf headers
426  * sechdrs: Pointer to section headers.
427  * relsec: section index of SHT_RELA section.
428  *
429  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
430  */
431 int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
432 				     Elf64_Shdr *sechdrs, unsigned int relsec)
433 {
434 	unsigned int i;
435 	Elf64_Rela *rel;
436 	Elf64_Sym *sym;
437 	void *location;
438 	Elf64_Shdr *section, *symtabsec;
439 	unsigned long address, sec_base, value;
440 	const char *strtab, *name, *shstrtab;
441 
442 	/*
443 	 * ->sh_offset has been modified to keep the pointer to section
444 	 * contents in memory
445 	 */
446 	rel = (void *)sechdrs[relsec].sh_offset;
447 
448 	/* Section to which relocations apply */
449 	section = &sechdrs[sechdrs[relsec].sh_info];
450 
451 	pr_debug("Applying relocate section %u to %u\n", relsec,
452 		 sechdrs[relsec].sh_info);
453 
454 	/* Associated symbol table */
455 	symtabsec = &sechdrs[sechdrs[relsec].sh_link];
456 
457 	/* String table */
458 	if (symtabsec->sh_link >= ehdr->e_shnum) {
459 		/* Invalid strtab section number */
460 		pr_err("Invalid string table section index %d\n",
461 		       symtabsec->sh_link);
462 		return -ENOEXEC;
463 	}
464 
465 	strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
466 
467 	/* section header string table */
468 	shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
469 
470 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
471 
472 		/*
473 		 * rel[i].r_offset contains byte offset from beginning
474 		 * of section to the storage unit affected.
475 		 *
476 		 * This is location to update (->sh_offset). This is temporary
477 		 * buffer where section is currently loaded. This will finally
478 		 * be loaded to a different address later, pointed to by
479 		 * ->sh_addr. kexec takes care of moving it
480 		 *  (kexec_load_segment()).
481 		 */
482 		location = (void *)(section->sh_offset + rel[i].r_offset);
483 
484 		/* Final address of the location */
485 		address = section->sh_addr + rel[i].r_offset;
486 
487 		/*
488 		 * rel[i].r_info contains information about symbol table index
489 		 * w.r.t which relocation must be made and type of relocation
490 		 * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
491 		 * these respectively.
492 		 */
493 		sym = (Elf64_Sym *)symtabsec->sh_offset +
494 				ELF64_R_SYM(rel[i].r_info);
495 
496 		if (sym->st_name)
497 			name = strtab + sym->st_name;
498 		else
499 			name = shstrtab + sechdrs[sym->st_shndx].sh_name;
500 
501 		pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
502 			 name, sym->st_info, sym->st_shndx, sym->st_value,
503 			 sym->st_size);
504 
505 		if (sym->st_shndx == SHN_UNDEF) {
506 			pr_err("Undefined symbol: %s\n", name);
507 			return -ENOEXEC;
508 		}
509 
510 		if (sym->st_shndx == SHN_COMMON) {
511 			pr_err("symbol '%s' in common section\n", name);
512 			return -ENOEXEC;
513 		}
514 
515 		if (sym->st_shndx == SHN_ABS)
516 			sec_base = 0;
517 		else if (sym->st_shndx >= ehdr->e_shnum) {
518 			pr_err("Invalid section %d for symbol %s\n",
519 			       sym->st_shndx, name);
520 			return -ENOEXEC;
521 		} else
522 			sec_base = sechdrs[sym->st_shndx].sh_addr;
523 
524 		value = sym->st_value;
525 		value += sec_base;
526 		value += rel[i].r_addend;
527 
528 		switch (ELF64_R_TYPE(rel[i].r_info)) {
529 		case R_X86_64_NONE:
530 			break;
531 		case R_X86_64_64:
532 			*(u64 *)location = value;
533 			break;
534 		case R_X86_64_32:
535 			*(u32 *)location = value;
536 			if (value != *(u32 *)location)
537 				goto overflow;
538 			break;
539 		case R_X86_64_32S:
540 			*(s32 *)location = value;
541 			if ((s64)value != *(s32 *)location)
542 				goto overflow;
543 			break;
544 		case R_X86_64_PC32:
545 		case R_X86_64_PLT32:
546 			value -= (u64)address;
547 			*(u32 *)location = value;
548 			break;
549 		default:
550 			pr_err("Unknown rela relocation: %llu\n",
551 			       ELF64_R_TYPE(rel[i].r_info));
552 			return -ENOEXEC;
553 		}
554 	}
555 	return 0;
556 
557 overflow:
558 	pr_err("Overflow in relocation type %d value 0x%lx\n",
559 	       (int)ELF64_R_TYPE(rel[i].r_info), value);
560 	return -ENOEXEC;
561 }
562 #endif /* CONFIG_KEXEC_FILE */
563 
564 static int
565 kexec_mark_range(unsigned long start, unsigned long end, bool protect)
566 {
567 	struct page *page;
568 	unsigned int nr_pages;
569 
570 	/*
571 	 * For physical range: [start, end]. We must skip the unassigned
572 	 * crashk resource with zero-valued "end" member.
573 	 */
574 	if (!end || start > end)
575 		return 0;
576 
577 	page = pfn_to_page(start >> PAGE_SHIFT);
578 	nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
579 	if (protect)
580 		return set_pages_ro(page, nr_pages);
581 	else
582 		return set_pages_rw(page, nr_pages);
583 }
584 
585 static void kexec_mark_crashkres(bool protect)
586 {
587 	unsigned long control;
588 
589 	kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
590 
591 	/* Don't touch the control code page used in crash_kexec().*/
592 	control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
593 	/* Control code page is located in the 2nd page. */
594 	kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
595 	control += KEXEC_CONTROL_PAGE_SIZE;
596 	kexec_mark_range(control, crashk_res.end, protect);
597 }
598 
599 void arch_kexec_protect_crashkres(void)
600 {
601 	kexec_mark_crashkres(true);
602 }
603 
604 void arch_kexec_unprotect_crashkres(void)
605 {
606 	kexec_mark_crashkres(false);
607 }
608 
609 int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, gfp_t gfp)
610 {
611 	/*
612 	 * If SME is active we need to be sure that kexec pages are
613 	 * not encrypted because when we boot to the new kernel the
614 	 * pages won't be accessed encrypted (initially).
615 	 */
616 	return set_memory_decrypted((unsigned long)vaddr, pages);
617 }
618 
619 void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages)
620 {
621 	/*
622 	 * If SME is active we need to reset the pages back to being
623 	 * an encrypted mapping before freeing them.
624 	 */
625 	set_memory_encrypted((unsigned long)vaddr, pages);
626 }
627