1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * handle transition of Linux booting another kernel
4  * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
5  */
6 
7 #define pr_fmt(fmt)	"kexec: " fmt
8 
9 #include <linux/mm.h>
10 #include <linux/kexec.h>
11 #include <linux/string.h>
12 #include <linux/gfp.h>
13 #include <linux/reboot.h>
14 #include <linux/numa.h>
15 #include <linux/ftrace.h>
16 #include <linux/io.h>
17 #include <linux/suspend.h>
18 #include <linux/vmalloc.h>
19 #include <linux/efi.h>
20 
21 #include <asm/init.h>
22 #include <asm/tlbflush.h>
23 #include <asm/mmu_context.h>
24 #include <asm/io_apic.h>
25 #include <asm/debugreg.h>
26 #include <asm/kexec-bzimage64.h>
27 #include <asm/setup.h>
28 #include <asm/set_memory.h>
29 
30 #ifdef CONFIG_ACPI
31 /*
32  * Used while adding mapping for ACPI tables.
33  * Can be reused when other iomem regions need be mapped
34  */
35 struct init_pgtable_data {
36 	struct x86_mapping_info *info;
37 	pgd_t *level4p;
38 };
39 
40 static int mem_region_callback(struct resource *res, void *arg)
41 {
42 	struct init_pgtable_data *data = arg;
43 	unsigned long mstart, mend;
44 
45 	mstart = res->start;
46 	mend = mstart + resource_size(res) - 1;
47 
48 	return kernel_ident_mapping_init(data->info, data->level4p, mstart, mend);
49 }
50 
51 static int
52 map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p)
53 {
54 	struct init_pgtable_data data;
55 	unsigned long flags;
56 	int ret;
57 
58 	data.info = info;
59 	data.level4p = level4p;
60 	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
61 
62 	ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
63 				  &data, mem_region_callback);
64 	if (ret && ret != -EINVAL)
65 		return ret;
66 
67 	/* ACPI tables could be located in ACPI Non-volatile Storage region */
68 	ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1,
69 				  &data, mem_region_callback);
70 	if (ret && ret != -EINVAL)
71 		return ret;
72 
73 	return 0;
74 }
75 #else
76 static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }
77 #endif
78 
79 #ifdef CONFIG_KEXEC_FILE
80 const struct kexec_file_ops * const kexec_file_loaders[] = {
81 		&kexec_bzImage64_ops,
82 		NULL
83 };
84 #endif
85 
86 static int
87 map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p)
88 {
89 #ifdef CONFIG_EFI
90 	unsigned long mstart, mend;
91 
92 	if (!efi_enabled(EFI_BOOT))
93 		return 0;
94 
95 	mstart = (boot_params.efi_info.efi_systab |
96 			((u64)boot_params.efi_info.efi_systab_hi<<32));
97 
98 	if (efi_enabled(EFI_64BIT))
99 		mend = mstart + sizeof(efi_system_table_64_t);
100 	else
101 		mend = mstart + sizeof(efi_system_table_32_t);
102 
103 	if (!mstart)
104 		return 0;
105 
106 	return kernel_ident_mapping_init(info, level4p, mstart, mend);
107 #endif
108 	return 0;
109 }
110 
111 static void free_transition_pgtable(struct kimage *image)
112 {
113 	free_page((unsigned long)image->arch.p4d);
114 	image->arch.p4d = NULL;
115 	free_page((unsigned long)image->arch.pud);
116 	image->arch.pud = NULL;
117 	free_page((unsigned long)image->arch.pmd);
118 	image->arch.pmd = NULL;
119 	free_page((unsigned long)image->arch.pte);
120 	image->arch.pte = NULL;
121 }
122 
123 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
124 {
125 	pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
126 	unsigned long vaddr, paddr;
127 	int result = -ENOMEM;
128 	p4d_t *p4d;
129 	pud_t *pud;
130 	pmd_t *pmd;
131 	pte_t *pte;
132 
133 	vaddr = (unsigned long)relocate_kernel;
134 	paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
135 	pgd += pgd_index(vaddr);
136 	if (!pgd_present(*pgd)) {
137 		p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
138 		if (!p4d)
139 			goto err;
140 		image->arch.p4d = p4d;
141 		set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
142 	}
143 	p4d = p4d_offset(pgd, vaddr);
144 	if (!p4d_present(*p4d)) {
145 		pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
146 		if (!pud)
147 			goto err;
148 		image->arch.pud = pud;
149 		set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
150 	}
151 	pud = pud_offset(p4d, vaddr);
152 	if (!pud_present(*pud)) {
153 		pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
154 		if (!pmd)
155 			goto err;
156 		image->arch.pmd = pmd;
157 		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
158 	}
159 	pmd = pmd_offset(pud, vaddr);
160 	if (!pmd_present(*pmd)) {
161 		pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
162 		if (!pte)
163 			goto err;
164 		image->arch.pte = pte;
165 		set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
166 	}
167 	pte = pte_offset_kernel(pmd, vaddr);
168 
169 	if (sev_active())
170 		prot = PAGE_KERNEL_EXEC;
171 
172 	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
173 	return 0;
174 err:
175 	return result;
176 }
177 
178 static void *alloc_pgt_page(void *data)
179 {
180 	struct kimage *image = (struct kimage *)data;
181 	struct page *page;
182 	void *p = NULL;
183 
184 	page = kimage_alloc_control_pages(image, 0);
185 	if (page) {
186 		p = page_address(page);
187 		clear_page(p);
188 	}
189 
190 	return p;
191 }
192 
193 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
194 {
195 	struct x86_mapping_info info = {
196 		.alloc_pgt_page	= alloc_pgt_page,
197 		.context	= image,
198 		.page_flag	= __PAGE_KERNEL_LARGE_EXEC,
199 		.kernpg_flag	= _KERNPG_TABLE_NOENC,
200 	};
201 	unsigned long mstart, mend;
202 	pgd_t *level4p;
203 	int result;
204 	int i;
205 
206 	level4p = (pgd_t *)__va(start_pgtable);
207 	clear_page(level4p);
208 
209 	if (sev_active()) {
210 		info.page_flag   |= _PAGE_ENC;
211 		info.kernpg_flag |= _PAGE_ENC;
212 	}
213 
214 	if (direct_gbpages)
215 		info.direct_gbpages = true;
216 
217 	for (i = 0; i < nr_pfn_mapped; i++) {
218 		mstart = pfn_mapped[i].start << PAGE_SHIFT;
219 		mend   = pfn_mapped[i].end << PAGE_SHIFT;
220 
221 		result = kernel_ident_mapping_init(&info,
222 						 level4p, mstart, mend);
223 		if (result)
224 			return result;
225 	}
226 
227 	/*
228 	 * segments's mem ranges could be outside 0 ~ max_pfn,
229 	 * for example when jump back to original kernel from kexeced kernel.
230 	 * or first kernel is booted with user mem map, and second kernel
231 	 * could be loaded out of that range.
232 	 */
233 	for (i = 0; i < image->nr_segments; i++) {
234 		mstart = image->segment[i].mem;
235 		mend   = mstart + image->segment[i].memsz;
236 
237 		result = kernel_ident_mapping_init(&info,
238 						 level4p, mstart, mend);
239 
240 		if (result)
241 			return result;
242 	}
243 
244 	/*
245 	 * Prepare EFI systab and ACPI tables for kexec kernel since they are
246 	 * not covered by pfn_mapped.
247 	 */
248 	result = map_efi_systab(&info, level4p);
249 	if (result)
250 		return result;
251 
252 	result = map_acpi_tables(&info, level4p);
253 	if (result)
254 		return result;
255 
256 	return init_transition_pgtable(image, level4p);
257 }
258 
259 static void set_idt(void *newidt, u16 limit)
260 {
261 	struct desc_ptr curidt;
262 
263 	/* x86-64 supports unaliged loads & stores */
264 	curidt.size    = limit;
265 	curidt.address = (unsigned long)newidt;
266 
267 	__asm__ __volatile__ (
268 		"lidtq %0\n"
269 		: : "m" (curidt)
270 		);
271 };
272 
273 
274 static void set_gdt(void *newgdt, u16 limit)
275 {
276 	struct desc_ptr curgdt;
277 
278 	/* x86-64 supports unaligned loads & stores */
279 	curgdt.size    = limit;
280 	curgdt.address = (unsigned long)newgdt;
281 
282 	__asm__ __volatile__ (
283 		"lgdtq %0\n"
284 		: : "m" (curgdt)
285 		);
286 };
287 
288 static void load_segments(void)
289 {
290 	__asm__ __volatile__ (
291 		"\tmovl %0,%%ds\n"
292 		"\tmovl %0,%%es\n"
293 		"\tmovl %0,%%ss\n"
294 		"\tmovl %0,%%fs\n"
295 		"\tmovl %0,%%gs\n"
296 		: : "a" (__KERNEL_DS) : "memory"
297 		);
298 }
299 
300 int machine_kexec_prepare(struct kimage *image)
301 {
302 	unsigned long start_pgtable;
303 	int result;
304 
305 	/* Calculate the offsets */
306 	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
307 
308 	/* Setup the identity mapped 64bit page table */
309 	result = init_pgtable(image, start_pgtable);
310 	if (result)
311 		return result;
312 
313 	return 0;
314 }
315 
316 void machine_kexec_cleanup(struct kimage *image)
317 {
318 	free_transition_pgtable(image);
319 }
320 
321 /*
322  * Do not allocate memory (or fail in any way) in machine_kexec().
323  * We are past the point of no return, committed to rebooting now.
324  */
325 void machine_kexec(struct kimage *image)
326 {
327 	unsigned long page_list[PAGES_NR];
328 	void *control_page;
329 	int save_ftrace_enabled;
330 
331 #ifdef CONFIG_KEXEC_JUMP
332 	if (image->preserve_context)
333 		save_processor_state();
334 #endif
335 
336 	save_ftrace_enabled = __ftrace_enabled_save();
337 
338 	/* Interrupts aren't acceptable while we reboot */
339 	local_irq_disable();
340 	hw_breakpoint_disable();
341 
342 	if (image->preserve_context) {
343 #ifdef CONFIG_X86_IO_APIC
344 		/*
345 		 * We need to put APICs in legacy mode so that we can
346 		 * get timer interrupts in second kernel. kexec/kdump
347 		 * paths already have calls to restore_boot_irq_mode()
348 		 * in one form or other. kexec jump path also need one.
349 		 */
350 		clear_IO_APIC();
351 		restore_boot_irq_mode();
352 #endif
353 	}
354 
355 	control_page = page_address(image->control_code_page) + PAGE_SIZE;
356 	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
357 
358 	page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
359 	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
360 	page_list[PA_TABLE_PAGE] =
361 	  (unsigned long)__pa(page_address(image->control_code_page));
362 
363 	if (image->type == KEXEC_TYPE_DEFAULT)
364 		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
365 						<< PAGE_SHIFT);
366 
367 	/*
368 	 * The segment registers are funny things, they have both a
369 	 * visible and an invisible part.  Whenever the visible part is
370 	 * set to a specific selector, the invisible part is loaded
371 	 * with from a table in memory.  At no other time is the
372 	 * descriptor table in memory accessed.
373 	 *
374 	 * I take advantage of this here by force loading the
375 	 * segments, before I zap the gdt with an invalid value.
376 	 */
377 	load_segments();
378 	/*
379 	 * The gdt & idt are now invalid.
380 	 * If you want to load them you must set up your own idt & gdt.
381 	 */
382 	set_gdt(phys_to_virt(0), 0);
383 	set_idt(phys_to_virt(0), 0);
384 
385 	/* now call it */
386 	image->start = relocate_kernel((unsigned long)image->head,
387 				       (unsigned long)page_list,
388 				       image->start,
389 				       image->preserve_context,
390 				       sme_active());
391 
392 #ifdef CONFIG_KEXEC_JUMP
393 	if (image->preserve_context)
394 		restore_processor_state();
395 #endif
396 
397 	__ftrace_enabled_restore(save_ftrace_enabled);
398 }
399 
400 /* arch-dependent functionality related to kexec file-based syscall */
401 
402 #ifdef CONFIG_KEXEC_FILE
403 void *arch_kexec_kernel_image_load(struct kimage *image)
404 {
405 	vfree(image->arch.elf_headers);
406 	image->arch.elf_headers = NULL;
407 
408 	if (!image->fops || !image->fops->load)
409 		return ERR_PTR(-ENOEXEC);
410 
411 	return image->fops->load(image, image->kernel_buf,
412 				 image->kernel_buf_len, image->initrd_buf,
413 				 image->initrd_buf_len, image->cmdline_buf,
414 				 image->cmdline_buf_len);
415 }
416 
417 /*
418  * Apply purgatory relocations.
419  *
420  * @pi:		Purgatory to be relocated.
421  * @section:	Section relocations applying to.
422  * @relsec:	Section containing RELAs.
423  * @symtabsec:	Corresponding symtab.
424  *
425  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
426  */
427 int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
428 				     Elf_Shdr *section, const Elf_Shdr *relsec,
429 				     const Elf_Shdr *symtabsec)
430 {
431 	unsigned int i;
432 	Elf64_Rela *rel;
433 	Elf64_Sym *sym;
434 	void *location;
435 	unsigned long address, sec_base, value;
436 	const char *strtab, *name, *shstrtab;
437 	const Elf_Shdr *sechdrs;
438 
439 	/* String & section header string table */
440 	sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
441 	strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset;
442 	shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
443 
444 	rel = (void *)pi->ehdr + relsec->sh_offset;
445 
446 	pr_debug("Applying relocate section %s to %u\n",
447 		 shstrtab + relsec->sh_name, relsec->sh_info);
448 
449 	for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) {
450 
451 		/*
452 		 * rel[i].r_offset contains byte offset from beginning
453 		 * of section to the storage unit affected.
454 		 *
455 		 * This is location to update. This is temporary buffer
456 		 * where section is currently loaded. This will finally be
457 		 * loaded to a different address later, pointed to by
458 		 * ->sh_addr. kexec takes care of moving it
459 		 *  (kexec_load_segment()).
460 		 */
461 		location = pi->purgatory_buf;
462 		location += section->sh_offset;
463 		location += rel[i].r_offset;
464 
465 		/* Final address of the location */
466 		address = section->sh_addr + rel[i].r_offset;
467 
468 		/*
469 		 * rel[i].r_info contains information about symbol table index
470 		 * w.r.t which relocation must be made and type of relocation
471 		 * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
472 		 * these respectively.
473 		 */
474 		sym = (void *)pi->ehdr + symtabsec->sh_offset;
475 		sym += ELF64_R_SYM(rel[i].r_info);
476 
477 		if (sym->st_name)
478 			name = strtab + sym->st_name;
479 		else
480 			name = shstrtab + sechdrs[sym->st_shndx].sh_name;
481 
482 		pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
483 			 name, sym->st_info, sym->st_shndx, sym->st_value,
484 			 sym->st_size);
485 
486 		if (sym->st_shndx == SHN_UNDEF) {
487 			pr_err("Undefined symbol: %s\n", name);
488 			return -ENOEXEC;
489 		}
490 
491 		if (sym->st_shndx == SHN_COMMON) {
492 			pr_err("symbol '%s' in common section\n", name);
493 			return -ENOEXEC;
494 		}
495 
496 		if (sym->st_shndx == SHN_ABS)
497 			sec_base = 0;
498 		else if (sym->st_shndx >= pi->ehdr->e_shnum) {
499 			pr_err("Invalid section %d for symbol %s\n",
500 			       sym->st_shndx, name);
501 			return -ENOEXEC;
502 		} else
503 			sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
504 
505 		value = sym->st_value;
506 		value += sec_base;
507 		value += rel[i].r_addend;
508 
509 		switch (ELF64_R_TYPE(rel[i].r_info)) {
510 		case R_X86_64_NONE:
511 			break;
512 		case R_X86_64_64:
513 			*(u64 *)location = value;
514 			break;
515 		case R_X86_64_32:
516 			*(u32 *)location = value;
517 			if (value != *(u32 *)location)
518 				goto overflow;
519 			break;
520 		case R_X86_64_32S:
521 			*(s32 *)location = value;
522 			if ((s64)value != *(s32 *)location)
523 				goto overflow;
524 			break;
525 		case R_X86_64_PC32:
526 		case R_X86_64_PLT32:
527 			value -= (u64)address;
528 			*(u32 *)location = value;
529 			break;
530 		default:
531 			pr_err("Unknown rela relocation: %llu\n",
532 			       ELF64_R_TYPE(rel[i].r_info));
533 			return -ENOEXEC;
534 		}
535 	}
536 	return 0;
537 
538 overflow:
539 	pr_err("Overflow in relocation type %d value 0x%lx\n",
540 	       (int)ELF64_R_TYPE(rel[i].r_info), value);
541 	return -ENOEXEC;
542 }
543 #endif /* CONFIG_KEXEC_FILE */
544 
545 static int
546 kexec_mark_range(unsigned long start, unsigned long end, bool protect)
547 {
548 	struct page *page;
549 	unsigned int nr_pages;
550 
551 	/*
552 	 * For physical range: [start, end]. We must skip the unassigned
553 	 * crashk resource with zero-valued "end" member.
554 	 */
555 	if (!end || start > end)
556 		return 0;
557 
558 	page = pfn_to_page(start >> PAGE_SHIFT);
559 	nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
560 	if (protect)
561 		return set_pages_ro(page, nr_pages);
562 	else
563 		return set_pages_rw(page, nr_pages);
564 }
565 
566 static void kexec_mark_crashkres(bool protect)
567 {
568 	unsigned long control;
569 
570 	kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
571 
572 	/* Don't touch the control code page used in crash_kexec().*/
573 	control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
574 	/* Control code page is located in the 2nd page. */
575 	kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
576 	control += KEXEC_CONTROL_PAGE_SIZE;
577 	kexec_mark_range(control, crashk_res.end, protect);
578 }
579 
580 void arch_kexec_protect_crashkres(void)
581 {
582 	kexec_mark_crashkres(true);
583 }
584 
585 void arch_kexec_unprotect_crashkres(void)
586 {
587 	kexec_mark_crashkres(false);
588 }
589 
590 /*
591  * During a traditional boot under SME, SME will encrypt the kernel,
592  * so the SME kexec kernel also needs to be un-encrypted in order to
593  * replicate a normal SME boot.
594  *
595  * During a traditional boot under SEV, the kernel has already been
596  * loaded encrypted, so the SEV kexec kernel needs to be encrypted in
597  * order to replicate a normal SEV boot.
598  */
599 int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, gfp_t gfp)
600 {
601 	if (sev_active())
602 		return 0;
603 
604 	/*
605 	 * If SME is active we need to be sure that kexec pages are
606 	 * not encrypted because when we boot to the new kernel the
607 	 * pages won't be accessed encrypted (initially).
608 	 */
609 	return set_memory_decrypted((unsigned long)vaddr, pages);
610 }
611 
612 void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages)
613 {
614 	if (sev_active())
615 		return;
616 
617 	/*
618 	 * If SME is active we need to reset the pages back to being
619 	 * an encrypted mapping before freeing them.
620 	 */
621 	set_memory_encrypted((unsigned long)vaddr, pages);
622 }
623