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