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