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