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/debugreg.h>
26 #include <asm/kexec-bzimage64.h>
27 
28 static struct kexec_file_ops *kexec_file_loaders[] = {
29 		&kexec_bzImage64_ops,
30 };
31 
32 static void free_transition_pgtable(struct kimage *image)
33 {
34 	free_page((unsigned long)image->arch.pud);
35 	free_page((unsigned long)image->arch.pmd);
36 	free_page((unsigned long)image->arch.pte);
37 }
38 
39 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
40 {
41 	pud_t *pud;
42 	pmd_t *pmd;
43 	pte_t *pte;
44 	unsigned long vaddr, paddr;
45 	int result = -ENOMEM;
46 
47 	vaddr = (unsigned long)relocate_kernel;
48 	paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
49 	pgd += pgd_index(vaddr);
50 	if (!pgd_present(*pgd)) {
51 		pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
52 		if (!pud)
53 			goto err;
54 		image->arch.pud = pud;
55 		set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
56 	}
57 	pud = pud_offset(pgd, vaddr);
58 	if (!pud_present(*pud)) {
59 		pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
60 		if (!pmd)
61 			goto err;
62 		image->arch.pmd = pmd;
63 		set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
64 	}
65 	pmd = pmd_offset(pud, vaddr);
66 	if (!pmd_present(*pmd)) {
67 		pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
68 		if (!pte)
69 			goto err;
70 		image->arch.pte = pte;
71 		set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
72 	}
73 	pte = pte_offset_kernel(pmd, vaddr);
74 	set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
75 	return 0;
76 err:
77 	free_transition_pgtable(image);
78 	return result;
79 }
80 
81 static void *alloc_pgt_page(void *data)
82 {
83 	struct kimage *image = (struct kimage *)data;
84 	struct page *page;
85 	void *p = NULL;
86 
87 	page = kimage_alloc_control_pages(image, 0);
88 	if (page) {
89 		p = page_address(page);
90 		clear_page(p);
91 	}
92 
93 	return p;
94 }
95 
96 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
97 {
98 	struct x86_mapping_info info = {
99 		.alloc_pgt_page	= alloc_pgt_page,
100 		.context	= image,
101 		.pmd_flag	= __PAGE_KERNEL_LARGE_EXEC,
102 	};
103 	unsigned long mstart, mend;
104 	pgd_t *level4p;
105 	int result;
106 	int i;
107 
108 	level4p = (pgd_t *)__va(start_pgtable);
109 	clear_page(level4p);
110 	for (i = 0; i < nr_pfn_mapped; i++) {
111 		mstart = pfn_mapped[i].start << PAGE_SHIFT;
112 		mend   = pfn_mapped[i].end << PAGE_SHIFT;
113 
114 		result = kernel_ident_mapping_init(&info,
115 						 level4p, mstart, mend);
116 		if (result)
117 			return result;
118 	}
119 
120 	/*
121 	 * segments's mem ranges could be outside 0 ~ max_pfn,
122 	 * for example when jump back to original kernel from kexeced kernel.
123 	 * or first kernel is booted with user mem map, and second kernel
124 	 * could be loaded out of that range.
125 	 */
126 	for (i = 0; i < image->nr_segments; i++) {
127 		mstart = image->segment[i].mem;
128 		mend   = mstart + image->segment[i].memsz;
129 
130 		result = kernel_ident_mapping_init(&info,
131 						 level4p, mstart, mend);
132 
133 		if (result)
134 			return result;
135 	}
136 
137 	return init_transition_pgtable(image, level4p);
138 }
139 
140 static void set_idt(void *newidt, u16 limit)
141 {
142 	struct desc_ptr curidt;
143 
144 	/* x86-64 supports unaliged loads & stores */
145 	curidt.size    = limit;
146 	curidt.address = (unsigned long)newidt;
147 
148 	__asm__ __volatile__ (
149 		"lidtq %0\n"
150 		: : "m" (curidt)
151 		);
152 };
153 
154 
155 static void set_gdt(void *newgdt, u16 limit)
156 {
157 	struct desc_ptr curgdt;
158 
159 	/* x86-64 supports unaligned loads & stores */
160 	curgdt.size    = limit;
161 	curgdt.address = (unsigned long)newgdt;
162 
163 	__asm__ __volatile__ (
164 		"lgdtq %0\n"
165 		: : "m" (curgdt)
166 		);
167 };
168 
169 static void load_segments(void)
170 {
171 	__asm__ __volatile__ (
172 		"\tmovl %0,%%ds\n"
173 		"\tmovl %0,%%es\n"
174 		"\tmovl %0,%%ss\n"
175 		"\tmovl %0,%%fs\n"
176 		"\tmovl %0,%%gs\n"
177 		: : "a" (__KERNEL_DS) : "memory"
178 		);
179 }
180 
181 /* Update purgatory as needed after various image segments have been prepared */
182 static int arch_update_purgatory(struct kimage *image)
183 {
184 	int ret = 0;
185 
186 	if (!image->file_mode)
187 		return 0;
188 
189 	/* Setup copying of backup region */
190 	if (image->type == KEXEC_TYPE_CRASH) {
191 		ret = kexec_purgatory_get_set_symbol(image, "backup_dest",
192 				&image->arch.backup_load_addr,
193 				sizeof(image->arch.backup_load_addr), 0);
194 		if (ret)
195 			return ret;
196 
197 		ret = kexec_purgatory_get_set_symbol(image, "backup_src",
198 				&image->arch.backup_src_start,
199 				sizeof(image->arch.backup_src_start), 0);
200 		if (ret)
201 			return ret;
202 
203 		ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
204 				&image->arch.backup_src_sz,
205 				sizeof(image->arch.backup_src_sz), 0);
206 		if (ret)
207 			return ret;
208 	}
209 
210 	return ret;
211 }
212 
213 int machine_kexec_prepare(struct kimage *image)
214 {
215 	unsigned long start_pgtable;
216 	int result;
217 
218 	/* Calculate the offsets */
219 	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
220 
221 	/* Setup the identity mapped 64bit page table */
222 	result = init_pgtable(image, start_pgtable);
223 	if (result)
224 		return result;
225 
226 	/* update purgatory as needed */
227 	result = arch_update_purgatory(image);
228 	if (result)
229 		return result;
230 
231 	return 0;
232 }
233 
234 void machine_kexec_cleanup(struct kimage *image)
235 {
236 	free_transition_pgtable(image);
237 }
238 
239 /*
240  * Do not allocate memory (or fail in any way) in machine_kexec().
241  * We are past the point of no return, committed to rebooting now.
242  */
243 void machine_kexec(struct kimage *image)
244 {
245 	unsigned long page_list[PAGES_NR];
246 	void *control_page;
247 	int save_ftrace_enabled;
248 
249 #ifdef CONFIG_KEXEC_JUMP
250 	if (image->preserve_context)
251 		save_processor_state();
252 #endif
253 
254 	save_ftrace_enabled = __ftrace_enabled_save();
255 
256 	/* Interrupts aren't acceptable while we reboot */
257 	local_irq_disable();
258 	hw_breakpoint_disable();
259 
260 	if (image->preserve_context) {
261 #ifdef CONFIG_X86_IO_APIC
262 		/*
263 		 * We need to put APICs in legacy mode so that we can
264 		 * get timer interrupts in second kernel. kexec/kdump
265 		 * paths already have calls to disable_IO_APIC() in
266 		 * one form or other. kexec jump path also need
267 		 * one.
268 		 */
269 		disable_IO_APIC();
270 #endif
271 	}
272 
273 	control_page = page_address(image->control_code_page) + PAGE_SIZE;
274 	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
275 
276 	page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
277 	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
278 	page_list[PA_TABLE_PAGE] =
279 	  (unsigned long)__pa(page_address(image->control_code_page));
280 
281 	if (image->type == KEXEC_TYPE_DEFAULT)
282 		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
283 						<< PAGE_SHIFT);
284 
285 	/*
286 	 * The segment registers are funny things, they have both a
287 	 * visible and an invisible part.  Whenever the visible part is
288 	 * set to a specific selector, the invisible part is loaded
289 	 * with from a table in memory.  At no other time is the
290 	 * descriptor table in memory accessed.
291 	 *
292 	 * I take advantage of this here by force loading the
293 	 * segments, before I zap the gdt with an invalid value.
294 	 */
295 	load_segments();
296 	/*
297 	 * The gdt & idt are now invalid.
298 	 * If you want to load them you must set up your own idt & gdt.
299 	 */
300 	set_gdt(phys_to_virt(0), 0);
301 	set_idt(phys_to_virt(0), 0);
302 
303 	/* now call it */
304 	image->start = relocate_kernel((unsigned long)image->head,
305 				       (unsigned long)page_list,
306 				       image->start,
307 				       image->preserve_context);
308 
309 #ifdef CONFIG_KEXEC_JUMP
310 	if (image->preserve_context)
311 		restore_processor_state();
312 #endif
313 
314 	__ftrace_enabled_restore(save_ftrace_enabled);
315 }
316 
317 void arch_crash_save_vmcoreinfo(void)
318 {
319 	VMCOREINFO_SYMBOL(phys_base);
320 	VMCOREINFO_SYMBOL(init_level4_pgt);
321 
322 #ifdef CONFIG_NUMA
323 	VMCOREINFO_SYMBOL(node_data);
324 	VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
325 #endif
326 	vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
327 			      (unsigned long)&_text - __START_KERNEL);
328 }
329 
330 /* arch-dependent functionality related to kexec file-based syscall */
331 
332 int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
333 				  unsigned long buf_len)
334 {
335 	int i, ret = -ENOEXEC;
336 	struct kexec_file_ops *fops;
337 
338 	for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
339 		fops = kexec_file_loaders[i];
340 		if (!fops || !fops->probe)
341 			continue;
342 
343 		ret = fops->probe(buf, buf_len);
344 		if (!ret) {
345 			image->fops = fops;
346 			return ret;
347 		}
348 	}
349 
350 	return ret;
351 }
352 
353 void *arch_kexec_kernel_image_load(struct kimage *image)
354 {
355 	vfree(image->arch.elf_headers);
356 	image->arch.elf_headers = NULL;
357 
358 	if (!image->fops || !image->fops->load)
359 		return ERR_PTR(-ENOEXEC);
360 
361 	return image->fops->load(image, image->kernel_buf,
362 				 image->kernel_buf_len, image->initrd_buf,
363 				 image->initrd_buf_len, image->cmdline_buf,
364 				 image->cmdline_buf_len);
365 }
366 
367 int arch_kimage_file_post_load_cleanup(struct kimage *image)
368 {
369 	if (!image->fops || !image->fops->cleanup)
370 		return 0;
371 
372 	return image->fops->cleanup(image->image_loader_data);
373 }
374 
375 int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
376 				 unsigned long kernel_len)
377 {
378 	if (!image->fops || !image->fops->verify_sig) {
379 		pr_debug("kernel loader does not support signature verification.");
380 		return -EKEYREJECTED;
381 	}
382 
383 	return image->fops->verify_sig(kernel, kernel_len);
384 }
385 
386 /*
387  * Apply purgatory relocations.
388  *
389  * ehdr: Pointer to elf headers
390  * sechdrs: Pointer to section headers.
391  * relsec: section index of SHT_RELA section.
392  *
393  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
394  */
395 int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
396 				     Elf64_Shdr *sechdrs, unsigned int relsec)
397 {
398 	unsigned int i;
399 	Elf64_Rela *rel;
400 	Elf64_Sym *sym;
401 	void *location;
402 	Elf64_Shdr *section, *symtabsec;
403 	unsigned long address, sec_base, value;
404 	const char *strtab, *name, *shstrtab;
405 
406 	/*
407 	 * ->sh_offset has been modified to keep the pointer to section
408 	 * contents in memory
409 	 */
410 	rel = (void *)sechdrs[relsec].sh_offset;
411 
412 	/* Section to which relocations apply */
413 	section = &sechdrs[sechdrs[relsec].sh_info];
414 
415 	pr_debug("Applying relocate section %u to %u\n", relsec,
416 		 sechdrs[relsec].sh_info);
417 
418 	/* Associated symbol table */
419 	symtabsec = &sechdrs[sechdrs[relsec].sh_link];
420 
421 	/* String table */
422 	if (symtabsec->sh_link >= ehdr->e_shnum) {
423 		/* Invalid strtab section number */
424 		pr_err("Invalid string table section index %d\n",
425 		       symtabsec->sh_link);
426 		return -ENOEXEC;
427 	}
428 
429 	strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
430 
431 	/* section header string table */
432 	shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
433 
434 	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
435 
436 		/*
437 		 * rel[i].r_offset contains byte offset from beginning
438 		 * of section to the storage unit affected.
439 		 *
440 		 * This is location to update (->sh_offset). This is temporary
441 		 * buffer where section is currently loaded. This will finally
442 		 * be loaded to a different address later, pointed to by
443 		 * ->sh_addr. kexec takes care of moving it
444 		 *  (kexec_load_segment()).
445 		 */
446 		location = (void *)(section->sh_offset + rel[i].r_offset);
447 
448 		/* Final address of the location */
449 		address = section->sh_addr + rel[i].r_offset;
450 
451 		/*
452 		 * rel[i].r_info contains information about symbol table index
453 		 * w.r.t which relocation must be made and type of relocation
454 		 * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
455 		 * these respectively.
456 		 */
457 		sym = (Elf64_Sym *)symtabsec->sh_offset +
458 				ELF64_R_SYM(rel[i].r_info);
459 
460 		if (sym->st_name)
461 			name = strtab + sym->st_name;
462 		else
463 			name = shstrtab + sechdrs[sym->st_shndx].sh_name;
464 
465 		pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
466 			 name, sym->st_info, sym->st_shndx, sym->st_value,
467 			 sym->st_size);
468 
469 		if (sym->st_shndx == SHN_UNDEF) {
470 			pr_err("Undefined symbol: %s\n", name);
471 			return -ENOEXEC;
472 		}
473 
474 		if (sym->st_shndx == SHN_COMMON) {
475 			pr_err("symbol '%s' in common section\n", name);
476 			return -ENOEXEC;
477 		}
478 
479 		if (sym->st_shndx == SHN_ABS)
480 			sec_base = 0;
481 		else if (sym->st_shndx >= ehdr->e_shnum) {
482 			pr_err("Invalid section %d for symbol %s\n",
483 			       sym->st_shndx, name);
484 			return -ENOEXEC;
485 		} else
486 			sec_base = sechdrs[sym->st_shndx].sh_addr;
487 
488 		value = sym->st_value;
489 		value += sec_base;
490 		value += rel[i].r_addend;
491 
492 		switch (ELF64_R_TYPE(rel[i].r_info)) {
493 		case R_X86_64_NONE:
494 			break;
495 		case R_X86_64_64:
496 			*(u64 *)location = value;
497 			break;
498 		case R_X86_64_32:
499 			*(u32 *)location = value;
500 			if (value != *(u32 *)location)
501 				goto overflow;
502 			break;
503 		case R_X86_64_32S:
504 			*(s32 *)location = value;
505 			if ((s64)value != *(s32 *)location)
506 				goto overflow;
507 			break;
508 		case R_X86_64_PC32:
509 			value -= (u64)address;
510 			*(u32 *)location = value;
511 			break;
512 		default:
513 			pr_err("Unknown rela relocation: %llu\n",
514 			       ELF64_R_TYPE(rel[i].r_info));
515 			return -ENOEXEC;
516 		}
517 	}
518 	return 0;
519 
520 overflow:
521 	pr_err("Overflow in relocation type %d value 0x%lx\n",
522 	       (int)ELF64_R_TYPE(rel[i].r_info), value);
523 	return -ENOEXEC;
524 }
525