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
32static struct kexec_file_ops *kexec_file_loaders[] = {
33		&kexec_bzImage64_ops,
34};
35#endif
36
37static 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
44static 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;
81err:
82	free_transition_pgtable(image);
83	return result;
84}
85
86static 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
101static 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
145static 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
160static 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
174static 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 */
188static 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, "backup_dest",
198				&image->arch.backup_load_addr,
199				sizeof(image->arch.backup_load_addr), 0);
200		if (ret)
201			return ret;
202
203		ret = kexec_purgatory_get_set_symbol(image, "backup_src",
204				&image->arch.backup_src_start,
205				sizeof(image->arch.backup_src_start), 0);
206		if (ret)
207			return ret;
208
209		ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
210				&image->arch.backup_src_sz,
211				sizeof(image->arch.backup_src_sz), 0);
212		if (ret)
213			return ret;
214	}
215
216	return ret;
217}
218#else /* !CONFIG_KEXEC_FILE */
219static inline int arch_update_purgatory(struct kimage *image)
220{
221	return 0;
222}
223#endif /* CONFIG_KEXEC_FILE */
224
225int machine_kexec_prepare(struct kimage *image)
226{
227	unsigned long start_pgtable;
228	int result;
229
230	/* Calculate the offsets */
231	start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
232
233	/* Setup the identity mapped 64bit page table */
234	result = init_pgtable(image, start_pgtable);
235	if (result)
236		return result;
237
238	/* update purgatory as needed */
239	result = arch_update_purgatory(image);
240	if (result)
241		return result;
242
243	return 0;
244}
245
246void machine_kexec_cleanup(struct kimage *image)
247{
248	free_transition_pgtable(image);
249}
250
251/*
252 * Do not allocate memory (or fail in any way) in machine_kexec().
253 * We are past the point of no return, committed to rebooting now.
254 */
255void machine_kexec(struct kimage *image)
256{
257	unsigned long page_list[PAGES_NR];
258	void *control_page;
259	int save_ftrace_enabled;
260
261#ifdef CONFIG_KEXEC_JUMP
262	if (image->preserve_context)
263		save_processor_state();
264#endif
265
266	save_ftrace_enabled = __ftrace_enabled_save();
267
268	/* Interrupts aren't acceptable while we reboot */
269	local_irq_disable();
270	hw_breakpoint_disable();
271
272	if (image->preserve_context) {
273#ifdef CONFIG_X86_IO_APIC
274		/*
275		 * We need to put APICs in legacy mode so that we can
276		 * get timer interrupts in second kernel. kexec/kdump
277		 * paths already have calls to disable_IO_APIC() in
278		 * one form or other. kexec jump path also need
279		 * one.
280		 */
281		disable_IO_APIC();
282#endif
283	}
284
285	control_page = page_address(image->control_code_page) + PAGE_SIZE;
286	memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
287
288	page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
289	page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
290	page_list[PA_TABLE_PAGE] =
291	  (unsigned long)__pa(page_address(image->control_code_page));
292
293	if (image->type == KEXEC_TYPE_DEFAULT)
294		page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
295						<< PAGE_SHIFT);
296
297	/*
298	 * The segment registers are funny things, they have both a
299	 * visible and an invisible part.  Whenever the visible part is
300	 * set to a specific selector, the invisible part is loaded
301	 * with from a table in memory.  At no other time is the
302	 * descriptor table in memory accessed.
303	 *
304	 * I take advantage of this here by force loading the
305	 * segments, before I zap the gdt with an invalid value.
306	 */
307	load_segments();
308	/*
309	 * The gdt & idt are now invalid.
310	 * If you want to load them you must set up your own idt & gdt.
311	 */
312	set_gdt(phys_to_virt(0), 0);
313	set_idt(phys_to_virt(0), 0);
314
315	/* now call it */
316	image->start = relocate_kernel((unsigned long)image->head,
317				       (unsigned long)page_list,
318				       image->start,
319				       image->preserve_context);
320
321#ifdef CONFIG_KEXEC_JUMP
322	if (image->preserve_context)
323		restore_processor_state();
324#endif
325
326	__ftrace_enabled_restore(save_ftrace_enabled);
327}
328
329void arch_crash_save_vmcoreinfo(void)
330{
331	VMCOREINFO_SYMBOL(phys_base);
332	VMCOREINFO_SYMBOL(init_level4_pgt);
333
334#ifdef CONFIG_NUMA
335	VMCOREINFO_SYMBOL(node_data);
336	VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
337#endif
338	vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
339			      kaslr_offset());
340}
341
342/* arch-dependent functionality related to kexec file-based syscall */
343
344#ifdef CONFIG_KEXEC_FILE
345int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
346				  unsigned long buf_len)
347{
348	int i, ret = -ENOEXEC;
349	struct kexec_file_ops *fops;
350
351	for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
352		fops = kexec_file_loaders[i];
353		if (!fops || !fops->probe)
354			continue;
355
356		ret = fops->probe(buf, buf_len);
357		if (!ret) {
358			image->fops = fops;
359			return ret;
360		}
361	}
362
363	return ret;
364}
365
366void *arch_kexec_kernel_image_load(struct kimage *image)
367{
368	vfree(image->arch.elf_headers);
369	image->arch.elf_headers = NULL;
370
371	if (!image->fops || !image->fops->load)
372		return ERR_PTR(-ENOEXEC);
373
374	return image->fops->load(image, image->kernel_buf,
375				 image->kernel_buf_len, image->initrd_buf,
376				 image->initrd_buf_len, image->cmdline_buf,
377				 image->cmdline_buf_len);
378}
379
380int arch_kimage_file_post_load_cleanup(struct kimage *image)
381{
382	if (!image->fops || !image->fops->cleanup)
383		return 0;
384
385	return image->fops->cleanup(image->image_loader_data);
386}
387
388int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
389				 unsigned long kernel_len)
390{
391	if (!image->fops || !image->fops->verify_sig) {
392		pr_debug("kernel loader does not support signature verification.");
393		return -EKEYREJECTED;
394	}
395
396	return image->fops->verify_sig(kernel, kernel_len);
397}
398
399/*
400 * Apply purgatory relocations.
401 *
402 * ehdr: Pointer to elf headers
403 * sechdrs: Pointer to section headers.
404 * relsec: section index of SHT_RELA section.
405 *
406 * TODO: Some of the code belongs to generic code. Move that in kexec.c.
407 */
408int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
409				     Elf64_Shdr *sechdrs, unsigned int relsec)
410{
411	unsigned int i;
412	Elf64_Rela *rel;
413	Elf64_Sym *sym;
414	void *location;
415	Elf64_Shdr *section, *symtabsec;
416	unsigned long address, sec_base, value;
417	const char *strtab, *name, *shstrtab;
418
419	/*
420	 * ->sh_offset has been modified to keep the pointer to section
421	 * contents in memory
422	 */
423	rel = (void *)sechdrs[relsec].sh_offset;
424
425	/* Section to which relocations apply */
426	section = &sechdrs[sechdrs[relsec].sh_info];
427
428	pr_debug("Applying relocate section %u to %u\n", relsec,
429		 sechdrs[relsec].sh_info);
430
431	/* Associated symbol table */
432	symtabsec = &sechdrs[sechdrs[relsec].sh_link];
433
434	/* String table */
435	if (symtabsec->sh_link >= ehdr->e_shnum) {
436		/* Invalid strtab section number */
437		pr_err("Invalid string table section index %d\n",
438		       symtabsec->sh_link);
439		return -ENOEXEC;
440	}
441
442	strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
443
444	/* section header string table */
445	shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
446
447	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
448
449		/*
450		 * rel[i].r_offset contains byte offset from beginning
451		 * of section to the storage unit affected.
452		 *
453		 * This is location to update (->sh_offset). This is temporary
454		 * buffer where section is currently loaded. This will finally
455		 * be loaded to a different address later, pointed to by
456		 * ->sh_addr. kexec takes care of moving it
457		 *  (kexec_load_segment()).
458		 */
459		location = (void *)(section->sh_offset + rel[i].r_offset);
460
461		/* Final address of the location */
462		address = section->sh_addr + rel[i].r_offset;
463
464		/*
465		 * rel[i].r_info contains information about symbol table index
466		 * w.r.t which relocation must be made and type of relocation
467		 * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
468		 * these respectively.
469		 */
470		sym = (Elf64_Sym *)symtabsec->sh_offset +
471				ELF64_R_SYM(rel[i].r_info);
472
473		if (sym->st_name)
474			name = strtab + sym->st_name;
475		else
476			name = shstrtab + sechdrs[sym->st_shndx].sh_name;
477
478		pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
479			 name, sym->st_info, sym->st_shndx, sym->st_value,
480			 sym->st_size);
481
482		if (sym->st_shndx == SHN_UNDEF) {
483			pr_err("Undefined symbol: %s\n", name);
484			return -ENOEXEC;
485		}
486
487		if (sym->st_shndx == SHN_COMMON) {
488			pr_err("symbol '%s' in common section\n", name);
489			return -ENOEXEC;
490		}
491
492		if (sym->st_shndx == SHN_ABS)
493			sec_base = 0;
494		else if (sym->st_shndx >= ehdr->e_shnum) {
495			pr_err("Invalid section %d for symbol %s\n",
496			       sym->st_shndx, name);
497			return -ENOEXEC;
498		} else
499			sec_base = sechdrs[sym->st_shndx].sh_addr;
500
501		value = sym->st_value;
502		value += sec_base;
503		value += rel[i].r_addend;
504
505		switch (ELF64_R_TYPE(rel[i].r_info)) {
506		case R_X86_64_NONE:
507			break;
508		case R_X86_64_64:
509			*(u64 *)location = value;
510			break;
511		case R_X86_64_32:
512			*(u32 *)location = value;
513			if (value != *(u32 *)location)
514				goto overflow;
515			break;
516		case R_X86_64_32S:
517			*(s32 *)location = value;
518			if ((s64)value != *(s32 *)location)
519				goto overflow;
520			break;
521		case R_X86_64_PC32:
522			value -= (u64)address;
523			*(u32 *)location = value;
524			break;
525		default:
526			pr_err("Unknown rela relocation: %llu\n",
527			       ELF64_R_TYPE(rel[i].r_info));
528			return -ENOEXEC;
529		}
530	}
531	return 0;
532
533overflow:
534	pr_err("Overflow in relocation type %d value 0x%lx\n",
535	       (int)ELF64_R_TYPE(rel[i].r_info), value);
536	return -ENOEXEC;
537}
538#endif /* CONFIG_KEXEC_FILE */
539