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
30static struct kexec_file_ops *kexec_file_loaders[] = {
31		&kexec_bzImage64_ops,
32};
33#endif
34
35static 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
42static 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;
79err:
80	free_transition_pgtable(image);
81	return result;
82}
83
84static 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
99static 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
143static 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
158static 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
172static 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 */
186static 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 */
217static inline int arch_update_purgatory(struct kimage *image)
218{
219	return 0;
220}
221#endif /* CONFIG_KEXEC_FILE */
222
223int 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
244void 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 */
253void 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
327void 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
343int 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
364void *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
378int 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
386int 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 */
406int 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
531overflow:
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