2 * handle transition of Linux booting another kernel
3 * Copyright (C) 2002-2005 Eric Biederman <ebiederm@xmission.com>
5 * This source code is licensed under the GNU General Public License,
6 * Version 2. See the file COPYING for more details.
9 #define pr_fmt(fmt) "kexec: " fmt
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>
19 #include <linux/suspend.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>
28 static struct kexec_file_ops *kexec_file_loaders[] = {
32 static void free_transition_pgtable(struct kimage *image)
34 free_page((unsigned long)image->arch.pud);
35 free_page((unsigned long)image->arch.pmd);
36 free_page((unsigned long)image->arch.pte);
39 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
44 unsigned long vaddr, paddr;
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);
54 image->arch.pud = pud;
55 set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
57 pud = pud_offset(pgd, vaddr);
58 if (!pud_present(*pud)) {
59 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
62 image->arch.pmd = pmd;
63 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
65 pmd = pmd_offset(pud, vaddr);
66 if (!pmd_present(*pmd)) {
67 pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
70 image->arch.pte = pte;
71 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
73 pte = pte_offset_kernel(pmd, vaddr);
74 set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC));
77 free_transition_pgtable(image);
81 static void *alloc_pgt_page(void *data)
83 struct kimage *image = (struct kimage *)data;
87 page = kimage_alloc_control_pages(image, 0);
89 p = page_address(page);
96 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
98 struct x86_mapping_info info = {
99 .alloc_pgt_page = alloc_pgt_page,
101 .pmd_flag = __PAGE_KERNEL_LARGE_EXEC,
103 unsigned long mstart, mend;
108 level4p = (pgd_t *)__va(start_pgtable);
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;
114 result = kernel_ident_mapping_init(&info,
115 level4p, mstart, mend);
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.
126 for (i = 0; i < image->nr_segments; i++) {
127 mstart = image->segment[i].mem;
128 mend = mstart + image->segment[i].memsz;
130 result = kernel_ident_mapping_init(&info,
131 level4p, mstart, mend);
137 return init_transition_pgtable(image, level4p);
140 static void set_idt(void *newidt, u16 limit)
142 struct desc_ptr curidt;
144 /* x86-64 supports unaliged loads & stores */
146 curidt.address = (unsigned long)newidt;
148 __asm__ __volatile__ (
155 static void set_gdt(void *newgdt, u16 limit)
157 struct desc_ptr curgdt;
159 /* x86-64 supports unaligned loads & stores */
161 curgdt.address = (unsigned long)newgdt;
163 __asm__ __volatile__ (
169 static void load_segments(void)
171 __asm__ __volatile__ (
177 : : "a" (__KERNEL_DS) : "memory"
181 /* Update purgatory as needed after various image segments have been prepared */
182 static int arch_update_purgatory(struct kimage *image)
186 if (!image->file_mode)
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);
197 ret = kexec_purgatory_get_set_symbol(image, "backup_src",
198 &image->arch.backup_src_start,
199 sizeof(image->arch.backup_src_start), 0);
203 ret = kexec_purgatory_get_set_symbol(image, "backup_sz",
204 &image->arch.backup_src_sz,
205 sizeof(image->arch.backup_src_sz), 0);
213 int machine_kexec_prepare(struct kimage *image)
215 unsigned long start_pgtable;
218 /* Calculate the offsets */
219 start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
221 /* Setup the identity mapped 64bit page table */
222 result = init_pgtable(image, start_pgtable);
226 /* update purgatory as needed */
227 result = arch_update_purgatory(image);
234 void machine_kexec_cleanup(struct kimage *image)
236 free_transition_pgtable(image);
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.
243 void machine_kexec(struct kimage *image)
245 unsigned long page_list[PAGES_NR];
247 int save_ftrace_enabled;
249 #ifdef CONFIG_KEXEC_JUMP
250 if (image->preserve_context)
251 save_processor_state();
254 save_ftrace_enabled = __ftrace_enabled_save();
256 /* Interrupts aren't acceptable while we reboot */
258 hw_breakpoint_disable();
260 if (image->preserve_context) {
261 #ifdef CONFIG_X86_IO_APIC
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
273 control_page = page_address(image->control_code_page) + PAGE_SIZE;
274 memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
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));
281 if (image->type == KEXEC_TYPE_DEFAULT)
282 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
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.
292 * I take advantage of this here by force loading the
293 * segments, before I zap the gdt with an invalid value.
297 * The gdt & idt are now invalid.
298 * If you want to load them you must set up your own idt & gdt.
300 set_gdt(phys_to_virt(0), 0);
301 set_idt(phys_to_virt(0), 0);
304 image->start = relocate_kernel((unsigned long)image->head,
305 (unsigned long)page_list,
307 image->preserve_context);
309 #ifdef CONFIG_KEXEC_JUMP
310 if (image->preserve_context)
311 restore_processor_state();
314 __ftrace_enabled_restore(save_ftrace_enabled);
317 void arch_crash_save_vmcoreinfo(void)
319 VMCOREINFO_SYMBOL(phys_base);
320 VMCOREINFO_SYMBOL(init_level4_pgt);
323 VMCOREINFO_SYMBOL(node_data);
324 VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
326 vmcoreinfo_append_str("KERNELOFFSET=%lx\n",
327 (unsigned long)&_text - __START_KERNEL);
330 /* arch-dependent functionality related to kexec file-based syscall */
332 int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
333 unsigned long buf_len)
335 int i, ret = -ENOEXEC;
336 struct kexec_file_ops *fops;
338 for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) {
339 fops = kexec_file_loaders[i];
340 if (!fops || !fops->probe)
343 ret = fops->probe(buf, buf_len);
353 void *arch_kexec_kernel_image_load(struct kimage *image)
355 vfree(image->arch.elf_headers);
356 image->arch.elf_headers = NULL;
358 if (!image->fops || !image->fops->load)
359 return ERR_PTR(-ENOEXEC);
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);
367 int arch_kimage_file_post_load_cleanup(struct kimage *image)
369 if (!image->fops || !image->fops->cleanup)
372 return image->fops->cleanup(image->image_loader_data);
375 int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
376 unsigned long kernel_len)
378 if (!image->fops || !image->fops->verify_sig) {
379 pr_debug("kernel loader does not support signature verification.");
380 return -EKEYREJECTED;
383 return image->fops->verify_sig(kernel, kernel_len);
387 * Apply purgatory relocations.
389 * ehdr: Pointer to elf headers
390 * sechdrs: Pointer to section headers.
391 * relsec: section index of SHT_RELA section.
393 * TODO: Some of the code belongs to generic code. Move that in kexec.c.
395 int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
396 Elf64_Shdr *sechdrs, unsigned int relsec)
402 Elf64_Shdr *section, *symtabsec;
403 unsigned long address, sec_base, value;
404 const char *strtab, *name, *shstrtab;
407 * ->sh_offset has been modified to keep the pointer to section
410 rel = (void *)sechdrs[relsec].sh_offset;
412 /* Section to which relocations apply */
413 section = &sechdrs[sechdrs[relsec].sh_info];
415 pr_debug("Applying relocate section %u to %u\n", relsec,
416 sechdrs[relsec].sh_info);
418 /* Associated symbol table */
419 symtabsec = &sechdrs[sechdrs[relsec].sh_link];
422 if (symtabsec->sh_link >= ehdr->e_shnum) {
423 /* Invalid strtab section number */
424 pr_err("Invalid string table section index %d\n",
429 strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
431 /* section header string table */
432 shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
434 for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
437 * rel[i].r_offset contains byte offset from beginning
438 * of section to the storage unit affected.
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()).
446 location = (void *)(section->sh_offset + rel[i].r_offset);
448 /* Final address of the location */
449 address = section->sh_addr + rel[i].r_offset;
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.
457 sym = (Elf64_Sym *)symtabsec->sh_offset +
458 ELF64_R_SYM(rel[i].r_info);
461 name = strtab + sym->st_name;
463 name = shstrtab + sechdrs[sym->st_shndx].sh_name;
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,
469 if (sym->st_shndx == SHN_UNDEF) {
470 pr_err("Undefined symbol: %s\n", name);
474 if (sym->st_shndx == SHN_COMMON) {
475 pr_err("symbol '%s' in common section\n", name);
479 if (sym->st_shndx == SHN_ABS)
481 else if (sym->st_shndx >= ehdr->e_shnum) {
482 pr_err("Invalid section %d for symbol %s\n",
483 sym->st_shndx, name);
486 sec_base = sechdrs[sym->st_shndx].sh_addr;
488 value = sym->st_value;
490 value += rel[i].r_addend;
492 switch (ELF64_R_TYPE(rel[i].r_info)) {
496 *(u64 *)location = value;
499 *(u32 *)location = value;
500 if (value != *(u32 *)location)
504 *(s32 *)location = value;
505 if ((s64)value != *(s32 *)location)
509 value -= (u64)address;
510 *(u32 *)location = value;
513 pr_err("Unknown rela relocation: %llu\n",
514 ELF64_R_TYPE(rel[i].r_info));
521 pr_err("Overflow in relocation type %d value 0x%lx\n",
522 (int)ELF64_R_TYPE(rel[i].r_info), value);