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Linux/arch/x86/kernel/machine_kexec_64.c

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  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
 32 static struct kexec_file_ops *kexec_file_loaders[] = {
 33                 &kexec_bzImage64_ops,
 34 };
 35 #endif
 36 
 37 static 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 
 44 static 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;
 81 err:
 82         free_transition_pgtable(image);
 83         return result;
 84 }
 85 
 86 static 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 
101 static 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 
145 static 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 
160 static 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 
174 static 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 */
188 static 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 */
219 static inline int arch_update_purgatory(struct kimage *image)
220 {
221         return 0;
222 }
223 #endif /* CONFIG_KEXEC_FILE */
224 
225 int 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 
246 void 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  */
255 void 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 
329 void 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
345 int 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 
366 void *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 
380 int 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 
388 #ifdef CONFIG_KEXEC_VERIFY_SIG
389 int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel,
390                                  unsigned long kernel_len)
391 {
392         if (!image->fops || !image->fops->verify_sig) {
393                 pr_debug("kernel loader does not support signature verification.");
394                 return -EKEYREJECTED;
395         }
396 
397         return image->fops->verify_sig(kernel, kernel_len);
398 }
399 #endif
400 
401 /*
402  * Apply purgatory relocations.
403  *
404  * ehdr: Pointer to elf headers
405  * sechdrs: Pointer to section headers.
406  * relsec: section index of SHT_RELA section.
407  *
408  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
409  */
410 int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr,
411                                      Elf64_Shdr *sechdrs, unsigned int relsec)
412 {
413         unsigned int i;
414         Elf64_Rela *rel;
415         Elf64_Sym *sym;
416         void *location;
417         Elf64_Shdr *section, *symtabsec;
418         unsigned long address, sec_base, value;
419         const char *strtab, *name, *shstrtab;
420 
421         /*
422          * ->sh_offset has been modified to keep the pointer to section
423          * contents in memory
424          */
425         rel = (void *)sechdrs[relsec].sh_offset;
426 
427         /* Section to which relocations apply */
428         section = &sechdrs[sechdrs[relsec].sh_info];
429 
430         pr_debug("Applying relocate section %u to %u\n", relsec,
431                  sechdrs[relsec].sh_info);
432 
433         /* Associated symbol table */
434         symtabsec = &sechdrs[sechdrs[relsec].sh_link];
435 
436         /* String table */
437         if (symtabsec->sh_link >= ehdr->e_shnum) {
438                 /* Invalid strtab section number */
439                 pr_err("Invalid string table section index %d\n",
440                        symtabsec->sh_link);
441                 return -ENOEXEC;
442         }
443 
444         strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset;
445 
446         /* section header string table */
447         shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset;
448 
449         for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
450 
451                 /*
452                  * rel[i].r_offset contains byte offset from beginning
453                  * of section to the storage unit affected.
454                  *
455                  * This is location to update (->sh_offset). This is temporary
456                  * buffer where section is currently loaded. This will finally
457                  * be loaded to a different address later, pointed to by
458                  * ->sh_addr. kexec takes care of moving it
459                  *  (kexec_load_segment()).
460                  */
461                 location = (void *)(section->sh_offset + rel[i].r_offset);
462 
463                 /* Final address of the location */
464                 address = section->sh_addr + rel[i].r_offset;
465 
466                 /*
467                  * rel[i].r_info contains information about symbol table index
468                  * w.r.t which relocation must be made and type of relocation
469                  * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
470                  * these respectively.
471                  */
472                 sym = (Elf64_Sym *)symtabsec->sh_offset +
473                                 ELF64_R_SYM(rel[i].r_info);
474 
475                 if (sym->st_name)
476                         name = strtab + sym->st_name;
477                 else
478                         name = shstrtab + sechdrs[sym->st_shndx].sh_name;
479 
480                 pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
481                          name, sym->st_info, sym->st_shndx, sym->st_value,
482                          sym->st_size);
483 
484                 if (sym->st_shndx == SHN_UNDEF) {
485                         pr_err("Undefined symbol: %s\n", name);
486                         return -ENOEXEC;
487                 }
488 
489                 if (sym->st_shndx == SHN_COMMON) {
490                         pr_err("symbol '%s' in common section\n", name);
491                         return -ENOEXEC;
492                 }
493 
494                 if (sym->st_shndx == SHN_ABS)
495                         sec_base = 0;
496                 else if (sym->st_shndx >= ehdr->e_shnum) {
497                         pr_err("Invalid section %d for symbol %s\n",
498                                sym->st_shndx, name);
499                         return -ENOEXEC;
500                 } else
501                         sec_base = sechdrs[sym->st_shndx].sh_addr;
502 
503                 value = sym->st_value;
504                 value += sec_base;
505                 value += rel[i].r_addend;
506 
507                 switch (ELF64_R_TYPE(rel[i].r_info)) {
508                 case R_X86_64_NONE:
509                         break;
510                 case R_X86_64_64:
511                         *(u64 *)location = value;
512                         break;
513                 case R_X86_64_32:
514                         *(u32 *)location = value;
515                         if (value != *(u32 *)location)
516                                 goto overflow;
517                         break;
518                 case R_X86_64_32S:
519                         *(s32 *)location = value;
520                         if ((s64)value != *(s32 *)location)
521                                 goto overflow;
522                         break;
523                 case R_X86_64_PC32:
524                         value -= (u64)address;
525                         *(u32 *)location = value;
526                         break;
527                 default:
528                         pr_err("Unknown rela relocation: %llu\n",
529                                ELF64_R_TYPE(rel[i].r_info));
530                         return -ENOEXEC;
531                 }
532         }
533         return 0;
534 
535 overflow:
536         pr_err("Overflow in relocation type %d value 0x%lx\n",
537                (int)ELF64_R_TYPE(rel[i].r_info), value);
538         return -ENOEXEC;
539 }
540 #endif /* CONFIG_KEXEC_FILE */
541 

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