/* * handle transition of Linux booting another kernel * Copyright (C) 2002-2005 Eric Biederman * * This source code is licensed under the GNU General Public License, * Version 2. See the file COPYING for more details. */ #define pr_fmt(fmt) "kexec: " fmt #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef CONFIG_KEXEC_FILE static struct kexec_file_ops *kexec_file_loaders[] = { &kexec_bzImage64_ops, }; #endif static void free_transition_pgtable(struct kimage *image) { free_page((unsigned long)image->arch.p4d); free_page((unsigned long)image->arch.pud); free_page((unsigned long)image->arch.pmd); free_page((unsigned long)image->arch.pte); } static int init_transition_pgtable(struct kimage *image, pgd_t *pgd) { p4d_t *p4d; pud_t *pud; pmd_t *pmd; pte_t *pte; unsigned long vaddr, paddr; int result = -ENOMEM; vaddr = (unsigned long)relocate_kernel; paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE); pgd += pgd_index(vaddr); if (!pgd_present(*pgd)) { p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL); if (!p4d) goto err; image->arch.p4d = p4d; set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE)); } p4d = p4d_offset(pgd, vaddr); if (!p4d_present(*p4d)) { pud = (pud_t *)get_zeroed_page(GFP_KERNEL); if (!pud) goto err; image->arch.pud = pud; set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE)); } pud = pud_offset(p4d, vaddr); if (!pud_present(*pud)) { pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL); if (!pmd) goto err; image->arch.pmd = pmd; set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE)); } pmd = pmd_offset(pud, vaddr); if (!pmd_present(*pmd)) { pte = (pte_t *)get_zeroed_page(GFP_KERNEL); if (!pte) goto err; image->arch.pte = pte; set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE)); } pte = pte_offset_kernel(pmd, vaddr); set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, PAGE_KERNEL_EXEC_NOENC)); return 0; err: free_transition_pgtable(image); return result; } static void *alloc_pgt_page(void *data) { struct kimage *image = (struct kimage *)data; struct page *page; void *p = NULL; page = kimage_alloc_control_pages(image, 0); if (page) { p = page_address(page); clear_page(p); } return p; } static int init_pgtable(struct kimage *image, unsigned long start_pgtable) { struct x86_mapping_info info = { .alloc_pgt_page = alloc_pgt_page, .context = image, .page_flag = __PAGE_KERNEL_LARGE_EXEC, .kernpg_flag = _KERNPG_TABLE_NOENC, }; unsigned long mstart, mend; pgd_t *level4p; int result; int i; level4p = (pgd_t *)__va(start_pgtable); clear_page(level4p); if (direct_gbpages) info.direct_gbpages = true; for (i = 0; i < nr_pfn_mapped; i++) { mstart = pfn_mapped[i].start << PAGE_SHIFT; mend = pfn_mapped[i].end << PAGE_SHIFT; result = kernel_ident_mapping_init(&info, level4p, mstart, mend); if (result) return result; } /* * segments's mem ranges could be outside 0 ~ max_pfn, * for example when jump back to original kernel from kexeced kernel. * or first kernel is booted with user mem map, and second kernel * could be loaded out of that range. */ for (i = 0; i < image->nr_segments; i++) { mstart = image->segment[i].mem; mend = mstart + image->segment[i].memsz; result = kernel_ident_mapping_init(&info, level4p, mstart, mend); if (result) return result; } return init_transition_pgtable(image, level4p); } static void set_idt(void *newidt, u16 limit) { struct desc_ptr curidt; /* x86-64 supports unaliged loads & stores */ curidt.size = limit; curidt.address = (unsigned long)newidt; __asm__ __volatile__ ( "lidtq %0\n" : : "m" (curidt) ); }; static void set_gdt(void *newgdt, u16 limit) { struct desc_ptr curgdt; /* x86-64 supports unaligned loads & stores */ curgdt.size = limit; curgdt.address = (unsigned long)newgdt; __asm__ __volatile__ ( "lgdtq %0\n" : : "m" (curgdt) ); }; static void load_segments(void) { __asm__ __volatile__ ( "\tmovl %0,%%ds\n" "\tmovl %0,%%es\n" "\tmovl %0,%%ss\n" "\tmovl %0,%%fs\n" "\tmovl %0,%%gs\n" : : "a" (__KERNEL_DS) : "memory" ); } #ifdef CONFIG_KEXEC_FILE /* Update purgatory as needed after various image segments have been prepared */ static int arch_update_purgatory(struct kimage *image) { int ret = 0; if (!image->file_mode) return 0; /* Setup copying of backup region */ if (image->type == KEXEC_TYPE_CRASH) { ret = kexec_purgatory_get_set_symbol(image, "purgatory_backup_dest", &image->arch.backup_load_addr, sizeof(image->arch.backup_load_addr), 0); if (ret) return ret; ret = kexec_purgatory_get_set_symbol(image, "purgatory_backup_src", &image->arch.backup_src_start, sizeof(image->arch.backup_src_start), 0); if (ret) return ret; ret = kexec_purgatory_get_set_symbol(image, "purgatory_backup_sz", &image->arch.backup_src_sz, sizeof(image->arch.backup_src_sz), 0); if (ret) return ret; } return ret; } #else /* !CONFIG_KEXEC_FILE */ static inline int arch_update_purgatory(struct kimage *image) { return 0; } #endif /* CONFIG_KEXEC_FILE */ int machine_kexec_prepare(struct kimage *image) { unsigned long start_pgtable; int result; /* Calculate the offsets */ start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT; /* Setup the identity mapped 64bit page table */ result = init_pgtable(image, start_pgtable); if (result) return result; /* update purgatory as needed */ result = arch_update_purgatory(image); if (result) return result; return 0; } void machine_kexec_cleanup(struct kimage *image) { free_transition_pgtable(image); } /* * Do not allocate memory (or fail in any way) in machine_kexec(). * We are past the point of no return, committed to rebooting now. */ void machine_kexec(struct kimage *image) { unsigned long page_list[PAGES_NR]; void *control_page; int save_ftrace_enabled; #ifdef CONFIG_KEXEC_JUMP if (image->preserve_context) save_processor_state(); #endif save_ftrace_enabled = __ftrace_enabled_save(); /* Interrupts aren't acceptable while we reboot */ local_irq_disable(); hw_breakpoint_disable(); if (image->preserve_context) { #ifdef CONFIG_X86_IO_APIC /* * We need to put APICs in legacy mode so that we can * get timer interrupts in second kernel. kexec/kdump * paths already have calls to disable_IO_APIC() in * one form or other. kexec jump path also need * one. */ disable_IO_APIC(); #endif } control_page = page_address(image->control_code_page) + PAGE_SIZE; memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE); page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page); page_list[VA_CONTROL_PAGE] = (unsigned long)control_page; page_list[PA_TABLE_PAGE] = (unsigned long)__pa(page_address(image->control_code_page)); if (image->type == KEXEC_TYPE_DEFAULT) page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page) << PAGE_SHIFT); /* * The segment registers are funny things, they have both a * visible and an invisible part. Whenever the visible part is * set to a specific selector, the invisible part is loaded * with from a table in memory. At no other time is the * descriptor table in memory accessed. * * I take advantage of this here by force loading the * segments, before I zap the gdt with an invalid value. */ load_segments(); /* * The gdt & idt are now invalid. * If you want to load them you must set up your own idt & gdt. */ set_gdt(phys_to_virt(0), 0); set_idt(phys_to_virt(0), 0); /* now call it */ image->start = relocate_kernel((unsigned long)image->head, (unsigned long)page_list, image->start, image->preserve_context, sme_active()); #ifdef CONFIG_KEXEC_JUMP if (image->preserve_context) restore_processor_state(); #endif __ftrace_enabled_restore(save_ftrace_enabled); } void arch_crash_save_vmcoreinfo(void) { VMCOREINFO_NUMBER(phys_base); VMCOREINFO_SYMBOL(init_top_pgt); #ifdef CONFIG_NUMA VMCOREINFO_SYMBOL(node_data); VMCOREINFO_LENGTH(node_data, MAX_NUMNODES); #endif vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset()); VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE); } /* arch-dependent functionality related to kexec file-based syscall */ #ifdef CONFIG_KEXEC_FILE int arch_kexec_kernel_image_probe(struct kimage *image, void *buf, unsigned long buf_len) { int i, ret = -ENOEXEC; struct kexec_file_ops *fops; for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) { fops = kexec_file_loaders[i]; if (!fops || !fops->probe) continue; ret = fops->probe(buf, buf_len); if (!ret) { image->fops = fops; return ret; } } return ret; } void *arch_kexec_kernel_image_load(struct kimage *image) { vfree(image->arch.elf_headers); image->arch.elf_headers = NULL; if (!image->fops || !image->fops->load) return ERR_PTR(-ENOEXEC); return image->fops->load(image, image->kernel_buf, image->kernel_buf_len, image->initrd_buf, image->initrd_buf_len, image->cmdline_buf, image->cmdline_buf_len); } int arch_kimage_file_post_load_cleanup(struct kimage *image) { if (!image->fops || !image->fops->cleanup) return 0; return image->fops->cleanup(image->image_loader_data); } #ifdef CONFIG_KEXEC_VERIFY_SIG int arch_kexec_kernel_verify_sig(struct kimage *image, void *kernel, unsigned long kernel_len) { if (!image->fops || !image->fops->verify_sig) { pr_debug("kernel loader does not support signature verification."); return -EKEYREJECTED; } return image->fops->verify_sig(kernel, kernel_len); } #endif /* * Apply purgatory relocations. * * ehdr: Pointer to elf headers * sechdrs: Pointer to section headers. * relsec: section index of SHT_RELA section. * * TODO: Some of the code belongs to generic code. Move that in kexec.c. */ int arch_kexec_apply_relocations_add(const Elf64_Ehdr *ehdr, Elf64_Shdr *sechdrs, unsigned int relsec) { unsigned int i; Elf64_Rela *rel; Elf64_Sym *sym; void *location; Elf64_Shdr *section, *symtabsec; unsigned long address, sec_base, value; const char *strtab, *name, *shstrtab; /* * ->sh_offset has been modified to keep the pointer to section * contents in memory */ rel = (void *)sechdrs[relsec].sh_offset; /* Section to which relocations apply */ section = &sechdrs[sechdrs[relsec].sh_info]; pr_debug("Applying relocate section %u to %u\n", relsec, sechdrs[relsec].sh_info); /* Associated symbol table */ symtabsec = &sechdrs[sechdrs[relsec].sh_link]; /* String table */ if (symtabsec->sh_link >= ehdr->e_shnum) { /* Invalid strtab section number */ pr_err("Invalid string table section index %d\n", symtabsec->sh_link); return -ENOEXEC; } strtab = (char *)sechdrs[symtabsec->sh_link].sh_offset; /* section header string table */ shstrtab = (char *)sechdrs[ehdr->e_shstrndx].sh_offset; for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) { /* * rel[i].r_offset contains byte offset from beginning * of section to the storage unit affected. * * This is location to update (->sh_offset). This is temporary * buffer where section is currently loaded. This will finally * be loaded to a different address later, pointed to by * ->sh_addr. kexec takes care of moving it * (kexec_load_segment()). */ location = (void *)(section->sh_offset + rel[i].r_offset); /* Final address of the location */ address = section->sh_addr + rel[i].r_offset; /* * rel[i].r_info contains information about symbol table index * w.r.t which relocation must be made and type of relocation * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get * these respectively. */ sym = (Elf64_Sym *)symtabsec->sh_offset + ELF64_R_SYM(rel[i].r_info); if (sym->st_name) name = strtab + sym->st_name; else name = shstrtab + sechdrs[sym->st_shndx].sh_name; pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n", name, sym->st_info, sym->st_shndx, sym->st_value, sym->st_size); if (sym->st_shndx == SHN_UNDEF) { pr_err("Undefined symbol: %s\n", name); return -ENOEXEC; } if (sym->st_shndx == SHN_COMMON) { pr_err("symbol '%s' in common section\n", name); return -ENOEXEC; } if (sym->st_shndx == SHN_ABS) sec_base = 0; else if (sym->st_shndx >= ehdr->e_shnum) { pr_err("Invalid section %d for symbol %s\n", sym->st_shndx, name); return -ENOEXEC; } else sec_base = sechdrs[sym->st_shndx].sh_addr; value = sym->st_value; value += sec_base; value += rel[i].r_addend; switch (ELF64_R_TYPE(rel[i].r_info)) { case R_X86_64_NONE: break; case R_X86_64_64: *(u64 *)location = value; break; case R_X86_64_32: *(u32 *)location = value; if (value != *(u32 *)location) goto overflow; break; case R_X86_64_32S: *(s32 *)location = value; if ((s64)value != *(s32 *)location) goto overflow; break; case R_X86_64_PC32: value -= (u64)address; *(u32 *)location = value; break; default: pr_err("Unknown rela relocation: %llu\n", ELF64_R_TYPE(rel[i].r_info)); return -ENOEXEC; } } return 0; overflow: pr_err("Overflow in relocation type %d value 0x%lx\n", (int)ELF64_R_TYPE(rel[i].r_info), value); return -ENOEXEC; } #endif /* CONFIG_KEXEC_FILE */ static int kexec_mark_range(unsigned long start, unsigned long end, bool protect) { struct page *page; unsigned int nr_pages; /* * For physical range: [start, end]. We must skip the unassigned * crashk resource with zero-valued "end" member. */ if (!end || start > end) return 0; page = pfn_to_page(start >> PAGE_SHIFT); nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1; if (protect) return set_pages_ro(page, nr_pages); else return set_pages_rw(page, nr_pages); } static void kexec_mark_crashkres(bool protect) { unsigned long control; kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect); /* Don't touch the control code page used in crash_kexec().*/ control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page)); /* Control code page is located in the 2nd page. */ kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect); control += KEXEC_CONTROL_PAGE_SIZE; kexec_mark_range(control, crashk_res.end, protect); } void arch_kexec_protect_crashkres(void) { kexec_mark_crashkres(true); } void arch_kexec_unprotect_crashkres(void) { kexec_mark_crashkres(false); } int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, gfp_t gfp) { /* * If SME is active we need to be sure that kexec pages are * not encrypted because when we boot to the new kernel the * pages won't be accessed encrypted (initially). */ return set_memory_decrypted((unsigned long)vaddr, pages); } void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages) { /* * If SME is active we need to reset the pages back to being * an encrypted mapping before freeing them. */ set_memory_encrypted((unsigned long)vaddr, pages); }