diff options
Diffstat (limited to 'arch/x86/kernel/machine_kexec_64.c')
| -rw-r--r-- | arch/x86/kernel/machine_kexec_64.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index c8875b5545e1..88404c440727 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -6,6 +6,8 @@ * Version 2. See the file COPYING for more details. */ +#define pr_fmt(fmt) "kexec: " fmt + #include <linux/mm.h> #include <linux/kexec.h> #include <linux/string.h> @@ -328,3 +330,143 @@ int arch_kimage_file_post_load_cleanup(struct kimage *image) return image->fops->cleanup(image); } + +/* + * 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; +} |