diff options
Diffstat (limited to 'arch/x86/tools/relocs.c')
| -rw-r--r-- | arch/x86/tools/relocs.c | 1195 |
1 files changed, 1195 insertions, 0 deletions
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c new file mode 100644 index 0000000000..d30949e25e --- /dev/null +++ b/arch/x86/tools/relocs.c @@ -0,0 +1,1195 @@ +// SPDX-License-Identifier: GPL-2.0 +/* This is included from relocs_32/64.c */ + +#define ElfW(type) _ElfW(ELF_BITS, type) +#define _ElfW(bits, type) __ElfW(bits, type) +#define __ElfW(bits, type) Elf##bits##_##type + +#define Elf_Addr ElfW(Addr) +#define Elf_Ehdr ElfW(Ehdr) +#define Elf_Phdr ElfW(Phdr) +#define Elf_Shdr ElfW(Shdr) +#define Elf_Sym ElfW(Sym) + +static Elf_Ehdr ehdr; +static unsigned long shnum; +static unsigned int shstrndx; +static unsigned int shsymtabndx; +static unsigned int shxsymtabndx; + +static int sym_index(Elf_Sym *sym); + +struct relocs { + uint32_t *offset; + unsigned long count; + unsigned long size; +}; + +static struct relocs relocs16; +static struct relocs relocs32; +#if ELF_BITS == 64 +static struct relocs relocs32neg; +static struct relocs relocs64; +#define FMT PRIu64 +#else +#define FMT PRIu32 +#endif + +struct section { + Elf_Shdr shdr; + struct section *link; + Elf_Sym *symtab; + Elf32_Word *xsymtab; + Elf_Rel *reltab; + char *strtab; +}; +static struct section *secs; + +static const char * const sym_regex_kernel[S_NSYMTYPES] = { +/* + * Following symbols have been audited. There values are constant and do + * not change if bzImage is loaded at a different physical address than + * the address for which it has been compiled. Don't warn user about + * absolute relocations present w.r.t these symbols. + */ + [S_ABS] = + "^(xen_irq_disable_direct_reloc$|" + "xen_save_fl_direct_reloc$|" + "VDSO|" + "__kcfi_typeid_|" + "__crc_)", + +/* + * These symbols are known to be relative, even if the linker marks them + * as absolute (typically defined outside any section in the linker script.) + */ + [S_REL] = + "^(__init_(begin|end)|" + "__x86_cpu_dev_(start|end)|" + "(__parainstructions|__alt_instructions)(_end)?|" + "(__iommu_table|__apicdrivers|__smp_locks)(_end)?|" + "__(start|end)_pci_.*|" +#if CONFIG_FW_LOADER + "__(start|end)_builtin_fw|" +#endif + "__(start|stop)___ksymtab(_gpl)?|" + "__(start|stop)___kcrctab(_gpl)?|" + "__(start|stop)___param|" + "__(start|stop)___modver|" + "__(start|stop)___bug_table|" + "__tracedata_(start|end)|" + "__(start|stop)_notes|" + "__end_rodata|" + "__end_rodata_aligned|" + "__initramfs_start|" + "(jiffies|jiffies_64)|" +#if ELF_BITS == 64 + "__per_cpu_load|" + "init_per_cpu__.*|" + "__end_rodata_hpage_align|" +#endif + "__vvar_page|" + "_end)$" +}; + + +static const char * const sym_regex_realmode[S_NSYMTYPES] = { +/* + * These symbols are known to be relative, even if the linker marks them + * as absolute (typically defined outside any section in the linker script.) + */ + [S_REL] = + "^pa_", + +/* + * These are 16-bit segment symbols when compiling 16-bit code. + */ + [S_SEG] = + "^real_mode_seg$", + +/* + * These are offsets belonging to segments, as opposed to linear addresses, + * when compiling 16-bit code. + */ + [S_LIN] = + "^pa_", +}; + +static const char * const *sym_regex; + +static regex_t sym_regex_c[S_NSYMTYPES]; +static int is_reloc(enum symtype type, const char *sym_name) +{ + return sym_regex[type] && + !regexec(&sym_regex_c[type], sym_name, 0, NULL, 0); +} + +static void regex_init(int use_real_mode) +{ + char errbuf[128]; + int err; + int i; + + if (use_real_mode) + sym_regex = sym_regex_realmode; + else + sym_regex = sym_regex_kernel; + + for (i = 0; i < S_NSYMTYPES; i++) { + if (!sym_regex[i]) + continue; + + err = regcomp(&sym_regex_c[i], sym_regex[i], + REG_EXTENDED|REG_NOSUB); + + if (err) { + regerror(err, &sym_regex_c[i], errbuf, sizeof(errbuf)); + die("%s", errbuf); + } + } +} + +static const char *sym_type(unsigned type) +{ + static const char *type_name[] = { +#define SYM_TYPE(X) [X] = #X + SYM_TYPE(STT_NOTYPE), + SYM_TYPE(STT_OBJECT), + SYM_TYPE(STT_FUNC), + SYM_TYPE(STT_SECTION), + SYM_TYPE(STT_FILE), + SYM_TYPE(STT_COMMON), + SYM_TYPE(STT_TLS), +#undef SYM_TYPE + }; + const char *name = "unknown sym type name"; + if (type < ARRAY_SIZE(type_name)) { + name = type_name[type]; + } + return name; +} + +static const char *sym_bind(unsigned bind) +{ + static const char *bind_name[] = { +#define SYM_BIND(X) [X] = #X + SYM_BIND(STB_LOCAL), + SYM_BIND(STB_GLOBAL), + SYM_BIND(STB_WEAK), +#undef SYM_BIND + }; + const char *name = "unknown sym bind name"; + if (bind < ARRAY_SIZE(bind_name)) { + name = bind_name[bind]; + } + return name; +} + +static const char *sym_visibility(unsigned visibility) +{ + static const char *visibility_name[] = { +#define SYM_VISIBILITY(X) [X] = #X + SYM_VISIBILITY(STV_DEFAULT), + SYM_VISIBILITY(STV_INTERNAL), + SYM_VISIBILITY(STV_HIDDEN), + SYM_VISIBILITY(STV_PROTECTED), +#undef SYM_VISIBILITY + }; + const char *name = "unknown sym visibility name"; + if (visibility < ARRAY_SIZE(visibility_name)) { + name = visibility_name[visibility]; + } + return name; +} + +static const char *rel_type(unsigned type) +{ + static const char *type_name[] = { +#define REL_TYPE(X) [X] = #X +#if ELF_BITS == 64 + REL_TYPE(R_X86_64_NONE), + REL_TYPE(R_X86_64_64), + REL_TYPE(R_X86_64_PC64), + REL_TYPE(R_X86_64_PC32), + REL_TYPE(R_X86_64_GOT32), + REL_TYPE(R_X86_64_PLT32), + REL_TYPE(R_X86_64_COPY), + REL_TYPE(R_X86_64_GLOB_DAT), + REL_TYPE(R_X86_64_JUMP_SLOT), + REL_TYPE(R_X86_64_RELATIVE), + REL_TYPE(R_X86_64_GOTPCREL), + REL_TYPE(R_X86_64_32), + REL_TYPE(R_X86_64_32S), + REL_TYPE(R_X86_64_16), + REL_TYPE(R_X86_64_PC16), + REL_TYPE(R_X86_64_8), + REL_TYPE(R_X86_64_PC8), +#else + REL_TYPE(R_386_NONE), + REL_TYPE(R_386_32), + REL_TYPE(R_386_PC32), + REL_TYPE(R_386_GOT32), + REL_TYPE(R_386_PLT32), + REL_TYPE(R_386_COPY), + REL_TYPE(R_386_GLOB_DAT), + REL_TYPE(R_386_JMP_SLOT), + REL_TYPE(R_386_RELATIVE), + REL_TYPE(R_386_GOTOFF), + REL_TYPE(R_386_GOTPC), + REL_TYPE(R_386_8), + REL_TYPE(R_386_PC8), + REL_TYPE(R_386_16), + REL_TYPE(R_386_PC16), +#endif +#undef REL_TYPE + }; + const char *name = "unknown type rel type name"; + if (type < ARRAY_SIZE(type_name) && type_name[type]) { + name = type_name[type]; + } + return name; +} + +static const char *sec_name(unsigned shndx) +{ + const char *sec_strtab; + const char *name; + sec_strtab = secs[shstrndx].strtab; + name = "<noname>"; + if (shndx < shnum) { + name = sec_strtab + secs[shndx].shdr.sh_name; + } + else if (shndx == SHN_ABS) { + name = "ABSOLUTE"; + } + else if (shndx == SHN_COMMON) { + name = "COMMON"; + } + return name; +} + +static const char *sym_name(const char *sym_strtab, Elf_Sym *sym) +{ + const char *name; + name = "<noname>"; + if (sym->st_name) { + name = sym_strtab + sym->st_name; + } + else { + name = sec_name(sym_index(sym)); + } + return name; +} + +static Elf_Sym *sym_lookup(const char *symname) +{ + int i; + for (i = 0; i < shnum; i++) { + struct section *sec = &secs[i]; + long nsyms; + char *strtab; + Elf_Sym *symtab; + Elf_Sym *sym; + + if (sec->shdr.sh_type != SHT_SYMTAB) + continue; + + nsyms = sec->shdr.sh_size/sizeof(Elf_Sym); + symtab = sec->symtab; + strtab = sec->link->strtab; + + for (sym = symtab; --nsyms >= 0; sym++) { + if (!sym->st_name) + continue; + if (strcmp(symname, strtab + sym->st_name) == 0) + return sym; + } + } + return 0; +} + +#if BYTE_ORDER == LITTLE_ENDIAN +#define le16_to_cpu(val) (val) +#define le32_to_cpu(val) (val) +#define le64_to_cpu(val) (val) +#endif +#if BYTE_ORDER == BIG_ENDIAN +#define le16_to_cpu(val) bswap_16(val) +#define le32_to_cpu(val) bswap_32(val) +#define le64_to_cpu(val) bswap_64(val) +#endif + +static uint16_t elf16_to_cpu(uint16_t val) +{ + return le16_to_cpu(val); +} + +static uint32_t elf32_to_cpu(uint32_t val) +{ + return le32_to_cpu(val); +} + +#define elf_half_to_cpu(x) elf16_to_cpu(x) +#define elf_word_to_cpu(x) elf32_to_cpu(x) + +#if ELF_BITS == 64 +static uint64_t elf64_to_cpu(uint64_t val) +{ + return le64_to_cpu(val); +} +#define elf_addr_to_cpu(x) elf64_to_cpu(x) +#define elf_off_to_cpu(x) elf64_to_cpu(x) +#define elf_xword_to_cpu(x) elf64_to_cpu(x) +#else +#define elf_addr_to_cpu(x) elf32_to_cpu(x) +#define elf_off_to_cpu(x) elf32_to_cpu(x) +#define elf_xword_to_cpu(x) elf32_to_cpu(x) +#endif + +static int sym_index(Elf_Sym *sym) +{ + Elf_Sym *symtab = secs[shsymtabndx].symtab; + Elf32_Word *xsymtab = secs[shxsymtabndx].xsymtab; + unsigned long offset; + int index; + + if (sym->st_shndx != SHN_XINDEX) + return sym->st_shndx; + + /* calculate offset of sym from head of table. */ + offset = (unsigned long)sym - (unsigned long)symtab; + index = offset / sizeof(*sym); + + return elf32_to_cpu(xsymtab[index]); +} + +static void read_ehdr(FILE *fp) +{ + if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) { + die("Cannot read ELF header: %s\n", + strerror(errno)); + } + if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) != 0) { + die("No ELF magic\n"); + } + if (ehdr.e_ident[EI_CLASS] != ELF_CLASS) { + die("Not a %d bit executable\n", ELF_BITS); + } + if (ehdr.e_ident[EI_DATA] != ELFDATA2LSB) { + die("Not a LSB ELF executable\n"); + } + if (ehdr.e_ident[EI_VERSION] != EV_CURRENT) { + die("Unknown ELF version\n"); + } + /* Convert the fields to native endian */ + ehdr.e_type = elf_half_to_cpu(ehdr.e_type); + ehdr.e_machine = elf_half_to_cpu(ehdr.e_machine); + ehdr.e_version = elf_word_to_cpu(ehdr.e_version); + ehdr.e_entry = elf_addr_to_cpu(ehdr.e_entry); + ehdr.e_phoff = elf_off_to_cpu(ehdr.e_phoff); + ehdr.e_shoff = elf_off_to_cpu(ehdr.e_shoff); + ehdr.e_flags = elf_word_to_cpu(ehdr.e_flags); + ehdr.e_ehsize = elf_half_to_cpu(ehdr.e_ehsize); + ehdr.e_phentsize = elf_half_to_cpu(ehdr.e_phentsize); + ehdr.e_phnum = elf_half_to_cpu(ehdr.e_phnum); + ehdr.e_shentsize = elf_half_to_cpu(ehdr.e_shentsize); + ehdr.e_shnum = elf_half_to_cpu(ehdr.e_shnum); + ehdr.e_shstrndx = elf_half_to_cpu(ehdr.e_shstrndx); + + shnum = ehdr.e_shnum; + shstrndx = ehdr.e_shstrndx; + + if ((ehdr.e_type != ET_EXEC) && (ehdr.e_type != ET_DYN)) + die("Unsupported ELF header type\n"); + if (ehdr.e_machine != ELF_MACHINE) + die("Not for %s\n", ELF_MACHINE_NAME); + if (ehdr.e_version != EV_CURRENT) + die("Unknown ELF version\n"); + if (ehdr.e_ehsize != sizeof(Elf_Ehdr)) + die("Bad ELF header size\n"); + if (ehdr.e_phentsize != sizeof(Elf_Phdr)) + die("Bad program header entry\n"); + if (ehdr.e_shentsize != sizeof(Elf_Shdr)) + die("Bad section header entry\n"); + + + if (shnum == SHN_UNDEF || shstrndx == SHN_XINDEX) { + Elf_Shdr shdr; + + if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) + die("Seek to %" FMT " failed: %s\n", ehdr.e_shoff, strerror(errno)); + + if (fread(&shdr, sizeof(shdr), 1, fp) != 1) + die("Cannot read initial ELF section header: %s\n", strerror(errno)); + + if (shnum == SHN_UNDEF) + shnum = elf_xword_to_cpu(shdr.sh_size); + + if (shstrndx == SHN_XINDEX) + shstrndx = elf_word_to_cpu(shdr.sh_link); + } + + if (shstrndx >= shnum) + die("String table index out of bounds\n"); +} + +static void read_shdrs(FILE *fp) +{ + int i; + Elf_Shdr shdr; + + secs = calloc(shnum, sizeof(struct section)); + if (!secs) { + die("Unable to allocate %ld section headers\n", + shnum); + } + if (fseek(fp, ehdr.e_shoff, SEEK_SET) < 0) { + die("Seek to %" FMT " failed: %s\n", + ehdr.e_shoff, strerror(errno)); + } + for (i = 0; i < shnum; i++) { + struct section *sec = &secs[i]; + if (fread(&shdr, sizeof(shdr), 1, fp) != 1) + die("Cannot read ELF section headers %d/%ld: %s\n", + i, shnum, strerror(errno)); + sec->shdr.sh_name = elf_word_to_cpu(shdr.sh_name); + sec->shdr.sh_type = elf_word_to_cpu(shdr.sh_type); + sec->shdr.sh_flags = elf_xword_to_cpu(shdr.sh_flags); + sec->shdr.sh_addr = elf_addr_to_cpu(shdr.sh_addr); + sec->shdr.sh_offset = elf_off_to_cpu(shdr.sh_offset); + sec->shdr.sh_size = elf_xword_to_cpu(shdr.sh_size); + sec->shdr.sh_link = elf_word_to_cpu(shdr.sh_link); + sec->shdr.sh_info = elf_word_to_cpu(shdr.sh_info); + sec->shdr.sh_addralign = elf_xword_to_cpu(shdr.sh_addralign); + sec->shdr.sh_entsize = elf_xword_to_cpu(shdr.sh_entsize); + if (sec->shdr.sh_link < shnum) + sec->link = &secs[sec->shdr.sh_link]; + } + +} + +static void read_strtabs(FILE *fp) +{ + int i; + for (i = 0; i < shnum; i++) { + struct section *sec = &secs[i]; + if (sec->shdr.sh_type != SHT_STRTAB) { + continue; + } + sec->strtab = malloc(sec->shdr.sh_size); + if (!sec->strtab) { + die("malloc of %" FMT " bytes for strtab failed\n", + sec->shdr.sh_size); + } + if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { + die("Seek to %" FMT " failed: %s\n", + sec->shdr.sh_offset, strerror(errno)); + } + if (fread(sec->strtab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read symbol table: %s\n", + strerror(errno)); + } + } +} + +static void read_symtabs(FILE *fp) +{ + int i,j; + + for (i = 0; i < shnum; i++) { + struct section *sec = &secs[i]; + int num_syms; + + switch (sec->shdr.sh_type) { + case SHT_SYMTAB_SHNDX: + sec->xsymtab = malloc(sec->shdr.sh_size); + if (!sec->xsymtab) { + die("malloc of %" FMT " bytes for xsymtab failed\n", + sec->shdr.sh_size); + } + if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { + die("Seek to %" FMT " failed: %s\n", + sec->shdr.sh_offset, strerror(errno)); + } + if (fread(sec->xsymtab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read extended symbol table: %s\n", + strerror(errno)); + } + shxsymtabndx = i; + continue; + + case SHT_SYMTAB: + num_syms = sec->shdr.sh_size / sizeof(Elf_Sym); + + sec->symtab = malloc(sec->shdr.sh_size); + if (!sec->symtab) { + die("malloc of %" FMT " bytes for symtab failed\n", + sec->shdr.sh_size); + } + if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { + die("Seek to %" FMT " failed: %s\n", + sec->shdr.sh_offset, strerror(errno)); + } + if (fread(sec->symtab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read symbol table: %s\n", + strerror(errno)); + } + for (j = 0; j < num_syms; j++) { + Elf_Sym *sym = &sec->symtab[j]; + + sym->st_name = elf_word_to_cpu(sym->st_name); + sym->st_value = elf_addr_to_cpu(sym->st_value); + sym->st_size = elf_xword_to_cpu(sym->st_size); + sym->st_shndx = elf_half_to_cpu(sym->st_shndx); + } + shsymtabndx = i; + continue; + + default: + continue; + } + } +} + + +static void read_relocs(FILE *fp) +{ + int i,j; + for (i = 0; i < shnum; i++) { + struct section *sec = &secs[i]; + if (sec->shdr.sh_type != SHT_REL_TYPE) { + continue; + } + sec->reltab = malloc(sec->shdr.sh_size); + if (!sec->reltab) { + die("malloc of %" FMT " bytes for relocs failed\n", + sec->shdr.sh_size); + } + if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { + die("Seek to %" FMT " failed: %s\n", + sec->shdr.sh_offset, strerror(errno)); + } + if (fread(sec->reltab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read symbol table: %s\n", + strerror(errno)); + } + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) { + Elf_Rel *rel = &sec->reltab[j]; + rel->r_offset = elf_addr_to_cpu(rel->r_offset); + rel->r_info = elf_xword_to_cpu(rel->r_info); +#if (SHT_REL_TYPE == SHT_RELA) + rel->r_addend = elf_xword_to_cpu(rel->r_addend); +#endif + } + } +} + + +static void print_absolute_symbols(void) +{ + int i; + const char *format; + + if (ELF_BITS == 64) + format = "%5d %016"PRIx64" %5"PRId64" %10s %10s %12s %s\n"; + else + format = "%5d %08"PRIx32" %5"PRId32" %10s %10s %12s %s\n"; + + printf("Absolute symbols\n"); + printf(" Num: Value Size Type Bind Visibility Name\n"); + for (i = 0; i < shnum; i++) { + struct section *sec = &secs[i]; + char *sym_strtab; + int j; + + if (sec->shdr.sh_type != SHT_SYMTAB) { + continue; + } + sym_strtab = sec->link->strtab; + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) { + Elf_Sym *sym; + const char *name; + sym = &sec->symtab[j]; + name = sym_name(sym_strtab, sym); + if (sym->st_shndx != SHN_ABS) { + continue; + } + printf(format, + j, sym->st_value, sym->st_size, + sym_type(ELF_ST_TYPE(sym->st_info)), + sym_bind(ELF_ST_BIND(sym->st_info)), + sym_visibility(ELF_ST_VISIBILITY(sym->st_other)), + name); + } + } + printf("\n"); +} + +static void print_absolute_relocs(void) +{ + int i, printed = 0; + const char *format; + + if (ELF_BITS == 64) + format = "%016"PRIx64" %016"PRIx64" %10s %016"PRIx64" %s\n"; + else + format = "%08"PRIx32" %08"PRIx32" %10s %08"PRIx32" %s\n"; + + for (i = 0; i < shnum; i++) { + struct section *sec = &secs[i]; + struct section *sec_applies, *sec_symtab; + char *sym_strtab; + Elf_Sym *sh_symtab; + int j; + if (sec->shdr.sh_type != SHT_REL_TYPE) { + continue; + } + sec_symtab = sec->link; + sec_applies = &secs[sec->shdr.sh_info]; + if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) { + continue; + } + sh_symtab = sec_symtab->symtab; + sym_strtab = sec_symtab->link->strtab; + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) { + Elf_Rel *rel; + Elf_Sym *sym; + const char *name; + rel = &sec->reltab[j]; + sym = &sh_symtab[ELF_R_SYM(rel->r_info)]; + name = sym_name(sym_strtab, sym); + if (sym->st_shndx != SHN_ABS) { + continue; + } + + /* Absolute symbols are not relocated if bzImage is + * loaded at a non-compiled address. Display a warning + * to user at compile time about the absolute + * relocations present. + * + * User need to audit the code to make sure + * some symbols which should have been section + * relative have not become absolute because of some + * linker optimization or wrong programming usage. + * + * Before warning check if this absolute symbol + * relocation is harmless. + */ + if (is_reloc(S_ABS, name) || is_reloc(S_REL, name)) + continue; + + if (!printed) { + printf("WARNING: Absolute relocations" + " present\n"); + printf("Offset Info Type Sym.Value " + "Sym.Name\n"); + printed = 1; + } + + printf(format, + rel->r_offset, + rel->r_info, + rel_type(ELF_R_TYPE(rel->r_info)), + sym->st_value, + name); + } + } + + if (printed) + printf("\n"); +} + +static void add_reloc(struct relocs *r, uint32_t offset) +{ + if (r->count == r->size) { + unsigned long newsize = r->size + 50000; + void *mem = realloc(r->offset, newsize * sizeof(r->offset[0])); + + if (!mem) + die("realloc of %ld entries for relocs failed\n", + newsize); + r->offset = mem; + r->size = newsize; + } + r->offset[r->count++] = offset; +} + +static void walk_relocs(int (*process)(struct section *sec, Elf_Rel *rel, + Elf_Sym *sym, const char *symname)) +{ + int i; + /* Walk through the relocations */ + for (i = 0; i < shnum; i++) { + char *sym_strtab; + Elf_Sym *sh_symtab; + struct section *sec_applies, *sec_symtab; + int j; + struct section *sec = &secs[i]; + + if (sec->shdr.sh_type != SHT_REL_TYPE) { + continue; + } + sec_symtab = sec->link; + sec_applies = &secs[sec->shdr.sh_info]; + if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) { + continue; + } + sh_symtab = sec_symtab->symtab; + sym_strtab = sec_symtab->link->strtab; + for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) { + Elf_Rel *rel = &sec->reltab[j]; + Elf_Sym *sym = &sh_symtab[ELF_R_SYM(rel->r_info)]; + const char *symname = sym_name(sym_strtab, sym); + + process(sec, rel, sym, symname); + } + } +} + +/* + * The .data..percpu section is a special case for x86_64 SMP kernels. + * It is used to initialize the actual per_cpu areas and to provide + * definitions for the per_cpu variables that correspond to their offsets + * within the percpu area. Since the values of all of the symbols need + * to be offsets from the start of the per_cpu area the virtual address + * (sh_addr) of .data..percpu is 0 in SMP kernels. + * + * This means that: + * + * Relocations that reference symbols in the per_cpu area do not + * need further relocation (since the value is an offset relative + * to the start of the per_cpu area that does not change). + * + * Relocations that apply to the per_cpu area need to have their + * offset adjusted by by the value of __per_cpu_load to make them + * point to the correct place in the loaded image (because the + * virtual address of .data..percpu is 0). + * + * For non SMP kernels .data..percpu is linked as part of the normal + * kernel data and does not require special treatment. + * + */ +static int per_cpu_shndx = -1; +static Elf_Addr per_cpu_load_addr; + +static void percpu_init(void) +{ + int i; + for (i = 0; i < shnum; i++) { + ElfW(Sym) *sym; + if (strcmp(sec_name(i), ".data..percpu")) + continue; + + if (secs[i].shdr.sh_addr != 0) /* non SMP kernel */ + return; + + sym = sym_lookup("__per_cpu_load"); + if (!sym) + die("can't find __per_cpu_load\n"); + + per_cpu_shndx = i; + per_cpu_load_addr = sym->st_value; + return; + } +} + +#if ELF_BITS == 64 + +/* + * Check to see if a symbol lies in the .data..percpu section. + * + * The linker incorrectly associates some symbols with the + * .data..percpu section so we also need to check the symbol + * name to make sure that we classify the symbol correctly. + * + * The GNU linker incorrectly associates: + * __init_begin + * __per_cpu_load + * + * The "gold" linker incorrectly associates: + * init_per_cpu__fixed_percpu_data + * init_per_cpu__gdt_page + */ +static int is_percpu_sym(ElfW(Sym) *sym, const char *symname) +{ + int shndx = sym_index(sym); + + return (shndx == per_cpu_shndx) && + strcmp(symname, "__init_begin") && + strcmp(symname, "__per_cpu_load") && + strncmp(symname, "init_per_cpu_", 13); +} + + +static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym, + const char *symname) +{ + unsigned r_type = ELF64_R_TYPE(rel->r_info); + ElfW(Addr) offset = rel->r_offset; + int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname); + + if (sym->st_shndx == SHN_UNDEF) + return 0; + + /* + * Adjust the offset if this reloc applies to the percpu section. + */ + if (sec->shdr.sh_info == per_cpu_shndx) + offset += per_cpu_load_addr; + + switch (r_type) { + case R_X86_64_NONE: + /* NONE can be ignored. */ + break; + + case R_X86_64_PC32: + case R_X86_64_PLT32: + /* + * PC relative relocations don't need to be adjusted unless + * referencing a percpu symbol. + * + * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32. + */ + if (is_percpu_sym(sym, symname)) + add_reloc(&relocs32neg, offset); + break; + + case R_X86_64_PC64: + /* + * Only used by jump labels + */ + if (is_percpu_sym(sym, symname)) + die("Invalid R_X86_64_PC64 relocation against per-CPU symbol %s\n", + symname); + break; + + case R_X86_64_32: + case R_X86_64_32S: + case R_X86_64_64: + /* + * References to the percpu area don't need to be adjusted. + */ + if (is_percpu_sym(sym, symname)) + break; + + if (shn_abs) { + /* + * Whitelisted absolute symbols do not require + * relocation. + */ + if (is_reloc(S_ABS, symname)) + break; + + die("Invalid absolute %s relocation: %s\n", + rel_type(r_type), symname); + break; + } + + /* + * Relocation offsets for 64 bit kernels are output + * as 32 bits and sign extended back to 64 bits when + * the relocations are processed. + * Make sure that the offset will fit. + */ + if ((int32_t)offset != (int64_t)offset) + die("Relocation offset doesn't fit in 32 bits\n"); + + if (r_type == R_X86_64_64) + add_reloc(&relocs64, offset); + else + add_reloc(&relocs32, offset); + break; + + default: + die("Unsupported relocation type: %s (%d)\n", + rel_type(r_type), r_type); + break; + } + + return 0; +} + +#else + +static int do_reloc32(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, + const char *symname) +{ + unsigned r_type = ELF32_R_TYPE(rel->r_info); + int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname); + + switch (r_type) { + case R_386_NONE: + case R_386_PC32: + case R_386_PC16: + case R_386_PC8: + case R_386_PLT32: + /* + * NONE can be ignored and PC relative relocations don't need + * to be adjusted. Because sym must be defined, R_386_PLT32 can + * be treated the same way as R_386_PC32. + */ + break; + + case R_386_32: + if (shn_abs) { + /* + * Whitelisted absolute symbols do not require + * relocation. + */ + if (is_reloc(S_ABS, symname)) + break; + + die("Invalid absolute %s relocation: %s\n", + rel_type(r_type), symname); + break; + } + + add_reloc(&relocs32, rel->r_offset); + break; + + default: + die("Unsupported relocation type: %s (%d)\n", + rel_type(r_type), r_type); + break; + } + + return 0; +} + +static int do_reloc_real(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, + const char *symname) +{ + unsigned r_type = ELF32_R_TYPE(rel->r_info); + int shn_abs = (sym->st_shndx == SHN_ABS) && !is_reloc(S_REL, symname); + + switch (r_type) { + case R_386_NONE: + case R_386_PC32: + case R_386_PC16: + case R_386_PC8: + case R_386_PLT32: + /* + * NONE can be ignored and PC relative relocations don't need + * to be adjusted. Because sym must be defined, R_386_PLT32 can + * be treated the same way as R_386_PC32. + */ + break; + + case R_386_16: + if (shn_abs) { + /* + * Whitelisted absolute symbols do not require + * relocation. + */ + if (is_reloc(S_ABS, symname)) + break; + + if (is_reloc(S_SEG, symname)) { + add_reloc(&relocs16, rel->r_offset); + break; + } + } else { + if (!is_reloc(S_LIN, symname)) + break; + } + die("Invalid %s %s relocation: %s\n", + shn_abs ? "absolute" : "relative", + rel_type(r_type), symname); + break; + + case R_386_32: + if (shn_abs) { + /* + * Whitelisted absolute symbols do not require + * relocation. + */ + if (is_reloc(S_ABS, symname)) + break; + + if (is_reloc(S_REL, symname)) { + add_reloc(&relocs32, rel->r_offset); + break; + } + } else { + if (is_reloc(S_LIN, symname)) + add_reloc(&relocs32, rel->r_offset); + break; + } + die("Invalid %s %s relocation: %s\n", + shn_abs ? "absolute" : "relative", + rel_type(r_type), symname); + break; + + default: + die("Unsupported relocation type: %s (%d)\n", + rel_type(r_type), r_type); + break; + } + + return 0; +} + +#endif + +static int cmp_relocs(const void *va, const void *vb) +{ + const uint32_t *a, *b; + a = va; b = vb; + return (*a == *b)? 0 : (*a > *b)? 1 : -1; +} + +static void sort_relocs(struct relocs *r) +{ + qsort(r->offset, r->count, sizeof(r->offset[0]), cmp_relocs); +} + +static int write32(uint32_t v, FILE *f) +{ + unsigned char buf[4]; + + put_unaligned_le32(v, buf); + return fwrite(buf, 1, 4, f) == 4 ? 0 : -1; +} + +static int write32_as_text(uint32_t v, FILE *f) +{ + return fprintf(f, "\t.long 0x%08"PRIx32"\n", v) > 0 ? 0 : -1; +} + +static void emit_relocs(int as_text, int use_real_mode) +{ + int i; + int (*write_reloc)(uint32_t, FILE *) = write32; + int (*do_reloc)(struct section *sec, Elf_Rel *rel, Elf_Sym *sym, + const char *symname); + +#if ELF_BITS == 64 + if (!use_real_mode) + do_reloc = do_reloc64; + else + die("--realmode not valid for a 64-bit ELF file"); +#else + if (!use_real_mode) + do_reloc = do_reloc32; + else + do_reloc = do_reloc_real; +#endif + + /* Collect up the relocations */ + walk_relocs(do_reloc); + + if (relocs16.count && !use_real_mode) + die("Segment relocations found but --realmode not specified\n"); + + /* Order the relocations for more efficient processing */ + sort_relocs(&relocs32); +#if ELF_BITS == 64 + sort_relocs(&relocs32neg); + sort_relocs(&relocs64); +#else + sort_relocs(&relocs16); +#endif + + /* Print the relocations */ + if (as_text) { + /* Print the relocations in a form suitable that + * gas will like. + */ + printf(".section \".data.reloc\",\"a\"\n"); + printf(".balign 4\n"); + write_reloc = write32_as_text; + } + + if (use_real_mode) { + write_reloc(relocs16.count, stdout); + for (i = 0; i < relocs16.count; i++) + write_reloc(relocs16.offset[i], stdout); + + write_reloc(relocs32.count, stdout); + for (i = 0; i < relocs32.count; i++) + write_reloc(relocs32.offset[i], stdout); + } else { +#if ELF_BITS == 64 + /* Print a stop */ + write_reloc(0, stdout); + + /* Now print each relocation */ + for (i = 0; i < relocs64.count; i++) + write_reloc(relocs64.offset[i], stdout); + + /* Print a stop */ + write_reloc(0, stdout); + + /* Now print each inverse 32-bit relocation */ + for (i = 0; i < relocs32neg.count; i++) + write_reloc(relocs32neg.offset[i], stdout); +#endif + + /* Print a stop */ + write_reloc(0, stdout); + + /* Now print each relocation */ + for (i = 0; i < relocs32.count; i++) + write_reloc(relocs32.offset[i], stdout); + } +} + +/* + * As an aid to debugging problems with different linkers + * print summary information about the relocs. + * Since different linkers tend to emit the sections in + * different orders we use the section names in the output. + */ +static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym, + const char *symname) +{ + printf("%s\t%s\t%s\t%s\n", + sec_name(sec->shdr.sh_info), + rel_type(ELF_R_TYPE(rel->r_info)), + symname, + sec_name(sym_index(sym))); + return 0; +} + +static void print_reloc_info(void) +{ + printf("reloc section\treloc type\tsymbol\tsymbol section\n"); + walk_relocs(do_reloc_info); +} + +#if ELF_BITS == 64 +# define process process_64 +#else +# define process process_32 +#endif + +void process(FILE *fp, int use_real_mode, int as_text, + int show_absolute_syms, int show_absolute_relocs, + int show_reloc_info) +{ + regex_init(use_real_mode); + read_ehdr(fp); + read_shdrs(fp); + read_strtabs(fp); + read_symtabs(fp); + read_relocs(fp); + if (ELF_BITS == 64) + percpu_init(); + if (show_absolute_syms) { + print_absolute_symbols(); + return; + } + if (show_absolute_relocs) { + print_absolute_relocs(); + return; + } + if (show_reloc_info) { + print_reloc_info(); + return; + } + emit_relocs(as_text, use_real_mode); +} |