/* Postprocess module symbol versions * * Copyright 2003 Kai Germaschewski * Copyright 2002-2004 Rusty Russell, IBM Corporation * Copyright 2006-2008 Sam Ravnborg * Based in part on module-init-tools/depmod.c,file2alias * * This software may be used and distributed according to the terms * of the GNU General Public License, incorporated herein by reference. * * Usage: modpost vmlinux module1.o module2.o ... */ #define _GNU_SOURCE #include #include #include #include #include #include #include #include "modpost.h" #include "../../include/linux/license.h" /* Are we using CONFIG_MODVERSIONS? */ static bool modversions; /* Is CONFIG_MODULE_SRCVERSION_ALL set? */ static bool all_versions; /* If we are modposting external module set to 1 */ static bool external_module; /* Only warn about unresolved symbols */ static bool warn_unresolved; /* How a symbol is exported */ static int sec_mismatch_count; static bool sec_mismatch_warn_only = true; /* ignore missing files */ static bool ignore_missing_files; /* If set to 1, only warn (instead of error) about missing ns imports */ static bool allow_missing_ns_imports; static bool error_occurred; /* * Cut off the warnings when there are too many. This typically occurs when * vmlinux is missing. ('make modules' without building vmlinux.) */ #define MAX_UNRESOLVED_REPORTS 10 static unsigned int nr_unresolved; enum export { export_plain, export_gpl, export_unknown }; /* In kernel, this size is defined in linux/module.h; * here we use Elf_Addr instead of long for covering cross-compile */ #define MODULE_NAME_LEN (64 - sizeof(Elf_Addr)) void __attribute__((format(printf, 2, 3))) modpost_log(enum loglevel loglevel, const char *fmt, ...) { va_list arglist; switch (loglevel) { case LOG_WARN: fprintf(stderr, "WARNING: "); break; case LOG_ERROR: fprintf(stderr, "ERROR: "); break; case LOG_FATAL: fprintf(stderr, "FATAL: "); break; default: /* invalid loglevel, ignore */ break; } fprintf(stderr, "modpost: "); va_start(arglist, fmt); vfprintf(stderr, fmt, arglist); va_end(arglist); if (loglevel == LOG_FATAL) exit(1); if (loglevel == LOG_ERROR) error_occurred = true; } static inline bool strends(const char *str, const char *postfix) { if (strlen(str) < strlen(postfix)) return false; return strcmp(str + strlen(str) - strlen(postfix), postfix) == 0; } void *do_nofail(void *ptr, const char *expr) { if (!ptr) fatal("Memory allocation failure: %s.\n", expr); return ptr; } char *read_text_file(const char *filename) { struct stat st; size_t nbytes; int fd; char *buf; fd = open(filename, O_RDONLY); if (fd < 0) { perror(filename); exit(1); } if (fstat(fd, &st) < 0) { perror(filename); exit(1); } buf = NOFAIL(malloc(st.st_size + 1)); nbytes = st.st_size; while (nbytes) { ssize_t bytes_read; bytes_read = read(fd, buf, nbytes); if (bytes_read < 0) { perror(filename); exit(1); } nbytes -= bytes_read; } buf[st.st_size] = '\0'; close(fd); return buf; } char *get_line(char **stringp) { char *orig = *stringp, *next; /* do not return the unwanted extra line at EOF */ if (!orig || *orig == '\0') return NULL; /* don't use strsep here, it is not available everywhere */ next = strchr(orig, '\n'); if (next) *next++ = '\0'; *stringp = next; return orig; } /* A list of all modules we processed */ LIST_HEAD(modules); static struct module *find_module(const char *modname) { struct module *mod; list_for_each_entry(mod, &modules, list) { if (strcmp(mod->name, modname) == 0) return mod; } return NULL; } static struct module *new_module(const char *modname) { struct module *mod; mod = NOFAIL(malloc(sizeof(*mod) + strlen(modname) + 1)); memset(mod, 0, sizeof(*mod)); INIT_LIST_HEAD(&mod->unresolved_symbols); strcpy(mod->name, modname); mod->is_vmlinux = (strcmp(modname, "vmlinux") == 0); /* * Set mod->is_gpl_compatible to true by default. If MODULE_LICENSE() * is missing, do not check the use for EXPORT_SYMBOL_GPL() becasue * modpost will exit wiht error anyway. */ mod->is_gpl_compatible = true; list_add_tail(&mod->list, &modules); return mod; } /* A hash of all exported symbols, * struct symbol is also used for lists of unresolved symbols */ #define SYMBOL_HASH_SIZE 1024 struct symbol { struct symbol *next; struct list_head list; /* link to module::unresolved_symbols */ struct module *module; char *namespace; unsigned int crc; bool crc_valid; bool weak; bool is_static; /* true if symbol is not global */ enum export export; /* Type of export */ char name[]; }; static struct symbol *symbolhash[SYMBOL_HASH_SIZE]; /* This is based on the hash algorithm from gdbm, via tdb */ static inline unsigned int tdb_hash(const char *name) { unsigned value; /* Used to compute the hash value. */ unsigned i; /* Used to cycle through random values. */ /* Set the initial value from the key size. */ for (value = 0x238F13AF * strlen(name), i = 0; name[i]; i++) value = (value + (((unsigned char *)name)[i] << (i*5 % 24))); return (1103515243 * value + 12345); } /** * Allocate a new symbols for use in the hash of exported symbols or * the list of unresolved symbols per module **/ static struct symbol *alloc_symbol(const char *name, struct symbol *next) { struct symbol *s = NOFAIL(malloc(sizeof(*s) + strlen(name) + 1)); memset(s, 0, sizeof(*s)); strcpy(s->name, name); s->next = next; s->is_static = true; return s; } /* For the hash of exported symbols */ static struct symbol *new_symbol(const char *name, struct module *module, enum export export) { unsigned int hash; hash = tdb_hash(name) % SYMBOL_HASH_SIZE; symbolhash[hash] = alloc_symbol(name, symbolhash[hash]); return symbolhash[hash]; } static void sym_add_unresolved(const char *name, struct module *mod, bool weak) { struct symbol *sym; sym = alloc_symbol(name, NULL); sym->weak = weak; list_add_tail(&sym->list, &mod->unresolved_symbols); } static struct symbol *find_symbol(const char *name) { struct symbol *s; /* For our purposes, .foo matches foo. PPC64 needs this. */ if (name[0] == '.') name++; for (s = symbolhash[tdb_hash(name) % SYMBOL_HASH_SIZE]; s; s = s->next) { if (strcmp(s->name, name) == 0) return s; } return NULL; } struct namespace_list { struct namespace_list *next; char namespace[]; }; static bool contains_namespace(struct namespace_list *list, const char *namespace) { for (; list; list = list->next) if (!strcmp(list->namespace, namespace)) return true; return false; } static void add_namespace(struct namespace_list **list, const char *namespace) { struct namespace_list *ns_entry; if (!contains_namespace(*list, namespace)) { ns_entry = NOFAIL(malloc(sizeof(struct namespace_list) + strlen(namespace) + 1)); strcpy(ns_entry->namespace, namespace); ns_entry->next = *list; *list = ns_entry; } } static bool module_imports_namespace(struct module *module, const char *namespace) { return contains_namespace(module->imported_namespaces, namespace); } static const struct { const char *str; enum export export; } export_list[] = { { .str = "EXPORT_SYMBOL", .export = export_plain }, { .str = "EXPORT_SYMBOL_GPL", .export = export_gpl }, { .str = "(unknown)", .export = export_unknown }, }; static const char *export_str(enum export ex) { return export_list[ex].str; } static enum export export_no(const char *s) { int i; if (!s) return export_unknown; for (i = 0; export_list[i].export != export_unknown; i++) { if (strcmp(export_list[i].str, s) == 0) return export_list[i].export; } return export_unknown; } static void *sym_get_data_by_offset(const struct elf_info *info, unsigned int secindex, unsigned long offset) { Elf_Shdr *sechdr = &info->sechdrs[secindex]; if (info->hdr->e_type != ET_REL) offset -= sechdr->sh_addr; return (void *)info->hdr + sechdr->sh_offset + offset; } static void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym) { return sym_get_data_by_offset(info, get_secindex(info, sym), sym->st_value); } static const char *sech_name(const struct elf_info *info, Elf_Shdr *sechdr) { return sym_get_data_by_offset(info, info->secindex_strings, sechdr->sh_name); } static const char *sec_name(const struct elf_info *info, int secindex) { return sech_name(info, &info->sechdrs[secindex]); } #define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0) static enum export export_from_secname(struct elf_info *elf, unsigned int sec) { const char *secname = sec_name(elf, sec); if (strstarts(secname, "___ksymtab+")) return export_plain; else if (strstarts(secname, "___ksymtab_gpl+")) return export_gpl; else return export_unknown; } static void sym_update_namespace(const char *symname, const char *namespace) { struct symbol *s = find_symbol(symname); /* * That symbol should have been created earlier and thus this is * actually an assertion. */ if (!s) { error("Could not update namespace(%s) for symbol %s\n", namespace, symname); return; } free(s->namespace); s->namespace = namespace[0] ? NOFAIL(strdup(namespace)) : NULL; } static struct symbol *sym_add_exported(const char *name, struct module *mod, enum export export) { struct symbol *s = find_symbol(name); if (!s) { s = new_symbol(name, mod, export); } else if (!external_module || s->module->is_vmlinux || s->module == mod) { warn("%s: '%s' exported twice. Previous export was in %s%s\n", mod->name, name, s->module->name, s->module->is_vmlinux ? "" : ".ko"); return s; } s->module = mod; s->export = export; return s; } static void sym_set_crc(const char *name, unsigned int crc) { struct symbol *s = find_symbol(name); /* * Ignore stand-alone __crc_*, which might be auto-generated symbols * such as __*_veneer in ARM ELF. */ if (!s) return; s->crc = crc; s->crc_valid = true; } static void *grab_file(const char *filename, size_t *size) { struct stat st; void *map = MAP_FAILED; int fd; fd = open(filename, O_RDONLY); if (fd < 0) return NULL; if (fstat(fd, &st)) goto failed; *size = st.st_size; map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); failed: close(fd); if (map == MAP_FAILED) return NULL; return map; } static void release_file(void *file, size_t size) { munmap(file, size); } static int parse_elf(struct elf_info *info, const char *filename) { unsigned int i; Elf_Ehdr *hdr; Elf_Shdr *sechdrs; Elf_Sym *sym; const char *secstrings; unsigned int symtab_idx = ~0U, symtab_shndx_idx = ~0U; hdr = grab_file(filename, &info->size); if (!hdr) { if (ignore_missing_files) { fprintf(stderr, "%s: %s (ignored)\n", filename, strerror(errno)); return 0; } perror(filename); exit(1); } info->hdr = hdr; if (info->size < sizeof(*hdr)) { /* file too small, assume this is an empty .o file */ return 0; } /* Is this a valid ELF file? */ if ((hdr->e_ident[EI_MAG0] != ELFMAG0) || (hdr->e_ident[EI_MAG1] != ELFMAG1) || (hdr->e_ident[EI_MAG2] != ELFMAG2) || (hdr->e_ident[EI_MAG3] != ELFMAG3)) { /* Not an ELF file - silently ignore it */ return 0; } /* Fix endianness in ELF header */ hdr->e_type = TO_NATIVE(hdr->e_type); hdr->e_machine = TO_NATIVE(hdr->e_machine); hdr->e_version = TO_NATIVE(hdr->e_version); hdr->e_entry = TO_NATIVE(hdr->e_entry); hdr->e_phoff = TO_NATIVE(hdr->e_phoff); hdr->e_shoff = TO_NATIVE(hdr->e_shoff); hdr->e_flags = TO_NATIVE(hdr->e_flags); hdr->e_ehsize = TO_NATIVE(hdr->e_ehsize); hdr->e_phentsize = TO_NATIVE(hdr->e_phentsize); hdr->e_phnum = TO_NATIVE(hdr->e_phnum); hdr->e_shentsize = TO_NATIVE(hdr->e_shentsize); hdr->e_shnum = TO_NATIVE(hdr->e_shnum); hdr->e_shstrndx = TO_NATIVE(hdr->e_shstrndx); sechdrs = (void *)hdr + hdr->e_shoff; info->sechdrs = sechdrs; /* Check if file offset is correct */ if (hdr->e_shoff > info->size) { fatal("section header offset=%lu in file '%s' is bigger than filesize=%zu\n", (unsigned long)hdr->e_shoff, filename, info->size); return 0; } if (hdr->e_shnum == SHN_UNDEF) { /* * There are more than 64k sections, * read count from .sh_size. */ info->num_sections = TO_NATIVE(sechdrs[0].sh_size); } else { info->num_sections = hdr->e_shnum; } if (hdr->e_shstrndx == SHN_XINDEX) { info->secindex_strings = TO_NATIVE(sechdrs[0].sh_link); } else { info->secindex_strings = hdr->e_shstrndx; } /* Fix endianness in section headers */ for (i = 0; i < info->num_sections; i++) { sechdrs[i].sh_name = TO_NATIVE(sechdrs[i].sh_name); sechdrs[i].sh_type = TO_NATIVE(sechdrs[i].sh_type); sechdrs[i].sh_flags = TO_NATIVE(sechdrs[i].sh_flags); sechdrs[i].sh_addr = TO_NATIVE(sechdrs[i].sh_addr); sechdrs[i].sh_offset = TO_NATIVE(sechdrs[i].sh_offset); sechdrs[i].sh_size = TO_NATIVE(sechdrs[i].sh_size); sechdrs[i].sh_link = TO_NATIVE(sechdrs[i].sh_link); sechdrs[i].sh_info = TO_NATIVE(sechdrs[i].sh_info); sechdrs[i].sh_addralign = TO_NATIVE(sechdrs[i].sh_addralign); sechdrs[i].sh_entsize = TO_NATIVE(sechdrs[i].sh_entsize); } /* Find symbol table. */ secstrings = (void *)hdr + sechdrs[info->secindex_strings].sh_offset; for (i = 1; i < info->num_sections; i++) { const char *secname; int nobits = sechdrs[i].sh_type == SHT_NOBITS; if (!nobits && sechdrs[i].sh_offset > info->size) { fatal("%s is truncated. sechdrs[i].sh_offset=%lu > " "sizeof(*hrd)=%zu\n", filename, (unsigned long)sechdrs[i].sh_offset, sizeof(*hdr)); return 0; } secname = secstrings + sechdrs[i].sh_name; if (strcmp(secname, ".modinfo") == 0) { if (nobits) fatal("%s has NOBITS .modinfo\n", filename); info->modinfo = (void *)hdr + sechdrs[i].sh_offset; info->modinfo_len = sechdrs[i].sh_size; } if (sechdrs[i].sh_type == SHT_SYMTAB) { unsigned int sh_link_idx; symtab_idx = i; info->symtab_start = (void *)hdr + sechdrs[i].sh_offset; info->symtab_stop = (void *)hdr + sechdrs[i].sh_offset + sechdrs[i].sh_size; sh_link_idx = sechdrs[i].sh_link; info->strtab = (void *)hdr + sechdrs[sh_link_idx].sh_offset; } /* 32bit section no. table? ("more than 64k sections") */ if (sechdrs[i].sh_type == SHT_SYMTAB_SHNDX) { symtab_shndx_idx = i; info->symtab_shndx_start = (void *)hdr + sechdrs[i].sh_offset; info->symtab_shndx_stop = (void *)hdr + sechdrs[i].sh_offset + sechdrs[i].sh_size; } } if (!info->symtab_start) fatal("%s has no symtab?\n", filename); /* Fix endianness in symbols */ for (sym = info->symtab_start; sym < info->symtab_stop; sym++) { sym->st_shndx = TO_NATIVE(sym->st_shndx); sym->st_name = TO_NATIVE(sym->st_name); sym->st_value = TO_NATIVE(sym->st_value); sym->st_size = TO_NATIVE(sym->st_size); } if (symtab_shndx_idx != ~0U) { Elf32_Word *p; if (symtab_idx != sechdrs[symtab_shndx_idx].sh_link) fatal("%s: SYMTAB_SHNDX has bad sh_link: %u!=%u\n", filename, sechdrs[symtab_shndx_idx].sh_link, symtab_idx); /* Fix endianness */ for (p = info->symtab_shndx_start; p < info->symtab_shndx_stop; p++) *p = TO_NATIVE(*p); } return 1; } static void parse_elf_finish(struct elf_info *info) { release_file(info->hdr, info->size); } static int ignore_undef_symbol(struct elf_info *info, const char *symname) { /* ignore __this_module, it will be resolved shortly */ if (strcmp(symname, "__this_module") == 0) return 1; /* ignore global offset table */ if (strcmp(symname, "_GLOBAL_OFFSET_TABLE_") == 0) return 1; if (info->hdr->e_machine == EM_PPC) /* Special register function linked on all modules during final link of .ko */ if (strstarts(symname, "_restgpr_") || strstarts(symname, "_savegpr_") || strstarts(symname, "_rest32gpr_") || strstarts(symname, "_save32gpr_") || strstarts(symname, "_restvr_") || strstarts(symname, "_savevr_")) return 1; if (info->hdr->e_machine == EM_PPC64) /* Special register function linked on all modules during final link of .ko */ if (strstarts(symname, "_restgpr0_") || strstarts(symname, "_savegpr0_") || strstarts(symname, "_restvr_") || strstarts(symname, "_savevr_") || strcmp(symname, ".TOC.") == 0) return 1; if (info->hdr->e_machine == EM_S390) /* Expoline thunks are linked on all kernel modules during final link of .ko */ if (strstarts(symname, "__s390_indirect_jump_r")) return 1; /* Do not ignore this symbol */ return 0; } static void handle_modversion(const struct module *mod, const struct elf_info *info, const Elf_Sym *sym, const char *symname) { unsigned int crc; if (sym->st_shndx == SHN_UNDEF) { warn("EXPORT symbol \"%s\" [%s%s] version generation failed, symbol will not be versioned.\n" "Is \"%s\" prototyped in ?\n", symname, mod->name, mod->is_vmlinux ? "" : ".ko", symname); return; } if (sym->st_shndx == SHN_ABS) { crc = sym->st_value; } else { unsigned int *crcp; /* symbol points to the CRC in the ELF object */ crcp = sym_get_data(info, sym); crc = TO_NATIVE(*crcp); } sym_set_crc(symname, crc); } static void handle_symbol(struct module *mod, struct elf_info *info, const Elf_Sym *sym, const char *symname) { const char *name; switch (sym->st_shndx) { case SHN_COMMON: if (strstarts(symname, "__gnu_lto_")) { /* Should warn here, but modpost runs before the linker */ } else warn("\"%s\" [%s] is COMMON symbol\n", symname, mod->name); break; case SHN_UNDEF: /* undefined symbol */ if (ELF_ST_BIND(sym->st_info) != STB_GLOBAL && ELF_ST_BIND(sym->st_info) != STB_WEAK) break; if (ignore_undef_symbol(info, symname)) break; if (info->hdr->e_machine == EM_SPARC || info->hdr->e_machine == EM_SPARCV9) { /* Ignore register directives. */ if (ELF_ST_TYPE(sym->st_info) == STT_SPARC_REGISTER) break; if (symname[0] == '.') { char *munged = NOFAIL(strdup(symname)); munged[0] = '_'; munged[1] = toupper(munged[1]); symname = munged; } } sym_add_unresolved(symname, mod, ELF_ST_BIND(sym->st_info) == STB_WEAK); break; default: /* All exported symbols */ if (strstarts(symname, "__ksymtab_")) { enum export export; name = symname + strlen("__ksymtab_"); export = export_from_secname(info, get_secindex(info, sym)); sym_add_exported(name, mod, export); } if (strcmp(symname, "init_module") == 0) mod->has_init = true; if (strcmp(symname, "cleanup_module") == 0) mod->has_cleanup = true; break; } } /** * Parse tag=value strings from .modinfo section **/ static char *next_string(char *string, unsigned long *secsize) { /* Skip non-zero chars */ while (string[0]) { string++; if ((*secsize)-- <= 1) return NULL; } /* Skip any zero padding. */ while (!string[0]) { string++; if ((*secsize)-- <= 1) return NULL; } return string; } static char *get_next_modinfo(struct elf_info *info, const char *tag, char *prev) { char *p; unsigned int taglen = strlen(tag); char *modinfo = info->modinfo; unsigned long size = info->modinfo_len; if (prev) { size -= prev - modinfo; modinfo = next_string(prev, &size); } for (p = modinfo; p; p = next_string(p, &size)) { if (strncmp(p, tag, taglen) == 0 && p[taglen] == '=') return p + taglen + 1; } return NULL; } static char *get_modinfo(struct elf_info *info, const char *tag) { return get_next_modinfo(info, tag, NULL); } /** * Test if string s ends in string sub * return 0 if match **/ static int strrcmp(const char *s, const char *sub) { int slen, sublen; if (!s || !sub) return 1; slen = strlen(s); sublen = strlen(sub); if ((slen == 0) || (sublen == 0)) return 1; if (sublen > slen) return 1; return memcmp(s + slen - sublen, sub, sublen); } static const char *sym_name(struct elf_info *elf, Elf_Sym *sym) { if (sym) return elf->strtab + sym->st_name; else return "(unknown)"; } /* The pattern is an array of simple patterns. * "foo" will match an exact string equal to "foo" * "*foo" will match a string that ends with "foo" * "foo*" will match a string that begins with "foo" * "*foo*" will match a string that contains "foo" */ static int match(const char *sym, const char * const pat[]) { const char *p; while (*pat) { const char *endp; p = *pat++; endp = p + strlen(p) - 1; /* "*foo*" */ if (*p == '*' && *endp == '*') { char *bare = NOFAIL(strndup(p + 1, strlen(p) - 2)); char *here = strstr(sym, bare); free(bare); if (here != NULL) return 1; } /* "*foo" */ else if (*p == '*') { if (strrcmp(sym, p + 1) == 0) return 1; } /* "foo*" */ else if (*endp == '*') { if (strncmp(sym, p, strlen(p) - 1) == 0) return 1; } /* no wildcards */ else { if (strcmp(p, sym) == 0) return 1; } } /* no match */ return 0; } /* sections that we do not want to do full section mismatch check on */ static const char *const section_white_list[] = { ".comment*", ".debug*", ".cranges", /* sh64 */ ".zdebug*", /* Compressed debug sections. */ ".GCC.command.line", /* record-gcc-switches */ ".mdebug*", /* alpha, score, mips etc. */ ".pdr", /* alpha, score, mips etc. */ ".stab*", ".note*", ".got*", ".toc*", ".xt.prop", /* xtensa */ ".xt.lit", /* xtensa */ ".arcextmap*", /* arc */ ".gnu.linkonce.arcext*", /* arc : modules */ ".cmem*", /* EZchip */ ".fmt_slot*", /* EZchip */ ".gnu.lto*", ".discard.*", NULL }; /* * This is used to find sections missing the SHF_ALLOC flag. * The cause of this is often a section specified in assembler * without "ax" / "aw". */ static void check_section(const char *modname, struct elf_info *elf, Elf_Shdr *sechdr) { const char *sec = sech_name(elf, sechdr); if (sechdr->sh_type == SHT_PROGBITS && !(sechdr->sh_flags & SHF_ALLOC) && !match(sec, section_white_list)) { warn("%s (%s): unexpected non-allocatable section.\n" "Did you forget to use \"ax\"/\"aw\" in a .S file?\n" "Note that for example contains\n" "section definitions for use in .S files.\n\n", modname, sec); } } #define ALL_INIT_DATA_SECTIONS \ ".init.setup", ".init.rodata", ".meminit.rodata", \ ".init.data", ".meminit.data" #define ALL_EXIT_DATA_SECTIONS \ ".exit.data", ".memexit.data" #define ALL_INIT_TEXT_SECTIONS \ ".init.text", ".meminit.text" #define ALL_EXIT_TEXT_SECTIONS \ ".exit.text", ".memexit.text" #define ALL_PCI_INIT_SECTIONS \ ".pci_fixup_early", ".pci_fixup_header", ".pci_fixup_final", \ ".pci_fixup_enable", ".pci_fixup_resume", \ ".pci_fixup_resume_early", ".pci_fixup_suspend" #define ALL_XXXINIT_SECTIONS MEM_INIT_SECTIONS #define ALL_XXXEXIT_SECTIONS MEM_EXIT_SECTIONS #define ALL_INIT_SECTIONS INIT_SECTIONS, ALL_XXXINIT_SECTIONS #define ALL_EXIT_SECTIONS EXIT_SECTIONS, ALL_XXXEXIT_SECTIONS #define DATA_SECTIONS ".data", ".data.rel" #define TEXT_SECTIONS ".text", ".text.unlikely", ".sched.text", \ ".kprobes.text", ".cpuidle.text", ".noinstr.text" #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \ ".fixup", ".entry.text", ".exception.text", ".text.*", \ ".coldtext", ".softirqentry.text" #define INIT_SECTIONS ".init.*" #define MEM_INIT_SECTIONS ".meminit.*" #define EXIT_SECTIONS ".exit.*" #define MEM_EXIT_SECTIONS ".memexit.*" #define ALL_TEXT_SECTIONS ALL_INIT_TEXT_SECTIONS, ALL_EXIT_TEXT_SECTIONS, \ TEXT_SECTIONS, OTHER_TEXT_SECTIONS /* init data sections */ static const char *const init_data_sections[] = { ALL_INIT_DATA_SECTIONS, NULL }; /* all init sections */ static const char *const init_sections[] = { ALL_INIT_SECTIONS, NULL }; /* All init and exit sections (code + data) */ static const char *const init_exit_sections[] = {ALL_INIT_SECTIONS, ALL_EXIT_SECTIONS, NULL }; /* all text sections */ static const char *const text_sections[] = { ALL_TEXT_SECTIONS, NULL }; /* data section */ static const char *const data_sections[] = { DATA_SECTIONS, NULL }; /* symbols in .data that may refer to init/exit sections */ #define DEFAULT_SYMBOL_WHITE_LIST \ "*driver", \ "*_template", /* scsi uses *_template a lot */ \ "*_timer", /* arm uses ops structures named _timer a lot */ \ "*_sht", /* scsi also used *_sht to some extent */ \ "*_ops", \ "*_probe", \ "*_probe_one", \ "*_console" static const char *const head_sections[] = { ".head.text*", NULL }; static const char *const linker_symbols[] = { "__init_begin", "_sinittext", "_einittext", NULL }; static const char *const optim_symbols[] = { "*.constprop.*", NULL }; enum mismatch { TEXT_TO_ANY_INIT, DATA_TO_ANY_INIT, TEXT_TO_ANY_EXIT, DATA_TO_ANY_EXIT, XXXINIT_TO_SOME_INIT, XXXEXIT_TO_SOME_EXIT, ANY_INIT_TO_ANY_EXIT, ANY_EXIT_TO_ANY_INIT, EXPORT_TO_INIT_EXIT, EXTABLE_TO_NON_TEXT, }; /** * Describe how to match sections on different criteria: * * @fromsec: Array of sections to be matched. * * @bad_tosec: Relocations applied to a section in @fromsec to a section in * this array is forbidden (black-list). Can be empty. * * @good_tosec: Relocations applied to a section in @fromsec must be * targeting sections in this array (white-list). Can be empty. * * @mismatch: Type of mismatch. * * @symbol_white_list: Do not match a relocation to a symbol in this list * even if it is targeting a section in @bad_to_sec. * * @handler: Specific handler to call when a match is found. If NULL, * default_mismatch_handler() will be called. * */ struct sectioncheck { const char *fromsec[20]; const char *bad_tosec[20]; const char *good_tosec[20]; enum mismatch mismatch; const char *symbol_white_list[20]; void (*handler)(const char *modname, struct elf_info *elf, const struct sectioncheck* const mismatch, Elf_Rela *r, Elf_Sym *sym, const char *fromsec); }; static void extable_mismatch_handler(const char *modname, struct elf_info *elf, const struct sectioncheck* const mismatch, Elf_Rela *r, Elf_Sym *sym, const char *fromsec); static const struct sectioncheck sectioncheck[] = { /* Do not reference init/exit code/data from * normal code and data */ { .fromsec = { TEXT_SECTIONS, NULL }, .bad_tosec = { ALL_INIT_SECTIONS, NULL }, .mismatch = TEXT_TO_ANY_INIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, { .fromsec = { DATA_SECTIONS, NULL }, .bad_tosec = { ALL_XXXINIT_SECTIONS, NULL }, .mismatch = DATA_TO_ANY_INIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, { .fromsec = { DATA_SECTIONS, NULL }, .bad_tosec = { INIT_SECTIONS, NULL }, .mismatch = DATA_TO_ANY_INIT, .symbol_white_list = { "*_template", "*_timer", "*_sht", "*_ops", "*_probe", "*_probe_one", "*_console", NULL }, }, { .fromsec = { TEXT_SECTIONS, NULL }, .bad_tosec = { ALL_EXIT_SECTIONS, NULL }, .mismatch = TEXT_TO_ANY_EXIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, { .fromsec = { DATA_SECTIONS, NULL }, .bad_tosec = { ALL_EXIT_SECTIONS, NULL }, .mismatch = DATA_TO_ANY_EXIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, /* Do not reference init code/data from meminit code/data */ { .fromsec = { ALL_XXXINIT_SECTIONS, NULL }, .bad_tosec = { INIT_SECTIONS, NULL }, .mismatch = XXXINIT_TO_SOME_INIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, /* Do not reference exit code/data from memexit code/data */ { .fromsec = { ALL_XXXEXIT_SECTIONS, NULL }, .bad_tosec = { EXIT_SECTIONS, NULL }, .mismatch = XXXEXIT_TO_SOME_EXIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, /* Do not use exit code/data from init code */ { .fromsec = { ALL_INIT_SECTIONS, NULL }, .bad_tosec = { ALL_EXIT_SECTIONS, NULL }, .mismatch = ANY_INIT_TO_ANY_EXIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, /* Do not use init code/data from exit code */ { .fromsec = { ALL_EXIT_SECTIONS, NULL }, .bad_tosec = { ALL_INIT_SECTIONS, NULL }, .mismatch = ANY_EXIT_TO_ANY_INIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, { .fromsec = { ALL_PCI_INIT_SECTIONS, NULL }, .bad_tosec = { INIT_SECTIONS, NULL }, .mismatch = ANY_INIT_TO_ANY_EXIT, .symbol_white_list = { NULL }, }, /* Do not export init/exit functions or data */ { .fromsec = { "__ksymtab*", NULL }, .bad_tosec = { INIT_SECTIONS, EXIT_SECTIONS, NULL }, .mismatch = EXPORT_TO_INIT_EXIT, .symbol_white_list = { DEFAULT_SYMBOL_WHITE_LIST, NULL }, }, { .fromsec = { "__ex_table", NULL }, /* If you're adding any new black-listed sections in here, consider * adding a special 'printer' for them in scripts/check_extable. */ .bad_tosec = { ".altinstr_replacement", NULL }, .good_tosec = {ALL_TEXT_SECTIONS , NULL}, .mismatch = EXTABLE_TO_NON_TEXT, .handler = extable_mismatch_handler, } }; static const struct sectioncheck *section_mismatch( const char *fromsec, const char *tosec) { int i; int elems = sizeof(sectioncheck) / sizeof(struct sectioncheck); const struct sectioncheck *check = §ioncheck[0]; /* * The target section could be the SHT_NUL section when we're * handling relocations to un-resolved symbols, trying to match it * doesn't make much sense and causes build failures on parisc * architectures. */ if (*tosec == '\0') return NULL; for (i = 0; i < elems; i++) { if (match(fromsec, check->fromsec)) { if (check->bad_tosec[0] && match(tosec, check->bad_tosec)) return check; if (check->good_tosec[0] && !match(tosec, check->good_tosec)) return check; } check++; } return NULL; } /** * Whitelist to allow certain references to pass with no warning. * * Pattern 1: * If a module parameter is declared __initdata and permissions=0 * then this is legal despite the warning generated. * We cannot see value of permissions here, so just ignore * this pattern. * The pattern is identified by: * tosec = .init.data * fromsec = .data* * atsym =__param* * * Pattern 1a: * module_param_call() ops can refer to __init set function if permissions=0 * The pattern is identified by: * tosec = .init.text * fromsec = .data* * atsym = __param_ops_* * * Pattern 2: * Many drivers utilise a *driver container with references to * add, remove, probe functions etc. * the pattern is identified by: * tosec = init or exit section * fromsec = data section * atsym = *driver, *_template, *_sht, *_ops, *_probe, * *probe_one, *_console, *_timer * * Pattern 3: * Whitelist all references from .head.text to any init section * * Pattern 4: * Some symbols belong to init section but still it is ok to reference * these from non-init sections as these symbols don't have any memory * allocated for them and symbol address and value are same. So even * if init section is freed, its ok to reference those symbols. * For ex. symbols marking the init section boundaries. * This pattern is identified by * refsymname = __init_begin, _sinittext, _einittext * * Pattern 5: * GCC may optimize static inlines when fed constant arg(s) resulting * in functions like cpumask_empty() -- generating an associated symbol * cpumask_empty.constprop.3 that appears in the audit. If the const that * is passed in comes from __init, like say nmi_ipi_mask, we get a * meaningless section warning. May need to add isra symbols too... * This pattern is identified by * tosec = init section * fromsec = text section * refsymname = *.constprop.* * * Pattern 6: * Hide section mismatch warnings for ELF local symbols. The goal * is to eliminate false positive modpost warnings caused by * compiler-generated ELF local symbol names such as ".LANCHOR1". * Autogenerated symbol names bypass modpost's "Pattern 2" * whitelisting, which relies on pattern-matching against symbol * names to work. (One situation where gcc can autogenerate ELF * local symbols is when "-fsection-anchors" is used.) **/ static int secref_whitelist(const struct sectioncheck *mismatch, const char *fromsec, const char *fromsym, const char *tosec, const char *tosym) { /* Check for pattern 1 */ if (match(tosec, init_data_sections) && match(fromsec, data_sections) && strstarts(fromsym, "__param")) return 0; /* Check for pattern 1a */ if (strcmp(tosec, ".init.text") == 0 && match(fromsec, data_sections) && strstarts(fromsym, "__param_ops_")) return 0; /* Check for pattern 2 */ if (match(tosec, init_exit_sections) && match(fromsec, data_sections) && match(fromsym, mismatch->symbol_white_list)) return 0; /* Check for pattern 3 */ if (match(fromsec, head_sections) && match(tosec, init_sections)) return 0; /* Check for pattern 4 */ if (match(tosym, linker_symbols)) return 0; /* Check for pattern 5 */ if (match(fromsec, text_sections) && match(tosec, init_sections) && match(fromsym, optim_symbols)) return 0; /* Check for pattern 6 */ if (strstarts(fromsym, ".L")) return 0; return 1; } static inline int is_arm_mapping_symbol(const char *str) { return str[0] == '$' && strchr("axtd", str[1]) && (str[2] == '\0' || str[2] == '.'); } /* * If there's no name there, ignore it; likewise, ignore it if it's * one of the magic symbols emitted used by current ARM tools. * * Otherwise if find_symbols_between() returns those symbols, they'll * fail the whitelist tests and cause lots of false alarms ... fixable * only by merging __exit and __init sections into __text, bloating * the kernel (which is especially evil on embedded platforms). */ static inline int is_valid_name(struct elf_info *elf, Elf_Sym *sym) { const char *name = elf->strtab + sym->st_name; if (!name || !strlen(name)) return 0; return !is_arm_mapping_symbol(name); } /** * Find symbol based on relocation record info. * In some cases the symbol supplied is a valid symbol so * return refsym. If st_name != 0 we assume this is a valid symbol. * In other cases the symbol needs to be looked up in the symbol table * based on section and address. * **/ static Elf_Sym *find_elf_symbol(struct elf_info *elf, Elf64_Sword addr, Elf_Sym *relsym) { Elf_Sym *sym; Elf_Sym *near = NULL; Elf64_Sword distance = 20; Elf64_Sword d; unsigned int relsym_secindex; if (relsym->st_name != 0) return relsym; relsym_secindex = get_secindex(elf, relsym); for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { if (get_secindex(elf, sym) != relsym_secindex) continue; if (ELF_ST_TYPE(sym->st_info) == STT_SECTION) continue; if (!is_valid_name(elf, sym)) continue; if (sym->st_value == addr) return sym; /* Find a symbol nearby - addr are maybe negative */ d = sym->st_value - addr; if (d < 0) d = addr - sym->st_value; if (d < distance) { distance = d; near = sym; } } /* We need a close match */ if (distance < 20) return near; else return NULL; } /* * Find symbols before or equal addr and after addr - in the section sec. * If we find two symbols with equal offset prefer one with a valid name. * The ELF format may have a better way to detect what type of symbol * it is, but this works for now. **/ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr, const char *sec) { Elf_Sym *sym; Elf_Sym *near = NULL; Elf_Addr distance = ~0; for (sym = elf->symtab_start; sym < elf->symtab_stop; sym++) { const char *symsec; if (is_shndx_special(sym->st_shndx)) continue; symsec = sec_name(elf, get_secindex(elf, sym)); if (strcmp(symsec, sec) != 0) continue; if (!is_valid_name(elf, sym)) continue; if (sym->st_value <= addr) { if ((addr - sym->st_value) < distance) { distance = addr - sym->st_value; near = sym; } else if ((addr - sym->st_value) == distance) { near = sym; } } } return near; } /* * Convert a section name to the function/data attribute * .init.text => __init * .memexitconst => __memconst * etc. * * The memory of returned value has been allocated on a heap. The user of this * method should free it after usage. */ static char *sec2annotation(const char *s) { if (match(s, init_exit_sections)) { char *p = NOFAIL(malloc(20)); char *r = p; *p++ = '_'; *p++ = '_'; if (*s == '.') s++; while (*s && *s != '.') *p++ = *s++; *p = '\0'; if (*s == '.') s++; if (strstr(s, "rodata") != NULL) strcat(p, "const "); else if (strstr(s, "data") != NULL) strcat(p, "data "); else strcat(p, " "); return r; } else { return NOFAIL(strdup("")); } } static int is_function(Elf_Sym *sym) { if (sym) return ELF_ST_TYPE(sym->st_info) == STT_FUNC; else return -1; } static void print_section_list(const char * const list[20]) { const char *const *s = list; while (*s) { fprintf(stderr, "%s", *s); s++; if (*s) fprintf(stderr, ", "); } fprintf(stderr, "\n"); } static inline void get_pretty_name(int is_func, const char** name, const char** name_p) { switch (is_func) { case 0: *name = "variable"; *name_p = ""; break; case 1: *name = "function"; *name_p = "()"; break; default: *name = "(unknown reference)"; *name_p = ""; break; } } /* * Print a warning about a section mismatch. * Try to find symbols near it so user can find it. * Check whitelist before warning - it may be a false positive. */ static void report_sec_mismatch(const char *modname, const struct sectioncheck *mismatch, const char *fromsec, unsigned long long fromaddr, const char *fromsym, int from_is_func, const char *tosec, const char *tosym, int to_is_func) { const char *from, *from_p; const char *to, *to_p; char *prl_from; char *prl_to; sec_mismatch_count++; get_pretty_name(from_is_func, &from, &from_p); get_pretty_name(to_is_func, &to, &to_p); warn("%s(%s+0x%llx): Section mismatch in reference from the %s %s%s " "to the %s %s:%s%s\n", modname, fromsec, fromaddr, from, fromsym, from_p, to, tosec, tosym, to_p); switch (mismatch->mismatch) { case TEXT_TO_ANY_INIT: prl_from = sec2annotation(fromsec); prl_to = sec2annotation(tosec); fprintf(stderr, "The function %s%s() references\n" "the %s %s%s%s.\n" "This is often because %s lacks a %s\n" "annotation or the annotation of %s is wrong.\n", prl_from, fromsym, to, prl_to, tosym, to_p, fromsym, prl_to, tosym); free(prl_from); free(prl_to); break; case DATA_TO_ANY_INIT: { prl_to = sec2annotation(tosec); fprintf(stderr, "The variable %s references\n" "the %s %s%s%s\n" "If the reference is valid then annotate the\n" "variable with __init* or __refdata (see linux/init.h) " "or name the variable:\n", fromsym, to, prl_to, tosym, to_p); print_section_list(mismatch->symbol_white_list); free(prl_to); break; } case TEXT_TO_ANY_EXIT: prl_to = sec2annotation(tosec); fprintf(stderr, "The function %s() references a %s in an exit section.\n" "Often the %s %s%s has valid usage outside the exit section\n" "and the fix is to remove the %sannotation of %s.\n", fromsym, to, to, tosym, to_p, prl_to, tosym); free(prl_to); break; case DATA_TO_ANY_EXIT: { prl_to = sec2annotation(tosec); fprintf(stderr, "The variable %s references\n" "the %s %s%s%s\n" "If the reference is valid then annotate the\n" "variable with __exit* (see linux/init.h) or " "name the variable:\n", fromsym, to, prl_to, tosym, to_p); print_section_list(mismatch->symbol_white_list); free(prl_to); break; } case XXXINIT_TO_SOME_INIT: case XXXEXIT_TO_SOME_EXIT: prl_from = sec2annotation(fromsec); prl_to = sec2annotation(tosec); fprintf(stderr, "The %s %s%s%s references\n" "a %s %s%s%s.\n" "If %s is only used by %s then\n" "annotate %s with a matching annotation.\n", from, prl_from, fromsym, from_p, to, prl_to, tosym, to_p, tosym, fromsym, tosym); free(prl_from); free(prl_to); break; case ANY_INIT_TO_ANY_EXIT: prl_from = sec2annotation(fromsec); prl_to = sec2annotation(tosec); fprintf(stderr, "The %s %s%s%s references\n" "a %s %s%s%s.\n" "This is often seen when error handling " "in the init function\n" "uses functionality in the exit path.\n" "The fix is often to remove the %sannotation of\n" "%s%s so it may be used outside an exit section.\n", from, prl_from, fromsym, from_p, to, prl_to, tosym, to_p, prl_to, tosym, to_p); free(prl_from); free(prl_to); break; case ANY_EXIT_TO_ANY_INIT: prl_from = sec2annotation(fromsec); prl_to = sec2annotation(tosec); fprintf(stderr, "The %s %s%s%s references\n" "a %s %s%s%s.\n" "This is often seen when error handling " "in the exit function\n" "uses functionality in the init path.\n" "The fix is often to remove the %sannotation of\n" "%s%s so it may be used outside an init section.\n", from, prl_from, fromsym, from_p, to, prl_to, tosym, to_p, prl_to, tosym, to_p); free(prl_from); free(prl_to); break; case EXPORT_TO_INIT_EXIT: prl_to = sec2annotation(tosec); fprintf(stderr, "The symbol %s is exported and annotated %s\n" "Fix this by removing the %sannotation of %s " "or drop the export.\n", tosym, prl_to, prl_to, tosym); free(prl_to); break; case EXTABLE_TO_NON_TEXT: fatal("There's a special handler for this mismatch type, " "we should never get here."); break; } fprintf(stderr, "\n"); } static void default_mismatch_handler(const char *modname, struct elf_info *elf, const struct sectioncheck* const mismatch, Elf_Rela *r, Elf_Sym *sym, const char *fromsec) { const char *tosec; Elf_Sym *to; Elf_Sym *from; const char *tosym; const char *fromsym; from = find_elf_symbol2(elf, r->r_offset, fromsec); fromsym = sym_name(elf, from); if (strstarts(fromsym, "reference___initcall")) return; tosec = sec_name(elf, get_secindex(elf, sym)); to = find_elf_symbol(elf, r->r_addend, sym); tosym = sym_name(elf, to); /* check whitelist - we may ignore it */ if (secref_whitelist(mismatch, fromsec, fromsym, tosec, tosym)) { report_sec_mismatch(modname, mismatch, fromsec, r->r_offset, fromsym, is_function(from), tosec, tosym, is_function(to)); } } static int is_executable_section(struct elf_info* elf, unsigned int section_index) { if (section_index > elf->num_sections) fatal("section_index is outside elf->num_sections!\n"); return ((elf->sechdrs[section_index].sh_flags & SHF_EXECINSTR) == SHF_EXECINSTR); } /* * We rely on a gross hack in section_rel[a]() calling find_extable_entry_size() * to know the sizeof(struct exception_table_entry) for the target architecture. */ static unsigned int extable_entry_size = 0; static void find_extable_entry_size(const char* const sec, const Elf_Rela* r) { /* * If we're currently checking the second relocation within __ex_table, * that relocation offset tells us the offsetof(struct * exception_table_entry, fixup) which is equal to sizeof(struct * exception_table_entry) divided by two. We use that to our advantage * since there's no portable way to get that size as every architecture * seems to go with different sized types. Not pretty but better than * hard-coding the size for every architecture.. */ if (!extable_entry_size) extable_entry_size = r->r_offset * 2; } static inline bool is_extable_fault_address(Elf_Rela *r) { /* * extable_entry_size is only discovered after we've handled the * _second_ relocation in __ex_table, so only abort when we're not * handling the first reloc and extable_entry_size is zero. */ if (r->r_offset && extable_entry_size == 0) fatal("extable_entry size hasn't been discovered!\n"); return ((r->r_offset == 0) || (r->r_offset % extable_entry_size == 0)); } #define is_second_extable_reloc(Start, Cur, Sec) \ (((Cur) == (Start) + 1) && (strcmp("__ex_table", (Sec)) == 0)) static void report_extable_warnings(const char* modname, struct elf_info* elf, const struct sectioncheck* const mismatch, Elf_Rela* r, Elf_Sym* sym, const char* fromsec, const char* tosec) { Elf_Sym* fromsym = find_elf_symbol2(elf, r->r_offset, fromsec); const char* fromsym_name = sym_name(elf, fromsym); Elf_Sym* tosym = find_elf_symbol(elf, r->r_addend, sym); const char* tosym_name = sym_name(elf, tosym); const char* from_pretty_name; const char* from_pretty_name_p; const char* to_pretty_name; const char* to_pretty_name_p; get_pretty_name(is_function(fromsym), &from_pretty_name, &from_pretty_name_p); get_pretty_name(is_function(tosym), &to_pretty_name, &to_pretty_name_p); warn("%s(%s+0x%lx): Section mismatch in reference" " from the %s %s%s to the %s %s:%s%s\n", modname, fromsec, (long)r->r_offset, from_pretty_name, fromsym_name, from_pretty_name_p, to_pretty_name, tosec, tosym_name, to_pretty_name_p); if (!match(tosec, mismatch->bad_tosec) && is_executable_section(elf, get_secindex(elf, sym))) fprintf(stderr, "The relocation at %s+0x%lx references\n" "section \"%s\" which is not in the list of\n" "authorized sections. If you're adding a new section\n" "and/or if this reference is valid, add \"%s\" to the\n" "list of authorized sections to jump to on fault.\n" "This can be achieved by adding \"%s\" to \n" "OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.\n", fromsec, (long)r->r_offset, tosec, tosec, tosec); } static void extable_mismatch_handler(const char* modname, struct elf_info *elf, const struct sectioncheck* const mismatch, Elf_Rela* r, Elf_Sym* sym, const char *fromsec) { const char* tosec = sec_name(elf, get_secindex(elf, sym)); sec_mismatch_count++; report_extable_warnings(modname, elf, mismatch, r, sym, fromsec, tosec); if (match(tosec, mismatch->bad_tosec)) fatal("The relocation at %s+0x%lx references\n" "section \"%s\" which is black-listed.\n" "Something is seriously wrong and should be fixed.\n" "You might get more information about where this is\n" "coming from by using scripts/check_extable.sh %s\n", fromsec, (long)r->r_offset, tosec, modname); else if (!is_executable_section(elf, get_secindex(elf, sym))) { if (is_extable_fault_address(r)) fatal("The relocation at %s+0x%lx references\n" "section \"%s\" which is not executable, IOW\n" "it is not possible for the kernel to fault\n" "at that address. Something is seriously wrong\n" "and should be fixed.\n", fromsec, (long)r->r_offset, tosec); else fatal("The relocation at %s+0x%lx references\n" "section \"%s\" which is not executable, IOW\n" "the kernel will fault if it ever tries to\n" "jump to it. Something is seriously wrong\n" "and should be fixed.\n", fromsec, (long)r->r_offset, tosec); } } static void check_section_mismatch(const char *modname, struct elf_info *elf, Elf_Rela *r, Elf_Sym *sym, const char *fromsec) { const char *tosec = sec_name(elf, get_secindex(elf, sym)); const struct sectioncheck *mismatch = section_mismatch(fromsec, tosec); if (mismatch) { if (mismatch->handler) mismatch->handler(modname, elf, mismatch, r, sym, fromsec); else default_mismatch_handler(modname, elf, mismatch, r, sym, fromsec); } } static unsigned int *reloc_location(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) { return sym_get_data_by_offset(elf, sechdr->sh_info, r->r_offset); } static int addend_386_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) { unsigned int r_typ = ELF_R_TYPE(r->r_info); unsigned int *location = reloc_location(elf, sechdr, r); switch (r_typ) { case R_386_32: r->r_addend = TO_NATIVE(*location); break; case R_386_PC32: r->r_addend = TO_NATIVE(*location) + 4; /* For CONFIG_RELOCATABLE=y */ if (elf->hdr->e_type == ET_EXEC) r->r_addend += r->r_offset; break; } return 0; } #ifndef R_ARM_CALL #define R_ARM_CALL 28 #endif #ifndef R_ARM_JUMP24 #define R_ARM_JUMP24 29 #endif #ifndef R_ARM_THM_CALL #define R_ARM_THM_CALL 10 #endif #ifndef R_ARM_THM_JUMP24 #define R_ARM_THM_JUMP24 30 #endif #ifndef R_ARM_THM_JUMP19 #define R_ARM_THM_JUMP19 51 #endif static int addend_arm_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) { unsigned int r_typ = ELF_R_TYPE(r->r_info); switch (r_typ) { case R_ARM_ABS32: /* From ARM ABI: (S + A) | T */ r->r_addend = (int)(long) (elf->symtab_start + ELF_R_SYM(r->r_info)); break; case R_ARM_PC24: case R_ARM_CALL: case R_ARM_JUMP24: case R_ARM_THM_CALL: case R_ARM_THM_JUMP24: case R_ARM_THM_JUMP19: /* From ARM ABI: ((S + A) | T) - P */ r->r_addend = (int)(long)(elf->hdr + sechdr->sh_offset + (r->r_offset - sechdr->sh_addr)); break; default: return 1; } return 0; } static int addend_mips_rel(struct elf_info *elf, Elf_Shdr *sechdr, Elf_Rela *r) { unsigned int r_typ = ELF_R_TYPE(r->r_info); unsigned int *location = reloc_location(elf, sechdr, r); unsigned int inst; if (r_typ == R_MIPS_HI16) return 1; /* skip this */ inst = TO_NATIVE(*location); switch (r_typ) { case R_MIPS_LO16: r->r_addend = inst & 0xffff; break; case R_MIPS_26: r->r_addend = (inst & 0x03ffffff) << 2; break; case R_MIPS_32: r->r_addend = inst; break; } return 0; } #ifndef EM_RISCV #define EM_RISCV 243 #endif #ifndef R_RISCV_SUB32 #define R_RISCV_SUB32 39 #endif static void section_rela(const char *modname, struct elf_info *elf, Elf_Shdr *sechdr) { Elf_Sym *sym; Elf_Rela *rela; Elf_Rela r; unsigned int r_sym; const char *fromsec; Elf_Rela *start = (void *)elf->hdr + sechdr->sh_offset; Elf_Rela *stop = (void *)start + sechdr->sh_size; fromsec = sech_name(elf, sechdr); fromsec += strlen(".rela"); /* if from section (name) is know good then skip it */ if (match(fromsec, section_white_list)) return; for (rela = start; rela < stop; rela++) { r.r_offset = TO_NATIVE(rela->r_offset); #if KERNEL_ELFCLASS == ELFCLASS64 if (elf->hdr->e_machine == EM_MIPS) { unsigned int r_typ; r_sym = ELF64_MIPS_R_SYM(rela->r_info); r_sym = TO_NATIVE(r_sym); r_typ = ELF64_MIPS_R_TYPE(rela->r_info); r.r_info = ELF64_R_INFO(r_sym, r_typ); } else { r.r_info = TO_NATIVE(rela->r_info); r_sym = ELF_R_SYM(r.r_info); } #else r.r_info = TO_NATIVE(rela->r_info); r_sym = ELF_R_SYM(r.r_info); #endif r.r_addend = TO_NATIVE(rela->r_addend); switch (elf->hdr->e_machine) { case EM_RISCV: if (!strcmp("__ex_table", fromsec) && ELF_R_TYPE(r.r_info) == R_RISCV_SUB32) continue; break; } sym = elf->symtab_start + r_sym; /* Skip special sections */ if (is_shndx_special(sym->st_shndx)) continue; if (is_second_extable_reloc(start, rela, fromsec)) find_extable_entry_size(fromsec, &r); check_section_mismatch(modname, elf, &r, sym, fromsec); } } static void section_rel(const char *modname, struct elf_info *elf, Elf_Shdr *sechdr) { Elf_Sym *sym; Elf_Rel *rel; Elf_Rela r; unsigned int r_sym; const char *fromsec; Elf_Rel *start = (void *)elf->hdr + sechdr->sh_offset; Elf_Rel *stop = (void *)start + sechdr->sh_size; fromsec = sech_name(elf, sechdr); fromsec += strlen(".rel"); /* if from section (name) is know good then skip it */ if (match(fromsec, section_white_list)) return; for (rel = start; rel < stop; rel++) { r.r_offset = TO_NATIVE(rel->r_offset); #if KERNEL_ELFCLASS == ELFCLASS64 if (elf->hdr->e_machine == EM_MIPS) { unsigned int r_typ; r_sym = ELF64_MIPS_R_SYM(rel->r_info); r_sym = TO_NATIVE(r_sym); r_typ = ELF64_MIPS_R_TYPE(rel->r_info); r.r_info = ELF64_R_INFO(r_sym, r_typ); } else { r.r_info = TO_NATIVE(rel->r_info); r_sym = ELF_R_SYM(r.r_info); } #else r.r_info = TO_NATIVE(rel->r_info); r_sym = ELF_R_SYM(r.r_info); #endif r.r_addend = 0; switch (elf->hdr->e_machine) { case EM_386: if (addend_386_rel(elf, sechdr, &r)) continue; break; case EM_ARM: if (addend_arm_rel(elf, sechdr, &r)) continue; break; case EM_MIPS: if (addend_mips_rel(elf, sechdr, &r)) continue; break; } sym = elf->symtab_start + r_sym; /* Skip special sections */ if (is_shndx_special(sym->st_shndx)) continue; if (is_second_extable_reloc(start, rel, fromsec)) find_extable_entry_size(fromsec, &r); check_section_mismatch(modname, elf, &r, sym, fromsec); } } /** * A module includes a number of sections that are discarded * either when loaded or when used as built-in. * For loaded modules all functions marked __init and all data * marked __initdata will be discarded when the module has been initialized. * Likewise for modules used built-in the sections marked __exit * are discarded because __exit marked function are supposed to be called * only when a module is unloaded which never happens for built-in modules. * The check_sec_ref() function traverses all relocation records * to find all references to a section that reference a section that will * be discarded and warns about it. **/ static void check_sec_ref(struct module *mod, const char *modname, struct elf_info *elf) { int i; Elf_Shdr *sechdrs = elf->sechdrs; /* Walk through all sections */ for (i = 0; i < elf->num_sections; i++) { check_section(modname, elf, &elf->sechdrs[i]); /* We want to process only relocation sections and not .init */ if (sechdrs[i].sh_type == SHT_RELA) section_rela(modname, elf, &elf->sechdrs[i]); else if (sechdrs[i].sh_type == SHT_REL) section_rel(modname, elf, &elf->sechdrs[i]); } } static char *remove_dot(char *s) { size_t n = strcspn(s, "."); if (n && s[n]) { size_t m = strspn(s + n + 1, "0123456789"); if (m && (s[n + m] == '.' || s[n + m] == 0)) s[n] = 0; /* strip trailing .prelink */ if (strends(s, ".prelink")) s[strlen(s) - 8] = '\0'; } return s; } static void read_symbols(const char *modname) { const char *symname; char *version; char *license; char *namespace; struct module *mod; struct elf_info info = { }; Elf_Sym *sym; if (!parse_elf(&info, modname)) return; { char *tmp; /* strip trailing .o */ tmp = NOFAIL(strdup(modname)); tmp[strlen(tmp) - 2] = '\0'; /* strip trailing .prelink */ if (strends(tmp, ".prelink")) tmp[strlen(tmp) - 8] = '\0'; mod = new_module(tmp); free(tmp); } if (!mod->is_vmlinux) { license = get_modinfo(&info, "license"); if (!license) error("missing MODULE_LICENSE() in %s\n", modname); while (license) { if (!license_is_gpl_compatible(license)) { mod->is_gpl_compatible = false; break; } license = get_next_modinfo(&info, "license", license); } namespace = get_modinfo(&info, "import_ns"); while (namespace) { add_namespace(&mod->imported_namespaces, namespace); namespace = get_next_modinfo(&info, "import_ns", namespace); } } for (sym = info.symtab_start; sym < info.symtab_stop; sym++) { symname = remove_dot(info.strtab + sym->st_name); handle_symbol(mod, &info, sym, symname); handle_moddevtable(mod, &info, sym, symname); } for (sym = info.symtab_start; sym < info.symtab_stop; sym++) { symname = remove_dot(info.strtab + sym->st_name); /* Apply symbol namespaces from __kstrtabns_ entries. */ if (strstarts(symname, "__kstrtabns_")) sym_update_namespace(symname + strlen("__kstrtabns_"), sym_get_data(&info, sym)); if (strstarts(symname, "__crc_")) handle_modversion(mod, &info, sym, symname + strlen("__crc_")); } // check for static EXPORT_SYMBOL_* functions && global vars for (sym = info.symtab_start; sym < info.symtab_stop; sym++) { unsigned char bind = ELF_ST_BIND(sym->st_info); if (bind == STB_GLOBAL || bind == STB_WEAK) { struct symbol *s = find_symbol(remove_dot(info.strtab + sym->st_name)); if (s) s->is_static = false; } } check_sec_ref(mod, modname, &info); if (!mod->is_vmlinux) { version = get_modinfo(&info, "version"); if (version || all_versions) get_src_version(mod->name, mod->srcversion, sizeof(mod->srcversion) - 1); } parse_elf_finish(&info); /* Our trick to get versioning for module struct etc. - it's * never passed as an argument to an exported function, so * the automatic versioning doesn't pick it up, but it's really * important anyhow */ if (modversions) sym_add_unresolved("module_layout", mod, false); } static void read_symbols_from_files(const char *filename) { FILE *in = stdin; char fname[PATH_MAX]; if (strcmp(filename, "-") != 0) { in = fopen(filename, "r"); if (!in) fatal("Can't open filenames file %s: %m", filename); } while (fgets(fname, PATH_MAX, in) != NULL) { if (strends(fname, "\n")) fname[strlen(fname)-1] = '\0'; read_symbols(fname); } if (in != stdin) fclose(in); } #define SZ 500 /* We first write the generated file into memory using the * following helper, then compare to the file on disk and * only update the later if anything changed */ void __attribute__((format(printf, 2, 3))) buf_printf(struct buffer *buf, const char *fmt, ...) { char tmp[SZ]; int len; va_list ap; va_start(ap, fmt); len = vsnprintf(tmp, SZ, fmt, ap); buf_write(buf, tmp, len); va_end(ap); } void buf_write(struct buffer *buf, const char *s, int len) { if (buf->size - buf->pos < len) { buf->size += len + SZ; buf->p = NOFAIL(realloc(buf->p, buf->size)); } strncpy(buf->p + buf->pos, s, len); buf->pos += len; } static void check_for_gpl_usage(enum export exp, const char *m, const char *s) { switch (exp) { case export_gpl: error("GPL-incompatible module %s.ko uses GPL-only symbol '%s'\n", m, s); break; case export_plain: case export_unknown: /* ignore */ break; } } static void check_exports(struct module *mod) { struct symbol *s, *exp; list_for_each_entry(s, &mod->unresolved_symbols, list) { const char *basename; exp = find_symbol(s->name); if (!exp) { if (!s->weak && nr_unresolved++ < MAX_UNRESOLVED_REPORTS) modpost_log(warn_unresolved ? LOG_WARN : LOG_ERROR, "\"%s\" [%s.ko] undefined!\n", s->name, mod->name); continue; } if (exp->module == mod) { error("\"%s\" [%s.ko] was exported without definition\n", s->name, mod->name); continue; } s->module = exp->module; s->crc_valid = exp->crc_valid; s->crc = exp->crc; basename = strrchr(mod->name, '/'); if (basename) basename++; else basename = mod->name; if (exp->namespace && !module_imports_namespace(mod, exp->namespace)) { modpost_log(allow_missing_ns_imports ? LOG_WARN : LOG_ERROR, "module %s uses symbol %s from namespace %s, but does not import it.\n", basename, exp->name, exp->namespace); add_namespace(&mod->missing_namespaces, exp->namespace); } if (!mod->is_gpl_compatible) check_for_gpl_usage(exp->export, basename, exp->name); } } static void check_modname_len(struct module *mod) { const char *mod_name; mod_name = strrchr(mod->name, '/'); if (mod_name == NULL) mod_name = mod->name; else mod_name++; if (strlen(mod_name) >= MODULE_NAME_LEN) error("module name is too long [%s.ko]\n", mod->name); } /** * Header for the generated file **/ static void add_header(struct buffer *b, struct module *mod) { buf_printf(b, "#include \n"); /* * Include build-salt.h after module.h in order to * inherit the definitions. */ buf_printf(b, "#define INCLUDE_VERMAGIC\n"); buf_printf(b, "#include \n"); buf_printf(b, "#include \n"); buf_printf(b, "#include \n"); buf_printf(b, "#include \n"); buf_printf(b, "\n"); buf_printf(b, "BUILD_SALT;\n"); buf_printf(b, "BUILD_LTO_INFO;\n"); buf_printf(b, "\n"); buf_printf(b, "MODULE_INFO(vermagic, VERMAGIC_STRING);\n"); buf_printf(b, "MODULE_INFO(name, KBUILD_MODNAME);\n"); buf_printf(b, "\n"); buf_printf(b, "__visible struct module __this_module\n"); buf_printf(b, "__section(\".gnu.linkonce.this_module\") = {\n"); buf_printf(b, "\t.name = KBUILD_MODNAME,\n"); if (mod->has_init) buf_printf(b, "\t.init = init_module,\n"); if (mod->has_cleanup) buf_printf(b, "#ifdef CONFIG_MODULE_UNLOAD\n" "\t.exit = cleanup_module,\n" "#endif\n"); buf_printf(b, "\t.arch = MODULE_ARCH_INIT,\n"); buf_printf(b, "};\n"); } static void add_intree_flag(struct buffer *b, int is_intree) { if (is_intree) buf_printf(b, "\nMODULE_INFO(intree, \"Y\");\n"); } /* Cannot check for assembler */ static void add_retpoline(struct buffer *b) { buf_printf(b, "\n#ifdef CONFIG_RETPOLINE\n"); buf_printf(b, "MODULE_INFO(retpoline, \"Y\");\n"); buf_printf(b, "#endif\n"); } static void add_staging_flag(struct buffer *b, const char *name) { if (strstarts(name, "drivers/staging")) buf_printf(b, "\nMODULE_INFO(staging, \"Y\");\n"); } /** * Record CRCs for unresolved symbols **/ static void add_versions(struct buffer *b, struct module *mod) { struct symbol *s; if (!modversions) return; buf_printf(b, "\n"); buf_printf(b, "static const struct modversion_info ____versions[]\n"); buf_printf(b, "__used __section(\"__versions\") = {\n"); list_for_each_entry(s, &mod->unresolved_symbols, list) { if (!s->module) continue; if (!s->crc_valid) { warn("\"%s\" [%s.ko] has no CRC!\n", s->name, mod->name); continue; } if (strlen(s->name) >= MODULE_NAME_LEN) { error("too long symbol \"%s\" [%s.ko]\n", s->name, mod->name); break; } buf_printf(b, "\t{ %#8x, \"%s\" },\n", s->crc, s->name); } buf_printf(b, "};\n"); } static void add_depends(struct buffer *b, struct module *mod) { struct symbol *s; int first = 1; /* Clear ->seen flag of modules that own symbols needed by this. */ list_for_each_entry(s, &mod->unresolved_symbols, list) { if (s->module) s->module->seen = s->module->is_vmlinux; } buf_printf(b, "\n"); buf_printf(b, "MODULE_INFO(depends, \""); list_for_each_entry(s, &mod->unresolved_symbols, list) { const char *p; if (!s->module) continue; if (s->module->seen) continue; s->module->seen = true; p = strrchr(s->module->name, '/'); if (p) p++; else p = s->module->name; buf_printf(b, "%s%s", first ? "" : ",", p); first = 0; } buf_printf(b, "\");\n"); } static void add_srcversion(struct buffer *b, struct module *mod) { if (mod->srcversion[0]) { buf_printf(b, "\n"); buf_printf(b, "MODULE_INFO(srcversion, \"%s\");\n", mod->srcversion); } } static void write_buf(struct buffer *b, const char *fname) { FILE *file; if (error_occurred) return; file = fopen(fname, "w"); if (!file) { perror(fname); exit(1); } if (fwrite(b->p, 1, b->pos, file) != b->pos) { perror(fname); exit(1); } if (fclose(file) != 0) { perror(fname); exit(1); } } static void write_if_changed(struct buffer *b, const char *fname) { char *tmp; FILE *file; struct stat st; file = fopen(fname, "r"); if (!file) goto write; if (fstat(fileno(file), &st) < 0) goto close_write; if (st.st_size != b->pos) goto close_write; tmp = NOFAIL(malloc(b->pos)); if (fread(tmp, 1, b->pos, file) != b->pos) goto free_write; if (memcmp(tmp, b->p, b->pos) != 0) goto free_write; free(tmp); fclose(file); return; free_write: free(tmp); close_write: fclose(file); write: write_buf(b, fname); } /* parse Module.symvers file. line format: * 0x12345678symbolmoduleexportnamespace **/ static void read_dump(const char *fname) { char *buf, *pos, *line; buf = read_text_file(fname); if (!buf) /* No symbol versions, silently ignore */ return; pos = buf; while ((line = get_line(&pos))) { char *symname, *namespace, *modname, *d, *export; unsigned int crc; struct module *mod; struct symbol *s; if (!(symname = strchr(line, '\t'))) goto fail; *symname++ = '\0'; if (!(modname = strchr(symname, '\t'))) goto fail; *modname++ = '\0'; if (!(export = strchr(modname, '\t'))) goto fail; *export++ = '\0'; if (!(namespace = strchr(export, '\t'))) goto fail; *namespace++ = '\0'; crc = strtoul(line, &d, 16); if (*symname == '\0' || *modname == '\0' || *d != '\0') goto fail; mod = find_module(modname); if (!mod) { mod = new_module(modname); mod->from_dump = true; } s = sym_add_exported(symname, mod, export_no(export)); s->is_static = false; sym_set_crc(symname, crc); sym_update_namespace(symname, namespace); } free(buf); return; fail: free(buf); fatal("parse error in symbol dump file\n"); } static void write_dump(const char *fname) { struct buffer buf = { }; struct symbol *symbol; const char *namespace; int n; for (n = 0; n < SYMBOL_HASH_SIZE ; n++) { symbol = symbolhash[n]; while (symbol) { if (!symbol->module->from_dump) { namespace = symbol->namespace; buf_printf(&buf, "0x%08x\t%s\t%s\t%s\t%s\n", symbol->crc, symbol->name, symbol->module->name, export_str(symbol->export), namespace ? namespace : ""); } symbol = symbol->next; } } write_buf(&buf, fname); free(buf.p); } static void write_namespace_deps_files(const char *fname) { struct module *mod; struct namespace_list *ns; struct buffer ns_deps_buf = {}; list_for_each_entry(mod, &modules, list) { if (mod->from_dump || !mod->missing_namespaces) continue; buf_printf(&ns_deps_buf, "%s.ko:", mod->name); for (ns = mod->missing_namespaces; ns; ns = ns->next) buf_printf(&ns_deps_buf, " %s", ns->namespace); buf_printf(&ns_deps_buf, "\n"); } write_if_changed(&ns_deps_buf, fname); free(ns_deps_buf.p); } struct dump_list { struct list_head list; const char *file; }; int main(int argc, char **argv) { struct module *mod; struct buffer buf = { }; char *missing_namespace_deps = NULL; char *dump_write = NULL, *files_source = NULL; int opt; int n; LIST_HEAD(dump_lists); struct dump_list *dl, *dl2; while ((opt = getopt(argc, argv, "ei:mnT:o:awENd:")) != -1) { switch (opt) { case 'e': external_module = true; break; case 'i': dl = NOFAIL(malloc(sizeof(*dl))); dl->file = optarg; list_add_tail(&dl->list, &dump_lists); break; case 'm': modversions = true; break; case 'n': ignore_missing_files = true; break; case 'o': dump_write = optarg; break; case 'a': all_versions = true; break; case 'T': files_source = optarg; break; case 'w': warn_unresolved = true; break; case 'E': sec_mismatch_warn_only = false; break; case 'N': allow_missing_ns_imports = true; break; case 'd': missing_namespace_deps = optarg; break; default: exit(1); } } list_for_each_entry_safe(dl, dl2, &dump_lists, list) { read_dump(dl->file); list_del(&dl->list); free(dl); } while (optind < argc) read_symbols(argv[optind++]); if (files_source) read_symbols_from_files(files_source); list_for_each_entry(mod, &modules, list) { char fname[PATH_MAX]; int ret; if (mod->is_vmlinux || mod->from_dump) continue; buf.pos = 0; check_modname_len(mod); check_exports(mod); add_header(&buf, mod); add_intree_flag(&buf, !external_module); add_retpoline(&buf); add_staging_flag(&buf, mod->name); add_versions(&buf, mod); add_depends(&buf, mod); add_moddevtable(&buf, mod); add_srcversion(&buf, mod); ret = snprintf(fname, sizeof(fname), "%s.mod.c", mod->name); if (ret >= sizeof(fname)) { error("%s: too long path was truncated\n", fname); continue; } write_if_changed(&buf, fname); } if (missing_namespace_deps) write_namespace_deps_files(missing_namespace_deps); if (dump_write) write_dump(dump_write); if (sec_mismatch_count && !sec_mismatch_warn_only) error("Section mismatches detected.\n" "Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.\n"); for (n = 0; n < SYMBOL_HASH_SIZE; n++) { struct symbol *s; for (s = symbolhash[n]; s; s = s->next) { if (s->is_static) error("\"%s\" [%s] is a static %s\n", s->name, s->module->name, export_str(s->export)); } } if (nr_unresolved > MAX_UNRESOLVED_REPORTS) warn("suppressed %u unresolved symbol warnings because there were too many)\n", nr_unresolved - MAX_UNRESOLVED_REPORTS); free(buf.p); return error_occurred ? 1 : 0; }