From patchwork Wed May 11 16:45:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Masahiro Yamada X-Patchwork-Id: 12846481 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0EED7C433F5 for ; Wed, 11 May 2022 16:50:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241439AbiEKQuC (ORCPT ); Wed, 11 May 2022 12:50:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45630 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345098AbiEKQt5 (ORCPT ); Wed, 11 May 2022 12:49:57 -0400 Received: from conuserg-08.nifty.com (conuserg-08.nifty.com [210.131.2.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 82BC795DE7; Wed, 11 May 2022 09:49:48 -0700 (PDT) Received: from grover.jp (133-32-177-133.west.xps.vectant.ne.jp [133.32.177.133]) (authenticated) by conuserg-08.nifty.com with ESMTP id 24BGlWbu031975; Thu, 12 May 2022 01:47:34 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conuserg-08.nifty.com 24BGlWbu031975 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1652287654; bh=Ny/f8Cu0+NLDcW52IfYAsg1OMd0z3nWmReT0kJbf6as=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ydw5y1kY1EZVnz64D+61N55M54VgwG1CXDXGA8qPqLHArs4b/rte/pkUN6rsM4GzX 6Ukz4I9u2wvM+XtU7/MPAP+V/QJBLbwFuVog7mHxEWOR5BU1n4kJMGgvVK3/z+lsBk ZNSTpFjVUzeW9LWKsOsa/OB/PzcKKV+W9crxRerOffLPqiCbrTeXgO9HsuSYVHPV9B LHKzipTz8BYUZbW8C/64fZCkKvnUVQxAsocrbK/sK8S5Q4cLllH0wJgQ6289rX5Y/b cTZYa8oT2yje+bQFw/Oj1BhUjqZKKsDMtl6XVHy1mkvKVAmgtVOuQkIyPYc8Q+pe7T jRZUZbsXHS7cg== X-Nifty-SrcIP: [133.32.177.133] From: Masahiro Yamada To: linux-kbuild@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Nathan Chancellor , Nick Desaulniers , Nicolas Schier , Peter Zijlstra , linux-modules@vger.kernel.org, llvm@lists.linux.dev, Ard Biesheuvel , Sami Tolvanen , Masahiro Yamada Subject: [PATCH v5 01/12] modpost: split the section mismatch checks into section-check.c Date: Thu, 12 May 2022 01:45:03 +0900 Message-Id: <20220511164514.2741934-2-masahiroy@kernel.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20220511164514.2741934-1-masahiroy@kernel.org> References: <20220511164514.2741934-1-masahiroy@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: modpost.c is too big, and the half of the code is for section checks. Split it. Also, move some related typedefs and macros from modpost.h to section-check.c Copy Sam's Copyright there. Commit b39927cf4cc5 ("kbuild: check for section mismatch during modpost stage") is the initial work for the section checks. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- Changes in v5: - Fix the build error (spotted by Nathan) - Do not do codying style changes (Suggested by Nick) - Copy Sam's copyright to the new file Changes in v4: - New patch scripts/mod/Makefile | 4 +- scripts/mod/modpost.c | 1202 +--------------------------------- scripts/mod/modpost.h | 34 +- scripts/mod/section-check.c | 1222 +++++++++++++++++++++++++++++++++++ 4 files changed, 1241 insertions(+), 1221 deletions(-) create mode 100644 scripts/mod/section-check.c diff --git a/scripts/mod/Makefile b/scripts/mod/Makefile index c9e38ad937fd..6e548eb6317d 100644 --- a/scripts/mod/Makefile +++ b/scripts/mod/Makefile @@ -5,7 +5,7 @@ CFLAGS_REMOVE_empty.o += $(CC_FLAGS_LTO) hostprogs-always-y += modpost mk_elfconfig always-y += empty.o -modpost-objs := modpost.o file2alias.o sumversion.o +modpost-objs := modpost.o section-check.o file2alias.o sumversion.o devicetable-offsets-file := devicetable-offsets.h @@ -16,7 +16,7 @@ targets += $(devicetable-offsets-file) devicetable-offsets.s # dependencies on generated files need to be listed explicitly -$(obj)/modpost.o $(obj)/file2alias.o $(obj)/sumversion.o: $(obj)/elfconfig.h +$(addprefix $(obj)/, $(modpost-objs)): $(obj)/elfconfig.h $(obj)/file2alias.o: $(obj)/$(devicetable-offsets-file) quiet_cmd_elfconfig = MKELF $@ diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index a78b75f0eeb0..e7e2c70a98f5 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -31,7 +31,7 @@ static bool external_module; /* Only warn about unresolved symbols */ static bool warn_unresolved; -static int sec_mismatch_count; +int sec_mismatch_count; static bool sec_mismatch_warn_only = true; /* ignore missing files */ static bool ignore_missing_files; @@ -310,8 +310,8 @@ static void add_namespace(struct list_head *head, const char *namespace) } } -static void *sym_get_data_by_offset(const struct elf_info *info, - unsigned int secindex, unsigned long offset) +void *sym_get_data_by_offset(const struct elf_info *info, + unsigned int secindex, unsigned long offset) { Elf_Shdr *sechdr = &info->sechdrs[secindex]; @@ -327,19 +327,17 @@ static void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym) sym->st_value); } -static const char *sech_name(const struct elf_info *info, Elf_Shdr *sechdr) +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) +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 void sym_update_namespace(const char *symname, const char *namespace) { struct symbol *s = find_symbol(symname); @@ -741,1196 +739,6 @@ 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, "."); diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h index d9daeff07b83..ffa4512e992f 100644 --- a/scripts/mod/modpost.h +++ b/scripts/mod/modpost.h @@ -52,28 +52,6 @@ #define ELF_R_TYPE ELF64_R_TYPE #endif -/* The 64-bit MIPS ELF ABI uses an unusual reloc format. */ -typedef struct -{ - Elf32_Word r_sym; /* Symbol index */ - unsigned char r_ssym; /* Special symbol for 2nd relocation */ - unsigned char r_type3; /* 3rd relocation type */ - unsigned char r_type2; /* 2nd relocation type */ - unsigned char r_type1; /* 1st relocation type */ -} _Elf64_Mips_R_Info; - -typedef union -{ - Elf64_Xword r_info_number; - _Elf64_Mips_R_Info r_info_fields; -} _Elf64_Mips_R_Info_union; - -#define ELF64_MIPS_R_SYM(i) \ - ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_sym) - -#define ELF64_MIPS_R_TYPE(i) \ - ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_type1) - #if KERNEL_ELFDATA != HOST_ELFDATA static inline void __endian(const void *src, void *dest, unsigned int size) @@ -96,6 +74,7 @@ static inline void __endian(const void *src, void *dest, unsigned int size) #endif +#define strstarts(str, prefix) (strncmp(str, prefix, strlen(prefix)) == 0) #define NOFAIL(ptr) do_nofail((ptr), #ptr) void *do_nofail(void *ptr, const char *expr); @@ -173,6 +152,10 @@ static inline unsigned int get_secindex(const struct elf_info *info, return info->symtab_shndx_start[sym - info->symtab_start]; } +/* section-check.c */ +void check_sec_ref(struct module *mod, const char *modname, + struct elf_info *elf); + /* file2alias.c */ void handle_moddevtable(struct module *mod, struct elf_info *info, Elf_Sym *sym, const char *symname); @@ -182,6 +165,13 @@ void add_moddevtable(struct buffer *buf, struct module *mod); void get_src_version(const char *modname, char sum[], unsigned sumlen); /* from modpost.c */ +extern int sec_mismatch_count; + +void *sym_get_data_by_offset(const struct elf_info *info, + unsigned int secindex, unsigned long offset); +const char *sech_name(const struct elf_info *info, Elf_Shdr *sechdr); +const char *sec_name(const struct elf_info *info, int secindex); + char *read_text_file(const char *filename); char *get_line(char **stringp); diff --git a/scripts/mod/section-check.c b/scripts/mod/section-check.c new file mode 100644 index 000000000000..c7467fe9af74 --- /dev/null +++ b/scripts/mod/section-check.c @@ -0,0 +1,1222 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2006-2008 Sam Ravnborg + */ + +#include +#include +#include + +#include "modpost.h" + +/* The 64-bit MIPS ELF ABI uses an unusual reloc format. */ +typedef struct +{ + Elf32_Word r_sym; /* Symbol index */ + unsigned char r_ssym; /* Special symbol for 2nd relocation */ + unsigned char r_type3; /* 3rd relocation type */ + unsigned char r_type2; /* 2nd relocation type */ + unsigned char r_type1; /* 1st relocation type */ +} _Elf64_Mips_R_Info; + +typedef union +{ + Elf64_Xword r_info_number; + _Elf64_Mips_R_Info r_info_fields; +} _Elf64_Mips_R_Info_union; + +#define ELF64_MIPS_R_SYM(i) \ + ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_sym) + +#define ELF64_MIPS_R_TYPE(i) \ + ((__extension__ (_Elf64_Mips_R_Info_union)(i)).r_info_fields.r_type1) + +/** + * 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. + **/ +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]); + } +}