From b5beffa20d83c4e15306c991ffd00de0d8628338 Mon Sep 17 00:00:00 2001 From: Alexander Lobakin Date: Tue, 24 May 2022 17:27:18 +0200 Subject: modpost: fix removing numeric suffixes With the `-z unique-symbol` linker flag or any similar mechanism, it is possible to trigger the following: ERROR: modpost: "param_set_uint.0" [vmlinux] is a static EXPORT_SYMBOL The reason is that for now the condition from remove_dot(): if (m && (s[n + m] == '.' || s[n + m] == 0)) which was designed to test if it's a dot or a '\0' after the suffix is never satisfied. This is due to that `s[n + m]` always points to the last digit of a numeric suffix, not on the symbol next to it (from a custom debug print added to modpost): param_set_uint.0, s[n + m] is '0', s[n + m + 1] is '\0' So it's off-by-one and was like that since 2014. Fix this for the sake of any potential upcoming features, but don't bother stable-backporting, as it's well hidden -- apart from that LD flag, it can be triggered only with GCC LTO which never landed upstream. Fixes: fcd38ed0ff26 ("scripts: modpost: fix compilation warning") Signed-off-by: Alexander Lobakin Reviewed-by: Petr Mladek Signed-off-by: Masahiro Yamada --- scripts/mod/modpost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'scripts/mod') diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 42e949cbc255..08f6989437bd 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1906,7 +1906,7 @@ static char *remove_dot(char *s) if (n && s[n]) { size_t m = strspn(s + n + 1, "0123456789"); - if (m && (s[n + m] == '.' || s[n + m] == 0)) + if (m && (s[n + m + 1] == '.' || s[n + m + 1] == 0)) s[n] = 0; /* strip trailing .prelink */ -- cgit v1.2.3 From d6b732666a1bae0df3c3ae06925043bba34502b1 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 24 May 2022 01:46:22 +0900 Subject: modpost: fix undefined behavior of is_arm_mapping_symbol() The return value of is_arm_mapping_symbol() is unpredictable when "$" is passed in. strchr(3) says: The strchr() and strrchr() functions return a pointer to the matched character or NULL if the character is not found. The terminating null byte is considered part of the string, so that if c is specified as '\0', these functions return a pointer to the terminator. When str[1] is '\0', strchr("axtd", str[1]) is not NULL, and str[2] is referenced (i.e. buffer overrun). Test code --------- char str1[] = "abc"; char str2[] = "ab"; strcpy(str1, "$"); strcpy(str2, "$"); printf("test1: %d\n", is_arm_mapping_symbol(str1)); printf("test2: %d\n", is_arm_mapping_symbol(str2)); Result ------ test1: 0 test2: 1 Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- scripts/mod/modpost.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'scripts/mod') diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 08f6989437bd..1092906867f0 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1180,7 +1180,8 @@ static int secref_whitelist(const struct sectioncheck *mismatch, static inline int is_arm_mapping_symbol(const char *str) { - return str[0] == '$' && strchr("axtd", str[1]) + return str[0] == '$' && + (str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x') && (str[2] == '\0' || str[2] == '.'); } -- cgit v1.2.3 From 76954527fe05354add150737aa1b9a6baa4a6ee5 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 24 May 2022 01:46:23 +0900 Subject: modpost: remove the unused argument of check_sec_ref() check_sec_ref() does not use the first parameter 'mod'. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- scripts/mod/modpost.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'scripts/mod') diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 1092906867f0..2806a5c528c8 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1884,8 +1884,7 @@ static void section_rel(const char *modname, struct elf_info *elf, * 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) +static void check_sec_ref(const char *modname, struct elf_info *elf) { int i; Elf_Shdr *sechdrs = elf->sechdrs; @@ -2091,7 +2090,7 @@ static void read_symbols(const char *modname) } } - check_sec_ref(mod, modname, &info); + check_sec_ref(modname, &info); if (!mod->is_vmlinux) { version = get_modinfo(&info, "version"); -- cgit v1.2.3 From c5c468dcc25efc0095361bb63b6255622e22f695 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 24 May 2022 01:46:25 +0900 Subject: modpost: reuse ARRAY_SIZE() macro for section_mismatch() Move ARRAY_SIZE() from file2alias.c to modpost.h to reuse it in section_mismatch(). Also, move the variable 'check' inside the for-loop. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- scripts/mod/file2alias.c | 2 -- scripts/mod/modpost.c | 7 +++---- scripts/mod/modpost.h | 3 +++ 3 files changed, 6 insertions(+), 6 deletions(-) (limited to 'scripts/mod') diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c index 5258247d78ac..e8a9c6816fec 100644 --- a/scripts/mod/file2alias.c +++ b/scripts/mod/file2alias.c @@ -734,8 +734,6 @@ static int do_vio_entry(const char *filename, void *symval, return 1; } -#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) - static void do_input(char *alias, kernel_ulong_t *arr, unsigned int min, unsigned int max) { diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 2806a5c528c8..fc8ba8585d23 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1049,8 +1049,6 @@ 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 @@ -1061,14 +1059,15 @@ static const struct sectioncheck *section_mismatch( if (*tosec == '\0') return NULL; - for (i = 0; i < elems; i++) { + for (i = 0; i < ARRAY_SIZE(sectioncheck); i++) { + const struct sectioncheck *check = §ioncheck[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; } diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h index d9daeff07b83..044bdfb894b7 100644 --- a/scripts/mod/modpost.h +++ b/scripts/mod/modpost.h @@ -97,6 +97,9 @@ static inline void __endian(const void *src, void *dest, unsigned int size) #endif #define NOFAIL(ptr) do_nofail((ptr), #ptr) + +#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0])) + void *do_nofail(void *ptr, const char *expr); struct buffer { -- cgit v1.2.3 From 68fef6704e38581f7462cb7aac349978fd4ca5cc Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Tue, 24 May 2022 01:46:26 +0900 Subject: modpost: squash if...else-if in find_elf_symbol2() if ((addr - sym->st_value) < distance) { distance = addr - sym->st_value; near = sym; } else if ((addr - sym->st_value) == distance) { near = sym; } is equivalent to: if (addr - sym->st_value <= distance) { distance = addr - sym->st_value; near = sym; } (The else-if block can overwrite 'distance' with the same value). Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- scripts/mod/modpost.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) (limited to 'scripts/mod') diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index fc8ba8585d23..b70a31b4245a 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1270,13 +1270,9 @@ static Elf_Sym *find_elf_symbol2(struct elf_info *elf, Elf_Addr addr, 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; - } + if (sym->st_value <= addr && addr - sym->st_value <= distance) { + distance = addr - sym->st_value; + near = sym; } } return near; -- cgit v1.2.3 From c25e1c55822f9b3b53ccbf88b85644317a525752 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 27 May 2022 19:01:49 +0900 Subject: kbuild: do not create *.prelink.o for Clang LTO or IBT When CONFIG_LTO_CLANG=y, additional intermediate *.prelink.o is created for each module. Also, objtool is postponed until LLVM IR is converted to ELF. CONFIG_X86_KERNEL_IBT works in a similar way to postpone objtool until objects are merged together. This commit stops generating *.prelink.o, so the build flow will look similar with/without LTO. The following figures show how the LTO build currently works, and how this commit is changing it. Current build flow ================== [1] single-object module $(LD) $(CC) +objtool $(LD) foo.c --------------------> foo.o -----> foo.prelink.o -----> foo.ko (LLVM IR) (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module $(LD) $(CC) $(AR) +objtool $(LD) foo1.c -----> foo1.o -----> foo.o -----> foo.prelink.o -----> foo.ko | (archive) (ELF) | (ELF) foo2.c -----> foo2.o --/ | (LLVM IR) foo.mod.o --/ (LLVM IR) One confusion is that foo.o in multi-object module is an archive despite of its suffix. New build flow ============== [1] single-object module Since there is only one object, there is no need to keep the LLVM IR. Use $(CC)+$(LD) to generate an ELF object in one build rule. When LTO is disabled, $(LD) is unneeded because $(CC) produces an ELF object. $(CC)+$(LD)+objtool $(LD) foo.c ----------------------------> foo.o ---------> foo.ko (ELF) | (ELF) | foo.mod.o --/ (LLVM IR) [2] multi-object module Previously, $(AR) was used to combine LLVM IR files into an archive, but there was no technical reason to do so. Use $(LD) to merge them into a single ELF object. $(LD) $(CC) +objtool $(LD) foo1.c ---------> foo1.o ---------> foo.o ---------> foo.ko | (ELF) | (ELF) foo2.c ---------> foo2.o ----/ | (LLVM IR) foo.mod.o --/ (LLVM IR) Signed-off-by: Masahiro Yamada Reviewed-by: Nicolas Schier Tested-by: Nathan Chancellor Reviewed-by: Sami Tolvanen Tested-by: Sedat Dilek # LLVM-14 (x86-64) Acked-by: Josh Poimboeuf --- scripts/Kbuild.include | 4 +++ scripts/Makefile.build | 63 +++++++++++++++-------------------------------- scripts/Makefile.lib | 7 ------ scripts/Makefile.modfinal | 5 ++-- scripts/Makefile.modpost | 9 ++----- scripts/mod/modpost.c | 7 ------ 6 files changed, 28 insertions(+), 67 deletions(-) (limited to 'scripts/mod') diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include index 3514c2149e9d..455a0a6ce12d 100644 --- a/scripts/Kbuild.include +++ b/scripts/Kbuild.include @@ -15,6 +15,10 @@ pound := \# # Name of target with a '.' as filename prefix. foo/bar.o => foo/.bar.o dot-target = $(dir $@).$(notdir $@) +### +# Name of target with a '.tmp_' as filename prefix. foo/bar.o => foo/.tmp_bar.o +tmp-target = $(dir $@).tmp_$(notdir $@) + ### # The temporary file to save gcc -MMD generated dependencies must not # contain a comma diff --git a/scripts/Makefile.build b/scripts/Makefile.build index f80196eef03a..cc7061258e42 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -88,10 +88,6 @@ endif targets-for-modules := $(foreach x, o mod $(if $(CONFIG_TRIM_UNUSED_KSYMS), usyms), \ $(patsubst %.o, %.$x, $(filter %.o, $(obj-m)))) -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -targets-for-modules += $(patsubst %.o, %.prelink.o, $(filter %.o, $(obj-m))) -endif - ifdef need-modorder targets-for-modules += $(obj)/modules.order endif @@ -152,8 +148,18 @@ $(obj)/%.ll: $(src)/%.c FORCE # The C file is compiled and updated dependency information is generated. # (See cmd_cc_o_c + relevant part of rule_cc_o_c) +is-single-obj-m = $(and $(part-of-module),$(filter $@, $(obj-m)),y) + +# When a module consists of a single object, there is no reason to keep LLVM IR. +# Make $(LD) covert LLVM IR to ELF here. +ifdef CONFIG_LTO_CLANG +cmd_ld_single_m = $(if $(is-single-obj-m), ; $(LD) $(ld_flags) -r -o $(tmp-target) $@; mv $(tmp-target) $@) +endif + quiet_cmd_cc_o_c = CC $(quiet_modtag) $@ - cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< $(cmd_objtool) + cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $< \ + $(cmd_ld_single_m) \ + $(cmd_objtool) ifdef CONFIG_MODVERSIONS # When module versioning is enabled the following steps are executed: @@ -219,7 +225,7 @@ objtool_args = \ $(if $(CONFIG_STACK_VALIDATION), --stackval) \ $(if $(CONFIG_HAVE_STATIC_CALL_INLINE), --static-call) \ --uaccess \ - $(if $($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT)), --link) \ + $(if $(delay-objtool), --link) \ $(if $(part-of-module), --module) \ $(if $(CONFIG_GCOV_KERNEL), --no-unreachable) @@ -228,21 +234,15 @@ cmd_gen_objtooldep = $(if $(objtool-enabled), { echo ; echo '$@: $$(wildcard $(o endif # CONFIG_OBJTOOL -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) - -# Skip objtool for LLVM bitcode -$(obj)/%.o: objtool-enabled := - -else - # 'OBJECT_FILES_NON_STANDARD := y': skip objtool checking for a directory # 'OBJECT_FILES_NON_STANDARD_foo.o := 'y': skip objtool checking for a file # 'OBJECT_FILES_NON_STANDARD_foo.o := 'n': override directory skip for a file -$(obj)/%.o: objtool-enabled = $(if $(filter-out y%, \ - $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y) +is-standard-object = $(if $(filter-out y%, $(OBJECT_FILES_NON_STANDARD_$(basetarget).o)$(OBJECT_FILES_NON_STANDARD)n),y) -endif +delay-objtool := $(or $(CONFIG_LTO_CLANG),$(CONFIG_X86_KERNEL_IBT)) + +$(obj)/%.o: objtool-enabled = $(if $(is-standard-object),$(if $(delay-objtool),$(is-single-obj-m),y)) ifdef CONFIG_TRIM_UNUSED_KSYMS cmd_gen_ksymdeps = \ @@ -271,24 +271,6 @@ $(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE $(call if_changed_rule,cc_o_c) $(call cmd,force_checksrc) -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -# Module .o files may contain LLVM bitcode, compile them into native code -# before ELF processing -quiet_cmd_cc_prelink_modules = LD [M] $@ - cmd_cc_prelink_modules = \ - $(LD) $(ld_flags) -r -o $@ \ - --whole-archive $(filter-out FORCE,$^) \ - $(cmd_objtool) - -# objtool was skipped for LLVM bitcode, run it now that we have compiled -# modules into native code -$(obj)/%.prelink.o: objtool-enabled = y -$(obj)/%.prelink.o: part-of-module := y - -$(obj)/%.prelink.o: $(obj)/%.o FORCE - $(call if_changed,cc_prelink_modules) -endif - cmd_mod = echo $(addprefix $(obj)/, $(call real-search, $*.o, .o, -objs -y -m)) | \ $(AWK) -v RS='( |\n)' '!x[$$0]++' > $@ @@ -298,7 +280,7 @@ $(obj)/%.mod: FORCE # List module undefined symbols cmd_undefined_syms = $(NM) $< | sed -n 's/^ *U //p' > $@ -$(obj)/%.usyms: $(obj)/%$(mod-prelink-ext).o FORCE +$(obj)/%.usyms: $(obj)/%.o FORCE $(call if_changed,undefined_syms) quiet_cmd_cc_lst_c = MKLST $@ @@ -420,16 +402,11 @@ $(obj)/modules.order: $(obj-m) FORCE $(obj)/lib.a: $(lib-y) FORCE $(call if_changed,ar) -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -quiet_cmd_link_multi-m = AR [M] $@ -cmd_link_multi-m = \ - rm -f $@; \ - $(AR) cDPrsT $@ @$(patsubst %.o,%.mod,$@) -else quiet_cmd_link_multi-m = LD [M] $@ - cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) -endif + cmd_link_multi-m = $(LD) $(ld_flags) -r -o $@ @$(patsubst %.o,%.mod,$@) $(cmd_objtool) +$(multi-obj-m): objtool-enabled := $(delay-objtool) +$(multi-obj-m): part-of-module := y $(multi-obj-m): %.o: %.mod FORCE $(call if_changed,link_multi-m) $(call multi_depend, $(multi-obj-m), .o, -objs -y -m) diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib index 0453a1904646..f75138385449 100644 --- a/scripts/Makefile.lib +++ b/scripts/Makefile.lib @@ -225,13 +225,6 @@ dtc_cpp_flags = -Wp,-MMD,$(depfile).pre.tmp -nostdinc \ $(addprefix -I,$(DTC_INCLUDE)) \ -undef -D__DTS__ -ifneq ($(CONFIG_LTO_CLANG)$(CONFIG_X86_KERNEL_IBT),) -# With CONFIG_LTO_CLANG, .o files in modules might be LLVM bitcode, so we -# need to run LTO to compile them into native code (.lto.o) before further -# processing. -mod-prelink-ext := .prelink -endif - # Useful for describing the dependency of composite objects # Usage: # $(call multi_depend, multi_used_targets, suffix_to_remove, suffix_to_add) diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index 7f39599e9fae..35100e981f4a 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -9,7 +9,7 @@ __modfinal: include include/config/auto.conf include $(srctree)/scripts/Kbuild.include -# for c_flags and mod-prelink-ext +# for c_flags include $(srctree)/scripts/Makefile.lib # find all modules listed in modules.order @@ -54,9 +54,8 @@ if_changed_except = $(if $(call newer_prereqs_except,$(2))$(cmd-check), \ $(cmd); \ printf '%s\n' 'cmd_$@ := $(make-cmd)' > $(dot-target).cmd, @:) - # Re-generate module BTFs if either module's .ko or vmlinux changed -$(modules): %.ko: %$(mod-prelink-ext).o %.mod.o scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE +$(modules): %.ko: %.o %.mod.o scripts/module.lds $(if $(KBUILD_BUILTIN),vmlinux) FORCE +$(call if_changed_except,ld_ko_o,vmlinux) ifdef CONFIG_DEBUG_INFO_BTF_MODULES +$(if $(newer-prereqs),$(call cmd,btf_ko)) diff --git a/scripts/Makefile.modpost b/scripts/Makefile.modpost index 8b343480813d..911606496341 100644 --- a/scripts/Makefile.modpost +++ b/scripts/Makefile.modpost @@ -41,9 +41,6 @@ __modpost: include include/config/auto.conf include $(srctree)/scripts/Kbuild.include -# for mod-prelink-ext -include $(srctree)/scripts/Makefile.lib - MODPOST = scripts/mod/modpost \ $(if $(CONFIG_MODVERSIONS),-m) \ $(if $(CONFIG_MODULE_SRCVERSION_ALL),-a) \ @@ -117,8 +114,6 @@ $(input-symdump): @echo >&2 ' Modules may not have dependencies or modversions.' @echo >&2 ' You may get many unresolved symbol warnings.' -modules := $(sort $(shell cat $(MODORDER))) - # KBUILD_MODPOST_WARN can be set to avoid error out in case of undefined symbols ifneq ($(KBUILD_MODPOST_WARN)$(filter-out $(existing-input-symdump), $(input-symdump)),) MODPOST += -w @@ -127,9 +122,9 @@ endif # Read out modules.order to pass in modpost. # Otherwise, allmodconfig would fail with "Argument list too long". quiet_cmd_modpost = MODPOST $@ - cmd_modpost = sed 's/\.ko$$/$(mod-prelink-ext)\.o/' $< | $(MODPOST) -T - + cmd_modpost = sed 's/ko$$/o/' $< | $(MODPOST) -T - -$(output-symdump): $(MODORDER) $(input-symdump) $(modules:.ko=$(mod-prelink-ext).o) FORCE +$(output-symdump): $(MODORDER) $(input-symdump) FORCE $(call if_changed,modpost) targets += $(output-symdump) diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index b70a31b4245a..e74224a6a8e8 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1903,10 +1903,6 @@ static char *remove_dot(char *s) size_t m = strspn(s + n + 1, "0123456789"); if (m && (s[n + m + 1] == '.' || s[n + m + 1] == 0)) s[n] = 0; - - /* strip trailing .prelink */ - if (strends(s, ".prelink")) - s[strlen(s) - 8] = '\0'; } return s; } @@ -2028,9 +2024,6 @@ static void read_symbols(const char *modname) /* 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); } -- cgit v1.2.3 From 31cb50b5590fe911077b8463ad01144fac8fa4f3 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Fri, 27 May 2022 19:01:51 +0900 Subject: kbuild: check static EXPORT_SYMBOL* by script instead of modpost The 'static' specifier and EXPORT_SYMBOL() are an odd combination. Commit 15bfc2348d54 ("modpost: check for static EXPORT_SYMBOL* functions") tried to detect it, but this check has false negatives. Here is the sample code. Makefile: obj-y += foo1.o foo2.o foo1.c: #include static void foo(void) {} EXPORT_SYMBOL(foo); foo2.c: void foo(void) {} foo1.c exports the static symbol 'foo', but modpost cannot catch it because it is fooled by foo2.c, which has a global symbol with the same name. s->is_static is cleared if a global symbol with the same name is found somewhere, but EXPORT_SYMBOL() and the global symbol do not necessarily belong to the same compilation unit. This check should be done per compilation unit, but I do not know how to do it in modpost. modpost runs against vmlinux.o or modules, which merges multiple objects, then forgets their origin. modpost cannot parse individual objects because they may not be ELF but LLVM IR when CONFIG_LTO_CLANG=y. Add a simple bash script to parse the output from ${NM}. This works for CONFIG_LTO_CLANG=y because llvm-nm can dump symbols of LLVM IR files. Revert 15bfc2348d54. Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers Tested-by: Nathan Chancellor Tested-by: Sedat Dilek # LLVM-14 (x86-64) --- scripts/Makefile.build | 4 +++ scripts/check-local-export | 65 ++++++++++++++++++++++++++++++++++++++++++++++ scripts/mod/modpost.c | 28 +------------------- 3 files changed, 70 insertions(+), 27 deletions(-) create mode 100755 scripts/check-local-export (limited to 'scripts/mod') diff --git a/scripts/Makefile.build b/scripts/Makefile.build index cc7061258e42..b6ae652a943f 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -249,9 +249,12 @@ cmd_gen_ksymdeps = \ $(CONFIG_SHELL) $(srctree)/scripts/gen_ksymdeps.sh $@ >> $(dot-target).cmd endif +cmd_check_local_export = $(srctree)/scripts/check-local-export $@ + define rule_cc_o_c $(call cmd_and_fixdep,cc_o_c) $(call cmd,gen_ksymdeps) + $(call cmd,check_local_export) $(call cmd,checksrc) $(call cmd,checkdoc) $(call cmd,gen_objtooldep) @@ -262,6 +265,7 @@ endef define rule_as_o_S $(call cmd_and_fixdep,as_o_S) $(call cmd,gen_ksymdeps) + $(call cmd,check_local_export) $(call cmd,gen_objtooldep) $(call cmd,gen_symversions_S) endef diff --git a/scripts/check-local-export b/scripts/check-local-export new file mode 100755 index 000000000000..2c46912be0ef --- /dev/null +++ b/scripts/check-local-export @@ -0,0 +1,65 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0-only +# +# Copyright (C) 2022 Masahiro Yamada +# +# Exit with error if a local exported symbol is found. +# EXPORT_SYMBOL should be used for global symbols. + +set -e + +declare -A symbol_types +declare -a export_symbols + +exit_code=0 + +while read value type name +do + # Skip the line if the number of fields is less than 3. + # + # case 1) + # For undefined symbols, the first field (value) is empty. + # The outout looks like this: + # " U _printk" + # It is unneeded to record undefined symbols. + # + # case 2) + # For Clang LTO, llvm-nm outputs a line with type 't' but empty name: + # "---------------- t" + if [[ -z ${name} ]]; then + continue + fi + + # save (name, type) in the associative array + symbol_types[${name}]=${type} + + # append the exported symbol to the array + if [[ ${name} == __ksymtab_* ]]; then + export_symbols+=(${name#__ksymtab_}) + fi + + # If there is no symbol in the object, ${NM} (both GNU nm and llvm-nm) + # shows 'no symbols' diagnostic (but exits with 0). It is harmless and + # hidden by '2>/dev/null'. However, it suppresses real error messages + # as well. Add a hand-crafted error message here. + # + # Use --quiet instead of 2>/dev/null when we upgrade the minimum version + # of binutils to 2.37, llvm to 13.0.0. + # + # Then, the following line will be really simple: + # done < <(${NM} --quiet ${1}) +done < <(${NM} ${1} 2>/dev/null || { echo "${0}: ${NM} failed" >&2; false; } ) + +# Catch error in the process substitution +wait $! + +for name in "${export_symbols[@]}" +do + # nm(3) says "If lowercase, the symbol is usually local" + if [[ ${symbol_types[$name]} =~ [a-z] ]]; then + echo "$@: error: local symbol '${name}' was exported" >&2 + exit_code=1 + fi +done + +exit ${exit_code} diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index e74224a6a8e8..9269735f85c5 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -212,7 +212,6 @@ struct symbol { unsigned int crc; bool crc_valid; bool weak; - bool is_static; /* true if symbol is not global */ bool is_gpl_only; /* exported by EXPORT_SYMBOL_GPL */ char name[]; }; @@ -242,7 +241,7 @@ static struct symbol *alloc_symbol(const char *name) memset(s, 0, sizeof(*s)); strcpy(s->name, name); - s->is_static = true; + return s; } @@ -2064,20 +2063,6 @@ static void read_symbols(const char *modname) sym_get_data(&info, sym)); } - // 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(modname, &info); if (!mod->is_vmlinux) { @@ -2507,7 +2492,6 @@ static void read_dump(const char *fname) mod->from_dump = true; } s = sym_add_exported(symname, mod, gpl_only); - s->is_static = false; sym_set_crc(s, crc); sym_update_namespace(symname, namespace); } @@ -2572,7 +2556,6 @@ int main(int argc, char **argv) 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; @@ -2648,15 +2631,6 @@ int main(int argc, char **argv) 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 EXPORT_SYMBOL\n", - s->name, s->module->name); - } - } if (nr_unresolved > MAX_UNRESOLVED_REPORTS) warn("suppressed %u unresolved symbol warnings because there were too many)\n", -- cgit v1.2.3 From 8c9ce89c5b63028dd3be43807f10b009cd2c6e51 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 30 May 2022 18:01:38 +0900 Subject: modpost: simplify mod->name allocation mod->name is set to the ELF filename with the suffix ".o" stripped. The current code calls strdup() and free() to manipulate the string, but a simpler approach is to pass new_module() with the name length subtracted by 2. Also, check if the passed filename ends with ".o" before stripping it. The current code blindly chops the suffix: tmp[strlen(tmp) - 2] = '\0' It will cause buffer under-run if strlen(tmp) < 2; Signed-off-by: Masahiro Yamada Reviewed-by: Nick Desaulniers --- scripts/mod/modpost.c | 25 ++++++++++++------------- 1 file changed, 12 insertions(+), 13 deletions(-) (limited to 'scripts/mod') diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 9269735f85c5..c1558bacf717 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -172,11 +172,11 @@ static struct module *find_module(const char *modname) return NULL; } -static struct module *new_module(const char *modname) +static struct module *new_module(const char *name, size_t namelen) { struct module *mod; - mod = NOFAIL(malloc(sizeof(*mod) + strlen(modname) + 1)); + mod = NOFAIL(malloc(sizeof(*mod) + namelen + 1)); memset(mod, 0, sizeof(*mod)); INIT_LIST_HEAD(&mod->exported_symbols); @@ -184,8 +184,9 @@ static struct module *new_module(const char *modname) INIT_LIST_HEAD(&mod->missing_namespaces); INIT_LIST_HEAD(&mod->imported_namespaces); - strcpy(mod->name, modname); - mod->is_vmlinux = (strcmp(modname, "vmlinux") == 0); + memcpy(mod->name, name, namelen); + mod->name[namelen] = '\0'; + mod->is_vmlinux = (strcmp(mod->name, "vmlinux") == 0); /* * Set mod->is_gpl_compatible to true by default. If MODULE_LICENSE() @@ -2017,16 +2018,14 @@ static void read_symbols(const char *modname) if (!parse_elf(&info, modname)) return; - { - char *tmp; - - /* strip trailing .o */ - tmp = NOFAIL(strdup(modname)); - tmp[strlen(tmp) - 2] = '\0'; - mod = new_module(tmp); - free(tmp); + if (!strends(modname, ".o")) { + error("%s: filename must be suffixed with .o\n", modname); + return; } + /* strip trailing .o */ + mod = new_module(modname, strlen(modname) - strlen(".o")); + if (!mod->is_vmlinux) { license = get_modinfo(&info, "license"); if (!license) @@ -2488,7 +2487,7 @@ static void read_dump(const char *fname) mod = find_module(modname); if (!mod) { - mod = new_module(modname); + mod = new_module(modname, strlen(modname)); mod->from_dump = true; } s = sym_add_exported(symname, mod, gpl_only); -- cgit v1.2.3 From a89227d769845eb9e9ab113f9f83df34d3c91db5 Mon Sep 17 00:00:00 2001 From: Masahiro Yamada Date: Mon, 30 May 2022 18:01:39 +0900 Subject: modpost: use fnmatch() to simplify match() Replace the own implementation for wildcard (glob) matching with a function call to fnmatch(). Also, change the return type to 'bool'. Signed-off-by: Masahiro Yamada --- scripts/mod/modpost.c | 74 +++++++++------------------------------------------ 1 file changed, 13 insertions(+), 61 deletions(-) (limited to 'scripts/mod') diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index c1558bacf717..29d5a841e215 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -13,6 +13,7 @@ #define _GNU_SOURCE #include +#include #include #include #include @@ -710,29 +711,6 @@ 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) @@ -741,48 +719,22 @@ static const char *sym_name(struct elf_info *elf, Elf_Sym *sym) 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" +/* + * Check whether the 'string' argument matches one of the 'patterns', + * an array of shell wildcard patterns (glob). + * + * Return true is there is a match. */ -static int match(const char *sym, const char * const pat[]) +static bool match(const char *string, const char *const patterns[]) { - const char *p; - while (*pat) { - const char *endp; - - p = *pat++; - endp = p + strlen(p) - 1; + const char *pattern; - /* "*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; - } + while ((pattern = *patterns++)) { + if (!fnmatch(pattern, string, 0)) + return true; } - /* no match */ - return 0; + + return false; } /* sections that we do not want to do full section mismatch check on */ -- cgit v1.2.3