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authorMasahiro Yamada <masahiroy@kernel.org>2022-05-27 19:01:51 +0900
committerMasahiro Yamada <masahiroy@kernel.org>2022-06-01 23:07:02 +0900
commit31cb50b5590fe911077b8463ad01144fac8fa4f3 (patch)
tree25e8abcf85190d0c3c1714bfa9bc4b793cc04292 /scripts/Makefile.build
parent534671e0ef5b652d6a983bc1c85c339f7dbfe6ce (diff)
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 <linux/export.h> 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 <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nathan Chancellor <nathan@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM-14 (x86-64)
Diffstat (limited to 'scripts/Makefile.build')
-rw-r--r--scripts/Makefile.build4
1 files changed, 4 insertions, 0 deletions
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