On Fri, May 13, 2022 at 08:39:26PM +0900, Masahiro Yamada wrote: > 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. > > It is true modpost gets access to the lists of all the member objects > (.vmlinux.objs and *.mod), but 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. > On parisc builds, this patch results in: Building parisc:allnoconfig ... failed -------------- Error log: scripts/check-local-export: sh /opt/buildbot/slave/next-next/build/arch/parisc/nm failed Guenter