Messages in this thread | | | Date | Tue, 7 Jun 2022 15:22:21 +0100 | Subject | Re: [PATCH v6 06/10] kbuild: check static EXPORT_SYMBOL* by script instead of modpost | From | Jon Hunter <> |
| |
On 13/05/2022 12:39, 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. > > Revert 15bfc2348d54. > > Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> > Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> > Tested-by: Nathan Chancellor <nathan@kernel.org>
One some older build machines this is causing some builds (ARM/ARM64) to fail ...
/dvs/git/dirty/git-master_l4t-upstream/kernel/scripts/check-local-export: line 54: wait: pid 48433 is not a child of this shell /dvs/git/dirty/git-master_l4t-upstream/kernel/scripts/Makefile.build:250: recipe for target 'scripts/mod/empty.o' failed make[2]: *** [scripts/mod/empty.o] Error 127 make[2]: *** Deleting file 'scripts/mod/empty.o' make[2]: *** Waiting for unfinished jobs.... /dvs/git/dirty/git-master_l4t-upstream/kernel/Makefile:1285: recipe for target 'prepare0' failed make[1]: *** [prepare0] Error 2 make[1]: Leaving directory '/dvs/git/dirty/git-master_l4t-upstream/artifacts/linux/arm64-defconfig-jetson' Makefile:228: recipe for target '__sub-make' failed make: *** [__sub-make] Error 2
Any ideas?
Thanks Jon
-- nvpublic
| |