On Tue, Nov 17, 2020 at 10:03:29PM +1100, Michael Ellerman wrote: > Nathan Chancellor <natechancellor@xxxxxxxxx> writes: > > Currently, '--orphan-handling=warn' is spread out across four different > > architectures in their respective Makefiles, which makes it a little > > unruly to deal with in case it needs to be disabled for a specific > > linker version (in this case, ld.lld 10.0.1). > > > > To make it easier to control this, hoist this warning into Kconfig and > > the main Makefile so that disabling it is simpler, as the warning will > > only be enabled in a couple places (main Makefile and a couple of > > compressed boot folders that blow away LDFLAGS_vmlinx) and making it > > conditional is easier due to Kconfig syntax. One small additional > > benefit of this is saving a call to ld-option on incremental builds > > because we will have already evaluated it for CONFIG_LD_ORPHAN_WARN. > > > > To keep the list of supported architectures the same, introduce > > CONFIG_ARCH_WANT_LD_ORPHAN_WARN, which an architecture can select to > > gain this automatically after all of the sections are specified and size > > asserted. A special thanks to Kees Cook for the help text on this > > config. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/1187 > > Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > --- > > Makefile | 6 ++++++ > > arch/Kconfig | 9 +++++++++ > > arch/arm/Kconfig | 1 + > > arch/arm/Makefile | 4 ---- > > arch/arm/boot/compressed/Makefile | 4 +++- > > arch/arm64/Kconfig | 1 + > > arch/arm64/Makefile | 4 ---- > > arch/powerpc/Kconfig | 1 + > > arch/powerpc/Makefile | 1 - > > Acked-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> (powerpc) > > > > arch/x86/Kconfig | 1 + > > arch/x86/Makefile | 3 --- > > arch/x86/boot/compressed/Makefile | 4 +++- > > init/Kconfig | 3 +++ > > 13 files changed, 28 insertions(+), 14 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index 008aba5f1a20..c443afd61886 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -984,6 +984,12 @@ ifeq ($(CONFIG_RELR),y) > > LDFLAGS_vmlinux += --pack-dyn-relocs=relr > > endif > > > > +# We never want expected sections to be placed heuristically by the > > +# linker. All sections should be explicitly named in the linker script. > > +ifeq ($(CONFIG_LD_ORPHAN_WARN),y) > > +LDFLAGS_vmlinux += --orphan-handling=warn > > +endif > > This is a nit, but you can use ifdef with bool CONFIG symbols in > Makefiles, which reads a bit nicer, eg: > > ifdef CONFIG_LD_ORPHAN_WARN > LDFLAGS_vmlinux += --orphan-handling=warn > endif That is indeed cleaner, I did not realize I could do that as long as the config was a boolean. I will use that in v2, which I will send along within the next few days to give Masahiro some time to comment. Cheers, Nathan
