Re: linux-next: build warning after merge of the tip tree

Kees Cook
2020-10-04T08:31:57Z

On Sun, Oct 04, 2020 at 10:24:37AM +1100, Stephen Rothwell wrote:
> Hi Kees,
>
> On Sat, 3 Oct 2020 14:54:46 -0700 Kees Cook <keescook@chromium.org> wrote:
> >
> > On Mon, Sep 14, 2020 at 01:22:49PM +1000, Stephen Rothwell wrote:
> > > Hi all,
> > >
> > > After merging the tip tree, today's linux-next build (x86_64 allmodconfig)
> > > produced this warning:
> > >
> > > x86_64-linux-gnu-ld: warning: orphan section `.ctors.65435' from `kernel/trace/trace_selftest_dynamic.o' being placed in section `.ctors.65435'
> > > [...]
> >
> > Is it only trace that is warning?
>
> Yes, it is only trace. it is always 65435 as well, in case that matters.
>
> > > gcc (Debian 10.2.0-5) 10.2.0
> > > GNU ld (GNU Binutils for Debian) 2.35
> >
> > I can't reproduce this with:
> >
> > gcc (Ubuntu 10.2.0-11ubuntu1) 10.2.0
> > GNU ld (GNU Binutils for Ubuntu) 2.35.1
> >
> > Are you running Debian testing or unstable? (I see binutils 2.35.1 is
> > in both, so was this fixed in the .1?)
> >
> > I will go build a Debian testing container...
>
> I am running testing. Just upgraded to 2.35.1 and the messages are
> still there. (I did a build of just tip/auto-latest - this is a cross
> build powerpc le hosted)

I assume CONFIG_CONSTRUCTORS is enabled for your build (it should be for
allmodconfig). Does this patch fix it? (I'm kind of blindly guessing
based on my understanding of where this could be coming from...)

diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
index e1843976754a..22f14956214a 100644
--- a/include/asm-generic/vmlinux.lds.h
+++ b/include/asm-generic/vmlinux.lds.h
@@ -701,6 +701,7 @@
#ifdef CONFIG_CONSTRUCTORS
#define KERNEL_CTORS() . = ALIGN(8); \
__ctors_start = .; \
+ KEEP(*(SORT(.ctors.*))) \
KEEP(*(.ctors)) \
KEEP(*(SORT(.init_array.*))) \
KEEP(*(.init_array)) \

--
Kees Cook