linux-kernel - Re: linux-next: build failure after merge of the kspp tree

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Date:   Fri, 27 Jul 2018 13:55:22 +0100
From:   Will Deacon <will.deacon@....com>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Kees Cook <keescook@...gle.com>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Alexander Popov <alex.popov@...ux.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Laura Abbott <labbott@...hat.com>
Subject: Re: linux-next: build failure after merge of the kspp tree

On Fri, Jul 27, 2018 at 08:55:11PM +1000, Stephen Rothwell wrote:
> On Fri, 27 Jul 2018 19:06:47 +1000 Stephen Rothwell <sfr@...b.auug.org.au> wrote:
> >
> > On Fri, 27 Jul 2018 19:02:07 +1000 Stephen Rothwell <sfr@...b.auug.org.au> wrote:
> > >
> > > After merging the kspp tree, today's linux-next build (x86_64
> > > allmodconfig) failed like this:
> > > 
> > > cc1: error: plugin stackleak_plugin should be specified before -fplugin-arg-stackleak_plugin-disable in the command line
> > > 
> > > Maybe caused by commit
> > > 
> > >   a8b9eaddb9c0 ("gcc-plugins: Add STACKLEAK plugin for tracking the kernel stack")
> > > 
> > > I have used the kspp tree from next-20180726 for today.  
> > 
> > Well, that obviously didn't work since the tree hasn't changed for a
> > few days.
> > 
> > I can't see what has interacted to make this happen, so I have dropped
> > the kspp tree for today.
> 
> Actually, it may have been caused by commit
> 
>   0b3e336601b8 ("arm64: Add support for STACKLEAK gcc plugin")
> 
> from the arm64 tree.

Thanks, Stephen. I managed to reproduce this by merging for-next/kspp from
Kees's tree and for-next/core from the arm64 tree. The failure happens when
building the EFI stub, so the commit you mention above is almost certainly
the culprit.

We build the stub with the following GCC invocation:

 gcc -Wp,-MD,drivers/firmware/efi/libstub/.efi-stub-helper.o.d  -nostdinc -isystem /usr/lib/gcc/x86_64-linux-gnu/4.9/include -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -mcmodel=small -m64 -D__KERNEL__ -O2 -fPIC -fno-strict-aliasing -mno-red-zone -mno-mmx -mno-sse -fshort-wchar -DDISABLE_BRANCH_PROFILING -D__NO_FORTIFY -ffreestanding -fno-stack-protector -fplugin-arg-stackleak_plugin-disable   -fno-builtin      -DKBUILD_BASENAME='"efi_stub_helper"' -DKBUILD_MODNAME='"efi_stub_helper"' -c -o drivers/firmware/efi/libstub/.tmp_efi-stub-helper.o drivers/firmware/efi/libstub/efi-stub-helper.c

so given that we're not passing any -fplugin= option anyway (because we
override KBUILD_CFLAGS for the stub), I don't understand why we need
to the disable option at all.

Laura?

Will