Date:   Fri, 19 Feb 2021 13:03:46 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Rob Herring <robh@...nel.org>,
        Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
Cc:     Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        "AKASHI, Takahiro" <takahiro.akashi@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Will Deacon <will@...nel.org>, Joe Perches <joe@...ches.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Michael Ellerman <mpe@...erman.id.au>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        James Morse <james.morse@....com>,
        Sasha Levin <sashal@...nel.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        linux-integrity@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        devicetree@...r.kernel.org,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [PATCH] of: error: 'const struct kimage' has no member named
 'arch'

On Fri, 2021-02-19 at 11:43 -0600, Rob Herring wrote:
> On Fri, Feb 19, 2021 at 10:57 AM Lakshmi Ramasubramanian
> <nramas@...ux.microsoft.com> wrote:
> >
> > On 2/19/21 6:16 AM, Rob Herring wrote:
> > > On Thu, Feb 18, 2021 at 8:53 PM Lakshmi Ramasubramanian
> > > <nramas@...ux.microsoft.com> wrote:
> > >>
> > >> On 2/18/21 5:13 PM, Thiago Jung Bauermann wrote:
> > >>>
> > >>> Lakshmi Ramasubramanian <nramas@...ux.microsoft.com> writes:
> > >>>
> > >>>> On 2/18/21 4:07 PM, Mimi Zohar wrote:
> > >>>>
> > >>>> Hi Mimi,
> > >>>>
> > >>>>> On Thu, 2021-02-18 at 14:33 -0800, Lakshmi Ramasubramanian wrote:
> > >>>>>> of_kexec_alloc_and_setup_fdt() defined in drivers/of/kexec.c builds
> > >>>>>> a new device tree object that includes architecture specific data
> > >>>>>> for kexec system call.  This should be defined only if the architecture
> > >>>>>> being built defines kexec architecture structure "struct kimage_arch".
> > >>>>>>
> > >>>>>> Define a new boolean config OF_KEXEC that is enabled if
> > >>>>>> CONFIG_KEXEC_FILE and CONFIG_OF_FLATTREE are enabled, and
> > >>>>>> the architecture is arm64 or powerpc64.  Build drivers/of/kexec.c
> > >>>>>> if CONFIG_OF_KEXEC is enabled.
> > >>>>>>
> > >>>>>> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
> > >>>>>> Fixes: 33488dc4d61f ("of: Add a common kexec FDT setup function")
> > >>>>>> Reported-by: kernel test robot <lkp@...el.com>
> > >>>>>> ---
> > >>>>>>     drivers/of/Kconfig  | 6 ++++++
> > >>>>>>     drivers/of/Makefile | 7 +------
> > >>>>>>     2 files changed, 7 insertions(+), 6 deletions(-)
> > >>>>>>
> > >>>>>> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
> > >>>>>> index 18450437d5d5..f2e8fa54862a 100644
> > >>>>>> --- a/drivers/of/Kconfig
> > >>>>>> +++ b/drivers/of/Kconfig
> > >>>>>> @@ -100,4 +100,10 @@ config OF_DMA_DEFAULT_COHERENT
> > >>>>>>             # arches should select this if DMA is coherent by default for OF devices
> > >>>>>>             bool
> > >>>>>>     +config OF_KEXEC
> > >>>>>> +  bool
> > >>>>>> +  depends on KEXEC_FILE
> > >>>>>> +  depends on OF_FLATTREE
> > >>>>>> +  default y if ARM64 || PPC64
> > >>>>>> +
> > >>>>>>     endif # OF
> > >>>>>> diff --git a/drivers/of/Makefile b/drivers/of/Makefile
> > >>>>>> index c13b982084a3..287579dd1695 100644
> > >>>>>> --- a/drivers/of/Makefile
> > >>>>>> +++ b/drivers/of/Makefile
> > >>>>>> @@ -13,11 +13,6 @@ obj-$(CONFIG_OF_RESERVED_MEM) += of_reserved_mem.o
> > >>>>>>     obj-$(CONFIG_OF_RESOLVE)  += resolver.o
> > >>>>>>     obj-$(CONFIG_OF_OVERLAY) += overlay.o
> > >>>>>>     obj-$(CONFIG_OF_NUMA) += of_numa.o
> > >>>>>> -
> > >>>>>> -ifdef CONFIG_KEXEC_FILE
> > >>>>>> -ifdef CONFIG_OF_FLATTREE
> > >>>>>> -obj-y     += kexec.o
> > >>>>>> -endif
> > >>>>>> -endif
> > >>>>>> +obj-$(CONFIG_OF_KEXEC) += kexec.o
> > >>>>>>       obj-$(CONFIG_OF_UNITTEST) += unittest-data/
> > >>>>> Is it possible to reuse CONFIG_HAVE_IMA_KEXEC here?
> > >>>>>
> > >>>>
> > >>>> For ppc64 CONFIG_HAVE_IMA_KEXEC is selected when CONFIG_KEXEC_FILE is enabled.
> > >>>> So I don't see a problem in reusing CONFIG_HAVE_IMA_KEXEC for ppc.
> > >>>>
> > >>>> But for arm64, CONFIG_HAVE_IMA_KEXEC is enabled in the final patch in the patch
> > >>>> set (the one for carrying forward IMA log across kexec for arm64). arm64 calls
> > >>>> of_kexec_alloc_and_setup_fdt() prior to enabling CONFIG_HAVE_IMA_KEXEC and hence
> > >>>> breaks the build for arm64.
> > >>>
> > >>> One problem is that I believe that this patch won't placate the robot,
> > >>> because IIUC it generates config files at random and this change still
> > >>> allows hppa and s390 to enable CONFIG_OF_KEXEC.
> > >>
> > >> I enabled CONFIG_OF_KEXEC for s390. With my patch applied,
> > >> CONFIG_OF_KEXEC is removed. So I think the robot enabling this config
> > >> would not be a problem.
> > >>
> > >>>
> > >>> Perhaps a new CONFIG_HAVE_KIMAGE_ARCH option? Not having that option
> > >>> would still allow building kexec.o, but would be used inside kexec.c to
> > >>> avoid accessing kimage.arch members.
> > >>>
> > >>
> > >> I think this is a good idea - a new CONFIG_HAVE_KIMAGE_ARCH, which will
> > >> be selected by arm64 and ppc for now. I tried this, and it fixes the
> > >> build issue.
> > >>
> > >> Although, the name for the new config can be misleading since PARISC,
> > >> for instance, also defines "struct kimage_arch". Perhaps,
> > >> CONFIG_HAVE_ELF_KIMAGE_ARCH since of_kexec_alloc_and_setup_fdt() is
> > >> accessing ELF specific fields in "struct kimage_arch"?
> > >>
> > >> Rob/Mimi - please let us know which approach you think is better.
> > >
> > > I'd just move the fields to kimage.
> > >
> >
> > I think Mimi's suggestion to use CONFIG_HAVE_IMA_KEXEC for building
> > drivers/of/kexec.c would work and also avoid the bisect issue if we do
> > the following:
> 
> That seems wrong given only a portion of the file depends on IMA. And
> it reduces our compile coverage.
 
I agree with you this is the wrong solution.  Lakshmi's patch
introduced a new option to prevent other arch's from including kexec.o,
which is the same functionality as CONFIG_HAVE_IMA_KEXEC.  I'm just not
sure what the right solution would be.

Mimi

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