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Subject: Re: [PATCH] of: error: 'const struct kimage' has no member named
 'arch'
From:   Mimi Zohar <zohar@linux.ibm.com>
To:     Thiago Jung Bauermann <bauerman@linux.ibm.com>,
        Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Cc:     robh@kernel.org, takahiro.akashi@linaro.org,
        gregkh@linuxfoundation.org, will@kernel.org, joe@perches.com,
        catalin.marinas@arm.com, mpe@ellerman.id.au, sfr@canb.auug.org.au,
        james.morse@arm.com, sashal@kernel.org, benh@kernel.crashing.org,
        linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org
Date:   Fri, 19 Feb 2021 09:41:46 -0500
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References: <20210218223305.2044-1-nramas@linux.microsoft.com>
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         <8b8c0b70-c7ab-33f3-b66c-9ea03388497b@linux.microsoft.com>
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On Fri, 2021-02-19 at 11:08 -0300, Thiago Jung Bauermann wrote:
> Lakshmi Ramasubramanian <nramas@linux.microsoft.com> writes:
> 
> > On 2/18/21 5:13 PM, Thiago Jung Bauermann wrote:
> >> Lakshmi Ramasubramanian <nramas@linux.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@linux.microsoft.com>
> >>>>> Fixes: 33488dc4d61f ("of: Add a common kexec FDT setup function")
> >>>>> Reported-by: kernel test robot <lkp@intel.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"?
> 
> Ah, right. I should have digged into the code before making my
> suggestion. CONFIG_HAVE_KIMAGE_ARCH isn't appropriate, indeed.
> 
> >
> > Rob/Mimi - please let us know which approach you think is better.
> 
> Ah! We can actually use the existing CONFIG_HAVE_IMA_KEXEC, no? I don't
> know why I didn't think of it before.

Including kexec.o based on CONFIG_HAVE_IMA_KEXEC is a bisect issue on
ARM64, as Lakshmi pointed out.   Defining a new, maybe temporary, flag
would solve the problem.

Mimi