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From:   Thiago Jung Bauermann <bauerman@linux.ibm.com>
To:     Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Cc:     Mimi Zohar <zohar@linux.ibm.com>, 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
Subject: Re: [PATCH] of: error: 'const struct kimage' has no member named
 'arch'
In-reply-to: <3ca0aa87-ca83-8024-4067-c2382a360db9@linux.microsoft.com>
Date:   Fri, 19 Feb 2021 11:08:55 -0300
Message-ID: <87eehcxi88.fsf@manicouagan.localdomain>
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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.

-- 
Thiago Jung Bauermann
IBM Linux Technology Center