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Subject: Re: [PATCH] of: error: 'const struct kimage' has no member named
 'arch'
To:     Thiago Jung Bauermann <bauerman@linux.ibm.com>,
        Mimi Zohar <zohar@linux.ibm.com>
Cc:     Rob Herring <robh@kernel.org>,
        "AKASHI, Takahiro" <takahiro.akashi@linaro.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Will Deacon <will@kernel.org>, Joe Perches <joe@perches.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        James Morse <james.morse@arm.com>,
        Sasha Levin <sashal@kernel.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        linux-integrity@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        devicetree@vger.kernel.org,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
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From:   Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Message-ID: <a683ac0e-5717-d419-7ae2-7cd9f2ec2ffb@linux.microsoft.com>
Date:   Fri, 19 Feb 2021 10:43:43 -0800
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On 2/19/21 10:09 AM, Thiago Jung Bauermann wrote:
> 
> Mimi Zohar <zohar@linux.ibm.com> writes:
> 
>> On Fri, 2021-02-19 at 11:43 -0600, Rob Herring wrote:
>>> On Fri, Feb 19, 2021 at 10:57 AM Lakshmi Ramasubramanian
>>> <nramas@linux.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@linux.microsoft.com> wrote:
>>>>>>
>>>>>> 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"?
>>>>>>
>>>>>> 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.
> 
> I think Rob's suggestion of just moving the elf_load_addr,
> elf_headers_sz fields (and for consistency, elf_headers as well even though it
> isn't used in tihs file) from kimage_arch to kimage.
> 
> The downside is that these fields will go unused on a number of
> architectures, but it's not worth complicating the code just because of
> it.
> 
> The patch to do that would have to go before "of: Add a common kexec FDT
> setup function". That should be enough to preserve bisectability for all arches.
> 

Agreed. I'll make this change and update.

  -lakshmi