Re: [PATCH v8 1/4] powerpc: Refactor kexec functions to move arch independent code to drivers/of

From: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
	bauerman@linux.ibm.com, robh@kernel.org,
	gregkh@linuxfoundation.org, james.morse@arm.com,
	catalin.marinas@arm.com, sashal@kernel.org, will@kernel.org,
	mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
	robh+dt@kernel.org, frowand.list@gmail.com,
	vincenzo.frascino@arm.com, mark.rutland@arm.com,
	dmitry.kasatkin@gmail.com, jmorris@namei.org, serge@hallyn.com,
	pasha.tatashin@soleen.com, allison@lohutok.net,
	kstewart@linuxfoundation.org, takahiro.akashi@linaro.org,
	tglx@linutronix.de, masahiroy@kernel.org, bhsharma@redhat.com,
	mbrugger@suse.com, hsinyi@chromium.org, tao.li@vivo.com,
	christophe.leroy@c-s.fr
Cc: linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
	devicetree@vger.kernel.org, prsriva@linux.microsoft.com,
	balajib@linux.microsoft.com
Subject: Re: [PATCH v8 1/4] powerpc: Refactor kexec functions to move arch independent code to drivers/of
Date: Tue, 3 Nov 2020 11:15:42 -0800	[thread overview]
Message-ID: <313e87c1-8f58-b1e0-db3e-950d2ee66927@linux.microsoft.com> (raw)
In-Reply-To: <506372c01decf59bc2ef39c92a86ba7f6f2ae81b.camel@linux.ibm.com>

On 11/3/20 6:55 AM, Mimi Zohar wrote:

Hi Mimi,

Thanks for reviewing the patches.

> On Fri, 2020-10-30 at 10:44 -0700, Lakshmi Ramasubramanian wrote:
>> The functions remove_ima_buffer() and delete_fdt_mem_rsv() that handle
>> carrying forward the IMA measurement logs on kexec for powerpc do not
>> have architecture specific code, but they are currently defined for
>> powerpc only.
> 
> ^ ... logs on kexec, do not have architecture specific code, but are
> currently limited to powerpc.
Will make this change.

> 
>>
>> remove_ima_buffer() and delete_fdt_mem_rsv() are used to remove
>> the IMA log entry from the device tree and free the memory reserved
>> for the log. These functions need to be defined even if the current
>> kernel does not support carrying forward IMA log across kexec since
>> the previous kernel could have supported that and therefore the current
>> kernel needs to free the allocation.
> 
> The first paragraph describes these function as "handle carrying
> forward the IMA measurement logs on kexec", while this paragraph says
> "are used to remove the IMA log entry".  Consider listing all of the
> functions being moved in the first paragrah, then "handle carrying
> forward" could be expanded to "carrying ... and removing".
Sure.

> 
>>
>> Rename remove_ima_buffer() to remove_ima_kexec_buffer().
>> Define remove_ima_kexec_buffer() and delete_fdt_mem_rsv() in
>> drivers/of/fdt.c. A later patch in this series will use these functions
>> to free the allocation, if any, made by the previous kernel for ARM64.
> 
> - ^Define -> Move
> - Three functions are being moved, but only two are listed.
> "do_get_kexec_buffer" is not mentioned.
> - Don't refer to a later patch, but explain the purpose here.  For
> example, "Move ... , making them accessible to other archs."
Sure.

> 
>>
>> Define FDT_PROP_IMA_KEXEC_BUFFER for the chosen node, namely
>> "linux,ima-kexec-buffer", that is added to the DTB to hold
>> the address and the size of the memory reserved to carry
>> the IMA measurement log.
> 
> The above two paragraphs describe renaming a function and defining a
> chosen node.  These two preparatory changes should be made,
> independently of each other, prior to this patch.  This patch should be
> limited to moving code, with the subject line truncated to "move arch
> independent code to drivers/of".
> 

Just to be clear -

Split this patch into 3 parts as listed below:

PATCH #1: Rename remove_ima_buffer() to remove_ima_kexec_buffer()
PATCH #2: Define the chosen node
PATCH #3: Move the functions to drivers/of/fdt.c

Sure - I'll make the above changes and update patch descriptions 
accordingly.

thanks,
  -lakshmi