linux-kernel - Re: [PATCH v8 2/4] powerpc: Refactor kexec functions to move arch independent code to ima

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Message-ID: <397f1bbf-46bf-b522-616b-2e006ef30e70@linux.microsoft.com>
Date:   Tue, 3 Nov 2020 11:23:49 -0800
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     Mimi Zohar <zohar@...ux.ibm.com>, bauerman@...ux.ibm.com,
        robh@...nel.org, gregkh@...uxfoundation.org, james.morse@....com,
        catalin.marinas@....com, sashal@...nel.org, will@...nel.org,
        mpe@...erman.id.au, benh@...nel.crashing.org, paulus@...ba.org,
        robh+dt@...nel.org, frowand.list@...il.com,
        vincenzo.frascino@....com, mark.rutland@....com,
        dmitry.kasatkin@...il.com, jmorris@...ei.org, serge@...lyn.com,
        pasha.tatashin@...een.com, allison@...utok.net,
        kstewart@...uxfoundation.org, takahiro.akashi@...aro.org,
        tglx@...utronix.de, masahiroy@...nel.org, bhsharma@...hat.com,
        mbrugger@...e.com, hsinyi@...omium.org, tao.li@...o.com,
        christophe.leroy@....fr
Cc:     linux-integrity@...r.kernel.org, linux-kernel@...r.kernel.org,
        devicetree@...r.kernel.org, prsriva@...ux.microsoft.com,
        balajib@...ux.microsoft.com
Subject: Re: [PATCH v8 2/4] powerpc: Refactor kexec functions to move arch
 independent code to ima

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

Hi Mimi,

> 
> On Fri, 2020-10-30 at 10:44 -0700, Lakshmi Ramasubramanian wrote:
>> The functions ima_get_kexec_buffer() and ima_free_kexec_buffer(),
>> 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.
>>
>> Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to IMA
>> subsystem. A later patch in this series will use these functions for
>> carrying forward the IMA measurement log for ARM64.
>>
>> With the above refactoring arch/powerpc/kexec/ima.c contains only
>> functions used when CONFIG_IMA_KEXEC is enabled. Update Makefile
>> in arch/powerpc/kexec to include arch/powerpc/kexec/ima.c only
>> when CONFIG_IMA_KEXEC is enabled.
>>
>> Co-developed-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
>> Signed-off-by: Prakhar Srivastava <prsriva@...ux.microsoft.com>
>> Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
> 
> Similar comments to 1/4.
> -  Last line of first paragraph can be rephrased like " ... on kexec,
> do not contain architecture specific code, but are currently limited to
> powerpc."
Sure.

> -  This patch should be limited to moving existing functions.
> Truncate the Subject line to "Move arch independent IMA kexec functions
> to ima_kexec.c."
Will do.

> - Don't refer to a later patch, but explain the purpose here.  For
> example, "Move ... , making them accessible to other archs."
Sure.

> - The definition of "FDT_PROP_IMA_KEXEC_BUFFER" should be made as a
> separate, prepartory patch, prior to the existing 1/4.  The resulting
> code being moved in this patch (and similarly for 1/4) will be exactly
> the same as the code being deleted.

Definition of FDT_PROP_IMA_KEXEC_BUFFER will be made as a preparatory 
patch as you'd mentioned in the comments for [PATCH 1/4].

Will split [PATCH 2/4] as listed below:

PATCH #1: Move ima_get_kexec_buffer() and ima_free_kexec_buffer() to 
IMA, along with deleting them in arch/powerpc/kexec/ima.c

PATCH #2: Update arch/powerpc/kexec/Makefile and
           arch/powerpc/kexec/ima.c
           to compile when CONFIG_IMA_KEXEC is defined.

thanks,
  -lakshmi