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

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Message-ID: <5f2d658f63744387fe203bb215968100200b7fb6.camel@linux.ibm.com>
Date:   Tue, 03 Nov 2020 14:59:36 -0500
From:   Mimi Zohar <zohar@...ux.ibm.com>
To:     Lakshmi Ramasubramanian <nramas@...ux.microsoft.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 1/4] powerpc: Refactor kexec functions to move arch
 independent code to drivers/of

On Tue, 2020-11-03 at 11:15 -0800, Lakshmi Ramasubramanian wrote:
> 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.

Sorry, even with naming do_get_kexec_buffer(), the measurement list
isn't being carried across kexec.   Please adjust the wording.

> 
> > 
> >>
> >> 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

yes, thanks.

Mimi

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