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Subject: Re: [PATCH] bcache: make kobj_type structures constant
From:   Coly Li <colyli@suse.de>
In-Reply-To: <20230214152119.epkfhkojqjvokqmv@t-8ch.de>
Date:   Wed, 15 Feb 2023 00:16:03 +0800
Cc:     Kent Overstreet <kent.overstreet@gmail.com>,
        linux-bcache@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Transfer-Encoding: quoted-printable
Message-Id: <9DE71214-283C-4410-B5A4-22DFDA7021F4@suse.de>
References: <20230214-kobj_type-bcache-v1-1-cf00ead7bee7@weissschuh.net>
 <125CA8D6-D3B7-42FB-83BE-DCA688F2ACAF@suse.de>
 <20230214152119.epkfhkojqjvokqmv@t-8ch.de>
To:     =?utf-8?Q?Thomas_Wei=C3=9Fschuh?= <linux@weissschuh.net>
Precedence: bulk


> 2023=E5=B9=B42=E6=9C=8814=E6=97=A5 23:21=EF=BC=8CThomas Wei=C3=9Fschuh =
<linux@weissschuh.net> =E5=86=99=E9=81=93=EF=BC=9A
>=20
> On Tue, Feb 14, 2023 at 05:51:09PM +0800, Coly Li wrote:
>>=20
>>=20
>>> 2023=E5=B9=B42=E6=9C=8814=E6=97=A5 11:13=EF=BC=8CThomas Wei=C3=9Fschuh=
 <linux@weissschuh.net> =E5=86=99=E9=81=93=EF=BC=9A
>>>=20
>>> Since commit ee6d3dd4ed48 ("driver core: make kobj_type constant.")
>>> the driver core allows the usage of const struct kobj_type.
>>>=20
>>> Take advantage of this to constify the structure definitions to =
prevent
>>> modification at runtime.
>>>=20
>>=20
>> How the const structure definition can prevent modification at run =
time?
>=20
> It will be put into .rodata instead of .data by the compiler.
> The .rodata section is mapped as read-only via the pagetable.
>=20
> See Documentation/security/self-protection.rst
> "Function pointers and sensitive variables must not be writable".

I see. Thanks for the information.

This patch will be added into my testing queue, and submitted later.

Coly Li