linux-kernel - Re: [PATCH] vdso: Improve cmd_vdso_check to check all dynamic relocations

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Message-ID: <9ce45cd2-dcd8-11f8-e496-7efe3649e241@csgroup.eu>
Date:   Mon, 14 Nov 2022 12:31:41 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Fangrui Song <maskray@...gle.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...nel.org>
CC:     "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-csky@...r.kernel.org" <linux-csky@...r.kernel.org>,
        "linux-mips@...r.kernel.org" <linux-mips@...r.kernel.org>,
        "loongarch@...ts.linux.dev" <loongarch@...ts.linux.dev>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH] vdso: Improve cmd_vdso_check to check all dynamic
 relocations



Le 28/09/2022 à 07:25, Fangrui Song a écrit :
> On Sat, Sep 10, 2022 at 12:53 AM Fangrui Song <maskray@...gle.com> wrote:
>>
>> On 2022-08-30, Fangrui Song wrote:
>>> The actual intention is that no dynamic relocation exists. However, some
>>> GNU ld ports produce unneeded R_*_NONE. (If a port is not care enough to
>>> determine the exact .rel[a].dyn size, the trailing zeros become R_*_NONE
>>> relocations. E.g. powerpc64le ld as of 2.38 has the issue with
>>> defconfig.) R_*_NONE are generally no-op in the dynamic loaders. So just
>>> ignore them.
>>>
>>> With the change, we can remove ARCH_REL_TYPE_ABS. ARCH_REL_TYPE_ABS is a
>>> bit misnomer as ports may check RELAVETIVE/GLOB_DAT/JUMP_SLOT which are
>>> not called "absolute relocations". (The patch is motivated by the arm64
>>> port missing R_AARCH64_RELATIVE.)
>>>
>>> While here, replace "egrep" with "grep" as "egrep" is deprecated in GNU
>>> grep 3.7.
>>>
>>> Signed-off-by: Fangrui Song <maskray@...gle.com>
>>> ---
>>> [...]
>>>
>>
>> Ping.
> 
> Ping^2 :)

Can you explain which ARCH_REL_TYPE_ABS can be removed with this change ?
How is the verification done if ARCH_REL_TYPE_ABS is removed ?