From: Fangrui Song <maskray@google.com>
To: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Andy Lutomirski <luto@kernel.org>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-csky@vger.kernel.org" <linux-csky@vger.kernel.org>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>,
"loongarch@lists.linux.dev" <loongarch@lists.linux.dev>,
"linux-riscv@lists.infradead.org"
<linux-riscv@lists.infradead.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH] vdso: Improve cmd_vdso_check to check all dynamic relocations
Date: Mon, 14 Nov 2022 16:46:25 -0800 [thread overview]
Message-ID: <20221115004625.x4wl6zbg4iiuxl5t@google.com> (raw)
In-Reply-To: <9ce45cd2-dcd8-11f8-e496-7efe3649e241@csgroup.eu>
On 2022-11-14, Christophe Leroy wrote:
>
>
>Le 28/09/2022 à 07:25, Fangrui Song a écrit :
>> On Sat, Sep 10, 2022 at 12:53 AM Fangrui Song <maskray@google.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@google.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 ?
All ARCH_REL_TYPE_ABS relocation types can be removed. As explained, the
real intention is to check no dynamic relocation, and this is done by
the new
cmd_vdso_check = if $(READELF) -rW $@ | grep -v _NONE | grep -q "R_\w*_"; \
in this patch.
grep -v _NONE is to work around some GNU ld ports (and likely older releases
of some ports even if their latest versions are fixed) which produce
unneeded R_*_NONE dynamic relocations.
next prev parent reply other threads:[~2022-11-15 0:46 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-30 19:37 [PATCH] vdso: Improve cmd_vdso_check to check all dynamic relocations Fangrui Song
2022-09-10 7:53 ` Fangrui Song
2022-09-28 5:25 ` Fangrui Song
2022-11-14 12:31 ` Christophe Leroy
2022-11-15 0:46 ` Fangrui Song [this message]
2022-12-04 4:50 ` Fangrui Song
2022-12-04 16:58 ` Christophe Leroy
2022-12-18 18:31 ` Fangrui Song
2022-12-21 23:51 ` [PATCH v2] " Fangrui Song
2022-12-29 16:22 ` Palmer Dabbelt
2023-01-27 23:19 ` Fangrui Song
2023-03-10 14:35 ` Vincenzo Frascino
2023-03-10 19:10 ` Fangrui Song
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