linux-kernel - Re: [PATCH] kexec_file: Drop pr_err in weak implementations of arch_kexec_apply_relocations[

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1652864763.xpq371r1wx.naveen@linux.ibm.com>
Date:   Wed, 18 May 2022 14:48:30 +0530
From:   "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:     Baoquan He <bhe@...hat.com>, Michael Ellerman <mpe@...erman.id.au>
Cc:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        kexec@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH] kexec_file: Drop pr_err in weak implementations of
 arch_kexec_apply_relocations[_add]

Baoquan He wrote:
> On 05/18/22 at 12:26pm, Michael Ellerman wrote:
>> 
>> It seems that recordmcount is not really maintained anymore now that x86
>> uses objtool?
>> 
>> There've been several threads about fixing recordmcount, but none of
>> them seem to have lead to a solution.
>> 
>> These weak symbol vs recordmcount problems have been worked around going
>> back as far as 2020:
> 
> It gives me feeling that llvm or recordmcount should make adjustment,
> but not innocent kernel code, if there are a lot of places reported.
> I am curious how llvm or recordmcount dev respond to this.

As Michael stated, this is not just llvm - binutils has also adopted the 
same and "unused" section symbols are being dropped.

For recordmcount, there were a few threads and approaches that have been 
tried:
- https://patchwork.ozlabs.org/project/linuxppc-dev/patch/cd0f6bdfdf1ee096fb2c07e7b38940921b8e9118.1637764848.git.christophe.leroy@csgroup.eu/
- https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=297434&state=*

Objtool has picked up a more appropriate fix for this recently, and 
long-term, we would like to move to using objtool for ftrace purposes:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/tools/objtool/elf.c?id=4abff6d48dbcea8200c7ea35ba70c242d128ebf3

While that is being pursued, we want to unbreak some of the CI and users 
who are hitting this.


- Naveen