From: Miroslav Benes <mbenes@suse.cz>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Joe Lawrence <joe.lawrence@redhat.com>,
Jessica Yu <jeyu@kernel.org>,
x86@kernel.org, linux-kernel@vger.kernel.org,
mhiramat@kernel.org, bristot@redhat.com, jbaron@akamai.com,
torvalds@linux-foundation.org, tglx@linutronix.de,
mingo@kernel.org, namit@vmware.com, hpa@zytor.com,
luto@kernel.org, ard.biesheuvel@linaro.org,
live-patching@vger.kernel.org,
Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH v3 5/6] x86/ftrace: Use text_poke()
Date: Wed, 22 Jan 2020 11:09:56 +0100 (CET) [thread overview]
Message-ID: <alpine.LSU.2.21.2001221052331.15957@pobox.suse.cz> (raw)
In-Reply-To: <20200121161045.dhihqibnpyrk2lsu@treble>
> > > At this point, I only see downsides of -flive-patching, at least until
> > > we actually have real upstream code which needs it.
> >
> > Can you explain this? The option makes GCC to avoid optimizations which
> > are difficult to detect and would make live patching unsafe. I consider it
> > useful as it is, so if you shared the other downsides and what you meant
> > by real upstream code, we could discuss it.
>
> Only SLES needs it right? Why inflict it on other livepatch users? By
> "real upstream code" I mean there's no (documented) way to create live
> patches using the method which relies on this flag. So I don't see any
> upstream benefits for having it enabled.
I'd put it differently. SLES and upstream need it, RHEL does not need it.
Or anyone using kpatch-build. It is perfectly fine to prepare live patches
just from the source code using upstream live patching infrastructure.
After all, SLES is nothing else than upstream here. We were creating live
patches manually for quite a long time and only recently we have been
using Nicolai's klp-ccp automation (https://github.com/SUSE/klp-ccp).
So, everyone using upstream directly relies on the flag, which seems to be
a clear benefit to me. Reverting the patch would be a step back.
Also I think we're moving in the right direction to make the life of
upstream user easier with a proposal of klp-ccp and Petr's patch set to
split live patch modules. It is a path from inconvenient to comfortable
and not from impossible to possible.
Miroslav
next prev parent reply other threads:[~2020-01-22 10:10 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20191007081945.10951536.8@infradead.org>
[not found] ` <20191008104335.6fcd78c9@gandalf.local.home>
[not found] ` <20191009224135.2dcf7767@oasis.local.home>
[not found] ` <20191010092054.GR2311@hirez.programming.kicks-ass.net>
[not found] ` <20191010091956.48fbcf42@gandalf.local.home>
[not found] ` <20191010140513.GT2311@hirez.programming.kicks-ass.net>
[not found] ` <20191010115449.22044b53@gandalf.local.home>
[not found] ` <20191010172819.GS2328@hirez.programming.kicks-ass.net>
[not found] ` <20191011125903.GN2359@hirez.programming.kicks-ass.net>
[not found] ` <20191015130739.GA23565@linux-8ccs>
[not found] ` <20191015135634.GK2328@hirez.programming.kicks-ass.net>
2019-10-15 14:13 ` [PATCH v3 5/6] x86/ftrace: Use text_poke() Miroslav Benes
2019-10-15 15:06 ` Joe Lawrence
2019-10-15 15:31 ` Jessica Yu
2019-10-15 22:17 ` Joe Lawrence
2019-10-15 22:27 ` Steven Rostedt
2019-10-16 7:42 ` Peter Zijlstra
2019-10-16 10:15 ` Miroslav Benes
2019-10-21 15:05 ` Josh Poimboeuf
2020-01-20 16:50 ` Josh Poimboeuf
2020-01-21 8:35 ` Miroslav Benes
2020-01-21 16:10 ` Josh Poimboeuf
2020-01-22 10:09 ` Miroslav Benes [this message]
2020-01-22 21:42 ` Josh Poimboeuf
2020-01-28 9:28 ` Miroslav Benes
2020-01-28 15:00 ` Josh Poimboeuf
2020-01-28 15:40 ` Petr Mladek
2020-01-28 17:02 ` Josh Poimboeuf
2020-01-29 0:46 ` Jiri Kosina
2020-01-29 2:17 ` Josh Poimboeuf
2020-01-29 3:14 ` Jiri Kosina
2020-01-29 12:28 ` Miroslav Benes
2020-01-29 15:59 ` Josh Poimboeuf
2020-01-30 9:53 ` Petr Mladek
2020-01-30 14:17 ` Josh Poimboeuf
2020-01-31 7:17 ` Petr Mladek
2020-01-22 12:15 ` Miroslav Benes
2020-01-22 15:05 ` Miroslav Benes
2020-01-22 22:03 ` Josh Poimboeuf
2020-01-23 10:19 ` Martin Jambor
2019-10-16 7:49 ` Peter Zijlstra
2019-10-16 10:20 ` Miroslav Benes
2019-10-16 13:29 ` Miroslav Benes
2019-10-18 13:03 ` Jessica Yu
2019-10-18 13:40 ` Petr Mladek
2019-10-21 14:14 ` Jessica Yu
2019-10-21 15:31 ` Josh Poimboeuf
2019-10-22 8:27 ` Miroslav Benes
2019-10-22 14:31 ` Josh Poimboeuf
2019-10-23 9:04 ` Miroslav Benes
2019-10-16 6:51 ` Miroslav Benes
2019-10-16 9:23 ` Peter Zijlstra
2019-10-16 9:36 ` Jessica Yu
2019-10-16 9:51 ` Peter Zijlstra
2019-10-16 12:39 ` Peter Zijlstra
2019-10-22 8:45 ` Miroslav Benes
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=alpine.LSU.2.21.2001221052331.15957@pobox.suse.cz \
--to=mbenes@suse.cz \
--cc=ard.biesheuvel@linaro.org \
--cc=bristot@redhat.com \
--cc=hpa@zytor.com \
--cc=jbaron@akamai.com \
--cc=jeyu@kernel.org \
--cc=joe.lawrence@redhat.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=live-patching@vger.kernel.org \
--cc=luto@kernel.org \
--cc=mhiramat@kernel.org \
--cc=mingo@kernel.org \
--cc=namit@vmware.com \
--cc=peterz@infradead.org \
--cc=rdunlap@infradead.org \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).