From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, linux-kernel@vger.kernel.org,
rostedt@goodmis.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,
jeyu@kernel.org, live-patching@vger.kernel.org
Subject: Re: [PATCH v4 15/16] module: Move where we mark modules RO,X
Date: Thu, 24 Oct 2019 15:16:34 +0200 [thread overview]
Message-ID: <20191024131634.GC4131@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191023170025.f34g3vxaqr4f5gqh@treble>
On Wed, Oct 23, 2019 at 12:00:25PM -0500, Josh Poimboeuf wrote:
> > This then raises a number of questions:
> >
> > 1) why is that RELA (that obviously does not depend on any module)
> > applied so late?
>
> Good question. The 'pv_ops' symbol is exported by the core kernel, so I
> can't see any reason why we'd need to apply that rela late. In theory,
> kpatch-build isn't supposed to convert that to a klp rela. Maybe
> something went wrong in the patch creation code.
>
> I'm also questioning why we even need to apply the parainstructions
> section late. Maybe we can remove that apply_paravirt() call
> altogether, along with .klp.arch.parainstruction sections.
>
> I'll need to look into it...
Right, that really should be able to run early. Esp. after commit
11e86dc7f274 ("x86/paravirt: Detect over-sized patching bugs in paravirt_patch_call()")
paravirt patching is unconditional. We _never_ run with the indirect
call except very early boot, but modules should have them patched way
before their init section runs.
We rely on this for spectre-v2 and friends.
> > 3) Is there ever a possible module-dependent RELA to a paravirt /
> > alternative site?
>
> Good question...
> > Then for 3) we only have alternatives left, and I _think_ it unlikely to
> > be the case, but I'll have to have a hard look at that.
>
> I'm not sure about alternatives, but maybe we can enforce such
> limitations with tooling and/or kernel checks.
Right, so on IRC you implied you might have some additional details on
how alternatives were affected; did you manage to dig that up?
next prev parent reply other threads:[~2019-10-24 13:16 UTC|newest]
Thread overview: 70+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-18 7:35 [PATCH v4 00/16] Rewrite x86/ftrace to use text_poke (and more) Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 01/16] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 02/16] x86/alternatives: Update int3_emulate_push() comment Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 03/16] x86/alternatives,jump_label: Provide better text_poke() batching interface Peter Zijlstra
2019-10-21 8:48 ` Ingo Molnar
2019-10-21 9:21 ` Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 04/16] x86/alternatives: Add and use text_gen_insn() helper Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 05/16] x86/ftrace: Use text_poke() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 06/16] x86/mm: Remove set_kernel_text_r[ow]() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 07/16] x86/alternative: Add text_opcode_size() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 08/16] x86/ftrace: Use text_gen_insn() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 09/16] x86/alternative: Remove text_poke_loc::len Peter Zijlstra
2019-10-21 8:58 ` Ingo Molnar
2019-10-21 9:02 ` Ingo Molnar
2019-10-18 7:35 ` [PATCH v4 10/16] x86/alternative: Shrink text_poke_loc Peter Zijlstra
2019-10-21 9:01 ` Ingo Molnar
2019-10-21 9:25 ` Peter Zijlstra
2019-10-21 9:33 ` Ingo Molnar
2019-10-18 7:35 ` [PATCH v4 11/16] x86/kprobes: Convert to text-patching.h Peter Zijlstra
2019-10-21 14:57 ` Masami Hiramatsu
2019-10-18 7:35 ` [PATCH v4 12/16] x86/kprobes: Fix ordering Peter Zijlstra
2019-10-22 1:35 ` Masami Hiramatsu
2019-10-22 10:31 ` Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 13/16] arm/ftrace: Use __patch_text_real() Peter Zijlstra
2019-10-28 16:25 ` Will Deacon
2019-10-28 16:34 ` Peter Zijlstra
2019-10-28 16:35 ` Peter Zijlstra
2019-10-28 16:47 ` Will Deacon
2019-10-28 16:55 ` Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 14/16] module: Remove set_all_modules_text_*() Peter Zijlstra
2019-10-18 7:35 ` [PATCH v4 15/16] module: Move where we mark modules RO,X Peter Zijlstra
2019-10-21 13:53 ` Josh Poimboeuf
2019-10-21 14:14 ` Peter Zijlstra
2019-10-21 15:34 ` Peter Zijlstra
2019-10-21 15:44 ` Peter Zijlstra
2019-10-21 16:11 ` Peter Zijlstra
2019-10-22 11:31 ` Heiko Carstens
2019-10-22 12:31 ` Peter Zijlstra
2019-10-23 11:48 ` Peter Zijlstra
2019-10-23 15:16 ` Peter Zijlstra
2019-10-23 17:15 ` Josh Poimboeuf
2019-10-24 10:59 ` Peter Zijlstra
2019-10-24 18:31 ` Josh Poimboeuf
2019-10-24 20:33 ` Peter Zijlstra
2019-10-23 17:00 ` Josh Poimboeuf
2019-10-24 13:16 ` Peter Zijlstra [this message]
2019-10-25 6:44 ` Petr Mladek
2019-10-25 8:43 ` Peter Zijlstra
2019-10-25 10:06 ` Peter Zijlstra
2019-10-25 13:50 ` Josh Poimboeuf
2019-10-26 1:17 ` Josh Poimboeuf
2019-10-28 10:07 ` Peter Zijlstra
2019-10-28 10:43 ` Peter Zijlstra
2019-10-25 9:16 ` Peter Zijlstra
2019-10-22 2:21 ` Steven Rostedt
2019-10-22 20:24 ` Peter Zijlstra
2019-10-22 20:40 ` Steven Rostedt
2019-10-23 9:07 ` Peter Zijlstra
2019-10-23 18:52 ` Steven Rostedt
2019-10-24 10:16 ` Peter Zijlstra
2019-10-24 10:18 ` Peter Zijlstra
2019-10-24 15:00 ` Steven Rostedt
2019-10-24 16:43 ` Peter Zijlstra
2019-10-24 18:17 ` Steven Rostedt
2019-10-24 20:24 ` Peter Zijlstra
2019-10-24 20:28 ` Steven Rostedt
2019-10-18 7:35 ` [PATCH v4 16/16] ftrace: Merge ftrace_module_{init,enable}() Peter Zijlstra
2019-10-18 8:20 ` Peter Zijlstra
2019-10-21 9:09 ` [PATCH v4 00/16] Rewrite x86/ftrace to use text_poke (and more) Ingo Molnar
2019-10-21 13:38 ` Steven Rostedt
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=20191024131634.GC4131@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=ard.biesheuvel@linaro.org \
--cc=bristot@redhat.com \
--cc=hpa@zytor.com \
--cc=jbaron@akamai.com \
--cc=jeyu@kernel.org \
--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=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