linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, jbaron@akamai.com, rostedt@goodmis.org,
	ardb@kernel.org, linux-kernel@vger.kernel.org,
	sumit.garg@linaro.org, oliver.sang@intel.com, jarkko@kernel.org,
	jeyu@kernel.org
Subject: Re: [PATCH 3/3] static_call: Fix static_call_update() sanity check
Date: Fri, 19 Mar 2021 13:57:38 +0100	[thread overview]
Message-ID: <YFSfwimq/VLmo1Lw@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <YFOGvmWiJUDOHy7D@hirez.programming.kicks-ass.net>

On Thu, Mar 18, 2021 at 05:58:38PM +0100, Peter Zijlstra wrote:

> > For CONFIG_MODULE_UNLOAD, the code ends up in the normal text area, so
> > static_call_is_init() is false and kernel_text_address() is true.
> > 
> > For !CONFIG_MODULE_UNLOAD, the code gets discarded during module load,
> > so static_call_is_init() and kernel_text_address() are both false.  I
> > guess that will trigger a warning?
> 
> Oh gawd, more variants.
> 
> Afaict MODULE_UNLOAD, by virtue of that #ifdef in

!MODULE_UNLOAD (obv)

> rewrite_section_headers() won't even load the .exit sections. Afaict
> that will break: alterative, jump_label and static_call patching all in
> one go.

Jessica, can you explain how !MODULE_UNLOAD is supposed to work?
Alternatives, jump_labels and static_call all can have relocations into
__exit code. Not loading it at all would be BAD.

For alternatives all we really need it to discard it after init, for
jump_label and static_call we additinoally need to the code to identify
as init (ie, within_module_init() must return true for it).

  reply	other threads:[~2021-03-19 12:59 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-18 11:31 [PATCH 0/3] static_call() vs __exit fixes Peter Zijlstra
2021-03-18 11:31 ` [PATCH 1/3] static_call: Fix static_call_set_init() Peter Zijlstra
2021-03-19 12:25   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-03-18 11:31 ` [PATCH 2/3] static_call: Align static_call_is_init() patching condition Peter Zijlstra
2021-03-19 12:25   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-03-19 13:31   ` [PATCH 2/3] " Rasmus Villemoes
2021-03-19 14:13     ` Peter Zijlstra
2021-03-19 14:40       ` Rasmus Villemoes
2021-03-19 15:44         ` Rasmus Villemoes
2021-03-22 16:59         ` Peter Zijlstra
2021-03-18 11:31 ` [PATCH 3/3] static_call: Fix static_call_update() sanity check Peter Zijlstra
2021-03-18 11:42   ` Peter Zijlstra
2021-03-18 16:13   ` Josh Poimboeuf
2021-03-18 16:58     ` Peter Zijlstra
2021-03-19 12:57       ` Peter Zijlstra [this message]
2021-03-19 18:00         ` Steven Rostedt
2021-03-19 19:34           ` Peter Zijlstra
2021-03-19 20:57             ` Steven Rostedt
2021-03-22 14:50               ` Jessica Yu
2021-03-22 16:54                 ` Peter Zijlstra
2021-03-22 17:36                   ` Jessica Yu
2021-03-22 13:07           ` Jessica Yu
2021-03-22 14:06             ` Peter Zijlstra
2021-03-19 12:25   ` [tip: locking/urgent] " tip-bot2 for Peter Zijlstra
2021-03-18 12:15 ` [PATCH 0/3] static_call() vs __exit fixes Sumit Garg
2021-03-18 19:38 ` Jarkko Sakkinen

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=YFSfwimq/VLmo1Lw@hirez.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=ardb@kernel.org \
    --cc=jarkko@kernel.org \
    --cc=jbaron@akamai.com \
    --cc=jeyu@kernel.org \
    --cc=jpoimboe@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=oliver.sang@intel.com \
    --cc=rostedt@goodmis.org \
    --cc=sumit.garg@linaro.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).