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).
next prev parent 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
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