linux-kernel - Re: [RFC PATCH 2/2] livepatch: Clear relocation targets on a module removal

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Message-ID: <nycvar.YFH.7.76.1909051531020.31470@cbobk.fhfr.pm>
Date:   Thu, 5 Sep 2019 15:31:56 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
cc:     Petr Mladek <pmladek@...e.com>,
        Joe Lawrence <joe.lawrence@...hat.com>,
        Miroslav Benes <mbenes@...e.cz>, linux-kernel@...r.kernel.org,
        live-patching@...r.kernel.org
Subject: Re: [RFC PATCH 2/2] livepatch: Clear relocation targets on a module
 removal

On Thu, 5 Sep 2019, Josh Poimboeuf wrote:

> > All the indirect jumps are turned into alternatives when retpolines 
> > are in place.
> 
> Actually in C code those are done by the compiler as calls/jumps to
> __x86_indirect_thunk_*.

Sure, and the thunks do the redirection via JMP_NOSPEC / CALL_NOSPEC, 
which has alternative in it.

-- 
Jiri Kosina
SUSE Labs