linux-kernel - Re: [PATCH v3 1/3] jump_label: Explicitly disable jump labels in _

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Message-ID: <20180219125711.x5bhj7veuu77fizk@treble>
Date:   Mon, 19 Feb 2018 06:57:11 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     x86@...nel.org
Cc:     linux-kernel@...r.kernel.org, Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Jason Baron <jbaron@...mai.com>, Borislav Petkov <bp@...e.de>
Subject: Re: [PATCH v3 1/3] jump_label: Explicitly disable jump labels in
 __init code

On Sun, Feb 18, 2018 at 07:17:19PM -0600, Josh Poimboeuf wrote:
> After initmem has been freed, any jump labels in __init code are
> prevented from being written to by the kernel_text_address() check in
> __jump_label_update().  However, this check is quite broad.  If
> kernel_text_address() were to return false for any other reason, the
> jump label write would fail silently with no warning.
> 
> For jump labels in module init code, entry->code is set to zero to
> indicate that the entry is disabled.  Do the same thing for core kernel
> init code.  This makes the behavior more consistent, and will also make
> it more straightforward to detect non-init jump label write failures in
> the next patch.
> 
> Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>

NACK

0-day reports this doesn't build with CONFIG_MODULES=n:

   init/main.o: In function `kernel_init':
>> main.c:(.ref.text+0x98): undefined reference to `jump_label_invalidate_init'

-- 
Josh