linux-kernel - Re: [RFC][PATCH] x86/ftrace: Have ftrace trampolines turn read-only at the end of system boot up

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20200501092404.06d1adcb@gandalf.local.home>
Date:   Fri, 1 May 2020 09:24:04 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...capital.net>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [RFC][PATCH] x86/ftrace: Have ftrace trampolines turn read-only
 at the end of system boot up

On Fri, 1 May 2020 00:17:06 -0500
Josh Poimboeuf <jpoimboe@...hat.com> wrote:

> > Would it be easier to just call a new __text_poke_bp() which skips the
> > SYSTEM_BOOTING check, since you know the trampoline will always be
> > read-only?
> > 
> > Like:  
> 
> early_trace_init() is called after mm_init(), so I thought it might
> work, but I guess not:

Yeah, I was about to say that this happens before mm_init() ;-)

It's why we already have magic for enabling function tracing the first time.

Do you see anything wrong with this current solution? It probably needs
more comments, but I wanted to get acceptance on the logic before I go and
pretty it up and send a non RFC patch.

-- Steve