linux-kernel - Re: [patch 00/38] x86/retbleed: Call depth tracking mitigation

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Date:   Wed, 20 Jul 2022 15:43:44 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Johannes Wikner <kwikner@...z.ch>,
        Alyssa Milburn <alyssa.milburn@...ux.intel.com>,
        Jann Horn <jannh@...gle.com>, "H.J. Lu" <hjl.tools@...il.com>,
        Joao Moreira <joao.moreira@...el.com>,
        Joseph Nuzman <joseph.nuzman@...el.com>,
        Juergen Gross <jgross@...e.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>
Subject: Re: [patch 00/38] x86/retbleed: Call depth tracking mitigation

On Wed, 20 Jul 2022 12:36:38 -0700
Kees Cook <keescook@...omium.org> wrote:

> I'd rather not remove it (or do it dynamically) since the point is to
> test what has been generated by the toolchain/build process and stuffed
> into the .rodata section. i.e. making sure gadgets there can't be
> executed, that the boot-time section permission-setting works correctly,
> etc. Before the retbleed mitigation, this test worked for all
> architectures; I'd hate to regress it. :(

If you haven't noticed my reply, I wasn't able to come up with a one line
workaround, but I was able to come up with a two line workaround. Hopefully
that will be good enough to keep your little feature.

  https://lore.kernel.org/all/20220720151123.0e5bf61e@gandalf.local.home/

I'm currently running it under my entire ftrace test suite. If it passes,
I'll submit a formal patch.

-- Steve