linux-kernel - Re: [PATCH v3 0/6] Static calls

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: <20190110203023.GL2861@worktop.programming.kicks-ass.net>
Date:   Thu, 10 Jan 2019 21:30:23 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andy Lutomirski <luto@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Jason Baron <jbaron@...mai.com>, Jiri Kosina <jkosina@...e.cz>,
        David Laight <David.Laight@...LAB.COM>,
        Borislav Petkov <bp@...en8.de>,
        Julia Cartwright <julia@...com>, Jessica Yu <jeyu@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Nadav Amit <namit@...are.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Edward Cree <ecree@...arflare.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>
Subject: Re: [PATCH v3 0/6] Static calls

On Wed, Jan 09, 2019 at 04:59:35PM -0600, Josh Poimboeuf wrote:
> With this version, I stopped trying to use text_poke_bp(), and instead
> went with a different approach: if the call site destination doesn't
> cross a cacheline boundary, just do an atomic write.  Otherwise, keep
> using the trampoline indefinitely.

> - Get rid of the use of text_poke_bp(), in favor of atomic writes.
>   Out-of-line calls will be promoted to inline only if the call sites
>   don't cross cache line boundaries. [Linus/Andy]

Can we perserve why text_poke_bp() didn't work? I seem to have forgotten
again. The problem was poking the return address onto the stack from the
int3 handler, or something along those lines?