linux-kernel - Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64

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: <CALCETrU5cORg237=XvT332se8YPLq78zNPM+OsFTorXqLc05SQ@mail.gmail.com>
Date:   Thu, 29 Nov 2018 11:28:07 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     Steven Rostedt <rostedt@...dmis.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Andrew Lutomirski <luto@...nel.org>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        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@...com, jeyu@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>
Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call
 implementation for x86-64

On Thu, Nov 29, 2018 at 11:25 AM Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> On Thu, Nov 29, 2018 at 11:16 AM Steven Rostedt <rostedt@...dmis.org> wrote:
> >
> > But then we need to implement all numbers of parameters.
>
> Oh, I agree, it's nasty.
>
> But it's actually a nastiness that we've solved before. In particular,
> with the system call mappings, which have pretty much the exact same
> issue of "map unknown number of arguments to registers".
>
> Yes, it's different - there you map the unknown number of arguments to
> a structure access instead. And yes, the macros are unbelievably ugly.
> See
>
>     arch/x86/include/asm/syscall_wrapper.h
>
> and the __MAP() macro from
>
>     include/linux/syscalls.h
>
> so it's not pretty. But it would solve all the problems.
>

Until someone does:

struct foo foo;
static_call(thingy, foo);

For syscalls, we know better than to do that.  For static calls, I'm
less confident.