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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Sat, 6 Jan 2018 10:13:42 -0800
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Subject: Re: [PATCH v5 05/12] x86/retpoline/ftrace: Convert ftrace assembler
 indirect jumps
To: David Woodhouse <dwmw@amazon.co.uk>
Cc: Andi Kleen <ak@linux.intel.com>, Paul Turner <pjt@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Greg Kroah-Hartman <gregkh@linux-foundation.org>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Kees Cook <keescook@google.com>,
        Rik van Riel <riel@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Jiri Kosina <jikos@kernel.org>,
        One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
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On Sat, Jan 6, 2018 at 3:49 AM, David Woodhouse <dwmw@amazon.co.uk> wrote:
>
> -       call    *ftrace_trace_function
> +       movl    ftrace_trace_function, %ecx
> +       NOSPEC_CALL %ecx

Can't we just do

    NOSPEC_CALL ftrace_trace_function

now?

[ Goes off and looks ]

Oh. The AMD lfence version wants a register. Oh well.

             Linus