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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Thu, 29 Nov 2018 10:23:44 -0800
Message-ID: <CAHk-=wigLUgxDM6Dq2aS7efduffratP976Ggmpv4Ev4EOrJxyA@mail.gmail.com>
Subject: Re: [PATCH v2 4/4] x86/static_call: Add inline static call
 implementation for x86-64
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Andy Lutomirski <luto@amacapital.net>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Andrew Lutomirski <luto@kernel.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, mhiramat@kernel.org,
        jbaron@akamai.com, Jiri Kosina <jkosina@suse.cz>,
        David.Laight@aculab.com, bp@alien8.de, julia@ni.com,
        jeyu@kernel.org, Peter Anvin <hpa@zytor.com>
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On Thu, Nov 29, 2018 at 9:59 AM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> Do you realize that the cmpxchg used by the first attempts of the
> dynamic modification of code by ftrace was the source of the e1000e
> NVRAM corruption bug.

If you have a static call in IO memory, you have bigger problems than that.

What's your point?

Again - I will point out that the things you guys have tried to come
up with have been *WORSE*. Much worse.

               Linus