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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Mon, 6 May 2019 09:19:35 -0700
Message-ID: <CAHk-=wjs8hhEdLUb=rD1tZC-JzBHALpi0hQSNf=esw96Gnta6A@mail.gmail.com>
Subject: Re: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Andy Lutomirski <luto@kernel.org>,
        Nicolai Stange <nstange@suse.de>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H. Peter Anvin" <hpa@zytor.com>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Jiri Kosina <jikos@kernel.org>,
        Miroslav Benes <mbenes@suse.cz>,
        Petr Mladek <pmladek@suse.com>,
        Joe Lawrence <joe.lawrence@redhat.com>,
        Shuah Khan <shuah@kernel.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Mimi Zohar <zohar@linux.ibm.com>,
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        Nick Desaulniers <ndesaulniers@google.com>,
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On Mon, May 6, 2019 at 9:17 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> So what is it that doesn't actually work? I've looked at the patch
> even more, and I can't for the life of me see how it wouldn't work.

And I do still react to PeterZ's

 arch/x86/entry/entry_32.S            | 150 +++++++++++++++++++++++++++++------

vs

 arch/x86/entry/entry_32.S            |  7 ++++++-

for mine. And PeterZ's  apparently still had bugs.

Yes, mine can have bugs too, but I really *have* done some basic
testing, and with 6 lines of code, I think they are more localized.

                Linus