linux-kernel - Re: [patch V6 19/37] x86/irq: Convey vector as argument and not in ptregs

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Date:   Fri, 22 May 2020 21:54:10 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Josh Poimboeuf <jpoimboe@...hat.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Alexandre Chartre <alexandre.chartre@...cle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Will Deacon <will@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Wei Liu <wei.liu@...nel.org>,
        Michael Kelley <mikelley@...rosoft.com>,
        Jason Chen CJ <jason.cj.chen@...el.com>,
        Zhao Yakui <yakui.zhao@...el.com>,
        "Peter Zijlstra \(Intel\)" <peterz@...radead.org>
Subject: Re: [patch V6 19/37] x86/irq: Convey vector as argument and not in ptregs

Josh Poimboeuf <jpoimboe@...hat.com> writes:

> On Fri, May 22, 2020 at 02:48:53PM -0400, Boris Ostrovsky wrote:
>> > Yes. They just make objtool very unhappy:
>> >
>> > arch/x86/entry/entry_64.o: warning: objtool: .entry.text+0xfd0: special:
>> > can't find orig instruction
>> >
>> > Peter suggested to use:
>> >
>> >       .pos = .
>> >       .byte..
>> >       jmp
>> >       .nops (pos + 8) - .
>> 
>> 
>> Unfortunately this (.nops directive) only works for newer assemblers
>> (2.31, per
>> https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;a=blob_plain;f=gas/NEWS;h=9a3f352108e439754688e19e63a6235b38801182;hb=5eb617a71463fa6810cd14f57adfe7a1efc93a96)
>> 
>> 
>> I have 2.27 and things don't go well.
>
> A single nop should be fine, since gas will complain if it tries to move
> the IP backwards.

Yes. That's what I posted in the V9 thread :)

> (Also I'd vote for normal indentation instead of the "assembler magic
> at 4 spaces" thing.)

let me fix that