linux-kernel - Re: [patch V4 part 3 09/29] x86/entry/32: Provide macro to emit IDT entry stubs

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Message-ID: <CALCETrXUus+nQk5BmZLnjnPJ2ywuQg6RsNwqFfwCKpiir9o7wg@mail.gmail.com>
Date:   Sun, 10 May 2020 17:55:12 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, X86 ML <x86@...nel.org>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Andy Lutomirski <luto@...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>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Juergen Gross <jgross@...e.com>,
        Brian Gerst <brgerst@...il.com>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Will Deacon <will@...nel.org>
Subject: Re: [patch V4 part 3 09/29] x86/entry/32: Provide macro to emit IDT
 entry stubs

On Tue, May 5, 2020 at 7:15 AM Thomas Gleixner <tglx@...utronix.de> wrote:
>
> From: Thomas Gleixner <tglx@...utronix.de>
>
> 32 and 64 bit have unnecessary different ways to populate the exception
> entry code. Provide a idtentry macro which allows to consolidate all of
> that.
>
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Reviewed-by: Alexandre Chartre <alexandre.chartre@...cle.com>

Acked-by: Andy Lutomirski <luto@...nel.org>
> +       /* fixup %gs */
> +       GS_TO_REG %ecx
> +       movl    PT_GS(%esp), %edi               # get the function address
> +       REG_TO_PTGS %ecx
> +       SET_KERNEL_GS %ecx

This GS garbage remains an atrocity.  Some day if I'm inspired to
clean up 32-bit stuff, I'll decrapify it.