linux-kernel - Re: [patch 05/12] x86/irq: Provide macro for inlining irq stack switching

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Date:   Mon, 8 Feb 2021 14:42:09 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Kees Cook <keescook@...omium.org>
Subject: Re: [patch 05/12] x86/irq: Provide macro for inlining irq stack
 switching

On Thu, Feb 04, 2021 at 09:49:08PM +0100, Thomas Gleixner wrote:
>  #ifdef CONFIG_X86_64
> +
> +#ifdef CONFIG_UNWINDER_FRAME_POINTER
> +# define IRQSTACK_CALL_CONSTRAINT	, ASM_CALL_CONSTRAINT
> +#else
> +# define IRQSTACK_CALL_CONSTRAINT
> +#endif

Is this really needed?  i.e. does ASM_CALL_CONSTRAINT actually affect
code generation with !FRAME_POINTER?

If so then we should rework ASM_CALL_CONSTRAINT itself to be something
similar to the above, as it's only ever needed with frame pointers.

-- 
Josh