Re: [RFC v4 12/18] arm64: assembler: Add macro to annotate asm function having non standard stack-frame.

From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Raphael Gault <raphael.gault@arm.com>
Cc: raph.gault+kdev@gmail.com, peterz@infradead.org,
	catalin.marinas@arm.com, will.deacon@arm.com,
	linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	julien.thierry.kdev@gmail.com
Subject: Re: [RFC v4 12/18] arm64: assembler: Add macro to annotate asm function having non standard stack-frame.
Date: Thu, 22 Aug 2019 15:10:17 -0500	[thread overview]
Message-ID: <20190822201017.3w77h374qs5uyxso@treble> (raw)
In-Reply-To: <20190816122403.14994-13-raphael.gault@arm.com>

On Fri, Aug 16, 2019 at 01:23:57PM +0100, Raphael Gault wrote:
> Some functions don't have standard stack-frames but are intended
> this way. In order for objtool to ignore those particular cases
> we add a macro that enables us to annotate the cases we chose
> to mark as particular.
> 
> Signed-off-by: Raphael Gault <raphael.gault@arm.com>
> ---
>  include/linux/frame.h | 19 ++++++++++++++++++-
>  1 file changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/frame.h b/include/linux/frame.h
> index 02d3ca2d9598..1e35e58ab259 100644
> --- a/include/linux/frame.h
> +++ b/include/linux/frame.h
> @@ -11,14 +11,31 @@
>   *
>   * For more information, see tools/objtool/Documentation/stack-validation.txt.
>   */
> +#ifndef __ASSEMBLY__
>  #define STACK_FRAME_NON_STANDARD(func) \
>  	static void __used __section(.discard.func_stack_frame_non_standard) \
>  		*__func_stack_frame_non_standard_##func = func
> +#else
> +	/*
> +	 * This macro is the arm64 assembler equivalent of the
> +	 * macro STACK_FRAME_NON_STANDARD define at
> +	 * ~/include/linux/frame.h
> +	 */

This comment is a bit confusing as it's referring to its own header
file.  And it's not arm64-specific.  I don't think we really need a
comment here anyway.

> +	.macro	asm_stack_frame_non_standard	func
> +	.pushsection ".discard.func_stack_frame_non_standard"
> +	.quad	\func
> +	.popsection
> +	.endm

Can you call it STACK_FRAME_NON_STANDARD for consistency with the
non-asm version?

-- 
Josh

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