Re: [PATCH 2/3] arm64: lib: Use modern annotations for assembly functions

[Jiri Slaby <jslaby@suse.com>]

On 08. 01. 20, 13:29, Will Deacon wrote:
> On Tue, Jan 07, 2020 at 05:47:41PM +0000, Mark Brown wrote:
>> On Tue, Jan 07, 2020 at 02:44:46PM +0000, Will Deacon wrote:
>>> Jiri -- is it ok to omit the stack frame for leaf functions annotated with
>>> SYM_FUNC_START? I'm guessing it should be, since the link register isn't
>>> going to be clobbered. Could we update the documentation to reflect that?
>>
>> Yeah, the documentation isn't great on that.  I was going on the basis
>> of both trying to minimize changes to the generated output as part of
>> the bulk change and looking at it from the point of view of the caller -
>> if as in this case the caller thinks it's a regular C function it seems
>> sensible to annotate it as such.
> 
> Maybe a small tweak to the documentation as per below, indicating that the
> stack stuff is just an x86-specific example?
> 
> Jiri?

Yes, the text in the documentation was too x86-specific. Could you send
the below as a proper patch? Thanks.

> diff --git a/Documentation/asm-annotations.rst b/Documentation/asm-annotations.rst
> index f55c2bb74d00..32ea57483378 100644
> --- a/Documentation/asm-annotations.rst
> +++ b/Documentation/asm-annotations.rst
> @@ -73,10 +73,11 @@ The new macros are prefixed with the ``SYM_`` prefix and can be divided into
>  three main groups:
>  
>  1. ``SYM_FUNC_*`` -- to annotate C-like functions. This means functions with
> -   standard C calling conventions, i.e. the stack contains a return address at
> -   the predefined place and a return from the function can happen in a
> -   standard way. When frame pointers are enabled, save/restore of frame
> -   pointer shall happen at the start/end of a function, respectively, too.
> +   standard C calling conventions. For example, on x86, this means that the
> +   stack contains a return address at the predefined place and a return from
> +   the function can happen in a standard way. When frame pointers are enabled,
> +   save/restore of frame pointer shall happen at the start/end of a function,
> +   respectively, too.
>  
>     Checking tools like ``objtool`` should ensure such marked functions conform
>     to these rules. The tools can also easily annotate these functions with

thanks,
-- 
js
suse labs

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