linux-kernel - Re: [PATCH v4 16/19] gendwarfksyms: Add support for symbol type pointers

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Message-ID: <ba3199bd-e891-46af-832a-9194b64a3d39@suse.com>
Date: Wed, 23 Oct 2024 16:55:09 +0200
From: Petr Pavlu <petr.pavlu@...e.com>
To: Sami Tolvanen <samitolvanen@...gle.com>
Cc: Masahiro Yamada <masahiroy@...nel.org>,
 Luis Chamberlain <mcgrof@...nel.org>, Miguel Ojeda <ojeda@...nel.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Matthew Maurer <mmaurer@...gle.com>, Alex Gaynor <alex.gaynor@...il.com>,
 Gary Guo <gary@...yguo.net>, Petr Pavlu <petr.pavlu@...e.com>,
 Daniel Gomez <da.gomez@...sung.com>, Neal Gompa <neal@...pa.dev>,
 Hector Martin <marcan@...can.st>, Janne Grunau <j@...nau.net>,
 Miroslav Benes <mbenes@...e.cz>, Asahi Linux <asahi@...ts.linux.dev>,
 Sedat Dilek <sedat.dilek@...il.com>, linux-kbuild@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-modules@...r.kernel.org,
 rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v4 16/19] gendwarfksyms: Add support for symbol type
 pointers

On 10/8/24 20:38, Sami Tolvanen wrote:
> The compiler may choose not to emit type information in DWARF for
> external symbols. Clang, for example, does this for symbols not
> defined in the current TU.
> 
> To provide a way to work around this issue, add support for
> __gendwarfksyms_ptr_<symbol> pointers that force the compiler to emit
> the necessary type information in DWARF also for the missing symbols.
> 
> Example usage:
> 
>   #define GENDWARFKSYMS_PTR(sym) \
>       static typeof(sym) *__gendwarfksyms_ptr_##sym __used  \
>           __section(".discard.gendwarfksyms") = &sym;
> 
>   extern int external_symbol(void);
>   GENDWARFKSYMS_PTR(external_symbol);
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
> Acked-by: Neal Gompa <neal@...pa.dev>

Looks ok to me, feel free to add:

Reviewed-by: Petr Pavlu <petr.pavlu@...e.com>

-- Petr