Re: [RFC, PATCH, v3.9] default exported asm symbols to zero

[Adam Borowski <kilobyte@angband.pl>]

On Fri, Dec 02, 2016 at 01:40:27PM +0100, Arnd Bergmann wrote:
> With binutils-2.16 and before, a weak missing symbol was kept during the
> final link, and a missing CRC for an export would lead to that CRC
> being treated as zero implicitly. With binutils-2.17, the crc
> symbol gets dropped, and any module trying to use it will fail to
> load.
> 
> This sets the weak CRC symbol to zero explicitly, making it defined
> in vmlinux, which in turn lets us load the modules referring to
> that CRC.
> 
> The comment above the __CRC_SYMBOL macro suggests that this was
> always the intention, although it also seems that all symbols
> defined in C have a correct CRC these days, and only the exports
> that are now done in assembly need this.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---

Looks good, works for me, and, unlike faaae2a5, doesn't produce a nasty
user-scaring warning in normal operation.

> diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
> index 63554e9..59a3b2f 100644
> --- a/include/asm-generic/export.h
> +++ b/include/asm-generic/export.h
> @@ -54,6 +54,7 @@ KSYM(__kstrtab_\name):
>  KSYM(__kcrctab_\name):
>  	__put KSYM(__crc_\name)
>  	.weak KSYM(__crc_\name)
> +	.set KSYM(__crc_\name), 0
>  	.previous
>  #endif
>  #endif