linux-kernel - Re: [PATCH] powerpc: Do not consider weak unresolved symbol relocations as bad

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Message-ID: <ed319b1f-c6f4-7bad-f946-6c01fb202c7c@ghiti.fr>
Date:   Thu, 16 Jan 2020 14:49:19 -0500
From:   Alex Ghiti <alex@...ti.fr>
To:     Stephen Rothwell <sfr@...b.auug.org.au>
Cc:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
        Alexei Starovoitov <ast@...nel.org>,
        linux-next@...r.kernel.org, Zong Li <zong.li@...ive.com>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: Re: [PATCH] powerpc: Do not consider weak unresolved symbol
 relocations as bad

Hi Stephen,

On 1/15/20 6:39 PM, Stephen Rothwell wrote:
> Hi Alexandre,
>
> Thanks for sorting this out.  Just a few comments below.
>
> On Wed, 15 Jan 2020 15:46:48 -0500 Alexandre Ghiti <alex@...ti.fr> wrote:
>>   
>>   # Have Kbuild supply the path to objdump so we handle cross compilation.
>                                              ^
> "and nm"
>
>> +# Remove from the bad relocations those that match an undefined weak symbol
>> +# which will result in an absolute relocation to 0.
>> +# Weak unresolved symbols are of that form in nm output:
>> +# "                  w _binary__btf_vmlinux_bin_end"
>> +undef_weak_symbols=$($nm "$vmlinux" | awk -e '$1 ~ /w/ { print $2 }')
>> +
>> +while IFS= read -r weak_symbol; do
>> +	bad_relocs="$(echo -n "$bad_relocs" | sed "/$weak_symbol/d")"
>> +done <<< "$undef_weak_symbols"
> This is not a bash script, and the above is a bashism :-(
> Also, my version of awk (mawk) doesn't have a -e option.
>
> How about something like :
>
> undef_weak_symbols=$($nm "$vmlinux" | awk '$1 ~ /w/ { print $2 }')
> if [ "$undef_weak_symbols" ]; then
> 	bad_relocs="$(echo "$bad_relocs" | grep -F -w -v "$undef_weak_symbols")"
> fi
>
> Or do this near the top and add the grep to the others.

Yes that's quite better, thanks, I'll send a new version tomorrow.

Thanks again,

Alex