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

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Date:   Thu, 16 Jan 2020 10:39:32 +1100
From:   Stephen Rothwell <sfr@...b.auug.org.au>
To:     Alexandre Ghiti <alex@...ti.fr>
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 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.
-- 
Cheers,
Stephen Rothwell

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