[Unstable] libbpf: Fix readelf output parsing on powerpc with recent binutils

[Thadeu Lima de Souza Cascardo]

On Tue, Dec 03, 2019 at 02:09:34PM -0300, Thadeu Lima de Souza Cascardo wrote:
> From: Aurelien Jarno <aurelien at aurel32.net>
> 
> BugLink: https://bugs.launchpad.net/bugs/1854974
> 
> On powerpc with recent versions of binutils, readelf outputs an extra
> field when dumping the symbols of an object file. For example:
> 
>     35: 0000000000000838    96 FUNC    LOCAL  DEFAULT [<localentry>: 8]     1 btf_is_struct
> 
> The extra "[<localentry>: 8]" prevents the GLOBAL_SYM_COUNT variable to
> be computed correctly and causes the check_abi target to fail.
> 
> Fix that by looking for the symbol name in the last field instead of the
> 8th one. This way it should also cope with future extra fields.
> 
> Signed-off-by: Aurelien Jarno <aurelien at aurel32.net>
> Signed-off-by: Daniel Borkmann <daniel at iogearbox.net>
> Tested-by: Michael Ellerman <mpe at ellerman.id.au>
> Link: https://lore.kernel.org/bpf/20191201195728.4161537-1-aurelien@aurel32.net

(cherry picked from commit 3464afdf11f9a1e031e7858a05351ceca1792fea linux-next)

> Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo at canonical.com>
> ---
>  tools/lib/bpf/Makefile | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
> index 56ce6292071b..a7d7d35885c7 100644
> --- a/tools/lib/bpf/Makefile
> +++ b/tools/lib/bpf/Makefile
> @@ -145,7 +145,7 @@ PC_FILE		:= $(addprefix $(OUTPUT),$(PC_FILE))
>  
>  GLOBAL_SYM_COUNT = $(shell readelf -s --wide $(BPF_IN_SHARED) | \
>  			   cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' | \
> -			   awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$8}' | \
> +			   awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \
>  			   sort -u | wc -l)
>  VERSIONED_SYM_COUNT = $(shell readelf -s --wide $(OUTPUT)libbpf.so | \
>  			      grep -Eo '[^ ]+ at LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)
> @@ -217,7 +217,7 @@ check_abi: $(OUTPUT)libbpf.so
>  		     "versioned in $(VERSION_SCRIPT)." >&2;		 \
>  		readelf -s --wide $(OUTPUT)libbpf-in.o |		 \
>  		    cut -d "@" -f1 | sed 's/_v[0-9]_[0-9]_[0-9].*//' |	 \
> -		    awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$8}'|   \
> +		    awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'|  \
>  		    sort -u > $(OUTPUT)libbpf_global_syms.tmp;		 \
>  		readelf -s --wide $(OUTPUT)libbpf.so |			 \
>  		    grep -Eo '[^ ]+ at LIBBPF_' | cut -d@ -f1 |		 \
> -- 
> 2.20.1
> 
> 
> -- 
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