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

[Thadeu Lima de Souza Cascardo]

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
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