[adding Michael Ellerman, linux-ppc maintainer]
Hello Justin,
On Tue, 29 Sep 2020 at 14:54, Justin Forbes jmforbes@linuxtx.org wrote:
On Tue, Sep 29, 2020 at 6:53 AM Greg Kroah-Hartman gregkh@linuxfoundation.org wrote:
From: Tony Ambardar tony.ambardar@gmail.com
[ Upstream commit 746f534a4809e07f427f7d13d10f3a6a9641e5c3 ]
Encountered the following failure building libbpf from kernel 5.8.5 sources with GCC 8.4.0 and binutils 2.34: (long paths shortened)
Warning: Num of global symbols in sharedobjs/libbpf-in.o (234) does NOT match with num of versioned symbols in libbpf.so (236). Please make sure all LIBBPF_API symbols are versioned in libbpf.map. # --- libbpf_global_syms.tmp 2020-09-02 07:30:58.920084380 +0000 # +++ libbpf_versioned_syms.tmp 2020-09-02 07:30:58.924084388 +0000 @@ -1,3 +1,5 @@ +_fini +_init bpf_btf_get_fd_by_id bpf_btf_get_next_id bpf_create_map make[4]: *** [Makefile:210: check_abi] Error 1
Investigation shows _fini and _init are actually local symbols counted amongst global ones:
$ readelf --dyn-syms --wide libbpf.so|head -10
Symbol table '.dynsym' contains 343 entries: Num: Value Size Type Bind Vis Ndx Name 0: 00000000 0 NOTYPE LOCAL DEFAULT UND 1: 00004098 0 SECTION LOCAL DEFAULT 11 2: 00004098 8 FUNC LOCAL DEFAULT 11 _init@@LIBBPF_0.0.1 3: 00023040 8 FUNC LOCAL DEFAULT 14 _fini@@LIBBPF_0.0.1 4: 00000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.0.4 5: 00000000 0 OBJECT GLOBAL DEFAULT ABS LIBBPF_0.0.1 6: 0000ffa4 8 FUNC GLOBAL DEFAULT 12 bpf_object__find_map_by_offset@@LIBBPF_0.0.1
A previous commit filtered global symbols in sharedobjs/libbpf-in.o. Do the same with the libbpf.so DSO for consistent comparison.
Fixes: 306b267cb3c4 ("libbpf: Verify versioned symbols") Signed-off-by: Tony Ambardar Tony.Ambardar@gmail.com Signed-off-by: Alexei Starovoitov ast@kernel.org Acked-by: Andrii Nakryiko andriin@fb.com Link: https://lore.kernel.org/bpf/20200905214831.1565465-1-Tony.Ambardar@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org
This seems to work everywhere else, but breaks PPC64LE.
I also ran into a PPC build error while working on some bpf problems, but it seemed like a pre-existing PPC issue. I did submit an upstream fix, which is marked for stable and being reviewed by Michael. See here for discussion and the patch: https://lkml.org/lkml/2020/9/17/668.
Is that the same problem you encountered? Does that patch address your issue?
Thanks, Tony
Justin
tools/lib/bpf/Makefile | 2 ++ 1 file changed, 2 insertions(+)
--- a/tools/lib/bpf/Makefile +++ b/tools/lib/bpf/Makefile @@ -152,6 +152,7 @@ GLOBAL_SYM_COUNT = $(shell readelf -s -- awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \ sort -u | wc -l) VERSIONED_SYM_COUNT = $(shell readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}' | \ grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | sort -u | wc -l)CMD_TARGETS = $(LIB_TARGET) $(PC_FILE) @@ -219,6 +220,7 @@ check_abi: $(OUTPUT)libbpf.so awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \ sort -u > $(OUTPUT)libbpf_global_syms.tmp; \ readelf --dyn-syms --wide $(OUTPUT)libbpf.so | \
awk '/GLOBAL/ && /DEFAULT/ && !/UND/ {print $$NF}'| \ grep -Eo '[^ ]+@LIBBPF_' | cut -d@ -f1 | \ sort -u > $(OUTPUT)libbpf_versioned_syms.tmp; \ diff -u $(OUTPUT)libbpf_global_syms.tmp \