linux/tools/lib/bpf, branch v5.9

libbpf: Fix XDP program load regression for old kernels

2020-09-24T17:33:02Z

Fix regression in libbpf, introduced by XDP link change, which causes XDP programs to fail to be loaded into kernel due to specified BPF_XDP expected_attach_type. While kernel doesn't enforce expected_attach_type for BPF_PROG_TYPE_XDP, some old kernels already support XDP program, but they don't yet recognize expected_attach_type field in bpf_attr, so setting it to non-zero value causes program load to fail. Luckily, libbpf already has a mechanism to deal with such cases, so just make expected_attach_type optional for XDP programs. Fixes: dc8698cac7aa ("libbpf: Add support for BPF XDP link") Reported-by: Nikita Shirokov Reported-by: Udip Pant Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200924171705.3803628-1-andriin@fb.com

libbpf: Fix native endian assumption when parsing BTF

2020-09-21T19:50:49Z

Code in btf__parse_raw() fails to detect raw BTF of non-native endianness and assumes it must be ELF data, which then fails to parse as ELF and yields a misleading error message: root:/# bpftool btf dump file /sys/kernel/btf/vmlinux libbpf: failed to get EHDR from /sys/kernel/btf/vmlinux For example, this could occur after cross-compiling a BTF-enabled kernel for a target with non-native endianness, which is currently unsupported. Check for correct endianness and emit a clearer error message: root:/# bpftool btf dump file /sys/kernel/btf/vmlinux libbpf: non-native BTF endianness is not supported Fixes: 94a1fedd63ed ("libbpf: Add btf__parse_raw() and generic btf__parse() APIs") Signed-off-by: Tony Ambardar Signed-off-by: Daniel Borkmann Acked-by: John Fastabend Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/90f81508ecc57bc0da318e0fe0f45cfe49b17ea7.1600417359.git.Tony.Ambardar@gmail.com

tools/libbpf: Avoid counting local symbols in ABI check

2020-09-08T22:41:31Z

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 Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200905214831.1565465-1-Tony.Ambardar@gmail.com

libbpf: Remove arch-specific include path in Makefile

2020-09-03T13:45:00Z

Ubuntu mainline builds for ppc64le are failing with the below error (*): CALL /home/kernel/COD/linux/scripts/atomic/check-atomics.sh DESCEND bpf/resolve_btfids Auto-detecting system features: ... libelf: [ [32mon[m ] ... zlib: [ [32mon[m ] ... bpf: [ [31mOFF[m ] BPF API too old make[6]: *** [Makefile:295: bpfdep] Error 1 make[5]: *** [Makefile:54: /home/kernel/COD/linux/debian/build/build-generic/tools/bpf/resolve_btfids//libbpf.a] Error 2 make[4]: *** [Makefile:71: bpf/resolve_btfids] Error 2 make[3]: *** [/home/kernel/COD/linux/Makefile:1890: tools/bpf/resolve_btfids] Error 2 make[2]: *** [/home/kernel/COD/linux/Makefile:335: __build_one_by_one] Error 2 make[2]: Leaving directory '/home/kernel/COD/linux/debian/build/build-generic' make[1]: *** [Makefile:185: __sub-make] Error 2 make[1]: Leaving directory '/home/kernel/COD/linux' resolve_btfids needs to be build as a host binary and it needs libbpf. However, libbpf Makefile hardcodes an include path utilizing $(ARCH). This results in mixing of cross-architecture headers resulting in a build failure. The specific header include path doesn't seem necessary for a libbpf build. Hence, remove the same. (*) https://kernel.ubuntu.com/~kernel-ppa/mainline/v5.9-rc3/ppc64el/log Reported-by: Vaidyanathan Srinivasan Signed-off-by: Naveen N. Rao Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200902084246.1513055-1-naveen.n.rao@linux.vnet.ibm.com

libbpf: Fix build failure from uninitialized variable warning

2020-08-31T14:56:51Z

While compiling libbpf, some GCC versions (at least 8.4.0) have difficulty determining control flow and a emit warning for potentially uninitialized usage of 'map', which results in a build error if using "-Werror": In file included from libbpf.c:56: libbpf.c: In function '__bpf_object__open': libbpf_internal.h:59:2: warning: 'map' may be used uninitialized in this function [-Wmaybe-uninitialized] libbpf_print(level, "libbpf: " fmt, ##__VA_ARGS__); \ ^~~~~~~~~~~~ libbpf.c:5032:18: note: 'map' was declared here struct bpf_map *map, *targ_map; ^~~ The warning/error is false based on code inspection, so silence it with a NULL initialization. Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support") Reference: 063e68813391 ("libbpf: Fix false uninitialized variable warning") Signed-off-by: Tony Ambardar Signed-off-by: Daniel Borkmann Link: https://lore.kernel.org/bpf/20200831000304.1696435-1-Tony.Ambardar@gmail.com

libbpf: Fix map index used in error message

2020-08-20T14:21:27Z

The error message emitted by bpf_object__init_user_btf_maps() was using the wrong section ID. Signed-off-by: Toke Høiland-Jørgensen Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20200819110534.9058-1-toke@redhat.com

libbpf: Fix build on ppc64le architecture

2020-08-18T17:02:52Z

On ppc64le we get the following warning: In file included from btf_dump.c:16:0: btf_dump.c: In function ‘btf_dump_emit_struct_def’: ../include/linux/kernel.h:20:17: error: comparison of distinct pointer types lacks a cast [-Werror] (void) (&_max1 == &_max2); \ ^ btf_dump.c:882:11: note: in expansion of macro ‘max’ m_sz = max(0LL, btf__resolve_size(d->btf, m->type)); ^~~ Fix by explicitly casting to __s64, which is a return type from btf__resolve_size(). Fixes: 702eddc77a90 ("libbpf: Handle GCC built-in types for Arm NEON") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200818164456.1181661-1-andriin@fb.com

libbpf: Enforce 64-bitness of BTF for BPF object files

2020-08-13T23:45:41Z

BPF object files are always targeting 64-bit BPF target architecture, so enforce that at BTF level as well. Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200813204945.1020225-7-andriin@fb.com

libbpf: Handle BTF pointer sizes more carefully

2020-08-13T23:45:41Z

With libbpf and BTF it is pretty common to have libbpf built for one architecture, while BTF information was generated for a different architecture (typically, but not always, BPF). In such case, the size of a pointer might differ betweem architectures. libbpf previously was always making an assumption that pointer size for BTF is the same as native architecture pointer size, but that breaks for cases where libbpf is built as 32-bit library, while BTF is for 64-bit architecture. To solve this, add heuristic to determine pointer size by searching for `long` or `unsigned long` integer type and using its size as a pointer size. Also, allow to override the pointer size with a new API btf__set_pointer_size(), for cases where application knows which pointer size should be used. User application can check what libbpf "guessed" by looking at the result of btf__pointer_size(). If it's not 0, then libbpf successfully determined a pointer size, otherwise native arch pointer size will be used. For cases where BTF is parsed from ELF file, use ELF's class (32-bit or 64-bit) to determine pointer size. Fixes: 8a138aed4a80 ("bpf: btf: Add BTF support to libbpf") Fixes: 351131b51c7a ("libbpf: add btf_dump API for BTF-to-C conversion") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200813204945.1020225-5-andriin@fb.com

libbpf: Fix BTF-defined map-in-map initialization on 32-bit host arches

2020-08-13T23:45:41Z

Libbpf built in 32-bit mode should be careful about not conflating 64-bit BPF pointers in BPF ELF file and host architecture pointers. This patch fixes issue of incorrect initializating of map-in-map inner map slots due to such difference. Fixes: 646f02ffdd49 ("libbpf: Add BTF-defined map-in-map support") Signed-off-by: Andrii Nakryiko Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20200813204945.1020225-4-andriin@fb.com