kernel/linux.git/tools/lib/bpf/libbpf.c, branch v6.7.3

libbpf: Add link-based API for netkit

2023-10-24T23:06:58+00:00

This adds bpf_program__attach_netkit() API to libbpf. Overall it is very similar to tcx. The API looks as following: LIBBPF_API struct bpf_link * bpf_program__attach_netkit(const struct bpf_program *prog, int ifindex, const struct bpf_netkit_opts *opts); The struct bpf_netkit_opts is done in similar way as struct bpf_tcx_opts for supporting bpf_mprog control parameters. The attach location for the primary and peer device is derived from the program section "netkit/primary" and "netkit/peer", respectively. Signed-off-by: Daniel Borkmann Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/r/20231024214904.29825-4-daniel@iogearbox.net Signed-off-by: Martin KaFai Lau

libbpf: Add support for cgroup unix socket address hooks

2023-10-12T00:27:55+00:00

Add the necessary plumbing to hook up the new cgroup unix sockaddr hooks into libbpf. Signed-off-by: Daan De Meyer Link: https://lore.kernel.org/r/20231011185113.140426-6-daan.j.demeyer@gmail.com Signed-off-by: Martin KaFai Lau

libbpf: Allow Golang symbols in uprobe secdef

2023-09-29T21:32:20+00:00

Golang symbols in ELF files are different from C/C++ which contains special characters like '*', '(' and ')'. With generics, things get more complicated, there are symbols like: github.com/cilium/ebpf/internal.(*Deque[go.shape.interface { Format(fmt.State, int32); TypeName() string;github.com/cilium/ebpf/btf.copy() github.com/cilium/ebpf/btf.Type}]).Grow Matching such symbols using `%m[^\n]` in sscanf, this excludes newline which typically does not appear in ELF symbols. This should work in most use-cases and also work for unicode letters in identifiers. If newline do show up in ELF symbols, users can still attach to such symbol by specifying bpf_uprobe_opts::func_name. A working example can be found at this repo ([0]). [0]: https://github.com/chenhengqi/libbpf-go-symbols Suggested-by: Andrii Nakryiko Signed-off-by: Hengqi Chen Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230929155954.92448-1-hengqi.chen@gmail.com

libbpf: Support symbol versioning for uprobe

2023-09-22T21:27:36+00:00

In current implementation, we assume that symbol found in .dynsym section would have a version suffix and use it to compare with symbol user supplied. According to the spec ([0]), this assumption is incorrect, the version info of dynamic symbols are stored in .gnu.version and .gnu.version_d sections of ELF objects. For example: $ nm -D /lib/x86_64-linux-gnu/libc.so.6 | grep rwlock_wrlock 000000000009b1a0 T __pthread_rwlock_wrlock@GLIBC_2.2.5 000000000009b1a0 T pthread_rwlock_wrlock@@GLIBC_2.34 000000000009b1a0 T pthread_rwlock_wrlock@GLIBC_2.2.5 $ readelf -W --dyn-syms /lib/x86_64-linux-gnu/libc.so.6 | grep rwlock_wrlock 706: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 __pthread_rwlock_wrlock@GLIBC_2.2.5 2568: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 pthread_rwlock_wrlock@@GLIBC_2.34 2571: 000000000009b1a0 878 FUNC GLOBAL DEFAULT 15 pthread_rwlock_wrlock@GLIBC_2.2.5 In this case, specify pthread_rwlock_wrlock@@GLIBC_2.34 or pthread_rwlock_wrlock@GLIBC_2.2.5 in bpf_uprobe_opts::func_name won't work. Because the qualified name does NOT match `pthread_rwlock_wrlock` (without version suffix) in .dynsym sections. This commit implements the symbol versioning for dynsym and allows user to specify symbol in the following forms: - func - func@LIB_VERSION - func@@LIB_VERSION In case of symbol conflicts, error out and users should resolve it by specifying a qualified name. [0]: https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/symversion.html Signed-off-by: Hengqi Chen Signed-off-by: Andrii Nakryiko Reviewed-by: Alan Maguire Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20230918024813.237475-3-hengqi.chen@gmail.com

libbpf: Add support for custom exception callbacks

2023-09-16T16:36:43+00:00

Add support to libbpf to append exception callbacks when loading a program. The exception callback is found by discovering the declaration tag 'exception_callback:' and finding the callback in the value of the tag. The process is done in two steps. First, for each main program, the bpf_object__sanitize_and_load_btf function finds and marks its corresponding exception callback as defined by the declaration tag on it. Second, bpf_object__reloc_code is modified to append the indicated exception callback at the end of the instruction iteration (since exception callback will never be appended in that loop, as it is not directly referenced). Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20230912233214.1518551-16-memxor@gmail.com Signed-off-by: Alexei Starovoitov

libbpf: Refactor bpf_object__reloc_code

2023-09-16T16:36:43+00:00

Refactor bpf_object__append_subprog_code out of bpf_object__reloc_code to be able to reuse it to append subprog related code for the exception callback to the main program. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20230912233214.1518551-15-memxor@gmail.com Signed-off-by: Alexei Starovoitov

libbpf: Add bpf_object__unpin()

2023-08-24T00:10:09+00:00

For bpf_object__pin_programs() there is bpf_object__unpin_programs(). Likewise bpf_object__unpin_maps() for bpf_object__pin_maps(). But no bpf_object__unpin() for bpf_object__pin(). Adding the former adds symmetry to the API. It's also convenient for cleanup in application code. It's an API I would've used if it was available for a repro I was writing earlier. Signed-off-by: Daniel Xu Signed-off-by: Andrii Nakryiko Reviewed-by: Song Liu Link: https://lore.kernel.org/bpf/b2f9d41da4a350281a0b53a804d11b68327e14e5.1692832478.git.dxu@dxuuu.xyz

libbpf: Free btf_vmlinux when closing bpf_object

2023-08-22T23:16:31+00:00

I hit a memory leak when testing bpf_program__set_attach_target(). Basically, set_attach_target() may allocate btf_vmlinux, for example, when setting attach target for bpf_iter programs. But btf_vmlinux is freed only in bpf_object_load(), which means if we only open bpf object but not load it, setting attach target may leak btf_vmlinux. So let's free btf_vmlinux in bpf_object__close() anyway. Signed-off-by: Hao Luo Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20230822193840.1509809-1-haoluo@google.com

libbpf: Add uprobe multi link support to bpf_program__attach_usdt

2023-08-21T22:51:26+00:00

Adding support for usdt_manager_attach_usdt to use uprobe_multi link to attach to usdt probes. The uprobe_multi support is detected before the usdt program is loaded and its expected_attach_type is set accordingly. If uprobe_multi support is detected the usdt_manager_attach_usdt gathers uprobes info and calls bpf_program__attach_uprobe to create all needed uprobes. If uprobe_multi support is not detected the old behaviour stays. Also adding usdt.s program section for sleepable usdt probes. Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20230809083440.3209381-18-jolsa@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Add uprobe multi link detection

2023-08-21T22:51:26+00:00

Adding uprobe-multi link detection. It will be used later in bpf_program__attach_usdt function to check and use uprobe_multi link over standard uprobe links. Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20230809083440.3209381-17-jolsa@kernel.org Signed-off-by: Alexei Starovoitov