kernel/linux.git/tools/lib/bpf/libbpf.c, branch v6.18.22

libbpf: Fix -Wdiscarded-qualifiers under C23

2026-02-06T15:57:45+00:00

commit d70f79fef65810faf64dbae1f3a1b5623cdb2345 upstream. glibc ≥ 2.42 (GCC 15) defaults to -std=gnu23, which promotes -Wdiscarded-qualifiers to an error. In C23, strstr() and strchr() return "const char *". Change variable types to const char * where the pointers are never modified (res, sym_sfx, next_path). Suggested-by: Florian Weimer Suggested-by: Andrii Nakryiko Signed-off-by: Mikhail Gavrilov Link: https://lore.kernel.org/r/20251206092825.1471385-1-mikhail.v.gavrilov@gmail.com Signed-off-by: Alexei Starovoitov [ shung-hsi.yu: needed to fix kernel build failure due to libbpf since glibc 2.43+ (which adds 'const' qualifier to strstr) ] Signed-off-by: Shung-Hsi Yu Signed-off-by: Greg Kroah-Hartman

libbpf: move libbpf_sha256() implementation into libbpf_utils.c

2025-10-01T22:27:25+00:00

Move sha256 implementation out of already large and unwieldy libbpf.c into libbpf_utils.c where we'll keep reusable helpers. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20251001171326.3883055-5-andrii@kernel.org Signed-off-by: Alexei Starovoitov Acked-by: Eduard Zingerman

libbpf: move libbpf_errstr() into libbpf_utils.c

2025-10-01T22:27:25+00:00

Get rid of str_err.{c,h} by moving implementation of libbpf_errstr() into libbpf_utils.c and declarations into libbpf_internal.h. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20251001171326.3883055-4-andrii@kernel.org Signed-off-by: Alexei Starovoitov Acked-by: Eduard Zingerman

libbpf: remove unused libbpf_strerror_r and STRERR_BUFSIZE

2025-10-01T22:27:25+00:00

libbpf_strerror_r() is not exposed as public API and neither is it used inside libbpf itself. Remove it altogether. Same for STRERR_BUFSIZE, it's just an orphaned leftover constant which we missed to clean up some time earlier. Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20251001171326.3883055-3-andrii@kernel.org Signed-off-by: Alexei Starovoitov Acked-by: Eduard Zingerman

libbpf: Replace AF_ALG with open coded SHA-256

2025-09-28T11:25:31+00:00

Reimplement libbpf_sha256() using some basic SHA-256 C code. This eliminates the newly-added dependency on AF_ALG, which is a problematic UAPI that is not supported by all kernels. Make libbpf_sha256() return void, since it can no longer fail. This simplifies some callers. Also drop the unnecessary 'sha_out_sz' parameter. Finally, also fix the typo in "compute_sha_udpate_offsets". Fixes: c297fe3e9f99 ("libbpf: Implement SHA256 internal helper") Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20250928003833.138407-1-ebiggers@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Fix error when st-prefix_ops and ops from differ btf

2025-09-26T20:03:19+00:00

When a module registers a struct_ops, the struct_ops type and its corresponding map_value type ("bpf_struct_ops_") may reside in different btf objects, here are four possible case: +--------+---------------+-------------+---------------------------------+ | |bpf_struct_ops_| xxx_ops | | +--------+---------------+-------------+---------------------------------+ | case 0 | btf_vmlinux | btf_vmlinux | be used and reg only in vmlinux | +--------+---------------+-------------+---------------------------------+ | case 1 | btf_vmlinux | mod_btf | INVALID | +--------+---------------+-------------+---------------------------------+ | case 2 | mod_btf | btf_vmlinux | reg in mod but be used both in | | | | | vmlinux and mod. | +--------+---------------+-------------+---------------------------------+ | case 3 | mod_btf | mod_btf | be used and reg only in mod | +--------+---------------+-------------+---------------------------------+ Currently we figure out the mod_btf by searching with the struct_ops type, which makes it impossible to figure out the mod_btf when the struct_ops type is in btf_vmlinux while it's corresponding map_value type is in mod_btf (case 2). The fix is to use the corresponding map_value type ("bpf_struct_ops_") as the lookup anchor instead of the struct_ops type to figure out the `btf` and `mod_btf` via find_ksym_btf_id(), and then we can locate the kern_type_id via btf__find_by_name_kind() with the `btf` we just obtained from find_ksym_btf_id(). With this change the lookup obtains the correct btf and mod_btf for case 2, preserves correct behavior for other valid cases, and still fails as expected for the invalid scenario (case 1). Fixes: 590a00888250 ("bpf: libbpf: Add STRUCT_OPS support") Signed-off-by: D. Wythe Signed-off-by: Andrii Nakryiko Acked-by: Andrii Nakryiko Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20250926071751.108293-1-alibuda@linux.alibaba.com

libbpf: Support exclusive map creation

2025-09-19T02:11:42+00:00

Implement setters and getters that allow map to be registered as exclusive to the specified program. The registration should be done before the exclusive program is loaded. Signed-off-by: KP Singh Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20250914215141.15144-5-kpsingh@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Implement SHA256 internal helper

2025-09-19T02:11:42+00:00

Use AF_ALG sockets to not have libbpf depend on OpenSSL. The helper is used for the loader generation code to embed the metadata hash in the loader program and also by the bpf_map__make_exclusive API to calculate the hash of the program the map is exclusive to. Acked-by: Andrii Nakryiko Signed-off-by: KP Singh Link: https://lore.kernel.org/r/20250914215141.15144-4-kpsingh@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Fix reuse of DEVMAP

2025-08-15T23:52:50+00:00

Previously, re-using pinned DEVMAP maps would always fail, because get_map_info on a DEVMAP always returns flags with BPF_F_RDONLY_PROG set, but BPF_F_RDONLY_PROG being set on a map during creation is invalid. Thus, ignore the BPF_F_RDONLY_PROG flag in the flags returned from get_map_info when checking for compatibility with an existing DEVMAP. The same problem is handled in a third-party ebpf library: - https://github.com/cilium/ebpf/issues/925 - https://github.com/cilium/ebpf/pull/930 Fixes: 0cdbb4b09a06 ("devmap: Allow map lookups from eBPF") Signed-off-by: Yureka Lilian Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250814180113.1245565-3-yuka@yuka.dev

libbpf: Add the ability to suppress perf event enablement

2025-08-07T16:01:41+00:00

Automatically enabling a perf event after attaching a BPF prog to it is not always desirable. Add a new "dont_enable" field to struct bpf_perf_event_opts. While introducing "enable" instead would be nicer in that it would avoid a double negation in the implementation, it would make DECLARE_LIBBPF_OPTS() less efficient. Acked-by: Eduard Zingerman Suggested-by: Jiri Olsa Tested-by: Thomas Richter Co-developed-by: Thomas Richter Signed-off-by: Thomas Richter Signed-off-by: Ilya Leoshkevich Link: https://lore.kernel.org/r/20250806162417.19666-2-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov