kernel/linux.git/tools/lib/bpf/btf.c, branch linux-7.0.y

btf: Refactor the code by calling str_is_empty

2026-01-14T00:21:56+00:00

Calling the str_is_empty function to clarify the code and no functional changes are introduced. Signed-off-by: Donglin Peng Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260109130003.3313716-12-dolinux.peng@gmail.com

libbpf: Verify BTF sorting

2026-01-14T00:16:59+00:00

This patch checks whether the BTF is sorted by name in ascending order. If sorted, binary search will be used when looking up types. Signed-off-by: Donglin Peng Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260109130003.3313716-6-dolinux.peng@gmail.com

libbpf: Optimize type lookup with binary search for sorted BTF

2026-01-14T00:16:58+00:00

This patch introduces binary search optimization for BTF type lookups when the BTF instance contains sorted types. The optimization significantly improves performance when searching for types in large BTF instances with sorted types. For unsorted BTF, the implementation falls back to the original linear search. Signed-off-by: Donglin Peng Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20260109130003.3313716-5-dolinux.peng@gmail.com

libbpf: Add BTF permutation support for type reordering

2026-01-14T00:10:39+00:00

Introduce btf__permute() API to allow in-place rearrangement of BTF types. This function reorganizes BTF type order according to a provided array of type IDs, updating all type references to maintain consistency. Signed-off-by: Donglin Peng Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/20260109130003.3313716-2-dolinux.peng@gmail.com

libbpf: Add debug messaging in dedup equivalence/identity matching

2025-12-05T23:55:54+00:00

We have seen a number of issues like [1]; failures to deduplicate key kernel data structures like task_struct. These are often hard to debug from pahole even with verbose output, especially when identity/equivalence checks fail deep in a nested struct comparison. Here we add debug messages of the form libbpf: STRUCT 'task_struct' size=2560 vlen=194 cand_id[54222] canon_id[102820] shallow-equal but not equiv for field#23 'sched_class': 0 These will be emitted during dedup from pahole when --verbose/-V is specified. This greatly helps identify exactly where dedup failures are experienced. [1] https://lore.kernel.org/bpf/b8e8b560-bce5-414b-846d-0da6d22a9983@oracle.com/ Changes since v1: - updated debug messages to refer to shallow-equal, added ids (Andrii) Signed-off-by: Alan Maguire Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20251203191507.55565-1-alan.maguire@oracle.com

libbpf: Fix BTF dedup to support recursive typedef definitions

2025-11-15T01:07:20+00:00

Handle recursive typedefs in BTF deduplication Pahole fails to encode BTF for some Go projects (e.g. Kubernetes and Podman) due to recursive type definitions that create reference loops not representable in C. These recursive typedefs trigger a failure in the BTF deduplication algorithm. This patch extends btf_dedup_ref_type() to properly handle potential recursion for BTF_KIND_TYPEDEF, similar to how recursion is already handled for BTF_KIND_STRUCT. This allows pahole to successfully generate BTF for Go binaries using recursive types without impacting existing C-based workflows. Suggested-by: Tristan d'Audibert Co-developed-by: Martin Horth Co-developed-by: Ouail Derghal Co-developed-by: Guilhem Jazeron Co-developed-by: Ludovic Paillat Co-developed-by: Robin Theveniaut Signed-off-by: Martin Horth Signed-off-by: Ouail Derghal Signed-off-by: Guilhem Jazeron Signed-off-by: Ludovic Paillat Signed-off-by: Robin Theveniaut Signed-off-by: Paul Houssel Signed-off-by: Andrii Nakryiko Acked-by: Eduard Zingerman Link: https://lore.kernel.org/bpf/bf00857b1e06f282aac12f6834de7396a7547ba6.1763037045.git.paul.houssel@orange.com

libbpf: Fix parsing of multi-split BTF

2025-11-04T21:44:12+00:00

When creating multi-split BTF we correctly set the start string offset to be the size of the base string section plus the base BTF start string offset; the latter is needed for multi-split BTF since the offset is non-zero there. Unfortunately the BTF parsing case needed that logic and it was missed. Fixes: 4e29128a9ace ("libbpf/btf: Fix string handling to support multi-split BTF") Signed-off-by: Alan Maguire Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20251104203309.318429-2-alan.maguire@oracle.com

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: Handle unsupported mmap-based /sys/kernel/btf/vmlinux correctly

2025-06-06T21:07:07+00:00

libbpf_err_ptr() helpers are meant to return NULL and set errno, if there is an error. But btf_parse_raw_mmap() is meant to be used internally and is expected to return ERR_PTR() values. Because of this mismatch, when libbpf tries to mmap /sys/kernel/btf/vmlinux, we don't detect the error correctly with IS_ERR() check, and never fallback to old non-mmap-based way of loading vmlinux BTF. Fix this by using proper ERR_PTR() returns internally. Reported-by: Arnaldo Carvalho de Melo Reviewed-by: Arnaldo Carvalho de Melo Tested-by: Arnaldo Carvalho de Melo Fixes: 3c0421c93ce4 ("libbpf: Use mmap to parse vmlinux BTF from sysfs") Cc: Lorenz Bauer Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/r/20250606202134.2738910-1-andrii@kernel.org Signed-off-by: Alexei Starovoitov

libbpf: Use mmap to parse vmlinux BTF from sysfs

2025-05-23T17:06:28+00:00

Teach libbpf to use mmap when parsing vmlinux BTF from /sys. We don't apply this to fall-back paths on the regular file system because there is no way to ensure that modifications underlying the MAP_PRIVATE mapping are not visible to the process. Signed-off-by: Lorenz Bauer Signed-off-by: Andrii Nakryiko Tested-by: Alan Maguire Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20250520-vmlinux-mmap-v5-3-e8c941acc414@isovalent.com