This patch finalizes support for the proposed type match relation in libbpf by hooking it up to the TYPE_MATCH relocation. For this relocation to be handled correctly by LLVM we have D126838 (https://reviews.llvm.org/D126838). The main functionality is present behind the newly introduced bpf_core_type_matches macro (similar to bpf_core_type_exists). This macro can be used to check whether a local type has a "match" in a target BTF. Signed-off-by: Daniel Müller <deso@xxxxxxxxxx> --- tools/lib/bpf/bpf_core_read.h | 10 ++++++++++ tools/lib/bpf/libbpf.c | 6 ++++++ tools/lib/bpf/relo_core.c | 16 ++++++++++++---- tools/lib/bpf/relo_core.h | 2 ++ 4 files changed, 30 insertions(+), 4 deletions(-) diff --git a/tools/lib/bpf/bpf_core_read.h b/tools/lib/bpf/bpf_core_read.h index 2308f49..496e6a 100644 --- a/tools/lib/bpf/bpf_core_read.h +++ b/tools/lib/bpf/bpf_core_read.h @@ -184,6 +184,16 @@ enum bpf_enum_value_kind { #define bpf_core_type_exists(type) \ __builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_EXISTS) +/* + * Convenience macro to check that provided named type + * (struct/union/enum/typedef) "matches" that in a target kernel. + * Returns: + * 1, if the type matches in the target kernel's BTF; + * 0, if the type does not match any in the target kernel + */ +#define bpf_core_type_matches(type) \ + __builtin_preserve_type_info(*(typeof(type) *)0, BPF_TYPE_MATCHES) + /* * Convenience macro to get the byte size of a provided named type * (struct/union/enum/typedef) in a target kernel. diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 335467..92fc399 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -5735,6 +5735,12 @@ int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id, return __bpf_core_types_are_compat(local_btf, local_id, targ_btf, targ_id, 32); } +int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, + const struct btf *targ_btf, __u32 targ_id) +{ + return __bpf_core_types_match(local_btf, local_id, targ_btf, targ_id, false, 32); +} + static size_t bpf_core_hash_fn(const void *key, void *ctx) { return (size_t)key; diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c index b3f5d7e..5f1294c7 100644 --- a/tools/lib/bpf/relo_core.c +++ b/tools/lib/bpf/relo_core.c @@ -95,6 +95,7 @@ static const char *core_relo_kind_str(enum bpf_core_relo_kind kind) case BPF_CORE_TYPE_ID_LOCAL: return "local_type_id"; case BPF_CORE_TYPE_ID_TARGET: return "target_type_id"; case BPF_CORE_TYPE_EXISTS: return "type_exists"; + case BPF_CORE_TYPE_MATCHES: return "type_matches"; case BPF_CORE_TYPE_SIZE: return "type_size"; case BPF_CORE_ENUMVAL_EXISTS: return "enumval_exists"; case BPF_CORE_ENUMVAL_VALUE: return "enumval_value"; @@ -123,6 +124,7 @@ static bool core_relo_is_type_based(enum bpf_core_relo_kind kind) case BPF_CORE_TYPE_ID_LOCAL: case BPF_CORE_TYPE_ID_TARGET: case BPF_CORE_TYPE_EXISTS: + case BPF_CORE_TYPE_MATCHES: case BPF_CORE_TYPE_SIZE: return true; default: @@ -251,7 +253,7 @@ int __bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id, * - field 'a' access (corresponds to '2' in low-level spec); * - array element #3 access (corresponds to '3' in low-level spec). * - * Type-based relocations (TYPE_EXISTS/TYPE_SIZE, + * Type-based relocations (TYPE_EXISTS/TYPE_MATCHES/TYPE_SIZE, * TYPE_ID_LOCAL/TYPE_ID_TARGET) don't capture any field information. Their * spec and raw_spec are kept empty. * @@ -568,9 +570,14 @@ static int bpf_core_spec_match(struct bpf_core_spec *local_spec, targ_spec->relo_kind = local_spec->relo_kind; if (core_relo_is_type_based(local_spec->relo_kind)) { - return bpf_core_types_are_compat(local_spec->btf, - local_spec->root_type_id, - targ_btf, targ_id); + if (local_spec->relo_kind == BPF_CORE_TYPE_MATCHES) + return bpf_core_types_match(local_spec->btf, + local_spec->root_type_id, + targ_btf, targ_id); + else + return bpf_core_types_are_compat(local_spec->btf, + local_spec->root_type_id, + targ_btf, targ_id); } local_acc = &local_spec->spec[0]; @@ -819,6 +826,7 @@ static int bpf_core_calc_type_relo(const struct bpf_core_relo *relo, *validate = false; break; case BPF_CORE_TYPE_EXISTS: + case BPF_CORE_TYPE_MATCHES: *val = 1; break; case BPF_CORE_TYPE_SIZE: diff --git a/tools/lib/bpf/relo_core.h b/tools/lib/bpf/relo_core.h index 8462e0a..1c0566d 100644 --- a/tools/lib/bpf/relo_core.h +++ b/tools/lib/bpf/relo_core.h @@ -74,6 +74,8 @@ int bpf_core_types_are_compat(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf, __u32 targ_id); int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf, __u32 targ_id, bool behind_ptr, int level); +int bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const struct btf *targ_btf, + __u32 targ_id); size_t bpf_core_essential_name_len(const char *name); -- 2.30.2
