diff options
| author | Eduard Zingerman <eddyz87@gmail.com> | 2024-03-06 12:45:26 +0200 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2024-03-06 15:18:16 -0800 |
| commit | 6ebaa3fb88bbe4c33a0e01ce27007e1dd4fd133c (patch) | |
| tree | a57dae4f7884140f99d6b78f9a461b2b16f9f30d /tools/lib/bpf/features.c | |
| parent | 5ad0ecbe056a4ea5ffaa73e58503a2f87b119a59 (diff) | |
libbpf: Rewrite btf datasec names starting from '?'
Optional struct_ops maps are defined using question mark at the start
of the section name, e.g.:
SEC("?.struct_ops")
struct test_ops optional_map = { ... };
This commit teaches libbpf to detect if kernel allows '?' prefix
in datasec names, and if it doesn't then to rewrite such names
by replacing '?' with '_', e.g.:
DATASEC ?.struct_ops -> DATASEC _.struct_ops
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240306104529.6453-13-eddyz87@gmail.com
Diffstat (limited to 'tools/lib/bpf/features.c')
| -rw-r--r-- | tools/lib/bpf/features.c | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/tools/lib/bpf/features.c b/tools/lib/bpf/features.c index 6b0738ad7063..4e783cc7fc4b 100644 --- a/tools/lib/bpf/features.c +++ b/tools/lib/bpf/features.c @@ -147,6 +147,25 @@ static int probe_kern_btf_datasec(int token_fd) strs, sizeof(strs), token_fd)); } +static int probe_kern_btf_qmark_datasec(int token_fd) +{ + static const char strs[] = "\0x\0?.data"; + /* static int a; */ + __u32 types[] = { + /* int */ + BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4), /* [1] */ + /* VAR x */ /* [2] */ + BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_VAR, 0, 0), 1), + BTF_VAR_STATIC, + /* DATASEC ?.data */ /* [3] */ + BTF_TYPE_ENC(3, BTF_INFO_ENC(BTF_KIND_DATASEC, 0, 1), 4), + BTF_VAR_SECINFO_ENC(2, 0, 4), + }; + + return probe_fd(libbpf__load_raw_btf((char *)types, sizeof(types), + strs, sizeof(strs), token_fd)); +} + static int probe_kern_btf_float(int token_fd) { static const char strs[] = "\0float"; @@ -534,6 +553,9 @@ static struct kern_feature_desc { [FEAT_ARG_CTX_TAG] = { "kernel-side __arg_ctx tag", probe_kern_arg_ctx_tag, }, + [FEAT_BTF_QMARK_DATASEC] = { + "BTF DATASEC names starting from '?'", probe_kern_btf_qmark_datasec, + }, }; bool feat_supported(struct kern_feature_cache *cache, enum kern_feature_id feat_id) |