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Merge branch 'bpf: Show target_{obj,btf}_id for tracing link'

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Yafang Shao says:

====================
The target_btf_id can help us understand which kernel function is
linked by a tracing prog. The target_btf_id and target_obj_id have
already been exposed to userspace, so we just need to show them.

For some other link types like perf_event and kprobe_multi, it is not
easy to find which functions are attached either. We may support
->fill_link_info for them in the future.

v1->v2:
- Skip showing them in the plain output for the old kernels. (Quentin)
- Coding improvement. (Andrii)
====================

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2023-05-19 10:06:45 -07:00
commit 9343184cb3
2 changed files with 15 additions and 2 deletions
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11
kernel/bpf/syscall.c
View file

@ -2968,10 +2968,17 @@ static void bpf_tracing_link_show_fdinfo(const struct bpf_link *link,
{
struct bpf_tracing_link *tr_link =
container_of(link, struct bpf_tracing_link, link.link);
u32 target_btf_id, target_obj_id;
bpf_trampoline_unpack_key(tr_link->trampoline->key,
&target_obj_id, &target_btf_id);
seq_printf(seq,
"attach_type:\t%d\n",
tr_link->attach_type);
"attach_type:\t%d\n"
"target_obj_id:\t%u\n"
"target_btf_id:\t%u\n",
tr_link->attach_type,
target_obj_id,
target_btf_id);
}
static int bpf_tracing_link_fill_link_info(const struct bpf_link *link,

6
tools/bpf/bpftool/link.c
View file

@ -195,6 +195,8 @@ static int show_link_close_json(int fd, struct bpf_link_info *info)
show_link_attach_type_json(info->tracing.attach_type,
json_wtr);
jsonw_uint_field(json_wtr, "target_obj_id", info->tracing.target_obj_id);
jsonw_uint_field(json_wtr, "target_btf_id", info->tracing.target_btf_id);
break;
case BPF_LINK_TYPE_CGROUP:
jsonw_lluint_field(json_wtr, "cgroup_id",
@ -375,6 +377,10 @@ static int show_link_close_plain(int fd, struct bpf_link_info *info)
printf("\n\tprog_type %u ", prog_info.type);
show_link_attach_type_plain(info->tracing.attach_type);
if (info->tracing.target_obj_id || info->tracing.target_btf_id)
printf("\n\ttarget_obj_id %u target_btf_id %u ",
info->tracing.target_obj_id,
info->tracing.target_btf_id);
break;
case BPF_LINK_TYPE_CGROUP:
printf("\n\tcgroup_id %zu ", (size_t)info->cgroup.cgroup_id);