diff options
| author | Alexander Lobakin <alobakin@pm.me> | 2023-07-07 10:54:22 +0100 |
|---|---|---|
| committer | Quentin Monnet <qmonnet+github@qoba.lt> | 2023-07-12 15:19:32 +0100 |
| commit | 1f5829e1e8b0bd4b3ac11629fe66aea2eb519ca8 (patch) | |
| tree | fe06eb5a193a24a08d641a12b28de0fa22555282 | |
| parent | 3073a602bc7863404885b4fa951d4bcbea69c943 (diff) | |
| download | bpftool-1f5829e1e8b0bd4b3ac11629fe66aea2eb519ca8.tar.gz | |
bpftool: use a local copy of perf_event to fix accessing :: Bpf_cookie
When CONFIG_PERF_EVENTS is not set, struct perf_event remains empty.
However, the structure is being used by bpftool indirectly via BTF.
This leads to:
skeleton/pid_iter.bpf.c:49:30: error: no member named 'bpf_cookie' in 'struct perf_event'
return BPF_CORE_READ(event, bpf_cookie);
~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
...
skeleton/pid_iter.bpf.c:49:9: error: returning 'void' from a function with incompatible result type '__u64' (aka 'unsigned long long')
return BPF_CORE_READ(event, bpf_cookie);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tools and samples can't use any CONFIG_ definitions, so the fields
used there should always be present.
Define struct perf_event___local with the `preserve_access_index`
attribute inside the pid_iter BPF prog to allow compiling on any
configs. CO-RE will substitute it with the real struct perf_event
accesses later on.
Fixes: cbdaf71f7e65 ("bpftool: Add bpf_cookie to link output")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20230707095425.168126-2-quentin@isovalent.com
| -rw-r--r-- | src/skeleton/pid_iter.bpf.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/src/skeleton/pid_iter.bpf.c b/src/skeleton/pid_iter.bpf.c index eb05ea5..e2af8e5 100644 --- a/src/skeleton/pid_iter.bpf.c +++ b/src/skeleton/pid_iter.bpf.c @@ -15,6 +15,10 @@ enum bpf_obj_type { BPF_OBJ_BTF, }; +struct perf_event___local { + u64 bpf_cookie; +} __attribute__((preserve_access_index)); + extern const void bpf_link_fops __ksym; extern const void bpf_map_fops __ksym; extern const void bpf_prog_fops __ksym; @@ -41,8 +45,8 @@ static __always_inline __u32 get_obj_id(void *ent, enum bpf_obj_type type) /* could be used only with BPF_LINK_TYPE_PERF_EVENT links */ static __u64 get_bpf_cookie(struct bpf_link *link) { + struct perf_event___local *event; struct bpf_perf_link *perf_link; - struct perf_event *event; perf_link = container_of(link, struct bpf_perf_link, link); event = BPF_CORE_READ(perf_link, perf_file, private_data); |