6.1-stable review patch. If anyone has any objections, please let me know.
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From: Alexander Lobakin alobakin@pm.me
[ Upstream commit 4cbeeb0dc02f8ac7b975b2ab0080ace53d43d62a ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c index eb05ea53afb12..e2af8e5fb29ec 100644 --- a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c +++ b/tools/bpf/bpftool/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);