6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alexander Lobakin <alobakin@xxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: Alexander Lobakin <alobakin@xxxxx>
Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20230707095425.168126-2-quentin@xxxxxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.40.1
