In order to allow the BPF program in bpftool's pid_iter.bpf.c to compile
correctly on hosts where vmlinux.h does not define
BPF_LINK_TYPE_PERF_EVENT (running kernel versions lower than 5.15, for
example), define and use a local copy of the enum value. This requires
LLVM 12 or newer to build the BPF program.
Fixes: cbdaf71f7e65 ("bpftool: Add bpf_cookie to link output")
Signed-off-by: Quentin Monnet <quentin@xxxxxxxxxxxxx>
---
tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
index 3a4c4f7d83d8..26004f0c5a6a 100644
--- a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
+++ b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
@@ -24,6 +24,10 @@ struct perf_event___local {
u64 bpf_cookie;
} __attribute__((preserve_access_index));
+enum bpf_link_type___local {
+ BPF_LINK_TYPE_PERF_EVENT___local = 7,
+};
+
extern const void bpf_link_fops __ksym;
extern const void bpf_map_fops __ksym;
extern const void bpf_prog_fops __ksym;
@@ -93,10 +97,13 @@ int iter(struct bpf_iter__task_file *ctx)
e.pid = task->tgid;
e.id = get_obj_id(file->private_data, obj_type);
- if (obj_type == BPF_OBJ_LINK) {
+ if (obj_type == BPF_OBJ_LINK &&
+ bpf_core_enum_value_exists(enum bpf_link_type___local,
+ BPF_LINK_TYPE_PERF_EVENT___local)) {
struct bpf_link *link = (struct bpf_link *) file->private_data;
- if (BPF_CORE_READ(link, type) == BPF_LINK_TYPE_PERF_EVENT) {
+ if (link->type == bpf_core_enum_value(enum bpf_link_type___local,
+ BPF_LINK_TYPE_PERF_EVENT___local)) {
e.has_bpf_cookie = true;
e.bpf_cookie = get_bpf_cookie(link);
}
--
2.34.1
