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authorAlexander Lobakin <alobakin@pm.me>2023-07-07 11:54:22 +0200
committerAndrii Nakryiko <andrii@kernel.org>2023-07-11 00:29:20 +0200
commit4cbeeb0dc02f8ac7b975b2ab0080ace53d43d62a (patch)
treeb8402a4ba990cf86f9d253581071f6a1ac57213f /tools
parentlibbpf: only reset sec_def handler when necessary (diff)
downloadlinux-4cbeeb0dc02f8ac7b975b2ab0080ace53d43d62a.tar.xz
linux-4cbeeb0dc02f8ac7b975b2ab0080ace53d43d62a.zip
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
Diffstat (limited to 'tools')
-rw-r--r--tools/bpf/bpftool/skeleton/pid_iter.bpf.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
index eb05ea53afb1..e2af8e5fb29e 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);