From: Hou Tao houtao1@huawei.com
mainline inclusion from mainline-v6.11-rc1 commit 0be9ae5486cd9e767138c13638820d240713f5f1 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAHA5K
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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Since commit 0108a4e9f358 ("bpf: ensure main program has an extable"), prog->aux->func[0]->kallsyms is left as uninitialized. For BPF programs with subprogs, the symbol for the main program is missing just as shown in the output of perf script below:
ffffffff81284b69 qp_trie_lookup_elem+0xb9 ([kernel.kallsyms]) ffffffffc0011125 bpf_prog_a4a0eb0651e6af8b_lookup_qp_trie+0x5d (bpf...) ffffffff8127bc2b bpf_for_each_array_elem+0x7b ([kernel.kallsyms]) ffffffffc00110a1 +0x25 () ffffffff8121a89a trace_call_bpf+0xca ([kernel.kallsyms])
Fix it by always using prog instead prog->aux->func[0] to emit ksymbol event for the main program. After the fix, the output of perf script will be correct:
ffffffff81284b96 qp_trie_lookup_elem+0xe6 ([kernel.kallsyms]) ffffffffc001382d bpf_prog_a4a0eb0651e6af8b_lookup_qp_trie+0x5d (bpf...) ffffffff8127bc2b bpf_for_each_array_elem+0x7b ([kernel.kallsyms]) ffffffffc0013779 bpf_prog_245c55ab25cfcf40_qp_trie_lookup+0x25 (bpf...) ffffffff8121a89a trace_call_bpf+0xca ([kernel.kallsyms])
Fixes: 0108a4e9f358 ("bpf: ensure main program has an extable") Signed-off-by: Hou Tao houtao1@huawei.com Signed-off-by: Daniel Borkmann daniel@iogearbox.net Tested-by: Yonghong Song yonghong.song@linux.dev Reviewed-by: Krister Johansen kjlx@templeofstupid.com Reviewed-by: Jiri Olsa jolsa@kernel.org Link: https://lore.kernel.org/bpf/20240714065533.1112616-1-houtao@huaweicloud.com Signed-off-by: Tengda Wu wutengda2@huawei.com --- kernel/events/core.c | 28 +++++++++++++--------------- 1 file changed, 13 insertions(+), 15 deletions(-)
diff --git a/kernel/events/core.c b/kernel/events/core.c index a8035a40d839..08823711a6f0 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8733,21 +8733,19 @@ static void perf_event_bpf_emit_ksymbols(struct bpf_prog *prog, bool unregister = type == PERF_BPF_EVENT_PROG_UNLOAD; int i;
- if (prog->aux->func_cnt == 0) { - perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, - (u64)(unsigned long)prog->bpf_func, - prog->jited_len, unregister, - prog->aux->ksym.name); - } else { - for (i = 0; i < prog->aux->func_cnt; i++) { - struct bpf_prog *subprog = prog->aux->func[i]; - - perf_event_ksymbol( - PERF_RECORD_KSYMBOL_TYPE_BPF, - (u64)(unsigned long)subprog->bpf_func, - subprog->jited_len, unregister, - subprog->aux->ksym.name); - } + perf_event_ksymbol(PERF_RECORD_KSYMBOL_TYPE_BPF, + (u64)(unsigned long)prog->bpf_func, + prog->jited_len, unregister, + prog->aux->ksym.name); + + for (i = 1; i < prog->aux->func_cnt; i++) { + struct bpf_prog *subprog = prog->aux->func[i]; + + perf_event_ksymbol( + PERF_RECORD_KSYMBOL_TYPE_BPF, + (u64)(unsigned long)subprog->bpf_func, + subprog->jited_len, unregister, + subprog->aux->ksym.name); } }