On Tue, Apr 01, 2025 at 03:06:22PM -0700, Andrii Nakryiko wrote: > On Tue, Apr 1, 2025 at 5:40 AM Tao Chen <[email protected]> wrote: > > > > 在 2025/4/1 19:03, Jiri Olsa 写道: > > > On Mon, Mar 31, 2025 at 05:47:45PM +0800, Tao Chen wrote: > > >> The target_fd and flags in link_create no used in multi_uprobe > > >> , return -EINVAL if they assigned, keep it same as other link > > >> attach apis. > > >> > > >> Fixes: 89ae89f53d20 ("bpf: Add multi uprobe link") > > >> Signed-off-by: Tao Chen <[email protected]> > > >> --- > > >> kernel/trace/bpf_trace.c | 3 +++ > > >> 1 file changed, 3 insertions(+) > > >> > > >> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c > > >> index 2f206a2a2..f7ebf17e3 100644 > > >> --- a/kernel/trace/bpf_trace.c > > >> +++ b/kernel/trace/bpf_trace.c > > >> @@ -3385,6 +3385,9 @@ int bpf_uprobe_multi_link_attach(const union > > >> bpf_attr *attr, struct bpf_prog *pr > > >> if (sizeof(u64) != sizeof(void *)) > > >> return -EOPNOTSUPP; > > >> > > >> + if (attr->link_create.target_fd || attr->link_create.flags) > > >> + return -EINVAL; > > > > > > I think the CI is failing because usdt code does uprobe multi detection > > > with target_fd = -1 and it fails and perf-uprobe fallback will fail on > > > not having enough file descriptors > > > > > > > Hi jiri > > > > As you said, i found it, thanks. > > > > static int probe_uprobe_multi_link(int token_fd) > > { > > LIBBPF_OPTS(bpf_prog_load_opts, load_opts, > > .expected_attach_type = BPF_TRACE_UPROBE_MULTI, > > .token_fd = token_fd, > > .prog_flags = token_fd ? BPF_F_TOKEN_FD : 0, > > ); > > LIBBPF_OPTS(bpf_link_create_opts, link_opts); > > struct bpf_insn insns[] = { > > BPF_MOV64_IMM(BPF_REG_0, 0), > > BPF_EXIT_INSN(), > > }; > > int prog_fd, link_fd, err; > > unsigned long offset = 0; > > > > prog_fd = bpf_prog_load(BPF_PROG_TYPE_KPROBE, NULL, "GPL", > > insns, ARRAY_SIZE(insns), &load_opts); > > if (prog_fd < 0) > > return -errno; > > > > /* Creating uprobe in '/' binary should fail with -EBADF. */ > > link_opts.uprobe_multi.path = "/"; > > link_opts.uprobe_multi.offsets = &offset; > > link_opts.uprobe_multi.cnt = 1; > > > > link_fd = bpf_link_create(prog_fd, -1, BPF_TRACE_UPROBE_MULTI, > > &link_opts); > > > > > but I think at this stage we will brake some user apps by introducing > > > this check, link ebpf go library, which passes 0 > > > > > > > So is it ok just check the flags? > > good catch, Jiri! Yep, let's validate just flags?
I think so.. I'll test that with ebpf/go to make sure we are safe at least there ;-) I'll let you know jirka > > pw-bot: cr > > > > > > jirka > > > > > > > > >> + > > >> if (!is_uprobe_multi(prog)) > > >> return -EINVAL; > > >> > > >> -- > > >> 2.43.0 > > >> > > > > > > -- > > Best Regards > > Tao Chen > >
