Re: [PATCHv2 bpf-next 12/24] libbpf: Add support for u[ret]probe.multi[.s] program sections

Jiri Olsa
2023-06-25T01:20:10Z

On Fri, Jun 23, 2023 at 01:40:13PM -0700, Andrii Nakryiko wrote:
> On Tue, Jun 20, 2023 at 1:37 AM Jiri Olsa <jolsa@kernel.org> wrote:
> >
> > Adding support for several uprobe_multi program sections
> > to allow auto attach of multi_uprobe programs.
> >
> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> > ---
> > tools/lib/bpf/libbpf.c | 40 ++++++++++++++++++++++++++++++++++++++++
> > 1 file changed, 40 insertions(+)
> >
> > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> > index d972cea4c658..e42080258ec7 100644
> > --- a/tools/lib/bpf/libbpf.c
> > +++ b/tools/lib/bpf/libbpf.c
> > @@ -8652,6 +8652,7 @@ static int attach_tp(const struct bpf_program *prog, long cookie, struct bpf_lin
> > static int attach_raw_tp(const struct bpf_program *prog, long cookie, struct bpf_link **link);
> > static int attach_trace(const struct bpf_program *prog, long cookie, struct bpf_link **link);
> > static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
> > +static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link);
> > static int attach_lsm(const struct bpf_program *prog, long cookie, struct bpf_link **link);
> > static int attach_iter(const struct bpf_program *prog, long cookie, struct bpf_link **link);
> >
> > @@ -8667,6 +8668,10 @@ static const struct bpf_sec_def section_defs[] = {
> > SEC_DEF("uretprobe.s+", KPROBE, 0, SEC_SLEEPABLE, attach_uprobe),
> > SEC_DEF("kprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
> > SEC_DEF("kretprobe.multi+", KPROBE, BPF_TRACE_KPROBE_MULTI, SEC_NONE, attach_kprobe_multi),
> > + SEC_DEF("uprobe.multi+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
> > + SEC_DEF("uretprobe.multi+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_NONE, attach_uprobe_multi),
> > + SEC_DEF("uprobe.multi.s+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
> > + SEC_DEF("uretprobe.multi.s+", KPROBE, BPF_TRACE_UPROBE_MULTI, SEC_SLEEPABLE, attach_uprobe_multi),
> > SEC_DEF("ksyscall+", KPROBE, 0, SEC_NONE, attach_ksyscall),
> > SEC_DEF("kretsyscall+", KPROBE, 0, SEC_NONE, attach_ksyscall),
> > SEC_DEF("usdt+", KPROBE, 0, SEC_NONE, attach_usdt),
> > @@ -10728,6 +10733,41 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru
> > return libbpf_get_error(*link);
> > }
> >
> > +static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, struct bpf_link **link)
> > +{
> > + char *probe_type = NULL, *binary_path = NULL, *func_name = NULL;
> > + LIBBPF_OPTS(bpf_uprobe_multi_opts, opts);
> > + int n, ret = -EINVAL;
> > +
> > + *link = NULL;
> > +
> > + n = sscanf(prog->sec_name, "%m[^/]/%m[^:]:%ms",
> > + &probe_type, &binary_path, &func_name);
> > + switch (n) {
> > + case 1:
> > + /* handle SEC("u[ret]probe") - format is valid, but auto-attach is impossible. */
> > + ret = 0;
> > + break;
> > + case 2:
> > + pr_warn("prog '%s': section '%s' missing ':function[+offset]' specification\n",
>
> message copy/pasted? We don't support +offset part, and it's not
> "function", but "pattern" or something along those lines?

yes, will fix

>
> > + prog->name, prog->sec_name);
> > + break;
> > + case 3:
> > + opts.retprobe = strcmp(probe_type, "uretprobe.multi");
>
> == 0

ok, thanks

jirka

>
>
> > + *link = bpf_program__attach_uprobe_multi_opts(prog, -1, binary_path, func_name, &opts);
> > + ret = libbpf_get_error(*link);
> > + break;
> > + default:
> > + pr_warn("prog '%s': invalid format of section definition '%s'\n", prog->name,
> > + prog->sec_name);
> > + break;
> > + }
> > + free(probe_type);
> > + free(binary_path);
> > + free(func_name);
> > + return ret;
> > +}
> > +
> > static void gen_uprobe_legacy_event_name(char *buf, size_t buf_sz,
> > const char *binary_path, uint64_t offset)
> > {
> > --
> > 2.41.0
> >