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

Andrii Nakryiko
2023-06-23T20:41:10Z

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?

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

== 0

> + *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
>