On Mon, Apr 22, 2024 at 5:13 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
>
> Adding support to attach program in kprobe multi session mode
> with bpf_program__attach_kprobe_multi_opts function.
>
> Adding session bool to bpf_kprobe_multi_opts struct that allows
> to load and attach the bpf program via kprobe multi session.
> the attachment to create kprobe multi session.
>
> Also adding new program loader section that allows:
> SEC("kprobe.session/bpf_fentry_test*")
>
> and loads/attaches kprobe program as kprobe multi session.
>
> Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> ---
> tools/lib/bpf/bpf.c | 1 +
> tools/lib/bpf/libbpf.c | 40 ++++++++++++++++++++++++++++++++++++++--
> tools/lib/bpf/libbpf.h | 4 +++-
> 3 files changed, 42 insertions(+), 3 deletions(-)
>
Minor nits below, but LGTM overall:
Acked-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
> diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
> index c9f4e04f38fe..5f556e38910f 100644
> --- a/tools/lib/bpf/bpf.c
> +++ b/tools/lib/bpf/bpf.c
> @@ -766,6 +766,7 @@ int bpf_link_create(int prog_fd, int target_fd,
> return libbpf_err(-EINVAL);
> break;
> case BPF_TRACE_KPROBE_MULTI:
> + case BPF_TRACE_KPROBE_MULTI_SESSION:
> attr.link_create.kprobe_multi.flags = OPTS_GET(opts, kprobe_multi.flags, 0);
> attr.link_create.kprobe_multi.cnt = OPTS_GET(opts, kprobe_multi.cnt, 0);
> attr.link_create.kprobe_multi.syms = ptr_to_u64(OPTS_GET(opts, kprobe_multi.syms, 0));
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 97eb6e5dd7c8..ca605240205f 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -9272,6 +9272,7 @@ 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_kprobe_session(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);
> @@ -9288,6 +9289,7 @@ 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("kprobe.session+", KPROBE, BPF_TRACE_KPROBE_MULTI_SESSION, SEC_NONE, attach_kprobe_session),
> 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),
> @@ -11380,13 +11382,14 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
> struct kprobe_multi_resolve res = {
> .pattern = pattern,
> };
> + enum bpf_attach_type attach_type;
> struct bpf_link *link = NULL;
> char errmsg[STRERR_BUFSIZE];
> const unsigned long *addrs;
> int err, link_fd, prog_fd;
> + bool retprobe, session;
> const __u64 *cookies;
> const char **syms;
> - bool retprobe;
> size_t cnt;
>
> if (!OPTS_VALID(opts, bpf_kprobe_multi_opts))
> @@ -11425,6 +11428,13 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
> }
>
> retprobe = OPTS_GET(opts, retprobe, false);
> + session = OPTS_GET(opts, session, false);
> +
> + if (retprobe && session)
> + return libbpf_err_ptr(-EINVAL);
> +
> + attach_type = session ? BPF_TRACE_KPROBE_MULTI_SESSION :
> + BPF_TRACE_KPROBE_MULTI;
doesn't fit under 100?
>
> lopts.kprobe_multi.syms = syms;
> lopts.kprobe_multi.addrs = addrs;
> @@ -11439,7 +11449,7 @@ bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
> }
> link->detach = &bpf_link__detach_fd;
>
> - link_fd = bpf_link_create(prog_fd, 0, BPF_TRACE_KPROBE_MULTI, &lopts);
> + link_fd = bpf_link_create(prog_fd, 0, attach_type, &lopts);
> if (link_fd < 0) {
> err = -errno;
> pr_warn("prog '%s': failed to attach: %s\n",
> @@ -11545,6 +11555,32 @@ static int attach_kprobe_multi(const struct bpf_program *prog, long cookie, stru
> return libbpf_get_error(*link);
> }
>
> +static int attach_kprobe_session(const struct bpf_program *prog, long cookie,
> + struct bpf_link **link)
> +{
> + LIBBPF_OPTS(bpf_kprobe_multi_opts, opts, .session = true);
> + const char *spec;
> + char *pattern;
> + int n;
> +
> + *link = NULL;
> +
> + /* no auto-attach for SEC("kprobe.session") */
> + if (strcmp(prog->sec_name, "kprobe.session") == 0)
> + return 0;
> +
> + spec = prog->sec_name + sizeof("kprobe.session/") - 1;
> + n = sscanf(spec, "%m[a-zA-Z0-9_.*?]", &pattern);
> + if (n < 1) {
> + pr_warn("kprobe session pattern is invalid: %s\n", pattern);
> + return -EINVAL;
> + }
> +
> + *link = bpf_program__attach_kprobe_multi_opts(prog, pattern, &opts);
> + free(pattern);
> + return libbpf_get_error(*link);
let's try not to add new uses of libbpf_get_error? Would this work:
return *link ? 0 : -errno;
?
> +}
> +
> 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;
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 1333ae20ebe6..c3f77d9260fe 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -539,10 +539,12 @@ struct bpf_kprobe_multi_opts {
> size_t cnt;
> /* create return kprobes */
> bool retprobe;
> + /* create session kprobes */
> + bool session;
> size_t :0;
> };
>
> -#define bpf_kprobe_multi_opts__last_field retprobe
> +#define bpf_kprobe_multi_opts__last_field session
>
> LIBBPF_API struct bpf_link *
> bpf_program__attach_kprobe_multi_opts(const struct bpf_program *prog,
> --
> 2.44.0
>
