On Mon, Sep 30, 2024 at 02:36:35PM -0700, Andrii Nakryiko wrote:

On Sun, Sep 29, 2024 at 1:58 PM Jiri Olsa [off-list ref] wrote:

quoted

Adding support to attach program in uprobe session mode
with bpf_program__attach_uprobe_multi function.

Adding session bool to bpf_uprobe_multi_opts struct that allows
to load and attach the bpf program via uprobe session.
the attachment to create uprobe multi session.

Also adding new program loader section that allows:
  SEC("uprobe.session/bpf_fentry_test*")

and loads/attaches uprobe program as uprobe session.

Adding sleepable hook (uprobe.session.s) as well.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/lib/bpf/bpf.c    |  1 +
 tools/lib/bpf/libbpf.c | 21 ++++++++++++++++++---
 tools/lib/bpf/libbpf.h |  4 +++-
 3 files changed, 22 insertions(+), 4 deletions(-)

LGTM, though see the nit below

Acked-by: Andrii Nakryiko <andrii@kernel.org>

quoted

diff --git a/tools/lib/bpf/bpf.c b/tools/lib/bpf/bpf.c
index 2a4c71501a17..becdfa701c75 100644
--- a/tools/lib/bpf/bpf.c
+++ b/tools/lib/bpf/bpf.c

@@ -776,6 +776,7 @@ int bpf_link_create(int prog_fd, int target_fd,
                        return libbpf_err(-EINVAL);
                break;
        case BPF_TRACE_UPROBE_MULTI:
+       case BPF_TRACE_UPROBE_SESSION:
                attr.link_create.uprobe_multi.flags = OPTS_GET(opts, uprobe_multi.flags, 0);
                attr.link_create.uprobe_multi.cnt = OPTS_GET(opts, uprobe_multi.cnt, 0);
                attr.link_create.uprobe_multi.path = ptr_to_u64(OPTS_GET(opts, uprobe_multi.path, 0));

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 3587ed7ec359..563ff5e64269 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c

@@ -9410,8 +9410,10 @@ static const struct bpf_sec_def section_defs[] = {
        SEC_DEF("kprobe.session+",      KPROBE, BPF_TRACE_KPROBE_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.session+",      KPROBE, BPF_TRACE_UPROBE_SESSION, 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("uprobe.session.s+",    KPROBE, BPF_TRACE_UPROBE_SESSION, 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_USDT, attach_usdt),

@@ -11733,7 +11735,10 @@ static int attach_uprobe_multi(const struct bpf_program *prog, long cookie, stru
                ret = 0;
                break;
        case 3:
-               opts.retprobe = str_has_pfx(probe_type, "uretprobe.multi");
+               if (str_has_pfx(probe_type, "uprobe.session"))
+                       opts.session = true;
+               else
+                       opts.retprobe = str_has_pfx(probe_type, "uretprobe.multi");

nit: this is very non-uniform, can you please just do:

opts.session = str_has_pfx(probe_type, "uprobe.session");
opts.retprobe = str_has_pfx(probe_type, "uretprobe.multi");

There is no need to micro-optimize str_has_pfx() calls, IMO.

sure, will change

thanks,
jirka