libbpf-rs: Add test attaching a BPF program to a uprobe

This change adds a test that checks that we can correctly attach a BPF
program to a uprobe on a function.

Signed-off-by: Daniel Müller <deso@posteo.net>

Author: d-e-s-o

libbpf-rs/tests/bin/src/uprobe.bpf.c

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include "vmlinux.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/usdt.bpf.h>
+
+struct {
+    __uint(type, BPF_MAP_TYPE_RINGBUF);
+    __uint(max_entries, 4096 /* one page */);
+} ringbuf SEC(".maps");
+
+SEC("uprobe")
+int handle__uprobe(void *ctx)
+{
+    int *value;
+
+    value = bpf_ringbuf_reserve(&ringbuf, sizeof(int), 0);
+    if (value) {
+        *value = 1;
+        bpf_ringbuf_submit(value, 0);
+    }
+
+    return 0;
+}
+
+SEC("uprobe")
+int handle__uprobe_with_cookie(void *ctx)
+{
+    int *value;
+
+    value = bpf_ringbuf_reserve(&ringbuf, sizeof(int), 0);
+    if (value) {
+        *value = bpf_get_attach_cookie(ctx);
+        bpf_ringbuf_submit(value, 0);
+    }
+
+    return 0;
+}
+
+char LICENSE[] SEC("license") = "GPL";

libbpf-rs/tests/bin/uprobe.bpf.o

@@ -14,7 +14,7 @@ use scopeguard::defer;
 
 use libbpf_rs::{
     num_possible_cpus, Iter, Map, MapFlags, MapType, Object, ObjectBuilder, OpenObject,
-    ProgramType, TracepointOpts, UsdtOpts,
+    ProgramType, TracepointOpts, UprobeOpts, UsdtOpts,
 };
 
 fn get_test_object_path(filename: &str) -> PathBuf {
@@ -937,3 +937,72 @@ fn test_object_tracepoint_with_opts() {
 
     assert_eq!(result, cookie_val.into());
 }
+
+#[inline(never)]
+#[no_mangle]
+extern "C" fn uprobe_target() -> usize {
+    42
+}
+
+/// Check that we can attach a BPF program to a uprobe.
+#[test]
+fn test_object_uprobe_with_opts() {
+    bump_rlimit_mlock();
+
+    let mut obj = get_test_object("uprobe.bpf.o");
+    let prog = obj
+        .prog_mut("handle__uprobe")
+        .expect("Failed to find program");
+
+    let pid = unsafe { libc::getpid() };
+    let path = std::env::current_exe().expect("Failed to find executable name");
+    let func_offset = 0;
+    let opts = UprobeOpts {
+        func_name: "uprobe_target".to_string(),
+        ..Default::default()
+    };
+    let _link = prog
+        .attach_uprobe_with_opts(pid, path, func_offset, opts)
+        .expect("Failed to attach prog");
+
+    let map = obj.map("ringbuf").expect("Failed to get ringbuf map");
+    let action = || {
+        let _ = uprobe_target();
+    };
+    let result = with_ringbuffer(map, action);
+
+    assert_eq!(result, 1);
+}
+
+/// Check that we can attach a BPF program to a uprobe and access the cookie
+/// provided during attach.
+#[test]
+fn test_object_uprobe_with_cookie() {
+    bump_rlimit_mlock();
+
+    let cookie_val = 5u16;
+    let mut obj = get_test_object("uprobe.bpf.o");
+    let prog = obj
+        .prog_mut("handle__uprobe_with_cookie")
+        .expect("Failed to find program");
+
+    let pid = unsafe { libc::getpid() };
+    let path = std::env::current_exe().expect("Failed to find executable name");
+    let func_offset = 0;
+    let opts = UprobeOpts {
+        func_name: "uprobe_target".to_string(),
+        cookie: cookie_val.into(),
+        ..Default::default()
+    };
+    let _link = prog
+        .attach_uprobe_with_opts(pid, path, func_offset, opts)
+        .expect("Failed to attach prog");
+
+    let map = obj.map("ringbuf").expect("Failed to get ringbuf map");
+    let action = || {
+        let _ = uprobe_target();
+    };
+    let result = with_ringbuffer(map, action);
+
+    assert_eq!(result, cookie_val.into());
+}