selftests/net: add _find_bpf_obj() to search hw/ for BPF objects

Add _find_bpf_obj() helper to NetDrvContEnv that searches the test
directory first, then falls back to the hw/ subdirectory. This allows
tests outside drivers/net/hw/ (e.g. psp.py in drivers/net/) to find
BPF objects built in the hw/ directory.

Update _attach_bpf() and _attach_primary_rx_redirect_bpf() to use
_find_bpf_obj() for BPF object discovery.

Signed-off-by: Wei Wang <weibunny@fb.com>
Link: https://patch.msgid.link/20260608233118.2694144-6-weibunny.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

tools/testing/selftests/drivers/net/lib/py/env.py

@@ -512,10 +512,19 @@ class NetDrvContEnv(NetDrvEpEnv):
                 return map_id
         raise Exception(f"Failed to find .bss map for prog {prog_id}")
 
+    def _find_bpf_obj(self, name):
+        bpf_obj = self.test_dir / name
+        if bpf_obj.exists():
+            return bpf_obj
+        bpf_obj = self.test_dir / "hw" / name
+        if bpf_obj.exists():
+            return bpf_obj
+        return None
+
     def _attach_bpf(self):
-        bpf_obj = self.test_dir / "nk_forward.bpf.o"
-        if not bpf_obj.exists():
-            raise KsftSkipEx("BPF prog not found")
+        bpf_obj = self._find_bpf_obj("nk_forward.bpf.o")
+        if not bpf_obj:
+            raise KsftSkipEx("BPF prog nk_forward.bpf.o not found")
 
         if self._tc_ensure_clsact():
             self._tc_clsact_added = True
@@ -535,9 +544,9 @@ class NetDrvContEnv(NetDrvEpEnv):
 
     def _attach_primary_rx_redirect_bpf(self):
         """Attach BPF redirect program on the primary netkit ingress."""
-        bpf_obj = self.test_dir / "nk_primary_rx_redirect.bpf.o"
-        if not bpf_obj.exists():
-            raise KsftSkipEx("Primary RX redirect BPF prog not found")
+        bpf_obj = self._find_bpf_obj("nk_primary_rx_redirect.bpf.o")
+        if not bpf_obj:
+            raise KsftSkipEx("nk_primary_rx_redirect.bpf.o not found")
 
         if self._tc_ensure_clsact(self._nk_host_ifname):
             self._primary_rx_redirect_clsact_added = True