On 8/7/26 10:57, David Windsor wrote: > Add a regression test for the x86 BPF dispatcher's indirect-jump fallback > under FineIBT. > > This test can crash the kernel on an unfixed FineIBT build and so should > be run in a VM. > > Signed-off-by: David Windsor <[email protected]> > --- > .../bpf/prog_tests/xdp_dispatcher_fineibt.c | 47 +++++++++++++++++++ > .../bpf/progs/xdp_dispatcher_fineibt.c | 18 +++++++ > 2 files changed, 65 insertions(+) > create mode 100644 > tools/testing/selftests/bpf/prog_tests/xdp_dispatcher_fineibt.c > create mode 100644 tools/testing/selftests/bpf/progs/xdp_dispatcher_fineibt.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_dispatcher_fineibt.c > b/tools/testing/selftests/bpf/prog_tests/xdp_dispatcher_fineibt.c > new file mode 100644 > index 000000000000..2d3fc4034eb9 > --- /dev/null > +++ b/tools/testing/selftests/bpf/prog_tests/xdp_dispatcher_fineibt.c > @@ -0,0 +1,47 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 David Windsor */ > + > +/* > + * Regression test for the x86 BPF dispatcher's indirect-jump fallback > + * under FineIBT. > + * > + * WARNING > + * ------- > + * This test can crash the kernel, thus should be run in a VM. > + */ > +#include <uapi/linux/if_link.h> > +#include <test_progs.h> > +#include <network_helpers.h> > +#include "xdp_dispatcher_fineibt.skel.h" > + > +#define IFINDEX_LO 1 > + > +void test_xdp_dispatcher_fineibt(void) > +{ > + struct xdp_dispatcher_fineibt *skel; > + int err, attached_fd, unattached_fd; > + > + LIBBPF_OPTS(bpf_test_run_opts, topts, > + .data_in = &pkt_v4, > + .data_size_in = sizeof(pkt_v4), > + ); > + > + skel = xdp_dispatcher_fineibt__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel_open_and_load")) > + return; > + > + attached_fd = bpf_program__fd(skel->progs.xdp_dispatcher_attached); > + unattached_fd = bpf_program__fd(skel->progs.xdp_dispatcher_unattached); > + > + err = bpf_xdp_attach(IFINDEX_LO, attached_fd, XDP_FLAGS_SKB_MODE, NULL); > + if (!ASSERT_OK(err, "attach_prog")) > + goto out; > + > + err = bpf_prog_test_run_opts(unattached_fd, &topts); > + ASSERT_OK(err, "unattached_test_run"); > + ASSERT_EQ(topts.retval, XDP_PASS, "unattached_retval"); > + > + bpf_xdp_detach(IFINDEX_LO, XDP_FLAGS_SKB_MODE, NULL); > +out: > + xdp_dispatcher_fineibt__destroy(skel); > +} > diff --git a/tools/testing/selftests/bpf/progs/xdp_dispatcher_fineibt.c > b/tools/testing/selftests/bpf/progs/xdp_dispatcher_fineibt.c > new file mode 100644 > index 000000000000..b49b84f01c8e > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/xdp_dispatcher_fineibt.c > @@ -0,0 +1,18 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* Copyright (c) 2026 David Windsor */ > +#include <linux/bpf.h> > +#include <bpf/bpf_helpers.h> > + > +SEC("xdp") > +int xdp_dispatcher_attached(struct xdp_md *ctx) > +{ > + return XDP_PASS; > +} > + > +SEC("xdp") > +int xdp_dispatcher_unattached(struct xdp_md *ctx) > +{ > + return XDP_PASS; > +} > + > +char _license[] SEC("license") = "GPL";
Instead of creating xdp_dispatcher_fineibt.c, better to reuse xdp_dummy.c. Then, in xdp_dispatcher_fineibt.c, you can create two xdp_dummy skels, one for attaching, one for running. And, add the test to xdp_attach.c instead of new file prog_tests/xdp_dispatcher_fineibt.c? Thanks, Leon
