Re: [PATCH v2 bpf-next 5/5] selftest: Add tests for XDP programs in devmap entries

On 5/28/20 1:08 AM, Andrii Nakryiko wrote:

quoted

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c b/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c
new file mode 100644
index 000000000000..d81b2b366f39
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_devmap_attach.c

@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <uapi/linux/bpf.h>
+#include <linux/if_link.h>
+#include <test_progs.h>
+
+#define IFINDEX_LO 1
+
+void test_xdp_devmap_attach(void)
+{
+       struct bpf_prog_load_attr attr = {
+               .prog_type = BPF_PROG_TYPE_XDP,
+       };
+       struct bpf_object *obj, *dm_obj = NULL;
+       int err, dm_fd = -1, fd = -1, map_fd;
+       struct bpf_prog_info info = {};
+       struct devmap_val val = {
+               .ifindex = IFINDEX_LO,
+       };
+       __u32 id, len = sizeof(info);
+       __u32 duration = 0, idx = 0;
+
+       attr.file = "./test_xdp_with_devmap.o",
+       err = bpf_prog_load_xattr(&attr, &obj, &fd);

please use skeletons instead of loading .o files.

I will look into it.

quoted

+       if (CHECK(err, "load of xdp program with 8-byte devmap",
+                 "err %d errno %d\n", err, errno))
+               return;
+

[...]

quoted

diff --git a/tools/testing/selftests/bpf/progs/test_xdp_devmap2.c b/tools/testing/selftests/bpf/progs/test_xdp_devmap2.c
new file mode 100644
index 000000000000..64fc2c3cae01
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/test_xdp_devmap2.c

@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+/* program inserted into devmap entry */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+SEC("xdp_devmap_log")
+int xdpdm_devlog(struct xdp_md *ctx)
+{
+       char fmt[] = "devmap redirect: dev %u -> dev %u len %u\n";
+       void *data_end = (void *)(long)ctx->data_end;
+       void *data = (void *)(long)ctx->data;
+       unsigned int len = data_end - data;
+
+       bpf_trace_printk(fmt, sizeof(fmt), ctx->ingress_ifindex, ctx->egress_ifindex, len);

instead of just printing ifindexes, why not return them through global
variable and validate in a test?

The point of this program to access the egress_ifindex with the expected
attached type NOT set to BPF_XDP_DEVMAP to FAIL the verifier checks.