AF_XDP-interaction: Add BPF object/code for unit test

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>

Author: netoptimizer

AF_XDP-interaction/Makefile

@@ -3,6 +3,7 @@
 USER_TARGETS   := af_xdp_user
 USER_TARGETS   += btf_unit_test
 BPF_TARGETS    := af_xdp_kern
+BPF_TARGETS    += btf_unit_test_bpf
 
 # Define C-code objects USER_TARGETS needs
 USER_TARGETS_OBJS := common_params.o common_user_bpf_xdp.o

AF_XDP-interaction/btf_unit_test.c

@@ -128,5 +128,3 @@ int main(int argc, char **argv)
 
 	return EXIT_OK;
 }
-
-

AF_XDP-interaction/btf_unit_test_bpf.c

@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <linux/bpf.h>
+#include <bpf/bpf_helpers.h>
+
+#include <bpf/bpf_core_read.h> /* bpf_core_type_id_local */
+
+/*
+ * The xdp_hints_xxx struct's are stored in the XDP 'data_meta' area,
+ * which is located just in-front-of the raw packet payload data.
+ *
+ * Explaining the struct attribute's:
+ * ----------------------------------
+ * The struct must be 4 byte aligned (kernel requirement), which here
+ * is enforced by the struct __attribute__((aligned(4))).
+ *
+ * To avoid any C-struct padding attribute "packed" is used.
+ *
+ * NOTICE: Do NOT define __attribute__((preserve_access_index)) here,
+ * as libbpf will try to find a matching kernel data-structure,
+ * e.g. it will cause BPF-prog loading step to fail (with invalid func
+ * unknown#195896080 which is 0xbad2310 in hex for "bad relo").
+ */
+
+struct xdp_hints_fail001 {
+	__u64 hash64;
+	__u32 btf_id;
+	__u32 pad; /* Pad that breaks btf_id as last member */
+} __attribute__((aligned(4))) __attribute__((packed));
+
+/* Notice struct is without attribute "packed", thus (64-bit) C-compiler will
+ * add padding.  This will cause btf_id to NOT be the last member (which is a
+ * requirement).
+ */
+struct xdp_hints_fail002 {
+	__u64 hash64;
+	__u32 btf_id;
+} __attribute__((aligned(4))) /* not packed */;
+
+
+SEC("xdp")
+int xdp_prog_fail001(struct xdp_md *ctx)
+{
+	struct xdp_hints_fail001 *meta;
+	void *data;
+	int err;
+
+	err = bpf_xdp_adjust_meta(ctx, -(int)sizeof(*meta));
+	if (err)
+		return XDP_ABORTED;
+
+	data = (void *)(unsigned long)ctx->data;
+	meta = (void *)(unsigned long)ctx->data_meta;
+	if (meta + 1 > data) /* Verify meta area is accessible */
+		return XDP_ABORTED;
+
+	meta->btf_id = bpf_core_type_id_local(struct xdp_hints_fail001);
+	meta->hash64 = 0x4142434445464748;
+
+	return XDP_PASS;
+}
+
+SEC("xdp")
+int xdp_prog_fail002(struct xdp_md *ctx)
+{
+	struct xdp_hints_fail002 f002;
+	f002.btf_id = bpf_core_type_id_local(struct xdp_hints_fail002);
+	if (f002.btf_id == 0)
+		return XDP_ABORTED;
+
+	return XDP_PASS;
+}
+
+char _license[] SEC("license") = "GPL";