xdp: T2666: switch to example code provided by xdp-tutorial

1 files changed, 162 insertions, 0 deletions

diff --git a/src/xdp/common/common_libbpf.c b/src/xdp/common/common_libbpf.c
new file mode 100644
index 000000000..5788ecd9e
--- /dev/null
+++ b/src/xdp/common/common_libbpf.c
@@ -0,0 +1,162 @@
+/* Common function that with time should be moved to libbpf */
+
+#include <errno.h>
+#include <string.h>
+
+#include <bpf/bpf.h>
+#include <bpf/libbpf.h>
+
+#include "common_libbpf.h"
+
+/* From: include/linux/err.h */
+#define MAX_ERRNO       4095
+#define IS_ERR_VALUE(x) ((x) >= (unsigned long)-MAX_ERRNO)
+static inline bool IS_ERR_OR_NULL(const void *ptr)
+{
+        return (!ptr) || IS_ERR_VALUE((unsigned long)ptr);
+}
+
+#define pr_warning printf
+
+/* As close as possible to libbpf bpf_prog_load_xattr(), with the
+ * difference of handling pinned maps.
+ */
+int bpf_prog_load_xattr_maps(const struct bpf_prog_load_attr_maps *attr,
+			     struct bpf_object **pobj, int *prog_fd)
+{
+	struct bpf_object_open_attr open_attr = {
+		.file		= attr->file,
+		.prog_type	= attr->prog_type,
+	};
+	struct bpf_program *prog, *first_prog = NULL;
+	enum bpf_attach_type expected_attach_type;
+	enum bpf_prog_type prog_type;
+	struct bpf_object *obj;
+	struct bpf_map *map;
+	int err;
+	int i;
+
+	if (!attr)
+		return -EINVAL;
+	if (!attr->file)
+		return -EINVAL;
+
+
+	obj = bpf_object__open_xattr(&open_attr);
+	if (IS_ERR_OR_NULL(obj))
+		return -ENOENT;
+
+	bpf_object__for_each_program(prog, obj) {
+		/*
+		 * If type is not specified, try to guess it based on
+		 * section name.
+		 */
+		prog_type = attr->prog_type;
+		// Was: prog->prog_ifindex = attr->ifindex;
+		bpf_program__set_ifindex(prog, attr->ifindex);
+
+		expected_attach_type = attr->expected_attach_type;
+#if 0 /* Use internal libbpf variables */
+		if (prog_type == BPF_PROG_TYPE_UNSPEC) {
+			err = bpf_program__identify_section(prog, &prog_type,
+							    &expected_attach_type);
+			if (err < 0) {
+				bpf_object__close(obj);
+				return -EINVAL;
+			}
+		}
+#endif
+
+		bpf_program__set_type(prog, prog_type);
+		bpf_program__set_expected_attach_type(prog,
+						      expected_attach_type);
+
+		if (!first_prog)
+			first_prog = prog;
+	}
+
+	/* Reset attr->pinned_maps.map_fd to identify successful file load */
+	for (i = 0; i < attr->nr_pinned_maps; i++)
+		attr->pinned_maps[i].map_fd = -1;
+
+	bpf_map__for_each(map, obj) {
+		const char* mapname = bpf_map__name(map);
+
+		if (!bpf_map__is_offload_neutral(map))
+			bpf_map__set_ifindex(map, attr->ifindex);
+                        /* Was: map->map_ifindex = attr->ifindex; */
+
+		for (i = 0; i < attr->nr_pinned_maps; i++) {
+			struct bpf_pinned_map *pin_map = &attr->pinned_maps[i];
+			int fd;
+
+			if (strcmp(mapname, pin_map->name) != 0)
+				continue;
+
+			/* Matched, try opening pinned file */
+			fd = bpf_obj_get(pin_map->filename);
+			if (fd > 0) {
+				/* Use FD from pinned map as replacement */
+				bpf_map__reuse_fd(map, fd);
+				/* TODO: Might want to set internal map "name"
+				 * if opened pinned map didn't, to allow
+				 * bpf_object__find_map_fd_by_name() to work.
+				 */
+				pin_map->map_fd = fd;
+				continue;
+			}
+			/* Could not open pinned filename map, then this prog
+			 * should then pin the map, BUT this can only happen
+			 * after bpf_object__load().
+			 */
+		}
+	}
+
+	if (!first_prog) {
+		pr_warning("object file doesn't contain bpf program\n");
+		bpf_object__close(obj);
+		return -ENOENT;
+	}
+
+	err = bpf_object__load(obj);
+	if (err) {
+		bpf_object__close(obj);
+		return -EINVAL;
+	}
+
+	/* Pin the maps that were not loaded via pinned filename */
+	bpf_map__for_each(map, obj) {
+		const char* mapname = bpf_map__name(map);
+
+		for (i = 0; i < attr->nr_pinned_maps; i++) {
+			struct bpf_pinned_map *pin_map = &attr->pinned_maps[i];
+			int err;
+
+			if (strcmp(mapname, pin_map->name) != 0)
+				continue;
+
+			/* Matched, check if map is already loaded */
+			if (pin_map->map_fd != -1)
+				continue;
+
+			/* Needs to be pinned */
+			err = bpf_map__pin(map, pin_map->filename);
+			if (err)
+				continue;
+			pin_map->map_fd = bpf_map__fd(map);
+		}
+	}
+
+	/* Help user if requested map name that doesn't exist */
+	for (i = 0; i < attr->nr_pinned_maps; i++) {
+		struct bpf_pinned_map *pin_map = &attr->pinned_maps[i];
+
+		if (pin_map->map_fd < 0)
+			pr_warning("%s() requested mapname:%s not seen\n",
+				   __func__, pin_map->name);
+	}
+
+	*pobj = obj;
+	*prog_fd = bpf_program__fd(first_prog);
+	return 0;
+}