AF_XDP-interaction: Adapt lib_xsk_extend while trying to use

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

AF_XDP-interaction/af_xdp_user.c

@@ -32,6 +32,7 @@
 #include "common_user_bpf_xdp.h"
 // #include "common_libbpf.h"
 
+#include "lib_xsk_extend.h"
 
 #define NUM_FRAMES         4096
 #define FRAME_SIZE         XSK_UMEM__DEFAULT_FRAME_SIZE
@@ -625,7 +626,7 @@ int btf_walk_struct_members(struct btf *btf_obj, __s32 btf_id)
 	return 0;
 }
 
-__s32 btf_find_struct(struct btf *btf, char *name, __s64 *size)
+__s32 btf_find_struct(struct btf *btf, const char *name, __s64 *size)
 {
 	__s32 btf_id = btf__find_by_name_kind(btf, name, BTF_KIND_STRUCT);
 	__s64 sz = btf__resolve_size(btf, btf_id);
@@ -639,15 +640,31 @@ __s32 btf_find_struct(struct btf *btf, char *name, __s64 *size)
 	return btf_id;
 }
 
+static const char *name1 = "xdp_hints_mark";
+static const char *name2 = "xdp_hints_rx_time";
+
 int btf_info_via_bpf_object(struct bpf_object *bpf_obj)
 {
 	struct btf *btf = bpf_object__btf(bpf_obj);
-	char *name1 = "xdp_hints_mark";
-	char *name2 = "xdp_hints_rx_time";
 	__s64 size;
+	int err;
+
+	struct xsk_btf_info *xdp_hint_rx_time = NULL;
 
 	btf_find_struct(btf, name1, &size);
 	btf_find_struct(btf, name2, &size);
+
+	err = xsk_btf__init_xdp_hint(btf, name2, &xdp_hint_rx_time);
+	if (err) {
+		fprintf(stderr, "WARN(%d): Cannot xsk_btf__init_xdp_hint\n", err);
+		return err;
+	}
+	if (!xsk_btf__has_field("rx_ktime", xdp_hint_rx_time)) {
+		fprintf(stderr, "WARN: %s doesn't contain member rx_ktime\n",
+			name2);
+		return 1;
+	}
+
 	return 0;
 }
 

AF_XDP-interaction/lib_xsk_extend.c

@@ -1,18 +1,23 @@
 /* SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause) */
 
+/*
+ * Prototyping new API for userspace xsk/AF_XDP to access XDP-hints, which is
+ * BTF typed info in XDP metadata area (located just before packets headers).
+ */
 #include "hashmap.h"
 
 #include <errno.h>
 #include <stdlib.h>
+#include <stdio.h>
 
 #include <bpf/btf.h> /* provided by libbpf */
 
-int xsk_umem__btf_id(void *umem_data, const struct xsk_umem *umem)
+int xsk_umem__btf_id(void *umem_pkt_data, const struct xsk_umem *umem)
 {
 //	if (umem->config.xdp_headroom < sizeof(int))
 //		return -EINVAL;
 
-	return *(int *)(umem_data - sizeof(int));
+	return *(int *)(umem_pkt_data - sizeof(int));
 }
 
 
@@ -20,6 +25,7 @@ struct xsk_btf_info {
 	struct hashmap map;
 	struct btf *btf;
 	const struct btf_type *type;
+	//__u32 btf_id;
 };
 
 struct xsk_btf_entry {
@@ -56,33 +62,36 @@ static bool __xsk_equal_fn(const void *k1, const void *k2, void *ctx)
 	return k1 == k2;
 }
 
-int xsk_btf__init(__u32 btf_id, struct xsk_btf_info **xbi)
+int xsk_btf__init_xdp_hint(struct btf *btf_obj,
+			   const char *xdp_hints_name,
+			   struct xsk_btf_info **xbi)
 {
 	const struct btf_member *m;
 	const struct btf_type *t;
 	unsigned short vlen;
-	struct btf *btf;
 	int i, id, ret = 0;
 
 	if (!xbi)
 		return -EINVAL;
 
-	ret = btf__get_from_id(btf_id, &btf);
-	if (ret < 0)
-		return ret;
+//	ret = btf__get_from_id(btf_id, &btf); // Limits lookups to kernel BTF
+//	if (ret < 0)
+//		return ret;
 
-	id = btf__find_by_name(btf, "xdp_hints");
+	/* Require XDP-hints is defined as a struct */
+	id = btf__find_by_name_kind(btf_obj, xdp_hints_name, BTF_KIND_STRUCT);
 	if (id < 0) {
 		ret = id;
 		goto error_btf;
 	}
+	printf("XXX %s() id:%d\n", __func__, id);
 
-	t = btf__type_by_id(btf, id);
+	t = btf__type_by_id(btf_obj, id);
 
-	if (!BTF_INFO_KFLAG(t->info)) {
-		ret = -EINVAL;
-		goto error_btf;
-	}
+//	if (!BTF_INFO_KFLAG(t->info)) {
+//		ret = -EINVAL;
+//		goto error_btf;
+//	}
 
 	*xbi = malloc(sizeof(**xbi));
 	if (!*xbi) {
@@ -102,8 +111,9 @@ int xsk_btf__init(__u32 btf_id, struct xsk_btf_info **xbi)
 		}
 	}
 
-	(*xbi)->btf = btf;
+	(*xbi)->btf = btf_obj;
 	(*xbi)->type = t;
+	// (*xbi)->btf_id = id;
 
 	return ret;
 
@@ -112,7 +122,7 @@ error_entry:
 	free(*xbi);
 
 error_btf:
-	btf__free(btf);
+//	btf__free(btf);
 	return ret;
 }
 
@@ -128,6 +138,7 @@ static int __xsk_btf_field_entry(struct xsk_btf_info *xbi, const char *field,
 	for (i = 0; i < vlen; i++, m++) {
 		const struct btf_type *member_type;
 		const char *name = btf__name_by_offset(xbi->btf, m->name_off);
+		printf("XXX %s() i:%d name:%s\n", __func__, i, name);
 
 		if (strcmp(name, field))
 			continue;
@@ -155,10 +166,10 @@ bool xsk_btf__has_field(const char *field, struct xsk_btf_info *xbi)
 	if (!xbi)
 		return false;
 
-	return __xsk_btf_field_entry(xbi, field, NULL);
+	return __xsk_btf_field_entry(xbi, field, NULL) ? false : true;
 }
 
-void xsk_btf__free(struct xsk_btf_info *xbi)
+void xsk_btf__free_xdp_hint(struct xsk_btf_info *xbi)
 {
 	if (!xbi)
 		return;
@@ -188,6 +199,7 @@ int xsk_btf__read(void **dest, size_t size, const char *field, struct xsk_btf_in
 	if (entry->size != size)
 		return -EINVAL;
 
+	// XXX should we cache size for main xdp_hints struct?
 	*dest = (void *)((char *)addr - xbi->type->size + entry->offset);
 	return 0;
 }

AF_XDP-interaction/lib_xsk_extend.h

@@ -3,17 +3,21 @@
 #ifndef __LIB_XSK_EXTEND_H
 #define __LIB_XSK_EXTEND_H
 
-#define LIBBPF_API ""
+//#define LIBBPF_API ""
 
 LIBBPF_API int xsk_umem__btf_id(void *umem_data, const struct xsk_umem *umem);
 
 struct xsk_btf_info;
 
-LIBBPF_API int xsk_btf__init(__u32 btf_id, struct xsk_btf_info **xbi);
+LIBBPF_API int xsk_btf__init_xdp_hint(struct btf *btf_obj,
+				      const char *xdp_hints_name,
+				      struct xsk_btf_info **xbi);
+
+LIBBPF_API void xsk_btf__free_xdp_hint(struct xsk_btf_info *xbi);
+
 LIBBPF_API int xsk_btf__read(void **dest, size_t size, const char *field, struct xsk_btf_info *xbi,
 			     const void *addr);
 LIBBPF_API bool xsk_btf__has_field(const char *field, struct xsk_btf_info *xbi);
-LIBBPF_API void xsk_btf__free(struct xsk_btf_info *xbi);
 
 #define XSK_BTF_READ_INTO(dest, field, xbi, addr) ({ \
 	typeof(dest) *_d; \