Update libbpf to latest upstream version

Since libbpf now includes bpf_helpers.h, add the libbpf dir to the include
path and remove our own version of the helper. This requires rewriting all
the includes to use <bpf/bpf_helpers.h>, and some fiddling with include
paths.

Also, we need to import the bpf_legacy.h header from the kernel, since
we're using BPF_ANNOTATE_KV_PAIR in tracing02.

Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>

Author: tohojo

basic01-xdp-pass/xdp_pass_kern.c

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/bpf.h>
-#include "bpf_helpers.h"
+#include <bpf/bpf_helpers.h>
 
 SEC("xdp")
 int  xdp_prog_simple(struct xdp_md *ctx)

basic02-prog-by-name/xdp_prog_kern.c

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/bpf.h>
-#include "bpf_helpers.h"
+#include <bpf/bpf_helpers.h>
 
 /* Notice how this XDP/BPF-program contains several programs in the same source
  * file. These will each get their own section in the ELF file, and via libbpf

basic03-map-counter/xdp_prog_kern.c

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/bpf.h>
-#include "bpf_helpers.h"
+#include <bpf/bpf_helpers.h>
 
 #include "common_kern_user.h" /* defines: struct datarec; */
 

basic04-pinning-maps/xdp_prog_kern.c

@@ -1,19 +1,20 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/bpf.h>
-#include "bpf_helpers.h"
+#include <bpf/bpf_helpers.h>
 
 #include "common_kern_user.h" /* defines: struct datarec; */
 
 /* Lesson: See how a map is defined.
  * - Here an array with XDP_ACTION_MAX (max_)entries are created.
  * - The idea is to keep stats per (enum) xdp_action
  */
-struct bpf_map_def SEC("maps") xdp_stats_map = {
-	.type        = BPF_MAP_TYPE_PERCPU_ARRAY,
-	.key_size    = sizeof(__u32),
-	.value_size  = sizeof(struct datarec),
-	.max_entries = XDP_ACTION_MAX,
-};
+struct {
+	__uint(type, BPF_MAP_TYPE_PERCPU_ARRAY);
+	__uint(max_entries, XDP_ACTION_MAX);
+	__type(key, __u32);
+	__type(value, struct datarec);
+	__uint(pinning, 1);
+} xdp_stats_map SEC(".maps");
 
 /* LLVM maps __sync_fetch_and_add() as a built-in function to the BPF atomic add
  * instruction (that is BPF_STX | BPF_XADD | BPF_W for word sizes)

common/common.mk

@@ -45,6 +45,8 @@ CFLAGS += -I/usr/include/x86_64-linux-gnu
 CFLAGS += -I../headers/
 LDFLAGS ?= -L$(LIBBPF_DIR)
 
+BPF_CFLAGS ?= -I$(LIBBPF_DIR)/build/usr/include/ -I../headers/
+
 LIBS = -l:libbpf.a -lelf $(USER_LIBS)
 
 all: llvm-check $(USER_TARGETS) $(XDP_OBJ) $(COPY_LOADER) $(COPY_STATS)
@@ -111,7 +113,7 @@ $(XDP_OBJ): %.o: %.c  Makefile $(COMMON_MK) $(KERN_USER_H) $(EXTRA_DEPS)
 	$(CLANG) -S \
 	    -target bpf \
 	    -D __BPF_TRACING__ \
-	    $(CFLAGS) \
+	    $(BPF_CFLAGS) \
 	    -Wall \
 	    -Wno-unused-value \
 	    -Wno-pointer-sign \

common/rewrite_helpers.h

@@ -13,8 +13,8 @@
 #include <linux/ipv6.h>
 #include <linux/if_ether.h>
 
-#include "bpf_helpers.h"
-#include "bpf_endian.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
 
 /* Pops the outermost VLAN tag off the packet. Returns the popped VLAN ID on
  * success or negative errno on failure.