Update basic01 to be clean libxdp example

Signed-off-by: Donald Hunter <donald.hunter@gmail.com>

basic01-xdp-pass/Makefile

@@ -8,5 +8,6 @@ CLANG ?= clang
 CC := gcc
 
 COMMON_DIR = ../common
+COMMON_OBJS += $(COMMON_DIR)/common_user_bpf_xdp.o
 
 include $(COMMON_DIR)/common.mk

basic01-xdp-pass/README.org

@@ -87,29 +87,38 @@ is our C-function name.
 
 As you should understand by now, the BPF byte code is stored in an ELF file.
 To load this into the kernel, user space needs an ELF loader to read the
-file and pass it into the kernel in the right format. The *libbpf* library
-provides both an ELF loader and several BPF helper functions. In this
-tutorial you will learn how to write C code using this library, which is
-where our libelf-devel dependency comes from.
+file and pass it into the kernel in the right format.
+
+The *libbpf* library provides both an ELF loader and several BPF helper
+functions. It understands BPF Type Format (BTF) and implements [[https://nakryiko.com/posts/bpf-core-reference-guide/][CO-RE]]
+relocation as part of ELF loading, which is where our libelf-devel
+dependency comes from.
+
+The *libxdp* library provides helper functions for loading and installing
+XDP programs using the XDP multi-dispatch protocol and helper functions for
+using AF_XDP sockets. The *libxdp* library uses *libbpf* and adds extra
+features on top. In this tutorial you will learn how to write C code using
+the *libxdp* and *libbpf* libraries.
 
 The C code in [[file:xdp_pass_user.c]] (which gets compiled to the program
 =xdp_pass_user=) shows how to write a BPF loader specifically for our
 =xdp_pass_kern.o= ELF file. This loader attaches the program in the ELF file
 to an XDP hook on a network device.
 
-** Loading via iproute2 ip
-
 It does seem overkill to write a C program to simply load and attach a
 specific BPF-program. However, we still include this in the tutorial
 since it will help you integrate BPF into other Open Source projects.
 
-As an alternative to writing a new loader, the standard iproute2 tool also
-contains a BPF ELF loader. However, this loader is not based on libbpf,
-which unfortunately makes it incompatible when starting to use BPF maps.
+There are some alternatives to writing a new loader:
+
+ - The standard iproute2 tool
+ - The xdp-loader from xdp-tools
 
-The iproute2 loader can be used with the standard =ip= tool; so in this case
-you can actually load our ELF-file =xdp_pass_kern.o= (where we named our
-ELF section "xdp") like this:
+** Loading via iproute2 ip
+
+Iproute2 provides libbpf based BPF loading capability that can be used with
+the standard =ip= tool; so in this case you can actually load our ELF-file
+=xdp_pass_kern.o= (where we named our ELF section "xdp") like this:
 
 #+begin_example sh
  ip link set dev lo xdpgeneric obj xdp_pass_kern.o sec xdp
@@ -121,20 +130,48 @@ Listing the device via =ip link show= also shows the XDP info:
 $ ip link show dev lo
 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 xdpgeneric qdisc noqueue state UNKNOWN mode DEFAULT group default qlen 1000
     link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
-    prog/xdp id 220 tag 3b185187f1855c4c jited
+    prog/xdp id name xdp_prog_simple 220 tag 3b185187f1855c4c jited
 #+end_example
 
 Removing the XDP program again from the device:
 #+begin_example
  ip link set dev lo xdpgeneric off
 #+end_example
 
+It is important to note that the =ip= tool from iproute2 does not implement
+the XDP multi-dispatch protocol. When we use this tool, our program gets
+attached directly to the =lo= interface.
+
+** Loading using xdp-loader
+
+The xdp-tools project provides the =xdp-loader= tool which has commands for
+loading, unloading and showing the status of loaded XDP programs.
+
+We can load our =xdp_pass_kern.o= program and attach it using the XDP
+multi-dispatch protocol like this:
+
+#+begin_example sh
+ xdp-loader load -m skb lo xdp_pass_kern.o
+#+end_example
+
+We can show the status of the XDP programs attached to the device:
+
+#+begin_example sh
+$ xdp-loader status lo
+CURRENT XDP PROGRAM STATUS:
+
+Interface        Prio  Program name      Mode     ID   Tag               Chain actions
+--------------------------------------------------------------------------------------
+lo                     xdp_dispatcher    skb      486  94d5f00c20184d17
+ =>              50     xdp_prog_simple           493  3b185187f1855c4c  XDP_PASS
+#+end_example
+
 ** Loading using xdp_pass_user
 
 To load the program using our own loader, simply issue this command:
 
 #+begin_example sh
- $ sudo ./xdp_pass_user --dev lo --skb-mode
+ $ sudo ./xdp_pass_user --dev lo
  Success: Loading XDP prog name:xdp_prog_simple(id:225) on device:lo(ifindex:1)
 #+end_example
 
@@ -160,3 +197,4 @@ You can list XDP programs  on the device using different commands, and verify
 that the program ID is the same:
 - =ip link list dev lo=
 - =bpftool net list dev lo=
+- =xdp-loader status lo=

basic01-xdp-pass/xdp_pass_user.c

@@ -16,6 +16,7 @@ static const char *__doc__ = "Simple XDP prog doing XDP_PASS\n";
 #include <linux/if_link.h> /* depend on kernel-headers installed */
 
 #include "../common/common_params.h"
+#include "../common/common_user_bpf_xdp.h"
 
 static const struct option_wrapper long_options[] = {
 	{{"help",        no_argument,		NULL, 'h' },
@@ -33,32 +34,38 @@ static const struct option_wrapper long_options[] = {
 	{{"auto-mode",   no_argument,		NULL, 'A' },
 	 "Auto-detect SKB or native mode"},
 
-	{{"force",       no_argument,		NULL, 'F' },
-	 "Force install, replacing existing program on interface"},
-
-	{{"unload",      required_argument,		NULL, 'U' },
+	{{"unload",      required_argument,	NULL, 'U' },
 	 "Unload XDP program <id> instead of loading", "<id>"},
 
+	{{"unload-all",  no_argument,           NULL,  4  },
+	 "Unload all XDP programs on device"},
+
 	{{0, 0, NULL,  0 }, NULL, false}
 };
 
 
 int main(int argc, char **argv)
 {
-	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, opts);
-	DECLARE_LIBXDP_OPTS(xdp_program_opts, xdp_opts, 0);
+	struct bpf_prog_info info = {};
+	__u32 info_len = sizeof(info);
 	char filename[] = "xdp_pass_kern.o";
 	char progname[] = "xdp_prog_simple";
+	struct xdp_program *prog;
 	char errmsg[1024];
-	int err = EXIT_SUCCESS;
-	struct xdp_program *p;
+	int prog_fd, err; // = EXIT_SUCCESS;
 
 	struct config cfg = {
-		.xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST | XDP_FLAGS_DRV_MODE,
+		.attach_mode = XDP_MODE_UNSPEC,
 		.ifindex   = -1,
 		.do_unload = false,
 	};
 
+	DECLARE_LIBBPF_OPTS(bpf_object_open_opts, bpf_opts);
+	DECLARE_LIBXDP_OPTS(xdp_program_opts, xdp_opts,
+                            .open_filename = filename,
+                            .prog_name = progname,
+                            .opts = &bpf_opts);
+
 	parse_cmdline_args(argc, argv, long_options, &cfg, __doc__);
 	/* Required option */
 	if (cfg.ifindex == -1) {
@@ -67,39 +74,43 @@ int main(int argc, char **argv)
 		return EXIT_FAIL_OPTION;
 	}
 
-	if (cfg.do_unload) {
-		xdp_opts.id = cfg.prog_id;
-	} else {
-		xdp_opts.open_filename = filename;
-		xdp_opts.prog_name = progname;
-		xdp_opts.opts = &opts;
+        /* Unload a program by prog_id, or
+         * unload all programs on net device
+         */
+	if (cfg.do_unload || cfg.unload_all) {
+		err = do_unload(&cfg);
+		if (err) {
+			libxdp_strerror(err, errmsg, sizeof(errmsg));
+			fprintf(stderr, "Couldn't unload XDP program %s: %s\n",
+				progname, errmsg);
+			return err;
+		}
+
+		printf("Success: Unloading XDP prog name: %s\n", progname);
+		return EXIT_OK;
 	}
 
-	p = xdp_program__create(&xdp_opts);
-	err = libxdp_get_error(p);
+        /* Create an xdp_program froma a BPF ELF object file */
+	prog = xdp_program__create(&xdp_opts);
+	err = libxdp_get_error(prog);
 	if (err) {
 		libxdp_strerror(err, errmsg, sizeof(errmsg));
 		fprintf(stderr, "Couldn't get XDP program %s: %s\n",
 			progname, errmsg);
 		return err;
 	}
 
-	if (cfg.do_unload)
-		return xdp_program__detach(p, cfg.ifindex, cfg.attach_mode, 0);
-
-	err = xdp_program__attach(p, cfg.ifindex, cfg.attach_mode, 0);
+        /* Attach the xdp_program to the net device XDP hook */
+	err = xdp_program__attach(prog, cfg.ifindex, cfg.attach_mode, 0);
 	if (err) {
 		libxdp_strerror(err, errmsg, sizeof(errmsg));
 		fprintf(stderr, "Couldn't attach XDP program on iface '%s' : %s (%d)\n",
 			cfg.ifname, errmsg, err);
 		return err;
 	}
 
-	struct bpf_prog_info info = {};
-	__u32 info_len = sizeof(info);
-	int prog_fd = xdp_program__fd(p);
-
         /* This step is not really needed , BPF-info via bpf-syscall */
+	prog_fd = xdp_program__fd(prog);
 	err = bpf_obj_get_info_by_fd(prog_fd, &info, &info_len);
 	if (err) {
 		fprintf(stderr, "ERR: can't get prog info - %s\n",

common/common_params.c

@@ -182,6 +182,9 @@ void parse_cmdline_args(int argc, char **argv,
 			cfg->xsk_bind_flags &= ~XDP_COPY;
 			cfg->xsk_bind_flags |= XDP_ZEROCOPY;
 			break;
+		case 4: /* --unload-all */
+			cfg->unload_all = true;
+			break;
 		case 'h':
 			full_help = true;
 			/* fall-through */