add new system file

hc

2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/samples/bpf/xdp_fwd_user.c
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@@ -24,17 +24,25 @@
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 #include <fcntl.h>
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 #include <libgen.h>
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-#include "bpf/libbpf.h"
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+#include <bpf/libbpf.h>
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 #include <bpf/bpf.h>
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+static __u32 xdp_flags = XDP_FLAGS_UPDATE_IF_NOEXIST;
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-static int do_attach(int idx, int fd, const char *name)
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+static int do_attach(int idx, int prog_fd, int map_fd, const char *name)
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 {
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 	int err;
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-	err = bpf_set_link_xdp_fd(idx, fd, 0);
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-	if (err < 0)
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+	err = bpf_set_link_xdp_fd(idx, prog_fd, xdp_flags);
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+	if (err < 0) {
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 		printf("ERROR: failed to attach program to %s\n", name);
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+		return err;
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+	}
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+
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+	/* Adding ifindex as a possible egress TX port */
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+	err = bpf_map_update_elem(map_fd, &idx, &idx, 0);
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+	if (err)
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+		printf("ERROR: failed using device %s as TX-port\n", name);
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 	return err;
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 }
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@@ -43,10 +51,13 @@
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 {
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 	int err;
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-	err = bpf_set_link_xdp_fd(idx, -1, 0);
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+	err = bpf_set_link_xdp_fd(idx, -1, xdp_flags);
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 	if (err < 0)
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 		printf("ERROR: failed to detach program from %s\n", name);
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+	/* TODO: Remember to cleanup map, when adding use of shared map
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+	 *  bpf_map_delete_elem((map_fd, &idx);
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+	 */
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 	return err;
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 }
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@@ -67,17 +78,23 @@
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 	};
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 	const char *prog_name = "xdp_fwd";
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 	struct bpf_program *prog;
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+	int prog_fd, map_fd = -1;
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 	char filename[PATH_MAX];
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 	struct bpf_object *obj;
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 	int opt, i, idx, err;
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-	int prog_fd, map_fd;
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 	int attach = 1;
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 	int ret = 0;
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-	while ((opt = getopt(argc, argv, ":dD")) != -1) {
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+	while ((opt = getopt(argc, argv, ":dDSF")) != -1) {
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 		switch (opt) {
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 		case 'd':
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 			attach = 0;
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+			break;
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+		case 'S':
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+			xdp_flags |= XDP_FLAGS_SKB_MODE;
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+			break;
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+		case 'F':
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+			xdp_flags &= ~XDP_FLAGS_UPDATE_IF_NOEXIST;
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 			break;
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 		case 'D':
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 			prog_name = "xdp_fwd_direct";
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@@ -87,6 +104,9 @@
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 			return 1;
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 		}
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 	}
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+
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+	if (!(xdp_flags & XDP_FLAGS_SKB_MODE))
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+		xdp_flags |= XDP_FLAGS_DRV_MODE;
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 	if (optind == argc) {
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 		usage(basename(argv[0]));
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@@ -103,8 +123,14 @@
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 			return 1;
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 		}
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-		if (bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd))
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+		err = bpf_prog_load_xattr(&prog_load_attr, &obj, &prog_fd);
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+		if (err) {
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+			printf("Does kernel support devmap lookup?\n");
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+			/* If not, the error message will be:
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+			 *  "cannot pass map_type 14 into func bpf_map_lookup_elem#1"
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+			 */
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 			return 1;
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+		}
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 		prog = bpf_object__find_program_by_title(obj, prog_name);
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 		prog_fd = bpf_program__fd(prog);
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@@ -113,15 +139,11 @@
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 			return 1;
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 		}
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 		map_fd = bpf_map__fd(bpf_object__find_map_by_name(obj,
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-								  "tx_port"));
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+							"xdp_tx_ports"));
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 		if (map_fd < 0) {
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 			printf("map not found: %s\n", strerror(map_fd));
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 			return 1;
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 		}
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-	}
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-	if (attach) {
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-		for (i = 1; i < 64; ++i)
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-			bpf_map_update_elem(map_fd, &i, &i, 0);
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 	}
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 	for (i = optind; i < argc; ++i) {
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@@ -138,7 +160,7 @@
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 			if (err)
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 				ret = err;
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 		} else {
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-			err = do_attach(idx, prog_fd, argv[i]);
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+			err = do_attach(idx, prog_fd, map_fd, argv[i]);
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 			if (err)
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 				ret = err;
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 		}