selftests: net: move xdp_helper to net/lib

Move xdp_helper to net/lib to make it easier for other selftests to use
the helper.

Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://patch.msgid.link/20250425071018.36078-2-minhquangbui99@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

4 files changed, 164 insertions, 0 deletions

diff --git a/tools/testing/selftests/net/lib/.gitignore b/tools/testing/selftests/net/lib/.gitignore
index 1ebc6187f421..bbc97d6bf556 100644
--- a/tools/testing/selftests/net/lib/.gitignore
+++ b/tools/testing/selftests/net/lib/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
 csum
+xdp_helper
diff --git a/tools/testing/selftests/net/lib/Makefile b/tools/testing/selftests/net/lib/Makefile
index c22623b9a2a5..88c4bc461459 100644
--- a/tools/testing/selftests/net/lib/Makefile
+++ b/tools/testing/selftests/net/lib/Makefile
@@ -10,6 +10,7 @@ TEST_FILES += ../../../../net/ynl
 
 TEST_GEN_FILES += csum
 TEST_GEN_FILES += $(patsubst %.c,%.o,$(wildcard *.bpf.c))
+TEST_GEN_FILES += xdp_helper
 
 TEST_INCLUDES := $(wildcard py/*.py sh/*.sh)
 
diff --git a/tools/testing/selftests/net/lib/ksft.h b/tools/testing/selftests/net/lib/ksft.h
new file mode 100644
index 000000000000..17dc34a612c6
--- /dev/null
+++ b/tools/testing/selftests/net/lib/ksft.h
@@ -0,0 +1,56 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#if !defined(__NET_KSFT_H__)
+#define __NET_KSFT_H__
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static inline void ksft_ready(void)
+{
+	const char msg[7] = "ready\n";
+	char *env_str;
+	int fd;
+
+	env_str = getenv("KSFT_READY_FD");
+	if (env_str) {
+		fd = atoi(env_str);
+		if (!fd) {
+			fprintf(stderr, "invalid KSFT_READY_FD = '%s'\n",
+				env_str);
+			return;
+		}
+	} else {
+		fd = STDOUT_FILENO;
+	}
+
+	write(fd, msg, sizeof(msg));
+	if (fd != STDOUT_FILENO)
+		close(fd);
+}
+
+static inline void ksft_wait(void)
+{
+	char *env_str;
+	char byte;
+	int fd;
+
+	env_str = getenv("KSFT_WAIT_FD");
+	if (env_str) {
+		fd = atoi(env_str);
+		if (!fd) {
+			fprintf(stderr, "invalid KSFT_WAIT_FD = '%s'\n",
+				env_str);
+			return;
+		}
+	} else {
+		/* Not running in KSFT env, wait for input from STDIN instead */
+		fd = STDIN_FILENO;
+	}
+
+	read(fd, &byte, sizeof(byte));
+	if (fd != STDIN_FILENO)
+		close(fd);
+}
+
+#endif
diff --git a/tools/testing/selftests/net/lib/xdp_helper.c b/tools/testing/selftests/net/lib/xdp_helper.c
new file mode 100644
index 000000000000..d5bb8ac33efa
--- /dev/null
+++ b/tools/testing/selftests/net/lib/xdp_helper.c
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/socket.h>
+#include <linux/if_xdp.h>
+#include <linux/if_link.h>
+#include <net/if.h>
+#include <inttypes.h>
+
+#include "ksft.h"
+
+#define UMEM_SZ (1U << 16)
+#define NUM_DESC (UMEM_SZ / 2048)
+
+
+/* this is a simple helper program that creates an XDP socket and does the
+ * minimum necessary to get bind() to succeed.
+ *
+ * this test program is not intended to actually process packets, but could be
+ * extended in the future if that is actually needed.
+ *
+ * it is used by queues.py to ensure the xsk netlinux attribute is set
+ * correctly.
+ */
+int main(int argc, char **argv)
+{
+	struct xdp_umem_reg umem_reg = { 0 };
+	struct sockaddr_xdp sxdp = { 0 };
+	int num_desc = NUM_DESC;
+	void *umem_area;
+	int ifindex;
+	int sock_fd;
+	int queue;
+
+	if (argc != 3) {
+		fprintf(stderr, "Usage: %s ifindex queue_id\n", argv[0]);
+		return 1;
+	}
+
+	sock_fd = socket(AF_XDP, SOCK_RAW, 0);
+	if (sock_fd < 0) {
+		perror("socket creation failed");
+		/* if the kernel doesn't support AF_XDP, let the test program
+		 * know with -1. All other error paths return 1.
+		 */
+		if (errno == EAFNOSUPPORT)
+			return -1;
+		return 1;
+	}
+
+	/* "Probing mode", just checking if AF_XDP sockets are supported */
+	if (!strcmp(argv[1], "-") && !strcmp(argv[2], "-")) {
+		printf("AF_XDP support detected\n");
+		close(sock_fd);
+		return 0;
+	}
+
+	ifindex = atoi(argv[1]);
+	queue = atoi(argv[2]);
+
+	umem_area = mmap(NULL, UMEM_SZ, PROT_READ | PROT_WRITE, MAP_PRIVATE |
+			MAP_ANONYMOUS, -1, 0);
+	if (umem_area == MAP_FAILED) {
+		perror("mmap failed");
+		return 1;
+	}
+
+	umem_reg.addr = (uintptr_t)umem_area;
+	umem_reg.len = UMEM_SZ;
+	umem_reg.chunk_size = 2048;
+	umem_reg.headroom = 0;
+
+	setsockopt(sock_fd, SOL_XDP, XDP_UMEM_REG, &umem_reg,
+		   sizeof(umem_reg));
+	setsockopt(sock_fd, SOL_XDP, XDP_UMEM_FILL_RING, &num_desc,
+		   sizeof(num_desc));
+	setsockopt(sock_fd, SOL_XDP, XDP_UMEM_COMPLETION_RING, &num_desc,
+		   sizeof(num_desc));
+	setsockopt(sock_fd, SOL_XDP, XDP_RX_RING, &num_desc, sizeof(num_desc));
+
+	sxdp.sxdp_family = AF_XDP;
+	sxdp.sxdp_ifindex = ifindex;
+	sxdp.sxdp_queue_id = queue;
+	sxdp.sxdp_flags = 0;
+
+	if (bind(sock_fd, (struct sockaddr *)&sxdp, sizeof(sxdp)) != 0) {
+		munmap(umem_area, UMEM_SZ);
+		perror("bind failed");
+		close(sock_fd);
+		return 1;
+	}
+
+	ksft_ready();
+	ksft_wait();
+
+	/* parent program will write a byte to stdin when its ready for this
+	 * helper to exit
+	 */
+
+	close(sock_fd);
+	return 0;
+}