Merge branch 'bpf-fix-a-few-test-failures-with-64k-page-size'

Yonghong Song says:

====================
bpf: Fix a few test failures with 64K page size

Changelog:
  v2 -> v3:
    - v2: https://lore.kernel.org/bpf/20250611171519.2033193-1-yonghong.song@linux.dev/
    - Add additional comments for xdp_adjust_tail test.
    - Use actual kernel page size to set new_len for Patch 2 tests.
  v1 -> v2:
    - v1: https://lore.kernel.org/bpf/20250608165534.1019914-1-yonghong.song@linux.dev/
    - For xdp_adjust_tail, let kernel test_run can handle various page sizes for xdp progs.
    - For two change_tail tests, make code easier to understand.
    - Resolved a new test failure (xdp_do_redirect).
====================

Link: https://patch.msgid.link/20250612035027.2207299-1-yonghong.song@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net/bpf/test_run.c

@@ -1255,7 +1255,7 @@ int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
 		headroom -= ctx->data;
 	}
 
-	max_data_sz = 4096 - headroom - tailroom;
+	max_data_sz = PAGE_SIZE - headroom - tailroom;
 	if (size > max_data_sz) {
 		/* disallow live data mode for jumbo frames */
 		if (do_live)

tools/testing/selftests/bpf/prog_tests/xdp_adjust_tail.c

@@ -37,21 +37,26 @@ static void test_xdp_adjust_tail_shrink(void)
 	bpf_object__close(obj);
 }
 
-static void test_xdp_adjust_tail_grow(void)
+static void test_xdp_adjust_tail_grow(bool is_64k_pagesize)
 {
 	const char *file = "./test_xdp_adjust_tail_grow.bpf.o";
 	struct bpf_object *obj;
-	char buf[4096]; /* avoid segfault: large buf to hold grow results */
+	char buf[8192]; /* avoid segfault: large buf to hold grow results */
 	__u32 expect_sz;
 	int err, prog_fd;
 	LIBBPF_OPTS(bpf_test_run_opts, topts,
 		.data_in = &pkt_v4,
-		.data_size_in = sizeof(pkt_v4),
 		.data_out = buf,
 		.data_size_out = sizeof(buf),
 		.repeat = 1,
 	);
 
+	/* topts.data_size_in as a special signal to bpf prog */
+	if (is_64k_pagesize)
+		topts.data_size_in = sizeof(pkt_v4) - 1;
+	else
+		topts.data_size_in = sizeof(pkt_v4);
+
 	err = bpf_prog_test_load(file, BPF_PROG_TYPE_XDP, &obj, &prog_fd);
 	if (!ASSERT_OK(err, "test_xdp_adjust_tail_grow"))
 		return;
@@ -208,7 +213,7 @@ out:
 	bpf_object__close(obj);
 }
 
-static void test_xdp_adjust_frags_tail_grow(void)
+static void test_xdp_adjust_frags_tail_grow_4k(void)
 {
 	const char *file = "./test_xdp_adjust_tail_grow.bpf.o";
 	__u32 exp_size;
@@ -279,16 +284,93 @@ out:
 	bpf_object__close(obj);
 }
 
+static void test_xdp_adjust_frags_tail_grow_64k(void)
+{
+	const char *file = "./test_xdp_adjust_tail_grow.bpf.o";
+	__u32 exp_size;
+	struct bpf_program *prog;
+	struct bpf_object *obj;
+	int err, i, prog_fd;
+	__u8 *buf;
+	LIBBPF_OPTS(bpf_test_run_opts, topts);
+
+	obj = bpf_object__open(file);
+	if (libbpf_get_error(obj))
+		return;
+
+	prog = bpf_object__next_program(obj, NULL);
+	if (bpf_object__load(obj))
+		goto out;
+
+	prog_fd = bpf_program__fd(prog);
+
+	buf = malloc(262144);
+	if (!ASSERT_OK_PTR(buf, "alloc buf 256Kb"))
+		goto out;
+
+	/* Test case add 10 bytes to last frag */
+	memset(buf, 1, 262144);
+	exp_size = 90000 + 10;
+
+	topts.data_in = buf;
+	topts.data_out = buf;
+	topts.data_size_in = 90000;
+	topts.data_size_out = 262144;
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+
+	ASSERT_OK(err, "90Kb+10b");
+	ASSERT_EQ(topts.retval, XDP_TX, "90Kb+10b retval");
+	ASSERT_EQ(topts.data_size_out, exp_size, "90Kb+10b size");
+
+	for (i = 0; i < 90000; i++) {
+		if (buf[i] != 1)
+			ASSERT_EQ(buf[i], 1, "90Kb+10b-old");
+	}
+
+	for (i = 90000; i < 90010; i++) {
+		if (buf[i] != 0)
+			ASSERT_EQ(buf[i], 0, "90Kb+10b-new");
+	}
+
+	for (i = 90010; i < 262144; i++) {
+		if (buf[i] != 1)
+			ASSERT_EQ(buf[i], 1, "90Kb+10b-untouched");
+	}
+
+	/* Test a too large grow */
+	memset(buf, 1, 262144);
+	exp_size = 90001;
+
+	topts.data_in = topts.data_out = buf;
+	topts.data_size_in = 90001;
+	topts.data_size_out = 262144;
+	err = bpf_prog_test_run_opts(prog_fd, &topts);
+
+	ASSERT_OK(err, "90Kb+10b");
+	ASSERT_EQ(topts.retval, XDP_DROP, "90Kb+10b retval");
+	ASSERT_EQ(topts.data_size_out, exp_size, "90Kb+10b size");
+
+	free(buf);
+out:
+	bpf_object__close(obj);
+}
+
 void test_xdp_adjust_tail(void)
 {
+	int page_size = getpagesize();
+
 	if (test__start_subtest("xdp_adjust_tail_shrink"))
 		test_xdp_adjust_tail_shrink();
 	if (test__start_subtest("xdp_adjust_tail_grow"))
-		test_xdp_adjust_tail_grow();
+		test_xdp_adjust_tail_grow(page_size == 65536);
 	if (test__start_subtest("xdp_adjust_tail_grow2"))
 		test_xdp_adjust_tail_grow2();
 	if (test__start_subtest("xdp_adjust_frags_tail_shrink"))
 		test_xdp_adjust_frags_tail_shrink();
-	if (test__start_subtest("xdp_adjust_frags_tail_grow"))
-		test_xdp_adjust_frags_tail_grow();
+	if (test__start_subtest("xdp_adjust_frags_tail_grow")) {
+		if (page_size == 65536)
+			test_xdp_adjust_frags_tail_grow_64k();
+		else
+			test_xdp_adjust_frags_tail_grow_4k();
+	}
 }

tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c

@@ -66,16 +66,25 @@ static int attach_tc_prog(struct bpf_tc_hook *hook, int fd)
 #else
 #define MAX_PKT_SIZE 3408
 #endif
+
+#define PAGE_SIZE_4K  4096
+#define PAGE_SIZE_64K 65536
+
 static void test_max_pkt_size(int fd)
 {
-	char data[MAX_PKT_SIZE + 1] = {};
+	char data[PAGE_SIZE_64K + 1] = {};
 	int err;
 	DECLARE_LIBBPF_OPTS(bpf_test_run_opts, opts,
 			    .data_in = &data,
-			    .data_size_in = MAX_PKT_SIZE,
 			    .flags = BPF_F_TEST_XDP_LIVE_FRAMES,
 			    .repeat = 1,
 		);
+
+	if (getpagesize() == PAGE_SIZE_64K)
+		opts.data_size_in = MAX_PKT_SIZE + PAGE_SIZE_64K - PAGE_SIZE_4K;
+	else
+		opts.data_size_in = MAX_PKT_SIZE;
+
 	err = bpf_prog_test_run_opts(fd, &opts);
 	ASSERT_OK(err, "prog_run_max_size");
 

tools/testing/selftests/bpf/progs/test_sockmap_change_tail.c

@@ -1,8 +1,13 @@
 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (c) 2024 ByteDance */
-#include <linux/bpf.h>
+#include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
 
+#ifndef PAGE_SIZE
+#define PAGE_SIZE __PAGE_SIZE
+#endif
+#define BPF_SKB_MAX_LEN (PAGE_SIZE << 2)
+
 struct {
 	__uint(type, BPF_MAP_TYPE_SOCKMAP);
 	__uint(max_entries, 1);
@@ -31,7 +36,7 @@ int prog_skb_verdict(struct __sk_buff *skb)
 		change_tail_ret = bpf_skb_change_tail(skb, skb->len + 1, 0);
 		return SK_PASS;
 	} else if (data[0] == 'E') { /* Error */
-		change_tail_ret = bpf_skb_change_tail(skb, 65535, 0);
+		change_tail_ret = bpf_skb_change_tail(skb, BPF_SKB_MAX_LEN, 0);
 		return SK_PASS;
 	}
 	return SK_PASS;

tools/testing/selftests/bpf/progs/test_tc_change_tail.c

@@ -1,11 +1,11 @@
 // SPDX-License-Identifier: GPL-2.0
-#include <linux/bpf.h>
+#include "vmlinux.h"
 #include <bpf/bpf_helpers.h>
-#include <linux/if_ether.h>
-#include <linux/in.h>
-#include <linux/ip.h>
-#include <linux/udp.h>
-#include <linux/pkt_cls.h>
+
+#ifndef PAGE_SIZE
+#define PAGE_SIZE __PAGE_SIZE
+#endif
+#define BPF_SKB_MAX_LEN (PAGE_SIZE << 2)
 
 long change_tail_ret = 1;
 
@@ -94,7 +94,7 @@ int change_tail(struct __sk_buff *skb)
 			bpf_skb_change_tail(skb, len, 0);
 		return TCX_PASS;
 	} else if (payload[0] == 'E') { /* Error */
-		change_tail_ret = bpf_skb_change_tail(skb, 65535, 0);
+		change_tail_ret = bpf_skb_change_tail(skb, BPF_SKB_MAX_LEN, 0);
 		return TCX_PASS;
 	} else if (payload[0] == 'Z') { /* Zero */
 		change_tail_ret = bpf_skb_change_tail(skb, 0, 0);

tools/testing/selftests/bpf/progs/test_xdp_adjust_tail_grow.c

@@ -19,7 +19,9 @@ int _xdp_adjust_tail_grow(struct xdp_md *xdp)
 	/* Data length determine test case */
 
 	if (data_len == 54) { /* sizeof(pkt_v4) */
-		offset = 4096; /* test too large offset */
+		offset = 4096; /* test too large offset, 4k page size */
+	} else if (data_len == 53) { /* sizeof(pkt_v4) - 1 */
+		offset = 65536; /* test too large offset, 64k page size */
 	} else if (data_len == 74) { /* sizeof(pkt_v6) */
 		offset = 40;
 	} else if (data_len == 64) {
@@ -31,6 +33,10 @@ int _xdp_adjust_tail_grow(struct xdp_md *xdp)
 		offset = 10;
 	} else if (data_len == 9001) {
 		offset = 4096;
+	} else if (data_len == 90000) {
+		offset = 10; /* test a small offset, 64k page size */
+	} else if (data_len == 90001) {
+		offset = 65536; /* test too large offset, 64k page size */
 	} else {
 		return XDP_ABORTED; /* No matching test */
 	}