From: Magnus Karlsson <magnus.karlsson@intel.com>
Date: Wed, 22 Sep 2021 09:56:12 +0200
Subject: selftests: xsk: Change interleaving of packets in unaligned mode
Patch-mainline: v5.16-rc1
Git-commit: e4e9baf06a6ea6cfbf69db4c3766a0879329dda2
References: jsc#PED-1377

Change the interleaving of packets in unaligned mode. With the current
buffer addresses in the packet stream, the last buffer in the umem
could not be used as a large packet could potentially write over the
end of the umem. The kernel correctly threw this buffer address away
and refused to use it. This is perfectly fine for all regular packet
streams, but the ones used for unaligned mode have every other packet
being at some different offset. As we will add checks for correct
offsets in the next patch, this needs to be fixed. Just start these
page-boundary straddling buffers one page earlier so that the last
one is not on the last page of the umem, making all buffers valid.

Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210922075613.12186-13-magnus.karlsson@gmail.com
Acked-by: Shung-Hsi Yu <shung-hsi.yu@suse.com>
---
 tools/testing/selftests/bpf/xdpxceiver.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/tools/testing/selftests/bpf/xdpxceiver.c
+++ b/tools/testing/selftests/bpf/xdpxceiver.c
@@ -543,14 +543,14 @@ static void pkt_stream_replace(struct te
 	test->ifobj_rx->pkt_stream = pkt_stream;
 }
 
-static void pkt_stream_replace_half(struct test_spec *test, u32 pkt_len, u32 offset)
+static void pkt_stream_replace_half(struct test_spec *test, u32 pkt_len, int offset)
 {
 	struct xsk_umem_info *umem = test->ifobj_tx->umem;
 	struct pkt_stream *pkt_stream;
 	u32 i;
 
 	pkt_stream = pkt_stream_clone(umem, test->pkt_stream_default);
-	for (i = 0; i < test->pkt_stream_default->nb_pkts; i += 2) {
+	for (i = 1; i < test->pkt_stream_default->nb_pkts; i += 2) {
 		pkt_stream->pkts[i].addr = (i % umem->num_frames) * umem->frame_size + offset;
 		pkt_stream->pkts[i].len = pkt_len;
 	}
@@ -1209,7 +1209,7 @@ static bool testapp_unaligned(struct tes
 	test->ifobj_tx->umem->unaligned_mode = true;
 	test->ifobj_rx->umem->unaligned_mode = true;
 	/* Let half of the packets straddle a buffer boundrary */
-	pkt_stream_replace_half(test, PKT_SIZE, test->ifobj_tx->umem->frame_size - 32);
+	pkt_stream_replace_half(test, PKT_SIZE, -PKT_SIZE / 2);
 	test->ifobj_rx->pkt_stream->use_addr_for_fill = true;
 	testapp_validate_traffic(test);