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author | Alexander Lobakin <aleksander.lobakin@intel.com> | 2023-02-24 19:36:07 +0300 |
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committer | Martin KaFai Lau <martin.lau@kernel.org> | 2023-03-06 22:15:54 +0300 |
commit | 294635a8165a31408a8b3a24f9c74849ca3d8701 (patch) | |
tree | c8ab2cb242da4d3264cd0d3ede0f943c98d54dc1 /tools | |
parent | b7abcd9c656b982a99e18f795bb1cf81f84b656d (diff) | |
download | linux-294635a8165a31408a8b3a24f9c74849ca3d8701.tar.xz |
bpf, test_run: fix &xdp_frame misplacement for LIVE_FRAMES
&xdp_buff and &xdp_frame are bound in a way that
xdp_buff->data_hard_start == xdp_frame
It's always the case and e.g. xdp_convert_buff_to_frame() relies on
this.
IOW, the following:
for (u32 i = 0; i < 0xdead; i++) {
xdpf = xdp_convert_buff_to_frame(&xdp);
xdp_convert_frame_to_buff(xdpf, &xdp);
}
shouldn't ever modify @xdpf's contents or the pointer itself.
However, "live packet" code wrongly treats &xdp_frame as part of its
context placed *before* the data_hard_start. With such flow,
data_hard_start is sizeof(*xdpf) off to the right and no longer points
to the XDP frame.
Instead of replacing `sizeof(ctx)` with `offsetof(ctx, xdpf)` in several
places and praying that there are no more miscalcs left somewhere in the
code, unionize ::frm with ::data in a flex array, so that both starts
pointing to the actual data_hard_start and the XDP frame actually starts
being a part of it, i.e. a part of the headroom, not the context.
A nice side effect is that the maximum frame size for this mode gets
increased by 40 bytes, as xdp_buff::frame_sz includes everything from
data_hard_start (-> includes xdpf already) to the end of XDP/skb shared
info.
Also update %MAX_PKT_SIZE accordingly in the selftests code. Leave it
hardcoded for 64 bit && 4k pages, it can be made more flexible later on.
Minor: align `&head->data` with how `head->frm` is assigned for
consistency.
Minor #2: rename 'frm' to 'frame' in &xdp_page_head while at it for
clarity.
(was found while testing XDP traffic generator on ice, which calls
xdp_convert_frame_to_buff() for each XDP frame)
Fixes: b530e9e1063e ("bpf: Add "live packet" mode for XDP in BPF_PROG_RUN")
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://lore.kernel.org/r/20230224163607.2994755-1-aleksander.lobakin@intel.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'tools')
-rw-r--r-- | tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c index 2666c84dbd01..7271a18ab3e2 100644 --- a/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c +++ b/tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c @@ -65,12 +65,13 @@ static int attach_tc_prog(struct bpf_tc_hook *hook, int fd) } /* The maximum permissible size is: PAGE_SIZE - sizeof(struct xdp_page_head) - - * sizeof(struct skb_shared_info) - XDP_PACKET_HEADROOM = 3368 bytes + * SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) - XDP_PACKET_HEADROOM = + * 3408 bytes for 64-byte cacheline and 3216 for 256-byte one. */ #if defined(__s390x__) -#define MAX_PKT_SIZE 3176 +#define MAX_PKT_SIZE 3216 #else -#define MAX_PKT_SIZE 3368 +#define MAX_PKT_SIZE 3408 #endif static void test_max_pkt_size(int fd) { |