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authorAlexander Lobakin <aleksander.lobakin@intel.com>2023-02-24 17:36:07 +0100
committerMartin KaFai Lau <martin.lau@kernel.org>2023-03-06 11:15:54 -0800
commit294635a8165a31408a8b3a24f9c74849ca3d8701 (patch)
treec8ab2cb242da4d3264cd0d3ede0f943c98d54dc1 /net/bpf
parentb7abcd9c656b982a99e18f795bb1cf81f84b656d (diff)
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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 'net/bpf')
-rw-r--r--net/bpf/test_run.c19
1 files changed, 13 insertions, 6 deletions
diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 6f3d654b3339..f81b24320a36 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -97,8 +97,11 @@ reset:
struct xdp_page_head {
struct xdp_buff orig_ctx;
struct xdp_buff ctx;
- struct xdp_frame frm;
- u8 data[];
+ union {
+ /* ::data_hard_start starts here */
+ DECLARE_FLEX_ARRAY(struct xdp_frame, frame);
+ DECLARE_FLEX_ARRAY(u8, data);
+ };
};
struct xdp_test_data {
@@ -113,6 +116,10 @@ struct xdp_test_data {
u32 frame_cnt;
};
+/* tools/testing/selftests/bpf/prog_tests/xdp_do_redirect.c:%MAX_PKT_SIZE
+ * must be updated accordingly this gets changed, otherwise BPF selftests
+ * will fail.
+ */
#define TEST_XDP_FRAME_SIZE (PAGE_SIZE - sizeof(struct xdp_page_head))
#define TEST_XDP_MAX_BATCH 256
@@ -132,8 +139,8 @@ static void xdp_test_run_init_page(struct page *page, void *arg)
headroom -= meta_len;
new_ctx = &head->ctx;
- frm = &head->frm;
- data = &head->data;
+ frm = head->frame;
+ data = head->data;
memcpy(data + headroom, orig_ctx->data_meta, frm_len);
xdp_init_buff(new_ctx, TEST_XDP_FRAME_SIZE, &xdp->rxq);
@@ -223,7 +230,7 @@ static void reset_ctx(struct xdp_page_head *head)
head->ctx.data = head->orig_ctx.data;
head->ctx.data_meta = head->orig_ctx.data_meta;
head->ctx.data_end = head->orig_ctx.data_end;
- xdp_update_frame_from_buff(&head->ctx, &head->frm);
+ xdp_update_frame_from_buff(&head->ctx, head->frame);
}
static int xdp_recv_frames(struct xdp_frame **frames, int nframes,
@@ -285,7 +292,7 @@ static int xdp_test_run_batch(struct xdp_test_data *xdp, struct bpf_prog *prog,
head = phys_to_virt(page_to_phys(page));
reset_ctx(head);
ctx = &head->ctx;
- frm = &head->frm;
+ frm = head->frame;
xdp->frame_cnt++;
act = bpf_prog_run_xdp(prog, ctx);