Hi all, This patchset introduces a new kfunc bpf_xdp_pull_data() to allow pulling nonlinear xdp data. This may be useful when a driver places headers in fragments. When an xdp program would like to keep parsing packet headers using direct packet access, it can call bpf_xdp_pull_data() to make the header available in the linear data area. The kfunc can also be used to decapsulate the header in the nonlinear data, as currently there is no easy way to do this. This patchset also tries to fix an issue in the mlx5e driver. The driver curretly assumes the packet layout to be unchanged after xdp program runs and may generate packet with corrupted data or trigger kernel warning if xdp programs calls layout-changing kfunc such as bpf_xdp_adjust_tail(), bpf_xdp_adjust_head() or bpf_xdp_pull_data() introduced in this set. Tested with the added bpf selftest using bpf test_run and also on mlx5e with the tools/testing/selftests/drivers/net/xdp.py. mlx5e with striding RQ will produce xdp_buff with empty linear data. xdp.test_xdp_native_pass_mb would fail to parse the header before this patchset. Grateful for any feedback (especially the driver part). Thanks! Amery Amery Hung (7): net/mlx5e: Fix generating skb from nonlinear xdp_buff bpf: Allow bpf_xdp_shrink_data to shrink a frag from head and tail bpf: Support pulling non-linear xdp data bpf: Clear packet pointers after changing packet data in kfuncs bpf: Support specifying linear xdp packet data size in test_run selftests/bpf: Test bpf_xdp_pull_data selftests: drv-net: Pull data before parsing headers .../net/ethernet/mellanox/mlx5/core/en_rx.c | 59 ++++++++---- include/net/xdp_sock_drv.h | 21 +++- kernel/bpf/verifier.c | 13 +++ net/bpf/test_run.c | 9 +- net/core/filter.c | 81 +++++++++++++--- .../bpf/prog_tests/xdp_context_test_run.c | 4 +- .../selftests/bpf/prog_tests/xdp_pull_data.c | 96 +++++++++++++++++++ .../selftests/bpf/progs/test_xdp_pull_data.c | 36 +++++++ .../selftests/net/lib/xdp_native.bpf.c | 90 ++++++++++++++--- 9 files changed, 356 insertions(+), 53 deletions(-) create mode 100644 tools/testing/selftests/bpf/prog_tests/xdp_pull_data.c create mode 100644 tools/testing/selftests/bpf/progs/test_xdp_pull_data.c -- 2.47.3
