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Commit 17bedab2 authored by Martin KaFai Lau's avatar Martin KaFai Lau Committed by David S. Miller
Browse files

bpf: xdp: Allow head adjustment in XDP prog 



This patch allows XDP prog to extend/remove the packet
data at the head (like adding or removing header).  It is
done by adding a new XDP helper bpf_xdp_adjust_head().

It also renames bpf_helper_changes_skb_data() to
bpf_helper_changes_pkt_data() to better reflect
that XDP prog does not work on skb.

This patch adds one "xdp_adjust_head" bit to bpf_prog for the
XDP-capable driver to check if the XDP prog requires
bpf_xdp_adjust_head() support.  The driver can then decide
to error out during XDP_SETUP_PROG.

Signed-off-by: default avatarMartin KaFai Lau <kafai@fb.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarJohn Fastabend <john.r.fastabend@intel.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 8a03cf2c

arch/powerpc/net/bpf_jit_comp64.c

+2 −2
Original line number Diff line number Diff line
@@ -766,7 +766,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, 
			func = (u8 *) __bpf_call_base + imm;



			/* Save skb pointer if we need to re-cache skb data */

			if (bpf_helper_changes_skb_data(func))

			if (bpf_helper_changes_pkt_data(func))

				PPC_BPF_STL(3, 1, bpf_jit_stack_local(ctx));



			bpf_jit_emit_func_call(image, ctx, (u64)func);
@@ -775,7 +775,7 @@ static int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, 
			PPC_MR(b2p[BPF_REG_0], 3);



			/* refresh skb cache */

			if (bpf_helper_changes_skb_data(func)) {

			if (bpf_helper_changes_pkt_data(func)) {

				/* reload skb pointer to r3 */

				PPC_BPF_LL(3, 1, bpf_jit_stack_local(ctx));

				bpf_jit_emit_skb_loads(image, ctx);

arch/s390/net/bpf_jit_comp.c

+1 −1
Original line number Diff line number Diff line
@@ -981,7 +981,7 @@ static noinline int bpf_jit_insn(struct bpf_jit *jit, struct bpf_prog *fp, int i 
		EMIT2(0x0d00, REG_14, REG_W1);

		/* lgr %b0,%r2: load return value into %b0 */

		EMIT4(0xb9040000, BPF_REG_0, REG_2);

		if (bpf_helper_changes_skb_data((void *)func)) {

		if (bpf_helper_changes_pkt_data((void *)func)) {

			jit->seen |= SEEN_SKB_CHANGE;

			/* lg %b1,ST_OFF_SKBP(%r15) */

			EMIT6_DISP_LH(0xe3000000, 0x0004, BPF_REG_1, REG_0,

arch/x86/net/bpf_jit_comp.c

+1 −1
Original line number Diff line number Diff line
@@ -853,7 +853,7 @@ xadd: if (is_imm8(insn->off)) 
			func = (u8 *) __bpf_call_base + imm32;

			jmp_offset = func - (image + addrs[i]);

			if (seen_ld_abs) {

				reload_skb_data = bpf_helper_changes_skb_data(func);

				reload_skb_data = bpf_helper_changes_pkt_data(func);

				if (reload_skb_data) {

					EMIT1(0x57); /* push %rdi */

					jmp_offset += 22; /* pop, mov, sub, mov */

drivers/net/ethernet/mellanox/mlx4/en_netdev.c

+5 −0
Original line number Diff line number Diff line
@@ -2686,6 +2686,11 @@ static int mlx4_xdp_set(struct net_device *dev, struct bpf_prog *prog) 
	int err;

	int i;



	if (prog && prog->xdp_adjust_head) {

		en_err(priv, "Does not support bpf_xdp_adjust_head()\n");

		return -EOPNOTSUPP;

	}



	xdp_ring_num = prog ? priv->rx_ring_num : 0;



	/* No need to reconfigure buffers when simply swapping the

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

+5 −0
Original line number Diff line number Diff line
@@ -3183,6 +3183,11 @@ static int mlx5e_xdp_set(struct net_device *netdev, struct bpf_prog *prog) 
	bool reset, was_opened;

	int i;



	if (prog && prog->xdp_adjust_head) {

		netdev_err(netdev, "Does not support bpf_xdp_adjust_head()\n");

		return -EOPNOTSUPP;

	}



	mutex_lock(&priv->state_lock);



	if ((netdev->features & NETIF_F_LRO) && prog) {