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bpf: net: Remove TC_AT_INGRESS_OFFSET and SKB_MONO_DELIVERY_TIME_OFFSET macro

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This patch removes the TC_AT_INGRESS_OFFSET and
SKB_MONO_DELIVERY_TIME_OFFSET macros.  Instead, PKT_VLAN_PRESENT_OFFSET
is used because all of them are at the same offset.  Comment is added to
make it clear that changing the position of tc_at_ingress or
mono_delivery_time will require to adjust the defined macros.

The earlier discussion can be found here:
https://lore.kernel.org/bpf/419d994e-ff61-7c11-0ec7-11fefcb0186e@iogearbox.net/

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220309090450.3710955-1-kafai@fb.com
This commit is contained in:
Martin KaFai Lau 2022-03-09 01:04:50 -08:00 committed by Daniel Borkmann
parent 743bec1b78
commit 3b5d4ddf8f
2 changed files with 12 additions and 12 deletions
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10
include/linux/skbuff.h
View file

@ -960,10 +960,10 @@ struct sk_buff {
__u8 csum_complete_sw:1;
__u8 csum_level:2;
__u8 dst_pending_confirm:1;
__u8 mono_delivery_time:1;
__u8 mono_delivery_time:1; /* See SKB_MONO_DELIVERY_TIME_MASK */
#ifdef CONFIG_NET_CLS_ACT
__u8 tc_skip_classify:1;
__u8 tc_at_ingress:1;
__u8 tc_at_ingress:1; /* See TC_AT_INGRESS_MASK */
#endif
#ifdef CONFIG_IPV6_NDISC_NODETYPE
__u8 ndisc_nodetype:2;
@ -1062,7 +1062,9 @@ struct sk_buff {
#endif
#define PKT_TYPE_OFFSET offsetof(struct sk_buff, __pkt_type_offset)
/* if you move pkt_vlan_present around you also must adapt these constants */
/* if you move pkt_vlan_present, tc_at_ingress, or mono_delivery_time
* around, you also must adapt these constants.
*/
#ifdef __BIG_ENDIAN_BITFIELD
#define PKT_VLAN_PRESENT_BIT 7
#define TC_AT_INGRESS_MASK (1 << 0)
@ -1073,8 +1075,6 @@ struct sk_buff {
#define SKB_MONO_DELIVERY_TIME_MASK (1 << 5)
#endif
#define PKT_VLAN_PRESENT_OFFSET offsetof(struct sk_buff, __pkt_vlan_present_offset)
#define TC_AT_INGRESS_OFFSET offsetof(struct sk_buff, __pkt_vlan_present_offset)
#define SKB_MONO_DELIVERY_TIME_OFFSET offsetof(struct sk_buff, __pkt_vlan_present_offset)
#ifdef __KERNEL__
/*

14
net/core/filter.c
View file

@ -8896,7 +8896,7 @@ static struct bpf_insn *bpf_convert_dtime_type_read(const struct bpf_insn *si,
__u8 tmp_reg = BPF_REG_AX;
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg,
SKB_MONO_DELIVERY_TIME_OFFSET);
PKT_VLAN_PRESENT_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg,
SKB_MONO_DELIVERY_TIME_MASK);
*insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2);
@ -8912,7 +8912,7 @@ static struct bpf_insn *bpf_convert_dtime_type_read(const struct bpf_insn *si,
*insn++ = BPF_JMP_A(IS_ENABLED(CONFIG_NET_CLS_ACT) ? 6 : 1);
#ifdef CONFIG_NET_CLS_ACT
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET);
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, PKT_VLAN_PRESENT_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK);
*insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2);
/* At ingress, value_reg = 0 */
@ -8959,14 +8959,14 @@ static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_prog *prog,
if (!prog->delivery_time_access) {
__u8 tmp_reg = BPF_REG_AX;
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET);
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, PKT_VLAN_PRESENT_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK);
*insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 5);
/* @ingress, read __sk_buff->tstamp as the (rcv) timestamp,
* so check the skb->mono_delivery_time.
*/
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg,
SKB_MONO_DELIVERY_TIME_OFFSET);
PKT_VLAN_PRESENT_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg,
SKB_MONO_DELIVERY_TIME_MASK);
*insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 2);
@ -8992,18 +8992,18 @@ static struct bpf_insn *bpf_convert_tstamp_write(const struct bpf_prog *prog,
if (!prog->delivery_time_access) {
__u8 tmp_reg = BPF_REG_AX;
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, TC_AT_INGRESS_OFFSET);
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, PKT_VLAN_PRESENT_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK);
*insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg, 0, 3);
/* Writing __sk_buff->tstamp at ingress as the (rcv) timestamp.
* Clear the skb->mono_delivery_time.
*/
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg,
SKB_MONO_DELIVERY_TIME_OFFSET);
PKT_VLAN_PRESENT_OFFSET);
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg,
~SKB_MONO_DELIVERY_TIME_MASK);
*insn++ = BPF_STX_MEM(BPF_B, skb_reg, tmp_reg,
SKB_MONO_DELIVERY_TIME_OFFSET);
PKT_VLAN_PRESENT_OFFSET);
}
#endif