From 04aae213e719ec2bb310158c4025316ace50589b Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 20 Mar 2023 18:41:13 -0700 Subject: [PATCH 1/3] net: skbuff: rename __pkt_vlan_present_offset to __mono_tc_offset vlan_present is gone since commit 354259fa73e2 ("net: remove skb->vlan_present") rename the offset field to what BPF is currently looking for in this byte - mono_delivery_time and tc_at_ingress. Signed-off-by: Jakub Kicinski Link: https://lore.kernel.org/r/20230321014115.997841-2-kuba@kernel.org Signed-off-by: Martin KaFai Lau --- include/linux/skbuff.h | 4 ++-- net/core/filter.c | 8 ++++---- tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c | 6 +++--- 3 files changed, 9 insertions(+), 9 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 3f3a2a82a86b..5a63878a4550 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -955,7 +955,7 @@ struct sk_buff { __u8 csum_valid:1; /* private: */ - __u8 __pkt_vlan_present_offset[0]; + __u8 __mono_tc_offset[0]; /* public: */ __u8 remcsum_offload:1; __u8 csum_complete_sw:1; @@ -1078,7 +1078,7 @@ struct sk_buff { #define TC_AT_INGRESS_MASK (1 << 7) #define SKB_MONO_DELIVERY_TIME_MASK (1 << 5) #endif -#define PKT_VLAN_PRESENT_OFFSET offsetof(struct sk_buff, __pkt_vlan_present_offset) +#define SKB_BF_MONO_TC_OFFSET offsetof(struct sk_buff, __mono_tc_offset) #ifdef __KERNEL__ /* diff --git a/net/core/filter.c b/net/core/filter.c index 50f649f1b4a9..3370efad1dda 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -9185,7 +9185,7 @@ static struct bpf_insn *bpf_convert_tstamp_type_read(const struct bpf_insn *si, __u8 tmp_reg = BPF_REG_AX; *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, - PKT_VLAN_PRESENT_OFFSET); + SKB_BF_MONO_TC_OFFSET); *insn++ = BPF_JMP32_IMM(BPF_JSET, tmp_reg, SKB_MONO_DELIVERY_TIME_MASK, 2); *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_UNSPEC); @@ -9232,7 +9232,7 @@ static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_prog *prog, /* AX is needed because src_reg and dst_reg could be the same */ __u8 tmp_reg = BPF_REG_AX; - *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, PKT_VLAN_PRESENT_OFFSET); + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, SKB_BF_MONO_TC_OFFSET); *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, TC_AT_INGRESS_MASK | SKB_MONO_DELIVERY_TIME_MASK); *insn++ = BPF_JMP32_IMM(BPF_JNE, tmp_reg, @@ -9267,14 +9267,14 @@ static struct bpf_insn *bpf_convert_tstamp_write(const struct bpf_prog *prog, if (!prog->tstamp_type_access) { __u8 tmp_reg = BPF_REG_AX; - *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, PKT_VLAN_PRESENT_OFFSET); + *insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, SKB_BF_MONO_TC_OFFSET); /* Writing __sk_buff->tstamp as ingress, goto */ *insn++ = BPF_JMP32_IMM(BPF_JSET, tmp_reg, TC_AT_INGRESS_MASK, 1); /* goto */ *insn++ = BPF_JMP_A(2); /* : mono_delivery_time */ *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, ~SKB_MONO_DELIVERY_TIME_MASK); - *insn++ = BPF_STX_MEM(BPF_B, skb_reg, tmp_reg, PKT_VLAN_PRESENT_OFFSET); + *insn++ = BPF_STX_MEM(BPF_B, skb_reg, tmp_reg, SKB_BF_MONO_TC_OFFSET); } #endif diff --git a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c index d5fe3d4b936c..ae7b6e50e405 100644 --- a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c +++ b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c @@ -68,17 +68,17 @@ static struct test_case test_cases[] = { #if defined(__x86_64__) || defined(__aarch64__) { N(SCHED_CLS, struct __sk_buff, tstamp), - .read = "r11 = *(u8 *)($ctx + sk_buff::__pkt_vlan_present_offset);" + .read = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);" "w11 &= 160;" "if w11 != 0xa0 goto pc+2;" "$dst = 0;" "goto pc+1;" "$dst = *(u64 *)($ctx + sk_buff::tstamp);", - .write = "r11 = *(u8 *)($ctx + sk_buff::__pkt_vlan_present_offset);" + .write = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);" "if w11 & 0x80 goto pc+1;" "goto pc+2;" "w11 &= -33;" - "*(u8 *)($ctx + sk_buff::__pkt_vlan_present_offset) = r11;" + "*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r11;" "*(u64 *)($ctx + sk_buff::tstamp) = $src;", }, #endif From b94e032b7ad6318b36615f0e0cc3b0d61a5531e8 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 20 Mar 2023 18:41:14 -0700 Subject: [PATCH 2/3] net: skbuff: reorder bytes 2 and 3 of the bitfield BPF needs to know the offsets of fields it tries to access. Zero-length fields are added to make offsetof() work. This unfortunately partitions the bitfield (fields across the zero-length members can't be coalesced). Reorder bytes 2 and 3, BPF needs to know the offset of fields previously in byte 3 and some fields in byte 2 should really be optional. The two bytes are always in the same cacheline so it should not matter. Signed-off-by: Jakub Kicinski Link: https://lore.kernel.org/r/20230321014115.997841-3-kuba@kernel.org Signed-off-by: Martin KaFai Lau --- include/linux/skbuff.h | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 5a63878a4550..36d31e74db37 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -944,16 +944,6 @@ struct sk_buff { __u8 ip_summed:2; __u8 ooo_okay:1; - __u8 l4_hash:1; - __u8 sw_hash:1; - __u8 wifi_acked_valid:1; - __u8 wifi_acked:1; - __u8 no_fcs:1; - /* Indicates the inner headers are valid in the skbuff. */ - __u8 encapsulation:1; - __u8 encap_hdr_csum:1; - __u8 csum_valid:1; - /* private: */ __u8 __mono_tc_offset[0]; /* public: */ @@ -966,6 +956,16 @@ struct sk_buff { __u8 tc_skip_classify:1; __u8 tc_at_ingress:1; /* See TC_AT_INGRESS_MASK */ #endif + + __u8 l4_hash:1; + __u8 sw_hash:1; + __u8 wifi_acked_valid:1; + __u8 wifi_acked:1; + __u8 no_fcs:1; + /* Indicates the inner headers are valid in the skbuff. */ + __u8 encapsulation:1; + __u8 encap_hdr_csum:1; + __u8 csum_valid:1; #ifdef CONFIG_IPV6_NDISC_NODETYPE __u8 ndisc_nodetype:2; #endif From c0ba861117c3e8deb03855d7dc5a7717958bbb18 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Mon, 20 Mar 2023 18:41:15 -0700 Subject: [PATCH 3/3] net: skbuff: move the fields BPF cares about directly next to the offset marker To avoid more possible BPF dependencies with moving bitfields around keep the fields BPF cares about right next to the offset marker. Signed-off-by: Jakub Kicinski Link: https://lore.kernel.org/r/20230321014115.997841-4-kuba@kernel.org Signed-off-by: Martin KaFai Lau --- include/linux/skbuff.h | 18 +++++++++--------- .../selftests/bpf/prog_tests/ctx_rewrite.c | 8 ++++---- 2 files changed, 13 insertions(+), 13 deletions(-) diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h index 36d31e74db37..6aeb0e7b9511 100644 --- a/include/linux/skbuff.h +++ b/include/linux/skbuff.h @@ -947,15 +947,15 @@ struct sk_buff { /* private: */ __u8 __mono_tc_offset[0]; /* public: */ + __u8 mono_delivery_time:1; /* See SKB_MONO_DELIVERY_TIME_MASK */ +#ifdef CONFIG_NET_CLS_ACT + __u8 tc_at_ingress:1; /* See TC_AT_INGRESS_MASK */ + __u8 tc_skip_classify:1; +#endif __u8 remcsum_offload:1; __u8 csum_complete_sw:1; __u8 csum_level:2; __u8 dst_pending_confirm: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; /* See TC_AT_INGRESS_MASK */ -#endif __u8 l4_hash:1; __u8 sw_hash:1; @@ -1072,11 +1072,11 @@ struct sk_buff { * around, you also must adapt these constants. */ #ifdef __BIG_ENDIAN_BITFIELD -#define TC_AT_INGRESS_MASK (1 << 0) -#define SKB_MONO_DELIVERY_TIME_MASK (1 << 2) +#define SKB_MONO_DELIVERY_TIME_MASK (1 << 7) +#define TC_AT_INGRESS_MASK (1 << 6) #else -#define TC_AT_INGRESS_MASK (1 << 7) -#define SKB_MONO_DELIVERY_TIME_MASK (1 << 5) +#define SKB_MONO_DELIVERY_TIME_MASK (1 << 0) +#define TC_AT_INGRESS_MASK (1 << 1) #endif #define SKB_BF_MONO_TC_OFFSET offsetof(struct sk_buff, __mono_tc_offset) diff --git a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c index ae7b6e50e405..4951aa978f33 100644 --- a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c +++ b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c @@ -69,15 +69,15 @@ static struct test_case test_cases[] = { { N(SCHED_CLS, struct __sk_buff, tstamp), .read = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);" - "w11 &= 160;" - "if w11 != 0xa0 goto pc+2;" + "w11 &= 3;" + "if w11 != 0x3 goto pc+2;" "$dst = 0;" "goto pc+1;" "$dst = *(u64 *)($ctx + sk_buff::tstamp);", .write = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);" - "if w11 & 0x80 goto pc+1;" + "if w11 & 0x2 goto pc+1;" "goto pc+2;" - "w11 &= -33;" + "w11 &= -2;" "*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r11;" "*(u64 *)($ctx + sk_buff::tstamp) = $src;", },