Merge branch 'net: skbuff: skb bitfield compaction - bpf'

Jakub Kicinski says:

====================

I'm trying to make more of the sk_buff bits optional.
Move the BPF-accessed bits a little - because they must
be at coding-time-constant offsets they must precede any
optional bit. While at it clean up the naming a bit.

v1: https://lore.kernel.org/all/20230308003159.441580-1-kuba@kernel.org/
====================

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 3f3a2a8..6aeb0e7 100644 (file)
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -944,6 +944,19 @@ struct sk_buff {
        __u8                    ip_summed:2;
        __u8                    ooo_okay:1;
 
+       /* 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                    l4_hash:1;
        __u8                    sw_hash:1;
        __u8                    wifi_acked_valid:1;
@@ -953,19 +966,6 @@ struct sk_buff {
        __u8                    encapsulation:1;
        __u8                    encap_hdr_csum:1;
        __u8                    csum_valid:1;
-
-       /* private: */
-       __u8                    __pkt_vlan_present_offset[0];
-       /* public: */
-       __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
 #ifdef CONFIG_IPV6_NDISC_NODETYPE
        __u8                    ndisc_nodetype:2;
 #endif
@@ -1072,13 +1072,13 @@ 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 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 50f649f..3370efa 100644 (file)
--- 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 <clear> */
                *insn++ = BPF_JMP32_IMM(BPF_JSET, tmp_reg, TC_AT_INGRESS_MASK, 1);
                /* goto <store> */
                *insn++ = BPF_JMP_A(2);
                /* <clear>: 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 d5fe3d4..4951aa9 100644 (file)
--- 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 *)($ctx + sk_buff::__pkt_vlan_present_offset);"
-                        "w11 &= 160;"
-                        "if w11 != 0xa0 goto pc+2;"
+               .read  = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
+                        "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::__pkt_vlan_present_offset);"
-                        "if w11 & 0x80 goto pc+1;"
+               .write = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
+                        "if w11 & 0x2 goto pc+1;"
                         "goto pc+2;"
-                        "w11 &= -33;"
-                        "*(u8 *)($ctx + sk_buff::__pkt_vlan_present_offset) = r11;"
+                        "w11 &= -2;"
+                        "*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r11;"
                         "*(u64 *)($ctx + sk_buff::tstamp) = $src;",
        },
 #endif