[RFC PATCH bpf-next v4 2/2] net: Add additional bit to support clockid_t timestamp type
From: Abhishek Chauhan
Date: Wed Apr 17 2024 - 20:43:52 EST
tstamp_type is now set based on actual clockid_t compressed
into 2 bits.
To make the design scalable for future needs this commit bring in
the change to extend the tstamp_type:1 to tstamp_type:2 to support
other clockid_t timestamp.
We now support CLOCK_TAI as part of tstamp_type as part of this
commit with exisiting support CLOCK_MONOTONIC and CLOCK_REALTIME.
Link: https://lore.kernel.org/netdev/bc037db4-58bb-4861-ac31-a361a93841d3@xxxxxxxxx/
Signed-off-by: Abhishek Chauhan <quic_abchauha@xxxxxxxxxxx>
---
Changes since v3
- Carefully reviewed BPF APIs and made changes in
BPF code as well.
- Re-used actual clockid_t values since skbuff.h
indirectly includes uapi/linux/time.h
- Added CLOCK_TAI as part of the skb_set_delivery_time
handling instead of CLOCK_USER
- Added default in switch for unsupported and invalid
timestamp with an WARN_ONCE.
- All of the above comments were given by Willem
- Made changes in filter.c as per Martin's comments
to handle invalid cases in bpf code with addition of
SKB_TAI_DELIVERY_TIME_MASK
Changes since v2
- Minor changes to commit subject
Changes since v1
- identified additional changes in BPF framework.
- Bit shift in SKB_MONO_DELIVERY_TIME_MASK and TC_AT_INGRESS_MASK.
- Made changes in skb_set_delivery_time to keep changes similar to
previous code for mono_delivery_time and just setting tstamp_type
bit 1 for userspace timestamp.
include/linux/skbuff.h | 21 +++++++---
include/uapi/linux/bpf.h | 1 +
net/core/filter.c | 40 ++++++++++++++++---
net/ipv4/ip_output.c | 2 +-
net/ipv4/raw.c | 2 +-
net/ipv6/ip6_output.c | 2 +-
net/ipv6/raw.c | 2 +-
net/packet/af_packet.c | 7 ++--
.../selftests/bpf/prog_tests/ctx_rewrite.c | 13 ++++--
9 files changed, 68 insertions(+), 22 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 2e7811c7e4db..647522ef41cd 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -703,14 +703,17 @@ typedef unsigned char *sk_buff_data_t;
#endif
/**
- * tstamp_type:1 can take 2 values each
+ * tstamp_type:2 can take 4 values each
* represented by time base in skb
* 0x0 => real timestamp_type
* 0x1 => mono timestamp_type
+ * 0x2 => tai timestamp_type
+ * 0x3 => undefined timestamp_type
*/
enum skb_tstamp_type {
SKB_CLOCK_REAL, /* Time base is skb is REALTIME */
SKB_CLOCK_MONO, /* Time base is skb is MONOTONIC */
+ SKB_CLOCK_TAI, /* Time base in skb is TAI */
};
/**
@@ -833,7 +836,8 @@ enum skb_tstamp_type {
* @tstamp_type: When set, skb->tstamp has the
* delivery_time in mono clock base (i.e. EDT). Otherwise, the
* skb->tstamp has the (rcv) timestamp at ingress and
- * delivery_time at egress.
+ * delivery_time at egress or skb->tstamp defined by skb->sk->sk_clockid
+ * coming from userspace
* @napi_id: id of the NAPI struct this skb came from
* @sender_cpu: (aka @napi_id) source CPU in XPS
* @alloc_cpu: CPU which did the skb allocation.
@@ -961,7 +965,7 @@ struct sk_buff {
/* private: */
__u8 __mono_tc_offset[0];
/* public: */
- __u8 tstamp_type:1; /* See SKB_CLOCK_*_MASK */
+ __u8 tstamp_type:2; /* See skb_tstamp_type enum */
#ifdef CONFIG_NET_XGRESS
__u8 tc_at_ingress:1; /* See TC_AT_INGRESS_MASK */
__u8 tc_skip_classify:1;
@@ -1096,10 +1100,12 @@ struct sk_buff {
*/
#ifdef __BIG_ENDIAN_BITFIELD
#define SKB_MONO_DELIVERY_TIME_MASK (1 << 7)
-#define TC_AT_INGRESS_MASK (1 << 6)
+#define SKB_TAI_DELIVERY_TIME_MASK (1 << 6)
+#define TC_AT_INGRESS_MASK (1 << 5)
#else
#define SKB_MONO_DELIVERY_TIME_MASK (1 << 0)
-#define TC_AT_INGRESS_MASK (1 << 1)
+#define SKB_TAI_DELIVERY_TIME_MASK (1 << 1)
+#define TC_AT_INGRESS_MASK (1 << 2)
#endif
#define SKB_BF_MONO_TC_OFFSET offsetof(struct sk_buff, __mono_tc_offset)
@@ -4206,6 +4212,11 @@ static inline void skb_set_delivery_time(struct sk_buff *skb, ktime_t kt,
case CLOCK_MONOTONIC:
skb->tstamp_type = SKB_CLOCK_MONO;
break;
+ case CLOCK_TAI:
+ skb->tstamp_type = SKB_CLOCK_TAI;
+ break;
+ default:
+ WARN_ONCE(true, "clockid %d not supported", tstamp_type);
}
}
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index cee0a7915c08..1376ed5ece10 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -6209,6 +6209,7 @@ union { \
enum {
BPF_SKB_TSTAMP_UNSPEC,
BPF_SKB_TSTAMP_DELIVERY_MONO, /* tstamp has mono delivery time */
+ BPF_SKB_TSTAMP_DELIVERY_TAI, /* tstamp has tai delivery time */
/* For any BPF_SKB_TSTAMP_* that the bpf prog cannot handle,
* the bpf prog should handle it like BPF_SKB_TSTAMP_UNSPEC
* and try to deduce it by ingress, egress or skb->sk->sk_clockid.
diff --git a/net/core/filter.c b/net/core/filter.c
index b1192e672cbb..de86c42b5859 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -7711,6 +7711,12 @@ BPF_CALL_3(bpf_skb_set_tstamp, struct sk_buff *, skb,
skb->tstamp = tstamp;
skb->tstamp_type = SKB_CLOCK_MONO;
break;
+ case BPF_SKB_TSTAMP_DELIVERY_TAI:
+ if (!tstamp)
+ return -EINVAL;
+ skb->tstamp = tstamp;
+ skb->tstamp_type = SKB_CLOCK_TAI;
+ break;
case BPF_SKB_TSTAMP_UNSPEC:
if (tstamp)
return -EINVAL;
@@ -9372,10 +9378,16 @@ static struct bpf_insn *bpf_convert_tstamp_type_read(const struct bpf_insn *si,
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg,
SKB_BF_MONO_TC_OFFSET);
*insn++ = BPF_JMP32_IMM(BPF_JSET, tmp_reg,
- SKB_MONO_DELIVERY_TIME_MASK, 2);
+ SKB_MONO_DELIVERY_TIME_MASK | SKB_TAI_DELIVERY_TIME_MASK, 2);
+ *insn++ = BPF_JMP32_IMM(BPF_JSET, tmp_reg,
+ SKB_MONO_DELIVERY_TIME_MASK, 3);
+ *insn++ = BPF_JMP32_IMM(BPF_JSET, tmp_reg,
+ SKB_TAI_DELIVERY_TIME_MASK, 4);
*insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_UNSPEC);
*insn++ = BPF_JMP_A(1);
*insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_DELIVERY_MONO);
+ *insn++ = BPF_JMP_A(1);
+ *insn++ = BPF_MOV32_IMM(value_reg, BPF_SKB_TSTAMP_DELIVERY_TAI);
return insn;
}
@@ -9418,10 +9430,26 @@ static struct bpf_insn *bpf_convert_tstamp_read(const struct bpf_prog *prog,
__u8 tmp_reg = BPF_REG_AX;
*insn++ = BPF_LDX_MEM(BPF_B, tmp_reg, skb_reg, SKB_BF_MONO_TC_OFFSET);
+ /*check if all three bits are set*/
*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,
- TC_AT_INGRESS_MASK | SKB_MONO_DELIVERY_TIME_MASK, 2);
+ TC_AT_INGRESS_MASK | SKB_MONO_DELIVERY_TIME_MASK |
+ SKB_TAI_DELIVERY_TIME_MASK);
+ /*if all 3 bits are set jump 3 instructions and clear the register */
+ *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg,
+ TC_AT_INGRESS_MASK | SKB_MONO_DELIVERY_TIME_MASK |
+ SKB_TAI_DELIVERY_TIME_MASK, 4);
+ /*Now check Mono is set with ingress mask if so clear */
+ *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg,
+ TC_AT_INGRESS_MASK | SKB_MONO_DELIVERY_TIME_MASK, 3);
+ /*Now Check tai is set with ingress mask if so clear */
+ *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg,
+ TC_AT_INGRESS_MASK | SKB_TAI_DELIVERY_TIME_MASK, 2);
+ /*Now Check tai and mono are set if so clear */
+ *insn++ = BPF_JMP32_IMM(BPF_JEQ, tmp_reg,
+ SKB_MONO_DELIVERY_TIME_MASK |
+ SKB_TAI_DELIVERY_TIME_MASK, 1);
+ /* goto <store> */
+ *insn++ = BPF_JMP_A(2);
/* skb->tc_at_ingress && skb->tstamp_type:1,
* read 0 as the (rcv) timestamp.
*/
@@ -9456,9 +9484,11 @@ static struct bpf_insn *bpf_convert_tstamp_write(const struct bpf_prog *prog,
/* 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);
+ *insn++ = BPF_JMP_A(3);
/* <clear>: mono_delivery_time or (skb->tstamp_type:1) */
*insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, ~SKB_MONO_DELIVERY_TIME_MASK);
+ /* <clear>: tai delivery_time or (skb->tstamp_type:2) */
+ *insn++ = BPF_ALU32_IMM(BPF_AND, tmp_reg, ~SKB_TAI_DELIVERY_TIME_MASK);
*insn++ = BPF_STX_MEM(BPF_B, skb_reg, tmp_reg, SKB_BF_MONO_TC_OFFSET);
}
#endif
diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index f29349151203..91e80a3d411f 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1457,7 +1457,7 @@ struct sk_buff *__ip_make_skb(struct sock *sk,
skb->priority = (cork->tos != -1) ? cork->priority: READ_ONCE(sk->sk_priority);
skb->mark = cork->mark;
- skb->tstamp = cork->transmit_time;
+ skb_set_delivery_time(skb, cork->transmit_time, sk->sk_clockid);
/*
* Steal rt from cork.dst to avoid a pair of atomic_inc/atomic_dec
* on dst refcount
diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index dcb11f22cbf2..bbc46a40c8b6 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -360,7 +360,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
skb->protocol = htons(ETH_P_IP);
skb->priority = READ_ONCE(sk->sk_priority);
skb->mark = sockc->mark;
- skb->tstamp = sockc->transmit_time;
+ skb_set_delivery_time(skb, sockc->transmit_time, sk->sk_clockid);
skb_dst_set(skb, &rt->dst);
*rtp = NULL;
diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index a9e819115622..0b8193bdd98f 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1924,7 +1924,7 @@ struct sk_buff *__ip6_make_skb(struct sock *sk,
skb->priority = READ_ONCE(sk->sk_priority);
skb->mark = cork->base.mark;
- skb->tstamp = cork->base.transmit_time;
+ skb_set_delivery_time(skb, cork->base.transmit_time, sk->sk_clockid);
ip6_cork_steal_dst(skb, cork);
IP6_INC_STATS(net, rt->rt6i_idev, IPSTATS_MIB_OUTREQUESTS);
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 0d896ca7b589..625f3a917e50 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -621,7 +621,7 @@ static int rawv6_send_hdrinc(struct sock *sk, struct msghdr *msg, int length,
skb->protocol = htons(ETH_P_IPV6);
skb->priority = READ_ONCE(sk->sk_priority);
skb->mark = sockc->mark;
- skb->tstamp = sockc->transmit_time;
+ skb_set_delivery_time(skb, sockc->transmit_time, sk->sk_clockid);
skb_put(skb, length);
skb_reset_network_header(skb);
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 8c6d3fbb4ed8..356c96f23370 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2056,8 +2056,7 @@ static int packet_sendmsg_spkt(struct socket *sock, struct msghdr *msg,
skb->dev = dev;
skb->priority = READ_ONCE(sk->sk_priority);
skb->mark = READ_ONCE(sk->sk_mark);
- skb->tstamp = sockc.transmit_time;
-
+ skb_set_delivery_time(skb, sockc.transmit_time, sk->sk_clockid);
skb_setup_tx_timestamp(skb, sockc.tsflags);
if (unlikely(extra_len == 4))
@@ -2585,7 +2584,7 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
skb->dev = dev;
skb->priority = READ_ONCE(po->sk.sk_priority);
skb->mark = READ_ONCE(po->sk.sk_mark);
- skb->tstamp = sockc->transmit_time;
+ skb_set_delivery_time(skb, sockc->transmit_time, po->sk.sk_clockid);
skb_setup_tx_timestamp(skb, sockc->tsflags);
skb_zcopy_set_nouarg(skb, ph.raw);
@@ -3063,7 +3062,7 @@ static int packet_snd(struct socket *sock, struct msghdr *msg, size_t len)
skb->dev = dev;
skb->priority = READ_ONCE(sk->sk_priority);
skb->mark = sockc.mark;
- skb->tstamp = sockc.transmit_time;
+ skb_set_delivery_time(skb, sockc.transmit_time, sk->sk_clockid);
if (unlikely(extra_len == 4))
skb->no_fcs = 1;
diff --git a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
index 3b7c57fe55a5..9d0c33d7f52e 100644
--- a/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
+++ b/tools/testing/selftests/bpf/prog_tests/ctx_rewrite.c
@@ -69,15 +69,20 @@ static struct test_case test_cases[] = {
{
N(SCHED_CLS, struct __sk_buff, tstamp),
.read = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
- "w11 &= 3;"
- "if w11 != 0x3 goto pc+2;"
+ "w11 &= 7;"
+ "if w11 == 0x7 goto pc+4;"
+ "if w11 == 0x5 goto pc+3;"
+ "if w11 == 0x6 goto pc+2;"
+ "if w11 == 0x3 goto pc+1;"
+ "goto pc+2"
"$dst = 0;"
"goto pc+1;"
"$dst = *(u64 *)($ctx + sk_buff::tstamp);",
.write = "r11 = *(u8 *)($ctx + sk_buff::__mono_tc_offset);"
- "if w11 & 0x2 goto pc+1;"
- "goto pc+2;"
+ "if w11 & 0x4 goto pc+1;"
+ "goto pc+3;"
"w11 &= -2;"
+ "w11 &= -3;"
"*(u8 *)($ctx + sk_buff::__mono_tc_offset) = r11;"
"*(u64 *)($ctx + sk_buff::tstamp) = $src;",
},
--
2.25.1