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Message-Id: <20200420202643.87198-1-zenczykowski@gmail.com>
Date: Mon, 20 Apr 2020 13:26:43 -0700
From: Maciej Żenczykowski <zenczykowski@...il.com>
To: Maciej Żenczykowski <maze@...gle.com>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>
Cc: Linux Network Development Mailing List <netdev@...r.kernel.org>,
linux-kernel@...r.kernel.org,
"David S . Miller" <davem@...emloft.net>
Subject: [PATCH] net: bpf: add bpf_ktime_get_boot_ns()
From: Maciej Żenczykowski <maze@...gle.com>
On a device like a cellphone which is constantly suspending
and resuming CLOCK_MONOTONIC is not particularly useful for
keeping track of or reacting to external network events.
Instead you want to use CLOCK_BOOTTIME.
Hence add bpf_ktime_get_boot_ns() as a mirror of bpf_ktime_get_ns()
based around CLOCK_BOOTTIME instead of CLOCK_MONOTONIC.
Signed-off-by: Maciej Żenczykowski <maze@...gle.com>
---
drivers/media/rc/bpf-lirc.c | 2 ++
include/linux/bpf.h | 1 +
include/uapi/linux/bpf.h | 13 ++++++++++++-
kernel/bpf/core.c | 1 +
kernel/bpf/helpers.c | 12 ++++++++++++
kernel/trace/bpf_trace.c | 2 ++
net/core/filter.c | 2 ++
tools/include/uapi/linux/bpf.h | 13 ++++++++++++-
8 files changed, 44 insertions(+), 2 deletions(-)
diff --git a/drivers/media/rc/bpf-lirc.c b/drivers/media/rc/bpf-lirc.c
index 0f3417d161b8..069c42f22a8c 100644
--- a/drivers/media/rc/bpf-lirc.c
+++ b/drivers/media/rc/bpf-lirc.c
@@ -103,6 +103,8 @@ lirc_mode2_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_map_peek_elem_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
+ case BPF_FUNC_ktime_get_boot_ns:
+ return &bpf_ktime_get_boot_ns_proto;
case BPF_FUNC_tail_call:
return &bpf_tail_call_proto;
case BPF_FUNC_get_prandom_u32:
diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index fd2b2322412d..65217c52474d 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1502,6 +1502,7 @@ extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
extern const struct bpf_func_proto bpf_get_numa_node_id_proto;
extern const struct bpf_func_proto bpf_tail_call_proto;
extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
+extern const struct bpf_func_proto bpf_ktime_get_boot_ns_proto;
extern const struct bpf_func_proto bpf_get_current_pid_tgid_proto;
extern const struct bpf_func_proto bpf_get_current_uid_gid_proto;
extern const struct bpf_func_proto bpf_get_current_comm_proto;
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 2e29a671d67e..2e13b094438d 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -652,6 +652,16 @@ union bpf_attr {
* u64 bpf_ktime_get_ns(void)
* Description
* Return the time elapsed since system boot, in nanoseconds.
+ * Does not include time the system was suspended.
+ * See: clock_gettime(CLOCK_MONOTONIC)
+ * Return
+ * Current *ktime*.
+ *
+ * u64 bpf_ktime_get_boot_ns(void)
+ * Description
+ * Return the time elapsed since system boot, in nanoseconds.
+ * Does include the time the system was suspended.
+ * See: clock_gettime(CLOCK_BOOTTIME)
* Return
* Current *ktime*.
*
@@ -3151,7 +3161,8 @@ union bpf_attr {
FN(xdp_output), \
FN(get_netns_cookie), \
FN(get_current_ancestor_cgroup_id), \
- FN(sk_assign),
+ FN(sk_assign), \
+ FN(ktime_get_boot_ns),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 916f5132a984..d87877cd99c1 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2151,6 +2151,7 @@ const struct bpf_func_proto bpf_get_prandom_u32_proto __weak;
const struct bpf_func_proto bpf_get_smp_processor_id_proto __weak;
const struct bpf_func_proto bpf_get_numa_node_id_proto __weak;
const struct bpf_func_proto bpf_ktime_get_ns_proto __weak;
+const struct bpf_func_proto bpf_ktime_get_boot_ns_proto __weak;
const struct bpf_func_proto bpf_get_current_pid_tgid_proto __weak;
const struct bpf_func_proto bpf_get_current_uid_gid_proto __weak;
diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c
index a5158a179e81..fb3ecc5dee7f 100644
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -155,6 +155,18 @@ const struct bpf_func_proto bpf_ktime_get_ns_proto = {
.ret_type = RET_INTEGER,
};
+BPF_CALL_0(bpf_ktime_get_boot_ns)
+{
+ /* NMI safe access to clock boottime */
+ return ktime_get_boot_fast_ns();
+}
+
+const struct bpf_func_proto bpf_ktime_get_boot_ns_proto = {
+ .func = bpf_ktime_get_boot_ns,
+ .gpl_only = false,
+ .ret_type = RET_INTEGER,
+};
+
BPF_CALL_0(bpf_get_current_pid_tgid)
{
struct task_struct *task = current;
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index ca1796747a77..e875c95d3ced 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -797,6 +797,8 @@ bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
return &bpf_map_peek_elem_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
+ case BPF_FUNC_ktime_get_boot_ns:
+ return &bpf_ktime_get_boot_ns_proto;
case BPF_FUNC_tail_call:
return &bpf_tail_call_proto;
case BPF_FUNC_get_current_pid_tgid:
diff --git a/net/core/filter.c b/net/core/filter.c
index 755867867e57..ec567d1e6fb9 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -6009,6 +6009,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
return &bpf_tail_call_proto;
case BPF_FUNC_ktime_get_ns:
return &bpf_ktime_get_ns_proto;
+ case BPF_FUNC_ktime_get_boot_ns:
+ return &bpf_ktime_get_boot_ns_proto;
default:
break;
}
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index 2e29a671d67e..2e13b094438d 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -652,6 +652,16 @@ union bpf_attr {
* u64 bpf_ktime_get_ns(void)
* Description
* Return the time elapsed since system boot, in nanoseconds.
+ * Does not include time the system was suspended.
+ * See: clock_gettime(CLOCK_MONOTONIC)
+ * Return
+ * Current *ktime*.
+ *
+ * u64 bpf_ktime_get_boot_ns(void)
+ * Description
+ * Return the time elapsed since system boot, in nanoseconds.
+ * Does include the time the system was suspended.
+ * See: clock_gettime(CLOCK_BOOTTIME)
* Return
* Current *ktime*.
*
@@ -3151,7 +3161,8 @@ union bpf_attr {
FN(xdp_output), \
FN(get_netns_cookie), \
FN(get_current_ancestor_cgroup_id), \
- FN(sk_assign),
+ FN(sk_assign), \
+ FN(ktime_get_boot_ns),
/* integer value in 'imm' field of BPF_CALL instruction selects which helper
* function eBPF program intends to call
--
2.26.1.301.g55bc3eb7cb9-goog
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