From: =?UTF-8?q?Maciej=20=C5=BBenczykowski?= <maze@google.com>
Date: Sun, 26 Apr 2020 09:15:25 -0700
Subject: bpf: add bpf_ktime_get_boot_ns()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Patch-mainline: v5.8-rc1
Git-commit: 71d19214776e61b33da48f7c1b46e522c7f78221
References: bsc#1177028
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@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Gary Lin <glin@suse.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 | 14 ++++++++++++++
kernel/trace/bpf_trace.c | 2 ++
tools/include/uapi/linux/bpf.h | 13 ++++++++++++-
7 files changed, 44 insertions(+), 2 deletions(-)
--- a/drivers/media/rc/bpf-lirc.c
+++ b/drivers/media/rc/bpf-lirc.c
@@ -108,6 +108,8 @@ lirc_mode2_func_proto(enum bpf_func_id f
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:
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1509,6 +1509,7 @@ extern const struct bpf_func_proto bpf_g
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;
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -652,6 +652,8 @@ 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*.
*
@@ -3025,6 +3027,14 @@ union bpf_attr {
* * **-EOPNOTSUPP** Unsupported operation, for example a
* call from outside of TC ingress.
* * **-ESOCKTNOSUPPORT** Socket type not supported (reuseport).
+ *
+ * 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*.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -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
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -2156,6 +2156,7 @@ const struct bpf_func_proto bpf_get_pran
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;
--- a/kernel/bpf/helpers.c
+++ b/kernel/bpf/helpers.c
@@ -155,6 +155,18 @@ const struct bpf_func_proto bpf_ktime_ge
.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;
@@ -615,6 +627,8 @@ bpf_base_func_proto(enum bpf_func_id fun
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;
}
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -827,6 +827,8 @@ bpf_tracing_func_proto(enum bpf_func_id
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:
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -652,6 +652,8 @@ 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*.
*
@@ -3025,6 +3027,14 @@ union bpf_attr {
* * **-EOPNOTSUPP** Unsupported operation, for example a
* call from outside of TC ingress.
* * **-ESOCKTNOSUPPORT** Socket type not supported (reuseport).
+ *
+ * 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*.
*/
#define __BPF_FUNC_MAPPER(FN) \
FN(unspec), \
@@ -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