Commit 71d19214 authored by Maciej Żenczykowski's avatar Maciej Żenczykowski Committed by Alexei Starovoitov
Browse files

bpf: add bpf_ktime_get_boot_ns() 



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: default avatarMaciej Żenczykowski <maze@google.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 0a05861f

drivers/media/rc/bpf-lirc.c

+2 −0
Original line number Diff line number Diff line
@@ -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:

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -1509,6 +1509,7 @@ 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;

include/uapi/linux/bpf.h

+12 −1
Original line number Diff line number Diff line
@@ -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

kernel/bpf/core.c

+1 −0
Original line number Diff line number Diff line
@@ -2156,6 +2156,7 @@ 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;

kernel/bpf/helpers.c

+14 −0
Original line number Diff line number Diff line
@@ -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;
@@ -615,6 +627,8 @@ 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;

	}

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