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Commit 606274c5 authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by David S. Miller
Browse files

bpf: introduce bpf_get_current_task() helper 



over time there were multiple requests to access different data
structures and fields of task_struct current, so finally add
the helper to access 'current' as-is. Tracing bpf programs will do
the rest of walking the pointers via bpf_probe_read().
Note that current can be null and bpf program has to deal it with,
but even dumb passing null into bpf_probe_read() is still safe.

Suggested-by: default avatarBrendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d390238c

include/uapi/linux/bpf.h

+7 −0
Original line number Diff line number Diff line
@@ -357,6 +357,13 @@ enum bpf_func_id { 
	 */

	BPF_FUNC_get_hash_recalc,



	/**

	 * u64 bpf_get_current_task(void)

	 * Returns current task_struct

	 * Return: current

	 */

	BPF_FUNC_get_current_task,



	__BPF_FUNC_MAX_ID,

};

kernel/trace/bpf_trace.c

+13 −0
Original line number Diff line number Diff line
@@ -312,6 +312,17 @@ const struct bpf_func_proto *bpf_get_event_output_proto(void) 
	return &bpf_event_output_proto;

}



static u64 bpf_get_current_task(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)

{

	return (long) current;

}



static const struct bpf_func_proto bpf_get_current_task_proto = {

	.func		= bpf_get_current_task,

	.gpl_only	= true,

	.ret_type	= RET_INTEGER,

};



static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id)

{

	switch (func_id) {
@@ -329,6 +340,8 @@ static const struct bpf_func_proto *tracing_func_proto(enum bpf_func_id func_id) 
		return &bpf_tail_call_proto;

	case BPF_FUNC_get_current_pid_tgid:

		return &bpf_get_current_pid_tgid_proto;

	case BPF_FUNC_get_current_task:

		return &bpf_get_current_task_proto;

	case BPF_FUNC_get_current_uid_gid:

		return &bpf_get_current_uid_gid_proto;

	case BPF_FUNC_get_current_comm: