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: Brendan Gregg <brendan.d.gregg@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexei Starovoitov 2016-07-06 22:38:36 -07:00 committed by David S. Miller
parent d390238c4f
commit 606274c5ab
2 changed files with 20 additions and 0 deletions

View File

@ -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,
};

View File

@ -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: