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| author | Alexei Starovoitov <ast@fb.com> | 2016-07-06 22:38:36 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-07-09 00:00:16 -0400 |
| commit | 606274c5abd8e245add01bc7145a8cbb92b69ba8 (patch) | |
| tree | 762718058c0cf327284f07fa6c1eb2410ee3e0b7 | |
| parent | d390238c4fba7c87a3bcd859ce3373c864eb7b02 (diff) | |
| download | linux-606274c5abd8e245add01bc7145a8cbb92b69ba8.tar.gz linux-606274c5abd8e245add01bc7145a8cbb92b69ba8.tar.bz2 linux-606274c5abd8e245add01bc7145a8cbb92b69ba8.zip | |
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>
| -rw-r--r-- | include/uapi/linux/bpf.h | 7 | ||||
| -rw-r--r-- | kernel/trace/bpf_trace.c | 13 |
2 files changed, 20 insertions, 0 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index c14ca1cd6297..262a7e883b19 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -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, }; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index 19c5b4a5c3eb..094c716154ed 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -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: |