> On Jun 23, 2020, at 8:22 AM, Daniel Borkmann <daniel@xxxxxxxxxxxxx> wrote:
>
> On 6/23/20 9:08 AM, Song Liu wrote:
>> This helper can be used with bpf_iter__task to dump all /proc/*/stack to
>> a seq_file.
>> Signed-off-by: Song Liu <songliubraving@xxxxxx>
>> ---
>> include/uapi/linux/bpf.h | 10 +++++++++-
>> kernel/trace/bpf_trace.c | 21 +++++++++++++++++++++
>> scripts/bpf_helpers_doc.py | 2 ++
>> tools/include/uapi/linux/bpf.h | 10 +++++++++-
>> 4 files changed, 41 insertions(+), 2 deletions(-)
>> diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
>> index 19684813faaed..a30416b822fe3 100644
>> --- a/include/uapi/linux/bpf.h
>> +++ b/include/uapi/linux/bpf.h
>> @@ -3252,6 +3252,13 @@ union bpf_attr {
>> * case of **BPF_CSUM_LEVEL_QUERY**, the current skb->csum_level
>> * is returned or the error code -EACCES in case the skb is not
>> * subject to CHECKSUM_UNNECESSARY.
>> + *
>> + * int bpf_get_task_stack_trace(struct task_struct *task, void *entries, u32 size)
>> + * Description
>> + * Save a task stack trace into array *entries*. This is a wrapper
>> + * over stack_trace_save_tsk().
>> + * Return
>> + * Number of trace entries stored.
>> */
>> #define __BPF_FUNC_MAPPER(FN) \
>> FN(unspec), \
>> @@ -3389,7 +3396,8 @@ union bpf_attr {
>> FN(ringbuf_submit), \
>> FN(ringbuf_discard), \
>> FN(ringbuf_query), \
>> - FN(csum_level),
>> + FN(csum_level), \
>> + FN(get_task_stack_trace),
>> /* integer value in 'imm' field of BPF_CALL instruction selects which helper
>> * function eBPF program intends to call
>> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
>> index e729c9e587a07..2c13bcb5c2bce 100644
>> --- a/kernel/trace/bpf_trace.c
>> +++ b/kernel/trace/bpf_trace.c
>> @@ -1488,6 +1488,23 @@ static const struct bpf_func_proto bpf_get_stack_proto_raw_tp = {
>> .arg4_type = ARG_ANYTHING,
>> };
>> +BPF_CALL_3(bpf_get_task_stack_trace, struct task_struct *, task,
>> + void *, entries, u32, size)
>> +{
>> + return stack_trace_save_tsk(task, (unsigned long *)entries, size, 0);
>
> nit: cast not needed.
Will fix.
>
>> +}
>> +
>> +static int bpf_get_task_stack_trace_btf_ids[5];
>> +static const struct bpf_func_proto bpf_get_task_stack_trace_proto = {
>> + .func = bpf_get_task_stack_trace,
>> + .gpl_only = true,
>> + .ret_type = RET_INTEGER,
>> + .arg1_type = ARG_PTR_TO_BTF_ID,
>> + .arg2_type = ARG_PTR_TO_MEM,
>> + .arg3_type = ARG_CONST_SIZE_OR_ZERO,
>
> Is there a use-case to pass in entries == NULL + size == 0?
Not really. Will fix.
>
>> + .btf_id = bpf_get_task_stack_trace_btf_ids,
>> +};
>> +
