This helper can be used with bpf_iter__task to dump all /proc/*/stack to
a seq_file.

Signed-off-by: Song Liu <redacted>
---
 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);
+}
+
+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,

+       .btf_id         = bpf_get_task_stack_trace_btf_ids,
+};
+
 static const struct bpf_func_proto *
 raw_tp_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
 {

@@ -1521,6 +1538,10 @@ tracing_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
                return prog->expected_attach_type == BPF_TRACE_ITER ?
                       &bpf_seq_write_proto :
                       NULL;
+       case BPF_FUNC_get_task_stack_trace:
+               return prog->expected_attach_type == BPF_TRACE_ITER ?
+                       &bpf_get_task_stack_trace_proto :