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 <songliubrav...@fb.com>
---
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.
+}
+
+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?
+ .btf_id = bpf_get_task_stack_trace_btf_ids,
+};
+
