tools/bpf: add bpf_get_stack helper to tools headers

The tools header file bpf.h is synced with kernel uapi bpf.h.
The new helper is also added to bpf_helpers.h.

Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 40 insertions, 2 deletions

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index da77a9388947..1afb606a18b9 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -1767,6 +1767,40 @@ union bpf_attr {
  *              **CONFIG_XFRM** configuration option.
  *      Return
  *              0 on success, or a negative error in case of failure.
+ *
+ * int bpf_get_stack(struct pt_regs *regs, void *buf, u32 size, u64 flags)
+ *      Description
+ *              Return a user or a kernel stack in bpf program provided buffer.
+ *              To achieve this, the helper needs *ctx*, which is a pointer
+ *              to the context on which the tracing program is executed.
+ *              To store the stacktrace, the bpf program provides *buf* with
+ *              a nonnegative *size*.
+ *
+ *              The last argument, *flags*, holds the number of stack frames to
+ *              skip (from 0 to 255), masked with
+ *              **BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
+ *              the following flags:
+ *
+ *              **BPF_F_USER_STACK**
+ *                      Collect a user space stack instead of a kernel stack.
+ *              **BPF_F_USER_BUILD_ID**
+ *                      Collect buildid+offset instead of ips for user stack,
+ *                      only valid if **BPF_F_USER_STACK** is also specified.
+ *
+ *              **bpf_get_stack**\ () can collect up to
+ *              **PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
+ *              to sufficient large buffer size. Note that
+ *              this limit can be controlled with the **sysctl** program, and
+ *              that it should be manually increased in order to profile long
+ *              user stacks (such as stacks for Java programs). To do so, use:
+ *
+ *      ::
+ *
+ *              # sysctl kernel.perf_event_max_stack=<new value>
+ *
+ *      Return
+ *              a non-negative value equal to or less than size on success, or
+ *              a negative error in case of failure.
  */
 #define __BPF_FUNC_MAPPER(FN)           \
         FN(unspec),                     \
@@ -1835,7 +1869,8 @@ union bpf_attr {
         FN(msg_pull_data),              \
         FN(bind),                       \
         FN(xdp_adjust_tail),            \
-        FN(skb_get_xfrm_state),
+        FN(skb_get_xfrm_state),         \
+        FN(get_stack),
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper
  * function eBPF program intends to call
@@ -1869,11 +1904,14 @@ enum bpf_func_id {
 /* BPF_FUNC_skb_set_tunnel_key and BPF_FUNC_skb_get_tunnel_key flags. */
 #define BPF_F_TUNINFO_IPV6              (1ULL << 0)
 
-/* BPF_FUNC_get_stackid flags. */
+/* flags for both BPF_FUNC_get_stackid and BPF_FUNC_get_stack. */
 #define BPF_F_SKIP_FIELD_MASK           0xffULL
 #define BPF_F_USER_STACK                (1ULL << 8)
+/* flags used by BPF_FUNC_get_stackid only. */
 #define BPF_F_FAST_STACK_CMP            (1ULL << 9)
 #define BPF_F_REUSE_STACKID             (1ULL << 10)
+/* flags used by BPF_FUNC_get_stack only. */
+#define BPF_F_USER_BUILD_ID             (1ULL << 11)
 
 /* BPF_FUNC_skb_set_tunnel_key flags. */
 #define BPF_F_ZERO_CSUM_TX              (1ULL << 1)