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>

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index da77a938894760bc121f40a6ad3afb29833335ee..1afb606a18b991f2e7335569753ef7f93d664f14 100644 (file)
--- 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)

diff --git a/tools/testing/selftests/bpf/bpf_helpers.h b/tools/testing/selftests/bpf/bpf_helpers.h
index 69d7b918e66ab10b763fb759cff812520a8e7457..265f8e0e8ada8aa44587903b88cab2119bed4375 100644 (file)
--- a/tools/testing/selftests/bpf/bpf_helpers.h
+++ b/tools/testing/selftests/bpf/bpf_helpers.h
@@ -101,6 +101,8 @@ static int (*bpf_xdp_adjust_tail)(void *ctx, int offset) =
 static int (*bpf_skb_get_xfrm_state)(void *ctx, int index, void *state,
                                     int size, int flags) =
        (void *) BPF_FUNC_skb_get_xfrm_state;
+static int (*bpf_get_stack)(void *ctx, void *buf, int size, int flags) =
+       (void *) BPF_FUNC_get_stack;
 
 /* llvm builtin functions that eBPF C program may use to
  * emit BPF_LD_ABS and BPF_LD_IND instructions