bpf: add selftest for stackmap with BPF_F_STACK_BUILD_ID

test_stacktrace_build_id() is added. It accesses tracepoint urandom_read
with "dd" and "urandom_read" and gathers stack traces. Then it reads the
stack traces from the stackmap.

urandom_read is a statically link binary that reads from /dev/urandom.
test_stacktrace_build_id() calls readelf to read build ID of urandom_read
and compares it with build ID from the stackmap.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

1 files changed, 22 insertions, 0 deletions

diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h
index db6bdc375126..1944d0aee7e8 100644
--- a/tools/include/uapi/linux/bpf.h
+++ b/tools/include/uapi/linux/bpf.h
@@ -231,6 +231,28 @@ enum bpf_attach_type {
 #define BPF_F_RDONLY            (1U << 3)
 #define BPF_F_WRONLY            (1U << 4)
 
+/* Flag for stack_map, store build_id+offset instead of pointer */
+#define BPF_F_STACK_BUILD_ID    (1U << 5)
+
+enum bpf_stack_build_id_status {
+        /* user space need an empty entry to identify end of a trace */
+        BPF_STACK_BUILD_ID_EMPTY = 0,
+        /* with valid build_id and offset */
+        BPF_STACK_BUILD_ID_VALID = 1,
+        /* couldn't get build_id, fallback to ip */
+        BPF_STACK_BUILD_ID_IP = 2,
+};
+
+#define BPF_BUILD_ID_SIZE 20
+struct bpf_stack_build_id {
+        __s32           status;
+        unsigned char   build_id[BPF_BUILD_ID_SIZE];
+        union {
+                __u64   offset;
+                __u64   ip;
+        };
+};
+
 union bpf_attr {
         struct { /* anonymous struct used by BPF_MAP_CREATE command */
                 __u32   map_type;       /* one of enum bpf_map_type */