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/testing/selftests/bpf/urandom_read.c b/tools/testing/selftests/bpf/urandom_read.c
new file mode 100644
index 000000000000..4acfdebf36fa
--- /dev/null
+++ b/tools/testing/selftests/bpf/urandom_read.c
@@ -0,0 +1,22 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <stdlib.h>
+
+#define BUF_SIZE 256
+int main(void)
+{
+	int fd = open("/dev/urandom", O_RDONLY);
+	int i;
+	char buf[BUF_SIZE];
+
+	if (fd < 0)
+		return 1;
+	for (i = 0; i < 4; ++i)
+		read(fd, buf, BUF_SIZE);
+
+	close(fd);
+	return 0;
+}