2 files changed, 84 insertions, 0 deletions
diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index ed0b6ecf4..5a323d331 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -1068,6 +1068,20 @@ cc_binary(
 )
 
 cc_binary(
+    name = "kcov_test",
+    testonly = 1,
+    srcs = ["kcov.cc"],
+    linkstatic = 1,
+    deps = [
+        "//test/util:capability_util",
+        "//test/util:file_descriptor",
+        gtest,
+        "//test/util:test_main",
+        "//test/util:test_util",
+    ],
+)
+
+cc_binary(
     name = "kill_test",
     testonly = 1,
     srcs = ["kill.cc"],
diff --git a/test/syscalls/linux/kcov.cc b/test/syscalls/linux/kcov.cc
new file mode 100644
index 000000000..f3c30444e
--- /dev/null
+++ b/test/syscalls/linux/kcov.cc
@@ -0,0 +1,70 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <sys/errno.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+
+#include "gtest/gtest.h"
+#include "test/util/capability_util.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+// For this test to work properly, it must be run with coverage enabled. On
+// native Linux, this involves compiling the kernel with kcov enabled. For
+// gVisor, we need to enable the Go coverage tool, e.g.
+// bazel test --collect_coverage_data --instrumentation_filter=//pkg/... <test>.
+TEST(KcovTest, Kcov) {
+  SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability((CAP_DAC_OVERRIDE))));
+
+  constexpr int kSize = 4096;
+  constexpr int KCOV_INIT_TRACE = 0x80086301;
+  constexpr int KCOV_ENABLE = 0x6364;
+
+  int fd;
+  ASSERT_THAT(fd = open("/sys/kernel/debug/kcov", O_RDWR),
+              AnyOf(SyscallSucceeds(), SyscallFailsWithErrno(ENOENT)));
+
+  // Kcov not enabled.
+  SKIP_IF(errno == ENOENT);
+
+  ASSERT_THAT(ioctl(fd, KCOV_INIT_TRACE, kSize), SyscallSucceeds());
+  uint64_t* area = (uint64_t*)mmap(nullptr, kSize * sizeof(uint64_t),
+                                   PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+
+  ASSERT_TRUE(area != MAP_FAILED);
+  ASSERT_THAT(ioctl(fd, KCOV_ENABLE, 0), SyscallSucceeds());
+
+  for (int i = 0; i < 10; i++) {
+    // Make some syscalls to generate coverage data.
+    ASSERT_THAT(ioctl(fd, KCOV_ENABLE, 0), SyscallFailsWithErrno(EINVAL));
+  }
+
+  uint64_t num_pcs = *(uint64_t*)(area);
+  EXPECT_GT(num_pcs, 0);
+  for (uint64_t i = 1; i <= num_pcs; i++) {
+    // Verify that PCs are in the standard kernel range.
+    EXPECT_GT(area[i], 0xffffffff7fffffffL);
+  }
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor