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Diffstat (limited to 'test/syscalls/linux/kcov.cc')
| -rw-r--r-- | test/syscalls/linux/kcov.cc | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/test/syscalls/linux/kcov.cc b/test/syscalls/linux/kcov.cc new file mode 100644 index 000000000..6816c1fd0 --- /dev/null +++ b/test/syscalls/linux/kcov.cc @@ -0,0 +1,184 @@ +// 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 <atomic> + +#include "gtest/gtest.h" +#include "test/util/capability_util.h" +#include "test/util/file_descriptor.h" +#include "test/util/test_util.h" +#include "test/util/thread_util.h" + +namespace gvisor { +namespace testing { + +namespace { + +// For this set of tests to run, they 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>. + +constexpr char kcovPath[] = "/sys/kernel/debug/kcov"; +constexpr int kSize = 4096; +constexpr int KCOV_INIT_TRACE = 0x80086301; +constexpr int KCOV_ENABLE = 0x6364; +constexpr int KCOV_DISABLE = 0x6365; + +uint64_t* KcovMmap(int fd) { + return (uint64_t*)mmap(nullptr, kSize * sizeof(uint64_t), + PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); +} + +TEST(KcovTest, Kcov) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability((CAP_DAC_OVERRIDE)))); + + int fd; + ASSERT_THAT(fd = open(kcovPath, O_RDWR), + AnyOf(SyscallSucceeds(), SyscallFailsWithErrno(ENOENT))); + // Kcov not available. + SKIP_IF(errno == ENOENT); + auto fd_closer = Cleanup([fd]() { close(fd); }); + + ASSERT_THAT(ioctl(fd, KCOV_INIT_TRACE, kSize), SyscallSucceeds()); + uint64_t* area = KcovMmap(fd); + 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); + } + + ASSERT_THAT(ioctl(fd, KCOV_DISABLE, 0), SyscallSucceeds()); +} + +TEST(KcovTest, PrematureMmap) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability((CAP_DAC_OVERRIDE)))); + + int fd; + ASSERT_THAT(fd = open(kcovPath, O_RDWR), + AnyOf(SyscallSucceeds(), SyscallFailsWithErrno(ENOENT))); + // Kcov not available. + SKIP_IF(errno == ENOENT); + auto fd_closer = Cleanup([fd]() { close(fd); }); + + // Cannot mmap before KCOV_INIT_TRACE. + uint64_t* area = KcovMmap(fd); + ASSERT_TRUE(area == MAP_FAILED); +} + +// Tests that multiple kcov fds can be used simultaneously. +TEST(KcovTest, MultipleFds) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability((CAP_DAC_OVERRIDE)))); + + int fd1; + ASSERT_THAT(fd1 = open(kcovPath, O_RDWR), + AnyOf(SyscallSucceeds(), SyscallFailsWithErrno(ENOENT))); + // Kcov not available. + SKIP_IF(errno == ENOENT); + + int fd2; + ASSERT_THAT(fd2 = open(kcovPath, O_RDWR), SyscallSucceeds()); + auto fd_closer = Cleanup([fd1, fd2]() { + close(fd1); + close(fd2); + }); + + auto t1 = ScopedThread([&] { + ASSERT_THAT(ioctl(fd1, KCOV_INIT_TRACE, kSize), SyscallSucceeds()); + uint64_t* area = KcovMmap(fd1); + ASSERT_TRUE(area != MAP_FAILED); + ASSERT_THAT(ioctl(fd1, KCOV_ENABLE, 0), SyscallSucceeds()); + }); + + ASSERT_THAT(ioctl(fd2, KCOV_INIT_TRACE, kSize), SyscallSucceeds()); + uint64_t* area = KcovMmap(fd2); + ASSERT_TRUE(area != MAP_FAILED); + ASSERT_THAT(ioctl(fd2, KCOV_ENABLE, 0), SyscallSucceeds()); +} + +// Tests behavior for two threads trying to use the same kcov fd. +TEST(KcovTest, MultipleThreads) { + SKIP_IF(!ASSERT_NO_ERRNO_AND_VALUE(HaveCapability((CAP_DAC_OVERRIDE)))); + + int fd; + ASSERT_THAT(fd = open(kcovPath, O_RDWR), + AnyOf(SyscallSucceeds(), SyscallFailsWithErrno(ENOENT))); + // Kcov not available. + SKIP_IF(errno == ENOENT); + auto fd_closer = Cleanup([fd]() { close(fd); }); + + // Test the behavior of multiple threads trying to use the same kcov fd + // simultaneously. + std::atomic<bool> t1_enabled(false), t1_disabled(false), t2_failed(false), + t2_exited(false); + auto t1 = ScopedThread([&] { + ASSERT_THAT(ioctl(fd, KCOV_INIT_TRACE, kSize), SyscallSucceeds()); + uint64_t* area = KcovMmap(fd); + ASSERT_TRUE(area != MAP_FAILED); + ASSERT_THAT(ioctl(fd, KCOV_ENABLE, 0), SyscallSucceeds()); + t1_enabled = true; + + // After t2 has made sure that enabling kcov again fails, disable it. + while (!t2_failed) { + sched_yield(); + } + ASSERT_THAT(ioctl(fd, KCOV_DISABLE, 0), SyscallSucceeds()); + t1_disabled = true; + + // Wait for t2 to enable kcov and then exit, after which we should be able + // to enable kcov again, without needing to set up a new memory mapping. + while (!t2_exited) { + sched_yield(); + } + ASSERT_THAT(ioctl(fd, KCOV_ENABLE, 0), SyscallSucceeds()); + }); + + auto t2 = ScopedThread([&] { + // Wait for t1 to enable kcov, and make sure that enabling kcov again fails. + while (!t1_enabled) { + sched_yield(); + } + ASSERT_THAT(ioctl(fd, KCOV_ENABLE, 0), SyscallFailsWithErrno(EINVAL)); + t2_failed = true; + + // Wait for t1 to disable kcov, after which using fd should now succeed. + while (!t1_disabled) { + sched_yield(); + } + uint64_t* area = KcovMmap(fd); + ASSERT_TRUE(area != MAP_FAILED); + ASSERT_THAT(ioctl(fd, KCOV_ENABLE, 0), SyscallSucceeds()); + }); + + t2.Join(); + t2_exited = true; +} + +} // namespace + +} // namespace testing +} // namespace gvisor |