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// 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
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