2019-04-29 21:25:05 +00:00
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// Copyright 2018 The gVisor Authors.
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2018-12-10 22:41:40 +00:00
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <fcntl.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <string>
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#include "gmock/gmock.h"
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#include "gtest/gtest.h"
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#include "test/util/file_descriptor.h"
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#include "test/util/logging.h"
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#include "test/util/memory_util.h"
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2019-06-20 19:54:40 +00:00
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#include "test/util/multiprocess_util.h"
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2018-12-10 22:41:40 +00:00
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#include "test/util/posix_error.h"
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#include "test/util/temp_path.h"
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#include "test/util/test_util.h"
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namespace gvisor {
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namespace testing {
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namespace {
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void ExpectAllMappingBytes(Mapping const& m, char c) {
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auto const v = m.view();
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for (size_t i = 0; i < kPageSize; i++) {
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ASSERT_EQ(v[i], c) << "at offset " << i;
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}
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}
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// Equivalent to ExpectAllMappingBytes but async-signal-safe and with less
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// helpful failure messages.
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void CheckAllMappingBytes(Mapping const& m, char c) {
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auto const v = m.view();
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for (size_t i = 0; i < kPageSize; i++) {
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TEST_CHECK_MSG(v[i] == c, "mapping contains wrong value");
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}
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}
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TEST(MadviseDontneedTest, ZerosPrivateAnonPage) {
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auto m = ASSERT_NO_ERRNO_AND_VALUE(
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MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE));
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ExpectAllMappingBytes(m, 0);
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memset(m.ptr(), 1, m.len());
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ExpectAllMappingBytes(m, 1);
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ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
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ExpectAllMappingBytes(m, 0);
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}
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TEST(MadviseDontneedTest, ZerosCOWAnonPageInCallerOnly) {
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auto m = ASSERT_NO_ERRNO_AND_VALUE(
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MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE));
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ExpectAllMappingBytes(m, 0);
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memset(m.ptr(), 2, m.len());
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ExpectAllMappingBytes(m, 2);
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// Do madvise in a child process.
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pid_t pid = fork();
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CheckAllMappingBytes(m, 2);
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if (pid == 0) {
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TEST_PCHECK(madvise(m.ptr(), m.len(), MADV_DONTNEED) == 0);
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CheckAllMappingBytes(m, 0);
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_exit(0);
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}
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ASSERT_THAT(pid, SyscallSucceeds());
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int status = 0;
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ASSERT_THAT(waitpid(-1, &status, 0), SyscallSucceedsWithValue(pid));
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EXPECT_TRUE(WIFEXITED(status));
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EXPECT_EQ(WEXITSTATUS(status), 0);
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// The child's madvise should not have affected the parent.
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ExpectAllMappingBytes(m, 2);
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}
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TEST(MadviseDontneedTest, DoesNotModifySharedAnonPage) {
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auto m = ASSERT_NO_ERRNO_AND_VALUE(
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MmapAnon(kPageSize, PROT_READ | PROT_WRITE, MAP_SHARED));
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ExpectAllMappingBytes(m, 0);
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memset(m.ptr(), 3, m.len());
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ExpectAllMappingBytes(m, 3);
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ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
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ExpectAllMappingBytes(m, 3);
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}
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TEST(MadviseDontneedTest, CleansPrivateFilePage) {
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TempPath f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
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/* parent = */ GetAbsoluteTestTmpdir(),
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/* content = */ std::string(kPageSize, 4), TempPath::kDefaultFileMode));
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FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDWR));
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Mapping m = ASSERT_NO_ERRNO_AND_VALUE(Mmap(
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nullptr, kPageSize, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd.get(), 0));
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ExpectAllMappingBytes(m, 4);
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memset(m.ptr(), 5, m.len());
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ExpectAllMappingBytes(m, 5);
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ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
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ExpectAllMappingBytes(m, 4);
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}
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TEST(MadviseDontneedTest, DoesNotModifySharedFilePage) {
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TempPath f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
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/* parent = */ GetAbsoluteTestTmpdir(),
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/* content = */ std::string(kPageSize, 6), TempPath::kDefaultFileMode));
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FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDWR));
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Mapping m = ASSERT_NO_ERRNO_AND_VALUE(Mmap(
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nullptr, kPageSize, PROT_READ | PROT_WRITE, MAP_SHARED, fd.get(), 0));
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ExpectAllMappingBytes(m, 6);
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memset(m.ptr(), 7, m.len());
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ExpectAllMappingBytes(m, 7);
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ASSERT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
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ExpectAllMappingBytes(m, 7);
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}
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TEST(MadviseDontneedTest, IgnoresPermissions) {
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auto m =
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ASSERT_NO_ERRNO_AND_VALUE(MmapAnon(kPageSize, PROT_NONE, MAP_PRIVATE));
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EXPECT_THAT(madvise(m.ptr(), m.len(), MADV_DONTNEED), SyscallSucceeds());
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}
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2019-06-20 19:54:40 +00:00
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TEST(MadviseDontforkTest, AddressLength) {
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auto m =
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ASSERT_NO_ERRNO_AND_VALUE(MmapAnon(kPageSize, PROT_NONE, MAP_PRIVATE));
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char *addr = static_cast<char *>(m.ptr());
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// Address must be page aligned.
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EXPECT_THAT(madvise(addr + 1, kPageSize, MADV_DONTFORK),
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SyscallFailsWithErrno(EINVAL));
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// Zero length madvise always succeeds.
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EXPECT_THAT(madvise(addr, 0, MADV_DONTFORK), SyscallSucceeds());
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// Length must not roll over after rounding up.
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size_t badlen = std::numeric_limits<std::size_t>::max() - (kPageSize / 2);
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EXPECT_THAT(madvise(0, badlen, MADV_DONTFORK), SyscallFailsWithErrno(EINVAL));
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// Length need not be page aligned - it is implicitly rounded up.
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EXPECT_THAT(madvise(addr, 1, MADV_DONTFORK), SyscallSucceeds());
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EXPECT_THAT(madvise(addr, kPageSize, MADV_DONTFORK), SyscallSucceeds());
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}
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TEST(MadviseDontforkTest, DontforkShared) {
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// Mmap two shared file-backed pages and MADV_DONTFORK the second page.
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TempPath f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileWith(
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/* parent = */ GetAbsoluteTestTmpdir(),
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2019-06-28 22:28:24 +00:00
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/* content = */ std::string(kPageSize * 2, 2),
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TempPath::kDefaultFileMode));
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2019-06-20 19:54:40 +00:00
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FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDWR));
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Mapping m = ASSERT_NO_ERRNO_AND_VALUE(Mmap(
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nullptr, kPageSize * 2, PROT_READ | PROT_WRITE, MAP_SHARED, fd.get(), 0));
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const Mapping ms1 = Mapping(reinterpret_cast<void *>(m.addr()), kPageSize);
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const Mapping ms2 =
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Mapping(reinterpret_cast<void *>(m.addr() + kPageSize), kPageSize);
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m.release();
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ASSERT_THAT(madvise(ms2.ptr(), kPageSize, MADV_DONTFORK), SyscallSucceeds());
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const auto rest = [&] {
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// First page is mapped in child and modifications are visible to parent
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// via the shared mapping.
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TEST_CHECK(IsMapped(ms1.addr()));
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ExpectAllMappingBytes(ms1, 2);
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memset(ms1.ptr(), 1, kPageSize);
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ExpectAllMappingBytes(ms1, 1);
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// Second page must not be mapped in child.
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TEST_CHECK(!IsMapped(ms2.addr()));
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};
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EXPECT_THAT(InForkedProcess(rest), IsPosixErrorOkAndHolds(0));
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ExpectAllMappingBytes(ms1, 1); // page contents modified by child.
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ExpectAllMappingBytes(ms2, 2); // page contents unchanged.
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}
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TEST(MadviseDontforkTest, DontforkAnonPrivate) {
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// Mmap three anonymous pages and MADV_DONTFORK the middle page.
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Mapping m = ASSERT_NO_ERRNO_AND_VALUE(
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MmapAnon(kPageSize * 3, PROT_READ | PROT_WRITE, MAP_PRIVATE));
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const Mapping mp1 = Mapping(reinterpret_cast<void *>(m.addr()), kPageSize);
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const Mapping mp2 =
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Mapping(reinterpret_cast<void *>(m.addr() + kPageSize), kPageSize);
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const Mapping mp3 =
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Mapping(reinterpret_cast<void *>(m.addr() + 2 * kPageSize), kPageSize);
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m.release();
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ASSERT_THAT(madvise(mp2.ptr(), kPageSize, MADV_DONTFORK), SyscallSucceeds());
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// Verify that all pages are zeroed and memset the first, second and third
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// pages to 1, 2, and 3 respectively.
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ExpectAllMappingBytes(mp1, 0);
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memset(mp1.ptr(), 1, kPageSize);
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ExpectAllMappingBytes(mp2, 0);
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memset(mp2.ptr(), 2, kPageSize);
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ExpectAllMappingBytes(mp3, 0);
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memset(mp3.ptr(), 3, kPageSize);
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const auto rest = [&] {
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// Verify first page is mapped, verify its contents and then modify the
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// page. The mapping is private so the modifications are not visible to
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// the parent.
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TEST_CHECK(IsMapped(mp1.addr()));
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ExpectAllMappingBytes(mp1, 1);
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memset(mp1.ptr(), 11, kPageSize);
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ExpectAllMappingBytes(mp1, 11);
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// Verify second page is not mapped.
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TEST_CHECK(!IsMapped(mp2.addr()));
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// Verify third page is mapped, verify its contents and then modify the
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// page. The mapping is private so the modifications are not visible to
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// the parent.
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TEST_CHECK(IsMapped(mp3.addr()));
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ExpectAllMappingBytes(mp3, 3);
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memset(mp3.ptr(), 13, kPageSize);
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ExpectAllMappingBytes(mp3, 13);
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};
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EXPECT_THAT(InForkedProcess(rest), IsPosixErrorOkAndHolds(0));
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// The fork and COW by child should not affect the parent mappings.
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ExpectAllMappingBytes(mp1, 1);
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ExpectAllMappingBytes(mp2, 2);
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ExpectAllMappingBytes(mp3, 3);
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}
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2018-12-10 22:41:40 +00:00
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} // namespace
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} // namespace testing
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} // namespace gvisor
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