Christopher Ferris | e328673 | 2017-12-07 17:41:18 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2017 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | #include <errno.h> |
| 18 | #include <signal.h> |
| 19 | #include <stdint.h> |
| 20 | #include <stdio.h> |
| 21 | #include <stdlib.h> |
| 22 | #include <string.h> |
| 23 | #include <sys/mman.h> |
| 24 | #include <sys/ptrace.h> |
| 25 | #include <sys/types.h> |
| 26 | #include <sys/uio.h> |
| 27 | #include <sys/wait.h> |
| 28 | #include <unistd.h> |
| 29 | |
| 30 | #include <memory> |
| 31 | #include <vector> |
| 32 | |
| 33 | #include <benchmark/benchmark.h> |
| 34 | |
| 35 | #include <backtrace/Backtrace.h> |
| 36 | |
| 37 | #define AT_COMMON_SIZES Arg(1)->Arg(4)->Arg(8)->Arg(16)->Arg(100)->Arg(200)->Arg(500)->Arg(1024) |
| 38 | |
| 39 | static void Attach(pid_t pid) { |
| 40 | if (ptrace(PTRACE_ATTACH, pid, 0, 0) == -1) { |
| 41 | perror("Failed to attach"); |
| 42 | abort(); |
| 43 | } |
| 44 | |
| 45 | siginfo_t si; |
| 46 | // Wait for up to 5 seconds. |
| 47 | for (size_t i = 0; i < 5000; i++) { |
| 48 | if (ptrace(PTRACE_GETSIGINFO, pid, 0, &si) == 0) { |
| 49 | return; |
| 50 | } |
| 51 | usleep(1000); |
| 52 | } |
| 53 | printf("Remote process failed to stop in five seconds.\n"); |
| 54 | abort(); |
| 55 | } |
| 56 | |
| 57 | class ScopedPidReaper { |
| 58 | public: |
| 59 | ScopedPidReaper(pid_t pid) : pid_(pid) {} |
| 60 | ~ScopedPidReaper() { |
| 61 | kill(pid_, SIGKILL); |
| 62 | waitpid(pid_, nullptr, 0); |
| 63 | } |
| 64 | |
| 65 | private: |
| 66 | pid_t pid_; |
| 67 | }; |
| 68 | |
| 69 | static size_t ProcessVmRead(pid_t pid, uint64_t remote_src, void* dst, size_t len) { |
| 70 | struct iovec dst_iov = { |
| 71 | .iov_base = dst, .iov_len = len, |
| 72 | }; |
| 73 | |
| 74 | struct iovec src_iov = { |
| 75 | .iov_base = reinterpret_cast<void*>(remote_src), .iov_len = len, |
| 76 | }; |
| 77 | |
| 78 | ssize_t rc = process_vm_readv(pid, &dst_iov, 1, &src_iov, 1, 0); |
| 79 | return rc == -1 ? 0 : rc; |
| 80 | } |
| 81 | |
| 82 | static bool PtraceReadLong(pid_t pid, uint64_t addr, long* value) { |
| 83 | // ptrace() returns -1 and sets errno when the operation fails. |
| 84 | // To disambiguate -1 from a valid result, we clear errno beforehand. |
| 85 | errno = 0; |
| 86 | *value = ptrace(PTRACE_PEEKTEXT, pid, reinterpret_cast<void*>(addr), nullptr); |
| 87 | if (*value == -1 && errno) { |
| 88 | return false; |
| 89 | } |
| 90 | return true; |
| 91 | } |
| 92 | |
| 93 | static size_t PtraceRead(pid_t pid, uint64_t addr, void* dst, size_t bytes) { |
| 94 | size_t bytes_read = 0; |
| 95 | long data; |
| 96 | for (size_t i = 0; i < bytes / sizeof(long); i++) { |
| 97 | if (!PtraceReadLong(pid, addr, &data)) { |
| 98 | return bytes_read; |
| 99 | } |
| 100 | memcpy(dst, &data, sizeof(long)); |
| 101 | dst = reinterpret_cast<void*>(reinterpret_cast<uintptr_t>(dst) + sizeof(long)); |
| 102 | addr += sizeof(long); |
| 103 | bytes_read += sizeof(long); |
| 104 | } |
| 105 | |
| 106 | size_t left_over = bytes & (sizeof(long) - 1); |
| 107 | if (left_over) { |
| 108 | if (!PtraceReadLong(pid, addr, &data)) { |
| 109 | return bytes_read; |
| 110 | } |
| 111 | memcpy(dst, &data, left_over); |
| 112 | bytes_read += left_over; |
| 113 | } |
| 114 | return bytes_read; |
| 115 | } |
| 116 | |
| 117 | static void CreateRemoteProcess(size_t size, void** map, pid_t* pid) { |
| 118 | *map = mmap(nullptr, size, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); |
| 119 | if (*map == MAP_FAILED) { |
| 120 | perror("Can't allocate memory"); |
| 121 | abort(); |
| 122 | } |
| 123 | memset(*map, 0xaa, size); |
| 124 | |
| 125 | if ((*pid = fork()) == 0) { |
| 126 | for (volatile int i = 0;; i++) |
| 127 | ; |
| 128 | exit(1); |
| 129 | } |
| 130 | if (*pid < 0) { |
| 131 | perror("Failed to fork"); |
| 132 | abort(); |
| 133 | } |
| 134 | Attach(*pid); |
| 135 | // Don't need this map in the current process any more. |
| 136 | munmap(*map, size); |
| 137 | } |
| 138 | |
| 139 | static void BM_read_with_ptrace(benchmark::State& state) { |
| 140 | void* map; |
| 141 | pid_t pid; |
| 142 | CreateRemoteProcess(state.range(0), &map, &pid); |
| 143 | ScopedPidReaper reap(pid); |
| 144 | |
| 145 | std::vector<uint8_t> read_buffer(state.range(0)); |
| 146 | uint64_t addr = reinterpret_cast<uint64_t>(map); |
| 147 | while (state.KeepRunning()) { |
| 148 | if (PtraceRead(pid, addr, read_buffer.data(), read_buffer.size()) != read_buffer.size()) { |
| 149 | printf("Unexpected bad read.\n"); |
| 150 | abort(); |
| 151 | } |
| 152 | } |
| 153 | ptrace(PTRACE_DETACH, pid, 0, 0); |
| 154 | } |
| 155 | BENCHMARK(BM_read_with_ptrace)->AT_COMMON_SIZES; |
| 156 | |
| 157 | static void BM_read_with_process_vm_read(benchmark::State& state) { |
| 158 | void* map; |
| 159 | pid_t pid; |
| 160 | CreateRemoteProcess(state.range(0), &map, &pid); |
| 161 | ScopedPidReaper reap(pid); |
| 162 | |
| 163 | std::vector<uint8_t> read_buffer(state.range(0)); |
| 164 | uint64_t addr = reinterpret_cast<uint64_t>(map); |
| 165 | while (state.KeepRunning()) { |
| 166 | if (ProcessVmRead(pid, addr, read_buffer.data(), read_buffer.size()) != read_buffer.size()) { |
| 167 | printf("Unexpected bad read.\n"); |
| 168 | abort(); |
| 169 | } |
| 170 | } |
| 171 | ptrace(PTRACE_DETACH, pid, 0, 0); |
| 172 | } |
| 173 | BENCHMARK(BM_read_with_process_vm_read)->AT_COMMON_SIZES; |
| 174 | |
| 175 | static void BM_read_with_backtrace_object(benchmark::State& state) { |
| 176 | void* map; |
| 177 | pid_t pid; |
| 178 | CreateRemoteProcess(state.range(0), &map, &pid); |
| 179 | ScopedPidReaper reap(pid); |
| 180 | |
| 181 | std::unique_ptr<Backtrace> backtrace(Backtrace::Create(pid, BACKTRACE_CURRENT_THREAD)); |
| 182 | if (backtrace.get() == nullptr) { |
| 183 | printf("Failed to create backtrace.\n"); |
| 184 | abort(); |
| 185 | } |
| 186 | |
| 187 | uint64_t addr = reinterpret_cast<uint64_t>(map); |
| 188 | std::vector<uint8_t> read_buffer(state.range(0)); |
| 189 | while (state.KeepRunning()) { |
| 190 | if (backtrace->Read(addr, read_buffer.data(), read_buffer.size()) != read_buffer.size()) { |
| 191 | printf("Unexpected bad read.\n"); |
| 192 | abort(); |
| 193 | } |
| 194 | } |
| 195 | ptrace(PTRACE_DETACH, pid, 0, 0); |
| 196 | } |
| 197 | BENCHMARK(BM_read_with_backtrace_object)->AT_COMMON_SIZES; |